back to article Phased out: IT architect plugs hole in clean-freak admin's wiring design

Welcome again to On-Call, El Reg's weekly column that offers readers the chance to vent about their co-workers' ineptitude. This week, meet "Oscar", who tells us about the time he had to clean up after an overly tidy sysadmin. At the time, he was working as a consultant and IT architect for a government customer that was …

  1. Rich 11 Silver badge

    Plot twist? What plot twist?

    "I looked at the installation and realised the sysadmin had meticulously wired all the servers to the same phase," Oscar said.

    I'm going to go out on a limb here and say that we all saw this coming.

    1. defiler

      Re: Plot twist? What plot twist?

      Yarp. Still, whilst working in an old building we were proudly told by the beaming electrician who'd just finished a rewiring job that the three phases had been nicely isolated so that one carried the lights, the second all of the sockets, and the third the high-drain devices such as aircon, the kitchen appliances and the server cabinets...

      Those UPSs took a beating smoothing out that load.

      1. Neil Barnes Silver badge

        Re: Plot twist? What plot twist?

        Built a radio studio in a flat in Bangladesh once. Turned out that the habit there was (is?) to distribute the three phases coming into the building by lights, sockets, and aircon... but instead of rotating between flats they rotated between rooms to spread the load. Made for some interesting hunting down of earth loop hum.

        (as an aside, they would frequently black out one phase - not always the same one - to save power, which also made things interesting.)

        1. Richard 12 Silver badge

          Re: Plot twist? What plot twist?

          That makes no sense. Blacking out a single phase in a TPNE system increases the load on the neutral and means you either need a much bigger wire or you destroy equipment. Up to and including the entire building.

          1. John Miles

            Re: That makes no sense.

            since when has sense or reality ever got in the way of some manager's idea to save monry

          2. Anonymous Coward
            Anonymous Coward

            Re: Plot twist? What plot twist?

            In many parts of the world, Bangladesh included, the concept of make-it-work trumps adherence to "code", or saftey, or anything we take for granted in the developed world. See for an example (from Pakistan). You see it and you are simultaneously impressed and horrified!

    2. Prst. V.Jeltz Silver badge

      Re: Plot twist? What plot twist?

      "I'm going to go out on a limb here and say that we all saw this coming."

      Yup . just the mention of 3 phase...

      But its the on call section.

      Similar to if you're watching You've Been Framed and somebodys on a rope swing over a river ..... you know whats going to happen.

      1. Yet Another Anonymous coward Silver badge

        Re: Plot twist? What plot twist?

        "I'm going to go out on a limb here and say that we all saw this coming."

        I was going for - he somehow managed to use an extension lead to join two phases.

        We had a server basement broom cupboardroom where somebody needed a couple more 240v outlets and so had knocked a hole in the drywall and run an extension from another room - on a different phase. Server and monitor on 415V difference in supply - strangely nothing went wrong.

        1. Evil Auditor Silver badge

          Re: Plot twist? What plot twist?

          strangely nothing went wrong

          What should go wrong there? Even in my home installation I run the peripherals (screens and stuff) on one phase and workstations/servers distributed over all three phases. Strangely, I haven't been electrocuted yet ;-)

          1. Yet Another Anonymous coward Silver badge

            Re: Plot twist? What plot twist?

            >What should go wrong there?

            I'm old enough to remember TVs on 2wire leads where the chassis ground was connected to live or neutral at random.

            1. Antron Argaiv Silver badge
              Thumb Up

              Re: Plot twist? What plot twist?

              Not at random, it depended on which way you put the plug into the power socket.

              It was called "hot chassis" design and it saved a winding or possibly an entire transformer.

              You had nothing to complain about, the pressboard back of the cabinet served as an insulator, and as long as you didn't go poking around where you didn't belong, you were safe. Until your screwdriver slipped or your kids lost one of the knobs on the front. Made life more interesting.

              That's why we have polarised plugs and a ridge down one wire of the zip cord now.

              1. Colintd

                Re: Plot twist? What plot twist?

                Having worked on these, the chassis was normally hot 100% of the time, because the oncoming mains went through a bridge rectifier with no isolating transformer. The chassis was connected to the -ve side of the rectifier, so you have a nice half-wave 240V potential on the chassis.

                I was taught to work on these beasts with one hand in your pocket, as it minimized the chance of through body contact. More exciting was using a scope on these units, as connecting the shield (grounded) to the chassis (with 240V half wave) was a big no-no. The exciting approach was to let your scope float (plastic knobs only), the more sensible approach to use an isolating transformer for the TV, and then ground the chassis.

                1. Clive Harris

                  Re: Bridge rectifier?

                  These must have been more recent than the old valve TV's I worked on, way back in the last century. These ones had one mains terminal (hopefully neutral) connected directly to the chassis, with the HT provided by simple half-wave rectification of the mains. (No-one worried about mains waveform distortion in those days). This rectification was invariably done with a massive selenium rectifier about 8 inches long. Valve heaters were connected in series and driven directly from the mains via a big dropper resister. This generally had taps on it to adjust to different mains voltages.

                  These selenium rectifiers were notorious for the stink they made when they failed, which has been compared with a robot farting. Often a TV repairman would be greet with profuse apologies from the householder who couldn't work out the source of the smell and generally blamed their cat or dog.

                  1. Daniel 18

                    Re: Bridge rectifier?

                    "This rectification was invariably done with a massive selenium rectifier about 8 inches long."

                    This sounds like some kind of transitional technology to me. What year were these built, roughly?

                    I remember taking apart old TVs - no solid state rectifier though, that part was done with a vacuum tube, and the right tube gave you a full wave rectifier.

                  2. Unicornpiss

                    Re: Bridge rectifier?

                    "These selenium rectifiers were notorious for the stink they made when they failed, which has been compared with a robot farting."

                    Everything in that column of the periodic table forms stinky compounds and reeks when burned. (Eg. sulfur, selenium, tellurium, and presumably polonium too)

                    If you're bored, google "tellurium breath". Apparently it only takes a very small exposure to tellurium to make the breath, urine, sweat, etc. reek horribly of garlic for a very long time.

                    1. Anonymous Coward
                      Anonymous Coward

                      Re: Bridge rectifier?

                      Check out Derek Lowe's chem blog for more on this. Like: "Imagine 6 skunks wrapped in rubber innertubes and the whole thing is set ablaze. That might approach the metaphysical stench of this material"


                  3. Daytona955

                    Re: Bridge rectifier?

                    I remember getting old throw-out 405 line tellies to play with in my early teens (~1970), with selenium rectifiers. In one, I remember accidentally shorting out >1/2 the segments by mis-routing one of the connecting wires and letting it rest against one of the fins. The remaining segments objected to the over voltage went pop. And yes it really did stink. I wasn't very popular at home...

                    Drawing arcs with a screwdriver off the EHT was fun too. Until you got your finger too close to the edge of the insulated handle, and the arc jumped from blade to flesh!

                  4. Terje

                    Re: Bridge rectifier?

                    Be glad they were not using Tellurium, compound smelliness apparently increase as you go down that group of the periodic table S -> Se -> Te. I assume that Polonium compounds would be even worse, but there you have other problems to contend with that are more worrying then smell..

              2. Glen 1

                Re: Plot twist? What plot twist?

                Re: hot chassis

                Reminds me of the old Usenet yarn.

                Magic/More magic

                Don't get me started on the Story of Mel

                1. Unicornpiss

                  More wiring follies..

                  A friend of mine bought a house, and she asked me to take a look as every time she plugged in her computer monitor (CRT type) into a certain outlet, the circuit breaker would trip instantly. The monitor worked fine when plugged into any other outlet, and anything else plugged into the suspect outlet worked fine too.

                  The outlet was a standard 3-wire duplex outlet, like billions of others in the US. The house was somewhat older and parts of it still had 2-prong outlets. Upon pulling the outlet out of the wall, I found that to make this a 3-wire outlet, someone had wired the neutral and ground together, as there were only 2 conductors available from the panel. While this was a code violation, and a safety issue, it would have been mostly okay if the idiot that wired it hadn't mixed up the hot and neutral wires. So the neutral and ground were both hot, and her monitor apparently had some internal fault that led to the discovery.

                  This could have been lethal, if for example, someone was using an older power tool that had the metal case grounded for 'safety', then touched a pipe or similar with their other hand. A metal-cased power strip could have been shocking too..

              3. Robert Forsyth

                Re: Plot twist? What plot twist?

                The aerial lead made the aerial not the thing to grab in the loft or on the roof; may be an anti-theft measure?

          2. romanempire

            Re: Plot twist? What plot twist?

            "home installation"

            Unusual to have 3 phase in domestic premises.

            1. razorfishsl

              Re: Plot twist? What plot twist?

              No it's not

              In Hk & China it is REALLY REALLY common.

              The they do something stupid , like split it 1 phase per floor.

              But aircons are 1 phase....

            2. ssharwood

              Re: Plot twist? What plot twist?

              I've got it. Previous occupants ran a pottery studio and kiln in the shed out the back. Gently slope was a bastard to cover with a floating floor ...

            3. Daniel 18

              Re: Plot twist? What plot twist?


              If single phase power is 120V, three phase will come in at 208V.

              Instead, homes usually have a centre tapped feed, giving a choice of 120V or 240V single phase. The latter is used for things like clothes dryers, water heaters, central air conditioning, and stoves.

              Other things - stuff plugged into wall sockets, furnace motors, lights, sump pumps, garage doors, etc. are generally 120V.

              As a result connection is simpler and more compact than 240V, with no need for things like fuses in appliance plugs and the option of designing for a two prong plug.

              Also, it seems like 120V doesn't bite as hard as 240 - the few times I've had undue excitement with 120V, it wasn't too bad, but rather startling.

              The 208V stuff shows up in some moderately heavier commercial and industrial installations like store refrigeration systems, large AC units, I susect for elevators, some computer gear, and so on.

              The 'big stuff' may use higher voltages like 400, 600, or 800V... steel mills, motors moving 1100 tonne bridges, lock gates, subways, and the like generally go for higher voltages.

              (And while it may be a bit odd, if you put me in the motor room of a big lift bridge, I will actually go over and read the specification label on the motors...)

              As for frequencies, originally it was 110V at 25 Hz, but back somewhere around the 1930s, they decided that was inefficient and changed to 60 Hz - much better for transformers.

              When I was a kid, antique radio gear sometimes showed up with 25Hz transformers, which were way bigger and could be used at much higher loads on the newer 60 Hz current.

              1. Anonymous Coward
                Anonymous Coward

                Re: Plot twist? What plot twist?

                "As a result connection is simpler and more compact than 240V, with no need for things like fuses in appliance plugs and the option of designing for a two prong plug."

                I think you are confusing "240V" with "the crazy stuff they do in Britain". Pretty much the whole world runs 230/240V just fine without fuses in plugs and with 2-pin plugs for unearthed devices.

                Even in Britain probably 90% of those ridiculous plugs nowadays have a plastic third pin and no fuse, for the simple reason they are just a cheap localisation measure fitted to something that was designed to have a 'normal' 2-pin unearthed plug.

            4. H in The Hague

              Re: Plot twist? What plot twist?

              "Unusual to have 3 phase in domestic premises."

              Depends on the country. Here in NL it's usually 3 phases into the consumer unit/distribution board, with single outgoing phases to the house wiring. (Though you could fit a 3-phase breaker if you want to install some nice large machine tools in your home workshop :)

              Talking of breaker panels, had a beer a while ago with a chap who refurbished an old house (in the UK I think),he turned the power off at the first fuse box and at the second one. Then started cutting the old cables, cue flash, bang and molten wire cutters. Eventually he found the third fuse box behind some wallpaper.

              Here's one for the weekend.

              1. DuchessofDukeStreet

                Re: Plot twist? What plot twist?

                Moi, aussi....

                The previous owner of my flat was rather prone to doing random bits of DIY that really should have been done by a professional, so I have multiple plug sockets in rooms in random places, and mixes of wall and ceiling lights running off multiple circuits. When I first moved in, my dad was up helping me replace a nearly-antique fluorescent tube in the kitchen with something more modern that I could actually still but bulbs for. We worked out that there were two separate circuits in the main fuse box and switched off all the fuses to cut the entire power supply into the property, and dad picked up the drill. At which point the penny dropped that the mains-powered radio in the kitchen was still active....I've never yet worked out where that circuit comes into the property or how to turn it off. I've also never put a drill into any wall myself and warn any tradesman coming in - they've never solved it either but they've all survived.

            5. Beau

              Re: Plot twist? What plot twist?

              "Unusual to have 3 phase in domestic premises."

              You clearly don't live in Belgium! Our house built in the 1950s runs on 240v 3 phase 15A, and we consider that an improvement! As until a few years ago it was on the original 110v Split phase!

            6. JimJimmyJimson

              Re: Plot twist? What plot twist?

              Everyone around me has 3 phase. How else do you run a 4.5kw air conditioner? You're probably thinking of somewhere like the UK where ice is still considered a luxury item...

              1. GerryMC

                Re: Plot twist? What plot twist?

                In NZ, quite happily from the normal 240v single phase on a 20? amp circuit. Ovens are usually on a 32 amp breaker. (Actually IIRC it a 4.2kw unit)

                We only use one voltage for household stuff here.

                Unless you have a machine shop in the basement

            7. Terje

              Re: Plot twist? What plot twist?

              No, in the civilized part of the world that is entirely normal

            8. This post has been deleted by its author

    3. JulieM Silver badge

      Re: Plot twist? What plot twist?

      Have you never watched Casualty? It's usually pretty obvious within the first five minutes, who's going to be in the ambulance and why. Doesn't make it any less interesting, though.

  2. Anonymous Coward
    Anonymous Coward

    Whilst the overload wasn't clever...

    I would have expected the UPS to detect this and do something other than "let out the grey smoke that makes the chips work" - drop into bypass (to help clear fuses if there is a hard fault) or drop the load if that's not possible.

    1. Anonymous Coward
      Anonymous Coward

      Re: Whilst the overload wasn't clever...

      I have seen exactly that problem with one of the big UPS manufacturers that it could not handle severely unbalanced loads.

    2. Captain Scarlet

      Re: Whilst the overload wasn't clever...

      In my youth when a UPS had tripped because of a fault, the management card screamed about an input fault. Being a PFY, I went and thought thats odd and pressed the button to reset the UPS power input without thinking the UPS itself could be faulty.

      What followed was a lightshow from the 16Amp power input cable which had melted before my eyes and hoping it would retrip itself which is did shortly after. So for me its possible the UPS may have tripped but someone inexperienced might have commanded the device to try again, as thats exactly what I did and I will never ever do ever again.

  3. Anonymous Coward
    Anonymous Coward

    Reminds me of a time...

    ...that an airport I was working at had a water leak in the middle of the night. The contractors went under the check-in desks and isolated the individual UPSs in the area that was affected, just to be on the safe side (they weren't actually wet). Having stopped the leak and cleaned everything up, they plugged the UPSs back in again.

    About half an hour later, check-in started, everything was going fine, until that entire bank of check-in desks all died within 2 minutes of each other, and chaos ensued in the middle of the morning rush.

    Turns out the contractors hadn't plugged the UPSs back into the mains - they'd plugged them into themselves...

    1. Prst. V.Jeltz Silver badge

      Re: Reminds me of a time...

      I heard tell of a desktop support guy under a desk looking at a tangle of power cables. the problem turned out to be the "4 gang" adaptor was plugged into itself....

      1. The Oncoming Scorn Silver badge

        Re: Reminds me of a time...

        Last UK house, I put in spot lights (GU10) in the bathroom, the end light in the harness "failed" yet showed continuity when I used my DVM on the connector.

        I ended up making the harness into a loop which solved the issue, there were four lights*.

        *Icon ST-TNG

      2. Yet Another Anonymous coward Silver badge

        Re: Reminds me of a time...

        >. the problem turned out to be the "4 gang" adaptor was plugged into itself....

        Of course if you can make it work you are in the money

        1. Stevie

          Re:Of course if you can make it work

          Gallon of liquid helium, a magnet and you are sorted.


    2. jeffdyer

      Re: Reminds me of a time...

      On a similar note, it was my daughter's 10th birthday and the I'd taken the afternoon off, however some guy in sales had noticed that a network cable had come lose behind his computer and kindly plugged it back into the shared router under his desk.

      Unfortunately, he didn't tell anyone at the time, also, the cable was supposed to go into the back of his PC, so what he did infinite looped the router which took the whole network down.

      We ended up disconnecting everything from the main switch and plugging the cables back in one by one until we discovered the one connection that took everything down.

      Needless to say, I was late for the party. :(

    3. JimboSmith Silver badge

      Re: Reminds me of a time...

      One showroom I was at trying to run cable to a new location for the PDQ (card machine). I had used two four socket extension leads to create seven sockets coming off one 13A wall socket. I needed the PDQ to have a wall socket to itself and had labelled the extension sockets as for lighting only. The manager was worried that the wall socket might get overloaded with seven ornamental table lights plugged in. The bulbs on these things were a maximum of 40W and in a few of them they were low energy ones. The total came to under an amp of current from memory. I explained this and showed my working out because she wasn't 100%. I said it would be a different story if you had the microwave the kettle, a heater etc. on the same extension cord. She went white and showed me into the staff area where there was just that sort of thing going on despite ample power sockets being available. Some education followed with the staff about what not to do and new single socket extension cords were bought.

  4. John Sager

    Surprised the sockets on different phases were close enough together to connect the servers like that. I thought there were rules about spacing. A server installation I visited once had the cabinets on different phases far enough apart so you could not touch 2 at the same time.

    1. GlenP Silver badge

      That's my understanding as well.

      We had issues "back in the day" with Apricot networking not being cross phase tolerant. A new build for one of our clients was specified with turned-earth-pin plugs and sockets for the computers being all on a single phase.

      Despite this being accepted by the architects when we actually got in there (with only a couple of days to complete the installation) we found that firstly they hadn't supplied the special plugs (a motorcycle courier was arranged to bring them from Birmingham) and secondly that they hadn't wired them all to the same phase as "they're too close to the other sockets". They'd also totally ignored the instructions on the network cable install but we managed to work around that.

      This would all have been avoided if our request for a site meeting with the sparkies before they started work had been accepted but we were assured that the architect knows best!

      1. Chunky Munky

        NEVER assume the architect knows best! The school I work at has just had a building erected, one of the prime features is a light & airy glass walled atrium. As this was to be used as a meeting point/social area for older students, good WiFi coverage was essential. I requested a minium of 4 access points, one in each corner of the room, 2 - 3 metres from ground level. The architect knew better and instructed the builders to install them at roof height (2 storey building) & behind the false ceiling so they couldn't be seen as they would ruin the buildings asthetic (?). Unfortunately, the false ceiling had aluminium covered tiles and so formed a lovely Faraday cage.

        The builders were less than happy with having to move them :)

        1. frank ly

          All architects care about is building 'aesthtics' and will insist on anything if they think it maintains or improves their 'vision'. I've worked with people who install large scale systems (Power, HVAC, etc) and they've told me horror stories about architect decisions putting installation costs up and reducing the efficiency of installed systems.

          1. disgruntled yank


            Yesterday's NY Times carries an obituary of the engineer Robert Silman, who managed the repair work that kept and keeps Frank Lloyd Wright's Fallingwater house from falling into the water.

          2. JimboSmith Silver badge

            There was the architect I heard of who moved a satellite dish on the plans because it didn't "look right" there. They were ignorant of he fact that the new location had no line of sight to the satellite in question. Another was an interior designer who neglected to put more than two power sockets in a room designed to be a home office. The two sockets were located by the door and fairly useless as a result.

            1. Chairman of the Bored

              Two outlets only by the door?

              That's not even code in most countries. US National Electrical Code requires no more than 6' (1.8m) between receptacles in most residential rooms.

        2. JeffyPoooh

          "NEVER assume the architect knows best!"

          Understatement of the century.

          1. Prst. V.Jeltz Silver badge

            Re: "NEVER assume the architect knows best!"

            Havent we got enough different plans for house designs drawn up yet?

            You'd think work would be getting scarce.

            They seem to have perpetuated the myth they have to be consulted on every build.

            My building inspector told me I had to get an "Architect" to do lots of complicated maths to work out if my garage roof trusses were strong enough.

            Its not like I was the first person to do this. Its hardly a unique building.

            I said to the inspector:

            "If I had bought a sectional garage like that guy across the road would i need these calculations?"

            "No" , he said , "the vendor has already had the calculations done"

            "good" says me , "my trusses will be identical to those trusses , ergo my calculations have been done"

            "I suppose so" says the building inspector.

            Saved a few quid there!

            1. Martin an gof Silver badge

              Re: "NEVER assume the architect knows best!"

              Havent we got enough different plans for house designs drawn up yet?

              To be fair, it isn't always the architect.

              Yes, we had a few back-and-forth sessions with the architect who couldn't understand our specific instructions - for example, exactly which one of our children do you think is going to agree to sleep in the smallest bedroom when we asked for the children's rooms to be identical?

              Our main problem was actually the planners.

              The first planner (when we were still at the "here's a rough sketch I drew myself" stage) was categorical that we could not add a half an upper floor on to our bungalow.

              The second planner (who actually came to look at the site) agreed that we could, but that it would have to be oriented thusly, so we had an architect draw up a plan to suit.

              The third planner thought that layout looked daft and we should orient the upstairs portion at 90 degrees to the way the second planner insisted upon. This was the design which went through several iterations with the architect and...

              ...the plans which were finally passed were essentially properly dimensioned versions of the sketch I'd drawn right at the start!



              1. JimboSmith Silver badge

                Re: "NEVER assume the architect knows best!"

                Our main problem was actually the planners.

                I live in a listed building and I feel your pain. I also had to provide support to a relative who was trying to replace a conservatory on their listed home in the country. The house on all sides is surrounded by a large number of trees. There is no line of site from the house to any of the neighbouring properties. I did a plan of the entire property marking in blue the immediate area around the house. However the planners rejected this saying they wanted a plan of the entire property.marked in red. The scale was also apparently wrong, mine was too large which I didn't have a clue about. When I said neither of these requirements were listed anywhere they sent through the guidance sheet (that they should have sent before) which listed them..

            2. IsJustabloke

              Re: "NEVER assume the architect knows best!"

              "My building inspector told me I had to get an "Architect" to do lots of complicated maths to work out if my garage roof trusses were strong enough."

              That is not an Architects job... that is the job of an engineer. I would not step foot in a building that had it's engineering specs drawn up by an architect.

              1. Prst. V.Jeltz Silver badge

                That is not an Architects job

                dis is true I was generalising ..

                The architect just draws his fantasies on paper , like ,say , a toddler .

                Then an engineer actually does all the calculations , and working out how thick / strong things have to be to span the ridiculous distances the architect dreamed up

                Guess who gets the credit?


                1. Prst. V.Jeltz Silver badge

                  Re: That is not an Architects job

                  and btw , it's SET FOOT


                2. Lost it

                  Re: That is not an Architects job

                  That's because Architects are nothing more than failed artists. I once had one insist I removed the main structural centre leg in a supermarket on night shift. Because it was "in the way of his vision of the wavy roof tiling that was going in" I told him no, not happening. After three nights of this I was called in to explain why I was "not carrying out instructions according to my contract". I told them to get this ass of an architect on site and I would show him why. He actually went white...

                3. Rastor728

                  Re: That is not an Architects job

                  Architect draws fantasies

                  Engineer does math and changes the fantasies

                  Engineering Technician gets the blame for all the inherited problems and finally gets it all to work two weeks later.

            3. Anonymous Coward
              Anonymous Coward

              Re: "NEVER assume the architect knows best!"

              Idiot CTO: Haven't we got enough computer programs yet? I don't know why we have to hire all of these expensive programmers and software architects and testers. People make inventory management software all the time. Why when I worked across the street at $BIGCO we had an inventory management that looks just like the one you want to design here, just hire the offshore code monkeys to build it. It looks the same, ergo, the design has already been done.

              1. Prst. V.Jeltz Silver badge

                desinners who needs em

                You wouldnt write your own word processor would you? any more than a cricketer would make his own bat!

                You'd have thought we were done with clothes designers by now too.

                I mean - how many way can you make a pair of jeans?

                and food! we've done food , theres more than enough recipes!

          2. Yet Another Anonymous coward Silver badge

            Re: "NEVER assume the architect knows best!"

            Cough - Berlin airport - cough

        3. Mark 85

          NEVER assume the architect knows best!

          We techies don't. However, manglement does and they are the ones who get to talk to the architect. It's our job to clean up other people's messes and smile about it.

        4. SImon Hobson Bronze badge

          I requested a minium of 4 access points, one in each corner of the room

          And you admit to that in here ?

          Unless you disable 2.4GHz on all but 3 of them then you are artificially causing congestion - and that's assuming no other APs nearby. On 5.8G you'd be alright provided they all pick/have configured different channels.

          It's a myth perpetuated by people who don't understand the basics of wireless comms that adding more APs (especially in a small space) will "improve" the WiFi.

          1. Martin an gof Silver badge

            It's a myth perpetuated by people who don't understand the basics of wireless comms that adding more APs (especially in a small space) will "improve" the WiFi.

            Depends on the size of the room and the number of users expected. In a typical school hall in the UK I doubt that more than two APs are needed to cover the area from an RF point of view, either at 2.4 or 5GHz and in much of the world other than the US, four channels can usually be used adjacently at 2.4 (1, 5, 9, 13) without problem. Two or more APs on different channels could - theoretically, and assuming an even distribution of users between them - improve connections if there are lots of users.

            That said, I've met consumer and "prosumer" kit recently that does not do DFS and TPC which means that it is limited to four or five channels at 5GHz, so the situation isn't necessarily much better than at 2.4GHz!


            1. Baldrickk

              The worst I've seen was in the atrium of the "Hub" building at University. 4 floors high, with offices all up one side, fully wired for Wifi.

              Including a few phone hotspots, a Wifi scanner found 262 unique access point/SSID combinations (each access point provided access to three or four SSIDs, so that's 65-85 different visible access points providing the same networks, all on 2.4Ghz)

      2. PM from Hell

        Architect Smartitect

        I find new build installs are a;;ways a disaster in the making and every time it could have been avoided if the ICT team were allowed to speak directly to the contractors.

        Amongst the issues I've experienced were:

        A computer suite which overheated as the aircon outlet fed into a dummy clock tower. the builders decide to put plywood panels behind the openings to prevent pigeons nesting there making the tower almost airtight and preventing the heat exchanges working.

        The system ran for 48 hours before the heat buildup caused the environmental systems to power down the suite.

        A new library with public access computers and staff network on every floor where the inter floor ducting was made by embedding 6 inch waste pipes into the concrete floor. this meant that there was no space for the 100+ cables needing routing thorough the floors and we had to go to fibre, not a bad move but a very expensive option at the time and one which wasn't budgeted for,

        Finally getting on site to find the comms room was actually in the roof void and had sloping ceilings, we ended up with 6 different comms cabinets each of a different size and all crammed with equipment rather the 6 full height cabinets.

        A university where the comns 'cabinets' were actually doorways into a service void which ran the whole height of the building making installing equipment far more perilous than expected.

        Finally every single new build I have been involved in leaked. For some reason leaks always end up directly above racks of very expensive IT equipment, nylon sheeting is not part of my supply list for any new build.

        We even had an issues where network cables were laid in a hurry as the building was handed over late, cables were pulled thorough quickly, connected up to network points and tested, PC's installed over night and the room handed over the following morning as staff training was starting By 07:30 all the network points failed ad t turned put the cables had been under tension and had 'shrunk' overnight.

        Another item in my new build kit is now a 24 port switch and long Ethernet cable as at the network always seems to fail in at least one room when live use starts.

        1. Martin-73 Silver badge

          Re: Architect Smartitect

          Nothing like phases being wrong etc, or ethernet wiring... but one well known contractor who Love(ll) to build social housing, at least on a development i was presented with, had handily wired all the telephone wiring on one side of the building (one socket in each room) back to a main socket in the hallway... which then had a single cat 5 (not proper CW1308 but apparently that's normal now) back to the eternal NTE, and the other half back to the kitchen socket, and a second cat5 back to the NTE. (which has ONE set of wiring terminals)

          Result... 8 cables jammed in one normal phone jack (Krone IDC terminals rated for 'up to 2 connections' provided the wiring is smaller gauge) and 2 cables at the NTE with terminals rated for ONE wire only.

          The openreach chappe told me they'd done similar at blocks of apartments but because it was easier, he had 7 cables to contend with at each NTE.

          Some 8B connectors and a huge chocblock behind the hallway socket got the ONE working... but yeesh

    2. Richard 12 Silver badge

      That's a myth. It was a requirement added in the 14th ed of the UK wiring regulations, and removed in the 15th edition for being pointless - before BS7671 existed.

      1. GlenP Silver badge

        Thanks for the clarification. Obviously the contractors we had were working to 14th Edition standards then, even though 15th Edition had been introduced a few years before!

        1. Martin-73 Silver badge

          re: spacing of phases in the UK

          If i recall, it pre-dates AC even. If you had both 'outers' of a 200/400v to 250/500v DC system (centre earth) you had to have the meters and any accessories 6' apart so arm to arm contact was impossible.

          Usually a floor per 'line'.

          Something about the supply regs and anything over 250v nominal ? or was that for light sockets... old books

        2. the hatter

          It's a great safety feature where it make sense - why make it a possible failure mode when there's distance and load to accommodate doing it that way. But whether it's something like a simple high density data centre it becomes unworkable, and then literally impossible when you require diverse power feeds to even a single piece of kit for resilience.

    3. Anonymous Coward
      Anonymous Coward

      "Surprised the sockets on different phases were close enough together to connect the servers like that. I thought there were rules about spacing. A server installation I visited once had the cabinets on different phases far enough apart so you could not touch 2 at the same time."

      Well color your self surprised. Back in the day I worked (did I say work I meant slave labor as a summer intern) at a data center that used suns and powerpc servers . Each had a redundant power supply . Each power supply was plugged into a different phase . The thinking was if one phase had a bad day t hey other would pick up the slack and the redundant power supply would not be affected . But hey this same place that it was a good idea to have a unpaid 16 year old summer intern do admin duties of a jr tech because it was free labor. But hey for me on the plus side I learned how to properly cuss from and old cranky Scottish guy.

      1. Anonymous Coward
        Anonymous Coward

        Come to think about it, properly learning how to cuss is valuable asset in IT. Swear that guy could cuss in in 20 languages .

    4. Dwarf

      Surprised the sockets on different phases were close enough together to connect the servers like that. I thought there were rules about spacing. A server installation I visited once had the cabinets on different phases far enough apart so you could not touch 2 at the same time.

      So you've not worked on larger data centre kit that requires a 3 phase feed then ?

      Blade chassis, disk arrays, high end server platforms etc.

      There is absolutely no issue with having the phases close to each other. The problem is about appropriate training for the people working in the data centre. A suitably motivated person who want to go would have no problems finding a couple of IEC extension cables and two screwdrivers to jam into the sockets if they really wanted to go that way.

      1. Nate Amsden

        I deployed some new pdus recently(as in 0U rackmount pdus not large scale datacenter pdus). They are pretty neat as they alternate the phase on every outlet (and the outlets are color coded). pretty convenient, though the locations on the outlets could use some improvement, assuming related to the extra hardware to do the alternate outlet thing, 36 outlets on the 208v 30a 3phase though probably a good 2 and a half feet of no outlets on the bottom part of the pdu.

  5. Frank Bitterlich


    Disclaimer: I have zero experience with three-phase UPS...

    But wouldn't there be a circuit breaker for each phase output? I know that there is one on every one of the small single-phase UPSes I use.

    1. Wellyboot Silver badge

      Re: Huh?

      Only if you'd asked the sparky to put them in the build.

      Big 3-phase boxes I've worked with just have the output feed. Local power regulations generally decide what has to happen next. (with a splash of management penny pinching).

      I've specced breakers per phase per rack with resulting impressively large power panels at the end of each row to allow for future maintenance.

    2. JeffyPoooh

      Re: Huh?

      FB asked, "...a circuit breaker for each phase..."

      Yes, but typically all mechanicalky linked together. If any phase is overloaded, that CB will trip itself and the mechanical link will turn off the other two phases at the same time.


      1. AndyFl

        Re: Huh?

        Not always.

        I've done -48V DC power systems where the rectifiers are distributed across the 3 phases and disconnected the linkage between the incomer breakers them at the client request. The reasoning was that if a rectifier failed in a big way then it would only take out one phase, not all three.

        These power systems were for emergency service equipment with duplicated everything and no RCD/GFI in sight. Mind you the earthing systems were impressive.


    3. kain preacher

      Re: Huh?

      "Disclaimer: I have zero experience with three-phase UPS...

      But wouldn't there be a circuit breaker for each phase output? I know that there is one on every one of the small single-phase UPSes I use."

      In the US each phase is suppose to have it's on panel

      1. Will Godfrey Silver badge

        Re: Huh?

        I've worked with three phase systems for a {cough} few years. I will always fit mechanically linked breakers to anything that can draw a significant current. There are some 'interesting' runaway situations that can occur otherwise - mostly based on "but nobody would do that", such as: "Well the phases are nicely balanced so there's negligible total neutral current so we can run a thinner (cheaper) line".

        I've seen that, and the result when a printing press contactor lost one phase - smoke coming from a long line of ducting, and lots of (expensive) single phase kit going pop.

        1. Unicornpiss

          Mechanically linked breakers..

          In a previous life, I managed a restaurant and also did maintenance on some restaurant equipment, including conveyor ovens. We had a satellite operation in an auto plant's commissary about 50 miles away that I also oversaw.

          One evening I get a page (yes, that long ago) and the message is "Oven is down in Plant 2" So I bundle up my tools and drive 50 miles to troubleshoot the problem. After some head scratching I discover that one leg of the 3-phase power is not present. So I go hunt down one of the plant electricians, which takes quite a while, then we go on a snipe hunt for which electrical panel actually services the grimy receptacle. Eventually a panel is found and we verify that the breaker actually controls power to the outlet, but it's not tripped. It also appears to only be a 2-phase with the 2 breakers mechanically linked. The electrician verified this by taking the cover off the panel--only one screw was holding it and it came crashing to the floor when it was removed.

          Now we're both scratching our heads and with the help of another electrician and a ladder he begins tracing the wiring back from the outlet. He finds that 2 phases and the neutral are wired to the panel we found, but one diverges in a ceiling electrical box and runs to a panel about 50 yards away in another part of the labyrinthine plant. There, another 2-phase breaker is found with only one phase connected, and it was not just tripped, but defective to the point where you could practically make it trip by breathing on it.

          I can't imagine the level of incompetence/indifference/rushing to complete a job that would lead to wiring something this way, but it was one of the first displays of this sort that I'd experienced, contributing to barely anything surprising me these days.

          1. Chairman of the Bored
            Thumb Up

            Re: Mechanically linked breakers..

            +1 for "snipe hunt"

        2. Antron Argaiv Silver badge
          Thumb Up

          Re: Huh?

          A friend works on TV transmitters. They have a UPS which holds things up until the diesel generator comes online. TV transmitters draw a LOT of current. Therefore, it's a BIG UPS. And the diesel is big, too. Especially if they serve four or five transmitters at the same site.

          But, no matter how big the diesel is, if it doesn't start up, the TV goes off when the UPS uses up its batteries. Which is exactly what brought my friend out to the transmitter site that night, to discover that the people who had installed and "tested" the diesel, had not hooked it up to the UPS, so it never sensed the power failure, and never got the signal to start, even though it had worked perfectly when they tested it (with the manual start switch)

          Moral: test the WHOLE system, not just your part.

          1. Rich 11 Silver badge

            Re: Huh?

            Moral: test the WHOLE system, not just your part.

            Well, obviously. But how often do you get approval from manglement to risk the system going down by running those tests? If you're really, really lucky the entire team ends up working on the morning of Christmas day.

            1. Baldrickk

              Re: Huh?

              If you're really, really lucky the entire team ends up working on the morning of Christmas day.

              At a TV transmitter location? not likely - can't miss the Queen's Speech!

              An early tuesday morning maybe, say 02:00 would seem more likely, some time when the least viewers possible could be affected.

      2. Chestislav Achterkamp

        Re: Huh?

        What? Your standard 120v panel has 2 "phases" in it, and if industrial kit had to have separate panels for each phase, the result would be frigging huge. Beyond that, even at the utility level we have combined panels for three phase power. Why the hell you'd ever want separate panels for each phase is beyond me, it would make the protection systems basically impossible to build easily, the disconnects dangerous as sin, and load balancing and monitoring basically impossible.

        I'm going to guess you've only ever worked on residential style power systems. I'd personally place input and output circuit breakers unless the damage from shutting down would be worse than setting it on fire. Now, 3 phase circuits are supposed to have their breakers ganged(linked with a small pin through the breaker toggles). It is possible to run a three phase system with over a hundred amps of current imbalance between phases, but it takes life off the equipment(and the wimpy stuff in your normal three phase UPS would kind of explode) so the utility has imbalance monitoring systems on at least the transmission lines(the big towers/cables) but the relays to control the breakers for that are $5,000 apiece.

        But I understand how you could get the idea from residential power.

    4. Rastor728

      Re: Huh?

      "But wouldn't there be a circuit breaker for each phase output? I know that there is one on every one of the small single-phase UPSes I use."

      Transistors blow to protect the fuses, fuses blow to protect the breakers, breakers only blow as a last resort to "hopefully" stop the building from burning..

  6. g00ner

    Don't think this through

    The company l worked for at the time moved in a new building with a dedicated server room. The server room had a mixture of ups fed power and normal power sockets.

    When we experienced out first power cut, due to someone digging up the power cable outside the building l went down to the server room to shut down the servers in an orderly fashion. As we had been informed it would take sometime for the electricity to be restored.

    Small problem although all the servers were on a ups power feed none of the monitors or kvm's were. The clock was ticking as the ups battery only enough capacity 2 hours.

    Trying to figure out where to find a ups power feed whilst only the emergency lighting was on was great fun. Diving behind racks and pedastals tracing back all the spaghetti.

  7. Edwin

    Ah... the bypass switch

    Yes. It's a very satisfying and impressive switch to throw.

    For years, I have looked for an excuse to install something equally impressive (possibly with arc extinguishers?) at home, but not having much luck...

    1. DropBear

      Re: Ah... the bypass switch

      Take up ham radio as a hobby, get an outdoors long-wire aerial and you have the perfect excuse to connect it through one of those lovely bakelite-handle knife switches - the old radio handbook I read as a kid swore that these used to be switched over to a grounding lead in stormy weather...

      1. Martin-73 Silver badge

        Re: Ah... the bypass switch

        That wasn't the same radio handbook that told you how to make your own meter probes (for use on valve/tube equipment no less) out of solid brass rod with a 'tape cover to protect against shocks' ?

        1. DropBear

          Re: Ah... the bypass switch

          Not sure about that, but it definitely was the handbook illustrating how to make a "detector" out of a Gillette blade and a graphite pencil lead...

          1. Martin-73 Silver badge

            Re: Ah... the bypass switch

            Not the same book then, but it looks as if it's in similar vein

  8. Anonymous Coward
    Anonymous Coward

    Never trust the back of an envelope

    While working for a large carrier in Paris, I met with the electricians to ask as to their progress in wiring out our MDF with the requisite PDU diversity. I was assured that all the commando plugs were on the same phase and that I could power up the two Cisco 12000 GSR's that I had racked previously. I asked for some evidence of this, and was presented with an envelope on which the wiring diagram was scribbled!

    Being suspicious of this, I asked for someone to connect a multimeter across two sockets to verify they were on the same phase. Funnily enough, the electricians were rather surprised to see 400V of potential difference, and I congratulated myself at having saved the company around half a million dollars, eg the cost of one populated GSR. One million if I had been dumb enough to connect both at the same time.

    Great story for the "what's the most you've ever saved your previous employer" interview question :-)

    1. Antron Argaiv Silver badge
      Thumb Up

      Re: Never trust the back of an envelope

      Trust...but verify!

      // ALWAYS verify.

      1. Yet Another Anonymous coward Silver badge

        Re: Never trust the back of an envelope

        >Trust...but verify!

        Never Trust....

    2. Alien8n

      Re: Never trust the back of an envelope

      By a quick finger in the air calculation... probably somewhere in the region of about £10M. Twice.

      2 separate incidents where I was moonlighting as a weekend operative (while employed as a Product Engineer during the week) which ironically made me the highest ranking person in the building both times. Both times we had a sudden spike in failures of transistors at test. Cost of silicon, about 20p each, cost of final device about £20. Both times resulted in tracing the fault back to the silicon enabling us to test and dispose of the silicon instead of the finished product.

      In typical arrogant fashion we were still forced to use one batch of silicon as the US wafer fab refused to update their test limits, despite the obvious savings to the company as a whole, but as our factory was UK based we were treated as a customer and not part of the same company.

      This was the same company who then moved manufacturing to Mexico and demanded all the test equipment be supplied without safety cut-offs, which could have resulted in the Mexican staff being electrocuted. Needless to say the manufacturer's response was, "no safety cut-off, no machines"

  9. Anonymous Coward
    Anonymous Coward

    I was the sysadmin at a company that was being downsized (from about 30 to about 3 employees). Before I left I was asked to draw up a plan for the new server room in a small office they were moving into.

    I specified that the server room needed about 90 amps of power for all the equipment, so they would need to get an electrician to put in some dedicated feeds from the distribution board.

    The beancounter came back to me and said that the room had 4 double sockets, and since 8x13 is 104 amps, the existing wiring would be more than enough. I tried several times to explain that all 4 of the double sockets were on a single 30A ring main, but they clearly didn't want to understand.

    As I was about to be made redundant I decided it was their problem to deal with not mine.

    1. SImon Hobson Bronze badge

      Smaller scale, at the local church the boiler has failed (or rather, been condemned). So while the weather was cold we were using fan heaters to take the chill off - about all they could do, we all came prepared and kept our coats on.

      One day I get there and [name/position redacted to protect the guilty] told me that some of the sockets weren't working. WHGile I had limited the two fan heaters to 3kW total - he'd brought in a couple more and was surprised when they all went off. "But I was careful and plugged them into different sockets" he told me, meaning that there was only one socket in each double used. He just couldn't understand the idea of these all being fed through one bit of 15A fuse wire.

      He was also even more amazed that I could find the blown fuse and rewire it - he couldn't do more than look and see that none of the MCBs (retrofitted into the lighting board) had tripped. Yes, the place is long overdue for a bit of upgrading !

  10. trydk


    This case is a nice example of two mistakes (the missing protection on the UPS and the sysadmin's cabling) exacerbating each other with a rather bad result.

    Many comments go on architects and how aesthetics has priority over functionality, which I've seen in a number of cases.

    One of the more entertaining was a consolidated IT department moving into a new, open office environment. Huge room with lots of space. The Head of IT had asked me (IT architect, not building architect) what I thought. I suggested to have enough network connection points and power points spread across the whole area of the room to support at least one and a half or maybe even twice as many people as they expected to use the room. What they did instead was assigning just about enough for the number of people moving in, and all along one wall. So when they moved in, the room became littered with extension cords and long network cables running across the floor (high ceilings, so no-one tried to run them up there). In a month or so, the department increased in size and now the multi-socket extension cords had further extension cords attached, sometimes chained like three or four times. And the network was extended with consumer-level network switches to support the new people.


    1. Wensleydale Cheese

      Re: Planning

      "I suggested to have enough network connection points and power points spread across the whole area of the room to support at least one and a half or maybe even twice as many people as they expected to use the room."

      One place I worked used an excellent electrical contractor who really knew their stuff. When we asked for an extra n lines adding to the factory area, they said "We anticipated that, and doubled up on the lines we installed originally". Win-win - they simply had to connect the extra lines at each end, and the job was done in record time.

      Sadly that kind of client-customer relationship is rare.

      1. Korev Silver badge

        Re: Planning

        My work burnt out a cable to one of the major company data centres, it turned out that in the late 70s the contractor decided to put in a lower rated cable than it was supposed to. This led to a massive outage (not sure why the redundant systems didn’t work) and allowed IT to convince the senior people to invest in a huge new data centre.

  11. DaemonProcess

    get out quick

    Once when I was plugging in some storage in a machine room, at the other end I heard 3 electricians stood around a lifted floor tile arguing about which wire was the blue phase. When they finally agreed it was the black wire I hot-tailed it out of there before they connected it.

    Thankfully I didn't hear a bang.

    I had previously been in a building that had 2 phases connected together by accident one time and it wasn't nice. The bang was huge - like a direct lightning strike, it also blew up the substation in the corner of the car park. People in the same room as the incident were wandering around dazed for minutes, like zombies.

    1. defiler

      Re: get out quick

      2 phases connected together by accident one time and it wasn't nice. The bang was huge

      Yep. I was working in Charlotte Square in Edinburgh when somebody dropped a tool into a 3-phase about 1/4 of the way around the square from us. Power was off for the rest of the day. I was in reception at the time and there was a flash like a lightning strike.

      I know my limits on electricity. Sockets are fine. Consumer Unit is a job for a spark. 3-phase? Not going near that!

      1. Alien8n

        Re: get out quick

        As my step dad was blind I was taught how to do household electrics (before he lost his sight he was a sparky at a power station). This taught me enough to take one look at the botch job done by the previous owner of the house we now live in on the kitchen lights. Previous owner was an electronics engineer, which in no way shape or form makes them qualified to do household electrics as proven by what I discovered.

        Issue with the under-cupboard lighting, trace switch from wall to a junction box behind the cooker. Trace one direction under the sink to an open connector block directly underneath the taps. From there to several 5A spotlight units under the cupboards. Now back to the box behind the cupboard and trace in the other direction to... the 30A cooker main. All this meaning in the event of a fault with the lights the fuse wouldn't have tripped until after catastrophic failure, and as it was a home bodged installation all buildings and contents insurance from any resultant fire would have been null and void.

        Needless to say I disconnected those lights straight away.

        1. Anonymous Coward
          Anonymous Coward

          Re: get out quick

          I found out (by trying to cut a wire and getting a flash and loud bang for my trouble) that the overhead lights in my mom's kitchen are powered by TWO breakers. There is a switch in the kitchen, but a second switch in the dining room. Turning either one on will power the lights, and the breakers are wired to the switch not the fixture!

          I'm not really sure if that's against the electric code, but IMHO it sure as hell ought to be! Of course I was using insulated snips to cut it, knowing it might be live since the breaker box was unmarked and "flipping breakers until everything in the kitchen was off, so I could probably assume the non-functional overhead lights were also off" was not a 100% safe strategy. I probably should have turned the main off, but then I wouldn't have discovered how stupidly wired her house was!

          I wonder how common this sort of thing is? It was built in the late 70s, maybe that was considered OK then.

          1. J.G.Harston Silver badge

            Re: get out quick

            I was rewiring my brother ex-council house 20 years ago. Pulled the "downstairs lights" fuse and the stair lights go out. Ok, sorted, that's the right fuse. Start working on the electrics - bang! After a sit down and a cuppa, investigation turns out that the stairs lights - one light at bottom, one at the top, switch at the bottom, switch at the top - somebody had decided that naturally, that had to be wired to both the downstairs fuse *and* the *upstairs* fuse.

          2. Vincent Ballard

            Re: get out quick

            An organisation I volunteer for moved into a building which I suspect (from labels found) was previously a print shop or something similar. The power sockets in the main room were in little clusters sticking up from the floor, with cables running through ducts along the floor, up the walls, and into the ceiling space. I was asked to remove these obstructions and put sockets on the walls instead.

            Before starting work I checked that the mains breaker was off, then used a multimeter on one of the sockets to be sure. Disassembled that socket, and moved onto the next one, which gave me a nice 230V electric shock. It turns out that the building had two rings, and the sockets alternated between them.

          3. Martin-73 Silver badge

            Re: get out quick

            As an electrician, who does mostly domestic work with a smattering of commercial/light industrial, in the UK... the fed from 2 breakers/fed from different boards scenario is NOT rare at all. The favourite is to somehow crosswire the 2 ring mains, then take an unfused spur (wire right into a JB) for a light in the attic fed by bell wire. (yes, those all occurred together, on one job. very recently)

            Result: the light fixture fed with bell wire was effectively fused (not breakers, gen-yoo-wine wylex rewireable fuses) at 60 amps. Or the same rating as the rewireable, double pole fused mains intake before the meter.

            That one got rewired and the intake changed post haste by SSEN

        2. Anonymous Coward
          Anonymous Coward

          Re: get out quick

          "This taught me enough to take one look at the botch job done by the previous owner of the house we now live in"

          our house was built in 1877 so when I do any work on our home, I find all sorts of crappy jobs.

          The house, was run as a guest house from when it was built, but over the years some extensions were built, many of these extensions were done in the 60's and 70's and if anyone knows buildings in Blackpool, nothing was done with planning permission. and the only use for a book of regulations was to level up a joist

          electric was not something that was originally in the building and was installed later. and then as extensions to the structure were added, the electrics were just added in add hoc. I believe that one of the previous owners of the building was a builder, but was certainly not an electrician. looking at the quality of some of the building work, I imagine he was a fan of the western genre of movies.

          some of the problems I have found and since fixed include no earth bonding on central heating pipes. wire plastered into walls with no trunking. but my favourite was a shower that was installed in the private bedroom which had an electric socket right next to it and the cable supplying it was routed right under the shower tray.

          the bulk of the problems were that when somthing goes wrong, it was just patched together quickly and then a proper repair would be planned for out of season. but, the reality of it was that it was never fixed properly. so when I have come along many years later when something has failed I find all sorts of mess.

          the most common problem I find is that there was a rewire done some time in the late 70's or early 80's and now some of the sockets are starting to fail or have cracked. So far, not a singe socket that has been opened up has any insulation over the earth wires from the T&E, and it appears that as each socket was installed, the cable was pulled tight so there is no slack in the cable at all. So if the new socket does not have the connections in the exact same place, then the wires are not going to reach. This makes a five minute job into an afternoons work lifting floorboards and replacing cables.

          We have since rewired the entire property, But here a thing about the regulations, there are plenty of jobs that a concomitant DIY person can do for yourself, like install fused spares or a additional light. You can even replace an entire ring main, so long as you follow the original cable route exactly and none of it passes through a bathroom or kitchen. so, when I lifted a section of floor to replace a the first floor ring, and find that the knob head cut a notch out of the TOP of the joists to run cables across it, i am supposed to follow that route and not drill a hole through the joist for the cable to pass through...

          I get that the regs are there to stop idiots from burning houses down with crap wiring, but it also prevents me fixing the existing crap.

          1. Martin an gof Silver badge

            Re: get out quick

            Apologies in advance for brevity...

            no earth bonding on central heating pipes.

            A lot of things like this are because they weren't mandatory at the time the installation was designed. New editions of the regulations aren't retrospective unless you happen to be working on the part of the installation concerned.

            wire plastered into walls with no trunking.

            Not strictly necessary, even now. Plastic trunking might protect cable from the plasterer's trowel, but the 17th edition requires either burial 50mm deep or protection good enough to deflect (say) a picture nail or (more common) protection by an RCD.

            not a singe socket that has been opened up has any insulation over the earth wires from the T&E,

            Not, strictly speaking, insulation. It's mainly there as an indicator to identify the conductor.

            and it appears that as each socket was installed, the cable was pulled tight so there is no slack in the cable at all

            A properly applied crimp to add a couple of inches of wire will be at least as reliable as the screw terminals in the outlet, probably more so.

            find that the knob head cut a notch out of the TOP of the joists to run cables across it, i am supposed to follow that route and not drill a hole through the joist for the cable to pass through...

            Drilling a hole would just further weaken the joist, but re-using the notch isn't ideal die to the risk of nailing through the cable, even when you know it's there. In many cases it's possible to fit a plate across the notch, which my inspectors never whole-heartedly recommended, but seemed happy to accept.

            Safe Plate


          2. Alister
            Thumb Up

            Re: get out quick


            looking at the quality of some of the building work, I imagine he was a fan of the western genre of movies.

            I chortled at that.

            No, really...

    2. Mark 85

      Re: get out quick

      People in the same room as the incident were wandering around dazed for minutes, like zombies.

      I'm surprised that there's no mention of flash burns. They got lucky. I saw an electrician drop a large screwdriver into an power box in factory once. People 10 feet away got flash burns. The electrician didn't die but he was badly burned and off work for year.

    3. SImon Hobson Bronze badge

      Re: get out quick

      3 electricians stood around a lifted floor tile arguing about which wire was the blue phase. When they finally agreed it was the black wire

      The old saying is red to red, yellow to yellow, and blue to bits ...

      But thanks to harmonisation, what you describe isn't so far fetched - now our cabling is supposed to be brown, black, and grey for the three phase lines. It means that a blue wire in the trunking could be an old line wire (blue phase) or a new neutral; while a black wire could be an old neutral or a new phase line. And of course, when it's all aged a bit and everything looks a bit grey, and it;s covered in dirt, and your working in the darkest corner of the factory - they all look the same anyway, but the old colours were generally more discernible.

  12. Anonymous IV

    Compulsory pun

    "It was a phase worse than death..."

  13. Anonymous Coward
    Anonymous Coward

    I worked in a building that the electricity board accidently connected 2 phases across what should have been live/neutral and took out a fair chunk of the building. We spent most of the afternoon wandering up and down Edgware Rd buying up bulbs and replacements for those odd fuses that no one ever stocks. (most of the kit survived with just a blown fuse)

    I also worked in a building where the old PBX room had been partially converted to a server room now that 'modern' technology had shrunk the many racks of clockwork to a couple of cabinets. They had installed a cabinet of servers and a rack containing a mux and modems for remote access. To this had been added a cabinet full of fibre optic mux gear mainly for voice traffic and a final rack of odds and ends. As the room had been a PBX room the main power had been 50V DC, they had plugged the server cabinet into the first available mains socket and then the mux cabinet into the 1st... the fibre cabinet into the 2nd, 4th into the 3rd... all connected to a single 13A rubber socket on the end of a lead disappearing through a hole in the wall! Needless to say the rubber socket was red hot and had scorched a mark on the floor (luckily tiled). The electricians finally grudgingly agreed to forego the usual '2 working days' attendance (well it had probably been working for a couple of years like that... what does another couple of days scorching the floor matter)

    1. Adrian 4
  14. BinkyTheMagicPaperclip Silver badge

    Wiring limits

    I once went to a new machine room, if I remember correctly in the Republic of Ireland. It was smart, shiny, with incredibly neat wiring - a thousand miles away from cable horrors.

    Unfortunately the comms system we maintained wasn't working - modems were communicating with the server, but no calls were being answered. The wires from the modems were tied very neatly, and almost at 180 degrees round parts of the rack, where they had presumably broken inside. Cue a test of every individual modem, replacement of RJ11 wires, and a request not to be quite so fastidious. This was made worse by the fact that US Robotics don't have a standard RJ11 wiring, they use different connections for different models..

    I may have also managed the same at home, where one of the computers on a 28 port switch was rather slow web browsing. Eventually had a look at the switch stats and found it's negotiating at 100Mb instead of 1000Mb, cable has probably been bent a bit too much in the limited desk space, project tonight to move it on to a new shelf on the wall..

    1. Cynic_999

      Re: Wiring limits


      ...rather slow web browsing. Eventually had a look at the switch stats and found it's negotiating at 100Mb instead of 1000Mb


      You won't notice the difference between web browsing at 100Mbps and web browsing at 1000Mbps. The data is probably coming over an Internet link at below 100Mbps anyway. It's far more likely that the switch keeps re-negotiating the link speed due to long wires or Cat5 rather than Cat5e wiring being used - just configure the PC or router to fix the LAN at 100Mbps and it should be fine.

      1. Henry Wertz 1 Gold badge

        Re: Wiring limits

        Youre right, 100mbps is plenty. But I've seen this, a cable goes bad and it negotiates down to 100mbs... trouble being you then also get like 20 or 30% packet loss and maybe 1mbps throughput depending on what went wrong with the cable.

      2. BinkyTheMagicPaperclip Silver badge

        Re: Wiring limits

        Oh, sure, the Internet is currently 11-12Mb/s or so until I shortly get around to a fibre upgrade. I don't know if it's the negotiation, or re-transmits (there weren't any errors reported), but it was much more effective to replace a couple of quid of network cable with a new one rather than bother with fixing negotiation speeds. Also, if I want to copy on the local network I want to do so at 1Gb.

        Anyway, the switch has now been moved so the issue won't re-occur. Next up is replacing my ancient firewall hardware with something a little more embedded..

  15. Cynic_999

    Is that legal now?

    Decades ago when I had to read up on electrical regulations in order to re-wire my father's house which was supplied by 3-phase mains, there was a regulation that clearly stated that all the (single-phase) plug sockets in the same room had to be on the same phase.

    So I assume that either that regulation has been rescinded, or there is now an exemption for server rooms?

    1. Anonymous Coward
      Anonymous Coward

      Re: Is that legal now?

      What would be the reason for wanting all the receptacles in a room on the same phase?? Electrical/fire code almost always has some basis in safety, even if a pretty theoretical concern...not sure what safety would be compromised by having outlets on two different phases.

      1. Allan George Dyer

        Re: Is that legal now?

        @DougS - "Electrical/fire code almost always has some basis in safety, even if a pretty theoretical concern"

        Two appliances within touching distance would have 415V AC between them, and the insulation on each is approved for 240V. Theorhetically, even a single layer of the insulation would be over-engineered enough to withstand the higher voltage.

        1. Anonymous Coward
          Anonymous Coward

          Re: Is that legal now?

          Ah, so it is a rule that predates grounded receptacles. That's presumably why server rooms are exempt, along with anywhere else that's up to modern code.

          The business I own has three phase power, and the panels are wired in sequence on each side - i.e. from top to bottom breakers use phase 1, 2, 3, 1, 2, 3, etc. (standard US 120v, along with a few things that use "two phase" 208v, and rooftop HVAC units that use three phase 208v) so I've got multiple phases in the same room all over. I have three meters for different sections of the building, and each meter is fed by a separate utility phase.

          Since the main/middle section has almost outgrown the two panels that serve it, some later additions were wired from the single panels in adjacent sections. Once in a while the utility will have an outage that drops only one phase, so you get this seemingly random mismash of things that lose power and things that don't - i.e. one 'single panel' section will lose all power, plus a few things here and there in the main section, or most but not all of the main section will lose power. The first time it happened I had no clue what was going on, I thought the building was possessed! :)

          1. trydk

            Re: Is that legal now?


            I know nothing of the US electrical code (or whether you are based in the US) but in the UK (and in most of the rest of Europe, I think) all modern installations have RCD (Residual Current Detectors) that will trip if there's a difference in current leaving the Live wire and returning through Neutral. These RCD units will trip if current is flowing from Live through anything (incl. a person) to ground without actually returning through Neutral (e.g. the hair-dryer in the bathtub) or current flows between two phases (again nothing returns through Neutral). Special RCD units are used for multi-phase equipment that utilises the higher inter-phase voltage.

            1. Anonymous Coward
              Anonymous Coward

              Re: Is that legal now?

              Yes, we have the exact same thing but they are called ground fault circuit interrupters here, or GFCIs for short. They are required by code anywhere water may be present, like kitchens, bathrooms, patios, etc.

              There are also arc fault circuit interrupters or AFCIs which are a bit newer which detect arcs (but somehow distinguish between a non-problem arc like in the normal operation of a switch and one that could cause a fire) They are required by code in bedrooms.

              To my knowledge there aren't any GFCIs or AFCIs for multi phase circuits (i.e. hot/hot/ground 208v or hot/hot/hot/ground three phase 208v)

              1. Martin an gof Silver badge

                Re: Is that legal now?

                There are also arc fault circuit interrupters or AFCIs

                Not wanting to be too jingoistic here(*), but AFCIs are not standard equipment in most of the world, because few parts of the world have electrical installations as poorly designed as the US ;-)

                One of the benefits of a higher nominal voltage is that for the same power, current is lower. Put poor fittings (dodgy terminals) together with high currents and arcs are an almost inevitable result.

                A side benefit is the ability to deliver higher power using thinner cables - cable size is directly related to the current it carries, not to the voltage used.


                (*)mainly because I'm relying on third-party reports, having no personal experience of US electrics

                1. H in The Hague

                  Re: Is that legal now?

                  "AFCIs are not standard equipment in most of the world"

                  Actually, they've just been introduced in the 18th edition of BS 7671 (the UK requirements for electrical installations). This is because arcs can have a relatively high impedance, so you can get an arc which causes a fire but does not draw enough current to trip the circuit protection.


                  "Protection against thermal effects - A new Regulation has been introduced recommending the installation of arc fault detection devices (AFDDs) to mitigate the risk of fire in AC final circuits of a fixed installation due to the effects of arc fault currents."


        2. Martin an gof Silver badge

          Re: Is that legal now?

          the insulation on each is approved for 240V

          Standard insulation resistance checks on wiring and on appliances are carried out at 500V, so no problem there. In fact, properly maintained wiring with properly maintained appliances and labelled outlets shouldn't be a problem at all.


    2. Martin-73 Silver badge

      Re: Is that legal now?

      There is a difference in the wiring regulations between commercial and domestic wiring. Domestic needed all on one phase. Commercial can have multiple phases present even on 1ph only sockets... but labelling is required. Typically a sticker between the sockets saying '415v between', or latterly, 400v between.

  16. Apathy101

    Don't get me started on Architects who know best...

    New school built near me. 2 years after it's built the admin offices flood badly during really heavy rain.

    On investigation it was found that the single 100mm drain in the flat section of roof above the offices that was put in to collect ALL of the water from the surrounding area (~400sq meters) was blocked by fallen leaves. The water had followed the path of least resistance, as it does, into and down the walls of the offices below.

    According the the drawings we had there should have been another external drainpipe running down the outside of the building as a backup. This pipe was conspicuous by its absence. Turns out the architect had removed it as "it spoilt the look of the wall".

    1. Anomalous Cowturd

      Re: Don't get me started on Architects who know best...

      Or the Lidl store near me, that had to be demolished and rebuilt after numerous flooding incidents.

      Must have cost millions.

    2. Anonymous Coward
      Anonymous Coward

      Re: Don't get me started on Architects who know best...

      What would have stopped the other drainpipe from getting clogged up? No one noticed the first until water came inside the building, if it was draining down the other pipe they wouldn't know until it too became clogged.

      It would probably be better as a backup to have an open pipe that drains off the roof directly over the front entrance. Then you'd be SURE to notice the first pipe had clogged up, and get it fixed right away!

      Ought to be easy for an architect to hide a six inch section of open pipe sticking around with some trim detail, or the open mouth of a gargoyle if he wanted to go gothic.

  17. dnicholas

    We had an expensive "consultant" install two new hosts one fine weekend... Both boxes and both of their dual PSUs plugged into the same *unplugged* UPS. They powered on long enough to start all the VMs and then cut them off, un-gracefully, the the MD watching. Magnificent

  18. tweell

    Bigger UPS needed

    I had a remote site that went off-line when the power there was off for an extended period of time, their diesel generator didn't work and the UPS batteries finally ran out. The supervisor there sent an email to all blasting me for having provided a UPS that only ran for an hour before quitting. He demanded a minimum of four hours run time for the UPS. When I pointed out that the equipment was shutting down from overheat at an hour, he demanded that the UPS run the server room A/C as well.

    A UPS that could handle that load for that long was more expensive than a new diesel generator, and would need a building of its own to reside in. When that supervisor continued his demands, we went to upper management and laid out the situation. It turned out that the supervisor was supposed to pay for the diesel maintenance and testing, while IT would have to pay for the UPS. Happy ending, as the supervisor got retired instead of promoted.

  19. Anonymous Coward
    Anonymous Coward

    Bad power setups

    I started work at a company that was running Dell P2800 3U Rack servers x 8 from cheap 4 way extension leads directly connected to the mains!

    I came in one morning only to walk down the hall past the server room to hear...nothing! Oh shit I thought.

    Walked in the server room, (manky old storage room) to the smell of burnt plastic.

    Put my hand under the rack to pull out the extension without killing the power at the plug like a idiot.

    I was so lucky not to have put my fingers in the gaping melted hole in the top of it with the live connectors exposed.

    I went seriously ape shit at my boss and management but luckily kept my job and soon after had 3 phase and a decent UPS installed. We moved office not long after that and I was then involved in the design of the new server room.

    1. dubious

      Re: Bad power setups

      We once had just moved to a temporary site using a particular building for the main servers because that was where the previous occupants had their server room, and it had a genset.

      Shortly after moving, one evening I get a call from my guy covering the late shift that there was a power outage, and although miraculously the vintage generator managed to start itself, both UPSes were screaming about not getting a feed. He'd done all he could reasonably do, including manually switching over to the generator feed, but no joy.

      When I get on site I'm met by my guy looking a little sheepish and a strong smell of burning. Turns out that whatever the previous inhabitants had considered valuable enough to provide generator power to, the server room wasn't one of them. The single plug at the photocopier station just up the hall, though...

      Bless his heart, but he'd strung together 4 or so extension cables and evicted the Xerox.

      Red hot cables, an exciting scorch mark all along and up over the hall walls, and a smoking and now eternally dead socket, plus the knowledge that perhaps the fire alarm should be re-tested but by someone competent this time.

  20. This post has been deleted by its author

    1. Will Godfrey Silver badge

      Re: I know Fuck but I call Bollocks.

      Whatever you do, don't hold back...


      I don't know whether this is completely true, embellished, or a total fabrication, but I've lost count of the times I've heard people say "but that's impossible" or "nobody would do that" - expressions that Murphy up there is carefully listening out for.

      Also, I can easily believe a UPS could destroy itself. Very high power DC systems (which the UPS is internally) are notorious for self destruction. One small design error, or unexpected circumstance can start an arc that simply won't extinguish until there is nothing left to destroy.


      I didn't downvote you.

      1. This post has been deleted by its author

  21. Chairman of the Bored

    Not just failed artists

    Worked on some transmitter equipment made by a left coast firm that likes the color blue (*). REALLY likes the color blue. Every fscking wire and optical fiber in their control racks, hardware, etc is ... blue. Fun to troubleshoot? Not particularly. But another day, another hundreds of dollars.

    (*) Name rhymes with 'ETM Electromatic, Incorporated'

    1. Will Godfrey Silver badge

      Re: Not just failed artists

      Bean counters! Cheaper to bulk buy all the same.

      I once came across a case where it was all a slightly mottled fudge colour. When I told my then boss he laughed and said it was the natural colour of the plastic - to this day I'm not sure whether or not he was pulling my leg.

      1. Martin an gof Silver badge

        Re: Not just failed artists

        Cheaper to bulk buy all the same.

        Was once told a tale of an electronic equipment manufacturer who worked out that it was cheaper to redesign a circuit to use all 10k resistors - including building networks of the things when it wasn't possible to do a simple swap - than it was to buy the dozen or so different values the original circuit design called for. I was told this (IIRC - it's a while back now) by the owner of an electronics assembly business, in the days when surface mount components in "normal" kit were still rare. He was using it as an example of "and then they built it using SMDs and it was still smaller than the original circuit, despite using four times (or whatever) as many resistors" :-)


        1. Chairman of the Bored

          The cult of the small BOM

          All same resistor values... sometimes the manufacturing specialists have a point and we designers can do a better job drawing up something economical.

          Where my PHB have caused me fits though is when a design is right at the hairy edge of possible: high freq, high precision, extended temp range, works to full spec in an EMI hurricane, smaller than any other solution on the market... simultaneously. Loading up the reqs will always drive a designer to use fairly unique parts with aggressive tolerances and perhaps expensive production screening.

          And then when your design is deployed... the PHB will hire a bunch of Bangalore Banditos to "improve the value stream" by simplifying the design and cut production costs.., while still charging clients for full premium spec. This is usually done without informing the design team or customers. Customers become unhappy and quite rightfully demand their due per contract.

          PHB pulls an innocent, "who, me?" "These designers must really suck..." as he sips his boat drink and thinks of all the ho's and blow his bonus will cover.

          1. Martin an gof Silver badge

            Re: The cult of the small BOM

            Where my PHB have caused me fits though is when a design is right at the hairy edge of possible... And then when your design is deployed... the PHB will hire a bunch of Bangalore Banditos to "improve the value stream" by simplifying the design and cut production costs

            A classic case in point may have been the original Chinese-built batch of Raspberry Pis, which were specified with RFI "magnetics" in the Ethernet jacks, but built without them. This caused them to fail their RFI testing and although the Foundation officially called it a "substitution... by accident", it's not a great leap to suppose that someone at the factory specified a cheaper part in order to improve margin.

            At the same manufacturing facility I mentioned earlier, I was there partly to evaluate a piece of in-house designed test equipment that a previous employee had built and nearly got working before leaving for pastures new. I'm sure that at the time he'd had the idea it could have been a good step forward for the company - higher specification and lower costs than the equipment they were then buying-in - but it was built almost entirely out of hand-picked discrete logic, a mixture of 74ALS, 74F and other types which weren't always interchangeable due to extremely tight timing tolerances and would probably have been a nightmare to get "production ready".

            We moved on to other things.


            1. Chairman of the Bored

              Re: The cult of the small BOM

              @Martin an gof - nice! I did't know that rPi anecdote but it seems true to form for contract manufacture,

              Have an engineer similar to the who left you. Brilliant man but cheap (financially efficient). Never can bring himself to throw out any kit, no matter how broken, and of course none of the bustication gets documented or labelled. Cannot be bothered to fix anything because to his mind nothing is ever broken. "This amp oscillates badly, but Ive got this crushed and corroded bit of coax. If I C-clamp it here to move its suck out ... ok! amp plus cable stable. Hey! Gain is now really low, so I sill just delete this attenuator and save a few bucks... Ship it." Im expending large amounts of technician and field support labor dealing with his cheap crap.

              Revenge of the techs? Recently a whole skid of his favorite amps, cables, and broken cal standards 'accidentally ended up on a research vessel... and broke free (in sea state 0)... and fell overboard in really deep water'. I must confess I have a total lack of curiosity about how THAT happened.

  22. Herby

    Three phase power is fun!!

    Some equipment I was with when it was installed in the late 60's needed 3 phase power (before low power stuff) for operation. It also included a nice rotary machine (disk drive) that used three phase power as well. While the techs were there wiring it up, they actually tested to make sure that the phases were in order. They were, and all was fine. Later I found out that the equipment also had a phase sequence detector ahead of the motor relay to MAKE SURE that the phases were in the correct order. Pretty good design if you ask me.

    Oh, yes all the 3 phase circuit breakers had the phases linked so if one tripped, others would as well.

    That was 120-208 'Y' three phase. Then there is 120-0-120, 240, 240 "delta" three phase that has the "high" leg 208 volts above the "neutral" which isn't actually neutral, but the center of the other phase. It makes for interesting wiring if you think it is the other type as you smoke one of the three phases.

    Live and learn.

  23. OzBob

    I hate electricity

    at the best of times, so never f**k with it. So when I switched on a new HP Disk Array in the Data Centre, my co-worker thought it would be fun to pop a large balloon behind me and see my reaction. (which was to call him a c-bomb after my heart rate dropped back down to normal)

    1. Korev Silver badge

      Re: I hate electricity

      HP (RIP) arrays are bullet proof...

      Maybe not those though —>

  24. StuntMisanthrope

    F*** me! I’ll need a screwdriver and an adaptor.

    Sort out your bollocks electrical regulations or wire to UK standard. That’s why the shit keeps failing out of the wall. #itstheampsstupid

  25. The Oncoming Scorn Silver badge

    Bit Late - Anywayssss

    A colleague & friend of mine back in the UK was in-between being a IT guy & general Mr Fixit (Cider presses, old TV's pretty much anything).

    In the time that I worked with him he also qualified as a MOT inspector, he got approached by the architect who drew up his plans for his loft conversion to cast his eye over his design for a new garage & MOT test bay(s).

    He found himself swiftly corrected on his assumption of "It's just a garage!" on at least half a dozen points on what should be where & why, which bays could be used for solely for MOT testing & which ones couldn't.

    Icon because MOT.

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