back to article Lesson 1: Keep your mind on the ... why aren't the servers making any noise?

Ah, dear reader, yet again it is Monday, arriving with the same relentless regularity that has made it the bane of human workers and cartoon cats since time immemorial - or at least the early 1900s. But fear not, for The Reg is here to ease your passage into the working week with another instalment of Who, Me? in which we …

  1. Kevin Johnston

    Been there done that

    Fortunately it was only me that suffered...

    Was doing unit test work on a small weather radar display system and had just checked the HT side of the display was running correctly as 15kV. Got the urge for a coffee so made everything safe and wandered off to get one and once back I picked up where I had left off in the test script. Sadly as we all know following a script does not require thinking to be engaged and I was wondering what that tingling was when I realised I was leaning on the HT lead. I know there was hardly any current but even so I was very very lucky

    1. Korev Silver badge

      Re: Been there done that

      Sounds shocking...

    2. Korev Silver badge

      Re: Been there done that

      I hope you didn't feel to under the weather after the shock...

    3. chivo243 Silver badge

      Re: Been there done that

      The deafening silence of a quiet server room... I experienced that using the incorrect serial cable on a UPS. That's what you get when someone doesn't standardize because it costed a bit extra. Half of the UPS in service were APC the others Eaton.

      1. Marty McFly Silver badge
        Thumb Up

        Re: Been there done that

        > "Half of the UPS in service were APC the others Eaton."

        Sounds like a good way to avoid a single point of failure should one UPS vendor have a product defect. One server power supply to APC, the other to Eaton. Also means two different management consoles, which really makes it tough for the uninformed to 'accidentally' power cycle all the power inputs at once.

        >"I experienced that using the incorrect serial cable on a UPS."

        My opinion...That is different vendors being dicks to each other and the customer getting caught in the middle.

        1. chivo243 Silver badge

          Re: Been there done that

          Good points, but usually either APC or Eaton UPS was in a rack, but since that episode, I've taken to putting the provided serial cable into the UPS serial port it came with, coil it up nicely and attach it with non sticky tape.

          Yes, being dicks, making money off the differences...

        2. Giles C Silver badge

          Re: Been there done that

          Someone recently did that needed to check something on a ups and plugged a standard console cable in, UPS rebooted itself

          Then did a bit of searching and the brand of ups has a known issue that standard serial cables will cause them to reboot, but they don’t put a label on the port to tell the unsuspecting user…. Known as it has been that way for years

      2. Anonymous Coward
        Anonymous Coward

        Re: Been there done that

        I've also been there and done that...

        On my 3rd day of my wonderful new job...

        Fortunately they were all technical and their response was more " That's a stupid bloody protocol".

        Several years later I'm still working for them. They are so much nicer than some previous employers who would be screaming at you

    4. aerogems Silver badge

      Re: Been there done that

      Is that what AC/DC meant with the lyrics to their song Thunderstruck?

    5. Bruce Ordway

      Re: Been there... following a script does not require thinking to be engaged

      I asked a 6 year old on my street a question the other day & this was her reply:

      "I can't think when I'm thinking. You gave me a brain fart"!

      1. Anonymous Coward
        Anonymous Coward

        Re: Been there... following a script does not require thinking to be engaged

        sounds like an early start on a life of 'cant do' excuses , possibly inherited from M&D

        1. Anonymous Coward
          Anonymous Coward

          Re: Been there... following a script does not require thinking to be engaged

          "Can't do it, captain, with the wee bit of engine we have left!"

  2. SVD_NL Silver badge

    All fun and games until...

    "This was done using the time-honored method of jiggling each one until he found both ends. If one end was plugged in and the other was not, that cable could go."

    ...some idiot decides to re-use a cable with a broken clip and you jiggle it right out.

    Dodgy cables are the bane of my existence.

    1. b0llchit Silver badge

      Re: All fun and games until...

      That is why I always cut off the RJ45 connector when the clip comes off. Colleagues have been shouting and screaming at me for doing so, but it is better to have a hard failure than a heisenbug. Change the cable or replace the plug I say.

      1. spuck

        Re: All fun and games until...

        One of my lemmas: "Broken gets fixed; shoddy lasts forever"

      2. WanderingHaggis

        Re: All fun and games until...

        I had one user who found the clips annoying so deliberately broke it off to make it "easier to use". e also complained of having a really bad connection which was how I found out he was modifying the clips.

        1. Prst. V.Jeltz Silver badge

          Re: All fun and games until...

          That is horrifying !

          I wonder if he does that to his car's electrical plugs

  3. Fursty Ferret

    Interestingly, circuit breakers were redesigned some years ago to prevent exactly this scenario and in the event of overcurrent cannot be held closed.

    1. Sam not the Viking Silver badge

      Circuit Breakers

      We had to test a machine driven by a large motor supplied via diesel-generator. The motor-absorbed current when running was a bit less than the 600-A rating of the breaker but the starting current/time were too high/long to prevent a (correct) trip despite judicious adjustment of the 'settings'. These breakers are only designed for a small number of trips on high current so it wasn't something we could 'experiment' with for long.

      My older, wiser, bolder, colleague suggested we reduce the set-speed of the engine, set the AVR (automatic voltage-regulator) low and on manual control, connect and close the circuit-breaker (operating it from an external supply) and start the engine, alternator and motor all together when the loads, voltages and currents would be much reduced. We could then bring the whole set up to full speed within the trip parameters.... It needed good coordination between us and was a bit scary initially, but it worked..... To be fair, we did ask the genset supplier for his thoughts which were initially unprintable but their engineer was curious, pliable, interested and eventually persuaded. He came to see the procedure but stood well to one side with his hands firmly in his pockets.

      We used this procedure a few times until inverter-drives became more available making the process routine by comparison. We would not be able to do this with modern gensets.

      Reward --->

      1. Anonymous Coward
        Anonymous Coward

        Re: Circuit Breakers

        Not quite so complex a situation, but I remember from back in the '70s when we provided control systems complete with UPS's.

        But these systems had massive Drum memory systems (possibly at least 1M) and when these started up they drew a lot of current until up to speed.

        The additional cost of speccing the UPS for the resultant start up current was significant, so someone (not me) came up with the simple concept of adding a resistor into the supply circuit for the Drum; large enough to limit the current by dropping the voltage during start up conditions but small enough not to interfere with normal running.

        It worked. And became a standard fixture.

        1. BenDwire Silver badge

          Re: Circuit Breakers

          That's the same principal of wiring a 100W lamp in series with anything under repair. If the lamp glows brightly then there's a short in the primary circuit.

        2. swm

          Re: Circuit Breakers

          A lot of large squirrel cage motors have resistance for startup which is switched out once the motor is up to speed.

      2. LessWileyCoyote

        Re: Circuit Breakers

        Back in the 1970s, and while it was still in active use, I had a tour of RailMail, the underground rail system that carried parcels and letters between central London sorting offices - miniature driverless trains on a third-rail electrified system.

        The station setup included traction current circuit breakers, which looked like the sort of massive knife switches any self-respecting mad scientist had in his lab in B&W horror films. Below them were kept a massive pair of elbow-length leather gauntlets. I was told that occasionally a bit of metal might fall off a train, or a lost tool be kicked up, and bridge between the power and running rails, tripping the 750v breaker.

        Rather than sending someone out with a torch to search for the offending item, standard operating procedure was to don the gauntlets, close the breaker (with sparks) and hold it closed for a count of ten. Apparently this was usually enough to either knock the offending item off the rails or melt it, allowing operations to continue until close of service when a track walk could be done to find whatever remained of it.

        1. Bebu Silver badge
          Big Brother

          Re: Circuit Breakers - whose turn to be Igor?

          《don the gauntlets, close the breaker (with sparks) 》

          Sounds like that set up would have done Victor Frankenstein proud. ;)

          "Give it more welly, Igor!"

          Personally I would want more than a pair of leather gloves - more in the Darth Vader line or delegate the privilege to one of the more enthusiastic but less imaginative minions.

          1. David 132 Silver badge

            Re: Circuit Breakers - whose turn to be Igor?

            “For the last time, it’s pronounced ‘Fronkensteen’!”

            1. Yet Another Anonymous coward Silver badge

              Re: Circuit Breakers - whose turn to be Igor?

              Froderick ?

    2. ITMA Silver badge

      I don't think the makers of this one received that memo:

      I love BigClive's channel.. ;)

      1. MachDiamond Silver badge

        "I love BigClive's channel.. ;)"

        Clive is great. Sponsoring a meetup with him if I won a lottery is towards the top of the list of things to spend money on. I think I would decline any carbonated Jagermeister.

        1. BenDwire Silver badge

          It's the carbonated Marmite you really need to avoid ...

      2. Giles C Silver badge

        I only started watching him recently and hadn’t seen that video before, it just seems astonishing the amount of work that has gone into making a fake mechanism with the correct feel to the switch and then deliberately putting it in a useless device.

  4. Will Godfrey Silver badge
    IT Angle

    Sequential switches are your friend

    In the dim distant past I worked for a firm that built complete bespoke Audio/Video systems in 6ft racks for people with more money than sense. If the whole lot came on at once it would take out quite hefty contactors, so each rack was fitted with these switchers. For one rather large auditorium we even have to have built a 'slow' sequential switch for the lighting system.

    1. Anonymous Coward
      Anonymous Coward

      Re: Sequential switches are your friend

      Many moons ago, when Fibre Optics was the next-big-thing, some telco guys were tasked to install a fibre node the size of a small fridge in a data centre. Because the kit drew a hefty current at power up the instructions said to carry out a mains test before starting to make sure the mains was up to it. They plugged in their mains tester, hit the test button, which put a spike on the earth pin, and there was silence... deathly silence... well not immediately... deathly silence following the sound of fans spinning down

      For some reason the instruction to test the mains was swiftly amended to 'ensure the customer has had the mains tested by a competent electrician before starting'

  5. imanidiot Silver badge

    One of the more valuable things that learning to fly (unpowered aircraft in my case) has taught me is: Either you finish what you are doing before you let yourself get interrupted or start over from the start after an interruption. There is no in-between solution and getting interrupted is ALWAYS a choice. It's not a choice some people understand but that's their problem.

  6. H in The Hague

    Upstream breaker

    "He'd push the breaker back in, but each time he reconnected the power it popped right back out."

    Many circuit breakers have two trip mechanisms, a fast magnetic one based on overcurrent (which Hans tripped - protects against shorts and gross overloads) and a slower thermal mechanism to protect against limited overloads.

    If you trip a downstream breaker a couple of times on overcurrent then the upstream breaker might warm up and eventually trip. And often you won't have access to it, and it will disconnect more than just your own equipment :(

    1. Sam not the Viking Silver badge

      Re: Upstream breaker

      Oh you've triggered a real memory-storm.....

      The old P&B Golds relays: Thermal and magnetic protection. A masterpiece of manufacture, construction and setting for superb machine protection. Superseded by programmable devices these days. Setting these relays was an exercise in job satisfaction.

      1. Gene Cash Silver badge

        Re: Upstream breaker

        Holy sh*t. That relay is a work of art. And the epitome of steampunk. And probably very expensive. And I really really want one for the "something cool to look at" factor.

    2. Anonymous Coward
      Anonymous Coward

      Re: Upstream breaker

      Here's another thing that can happen: if you have a fairly large overload on some undersized wires, the circuit breaker can trip on the "slow" curve. You stubbornly reset it a few times, not realizing that the pvc insulation is getting softer and softer each time, untit its soft enough that the wires touch and your heavy load becomes a dead short (testing out the fast response part of the I²t curve)

      Anon because I still won't let certain techs work on some equipment around here.

    3. Giles C Silver badge

      Re: Upstream breaker

      Or they install the downstream breaker as a 100A one and feed it from a 40A breaker…. Yep took the complete comms room on a building out, until we found the problem, then had to go back into the dark comms room (no emergency lights for some reason) turn all the breakers off in the room and power them up sequentially so we could have the site running until the weekend when the electrician came in and fixed stuff….

  7. Anonymous Anti-ANC South African Coward Bronze badge

    I hate it when people interrupt me in the middle of something.

    This means that I have to start from the beginning, or sit for a long while staring into space wondering where I was before the interruption.

    Some days I just get so disillusioned with the interruptions that I go for a walkabout, just to clear my head.

    1. ChrisC Silver badge

      One of the many benefits of WFH is the ability to control such interruptions exactly according to YOUR present working state, rather than having to put up with how much OTHERS might be desperate to interrupt you...

      1. The Oncoming Scorn Silver badge

        One of the many reasons I script things, so interuptions don't disrupt my thought\task process & that things are done consistantly.

        1. MachDiamond Silver badge

          "One of the many reasons I script things, so interuptions don't disrupt my thought\task process & that things are done consistantly."

          It's great if you can do that and it's something that should be taught in school. Other times when the task is much more creative, it's much harder to work efficiently if interrupted a lot.

          I had a great mentor/boss years ago that taught me a bunch about planning. It was a home theatre/electronics company and we were often in the field. A big issue could be leaving parts or tools behind at the shop and not being able to complete a task. Before we left for a job, we had a list of tasks that we needed to complete and would sit quietly and walk ourselves through the process and make written notes on the parts and any special tools we might need. The time spent was much less than having to revisit a location to complete something or have to knock off early before getting all of the tasks planned done and dusted. Those lessons have been very useful for decades.

          1. Anonymous Coward
            Anonymous Coward

            A previous job involved some writing of procedures for technical work. One of the sections I always put in was a list of the tools/materials that would not normally be found in the tech's bag, for this very reason.

    2. getHandle

    3. bjzq888

      I just left a job a few months ago for this very reason. My coworker would bother me at all hours of the day, whether or not I looked busy, or whether or not I was on the phone. Even when on the phone they'd come over and tap me on the shoulder until I answered. It wasn't earth-shattering problems, either, it was things like "What's the command line name for Windows user manager?" "How many kilobytes in a gigabyte?" I was in the midst of doing things like setting up 802.1x or working on a database that wasn't running properly. It was getting to the point that I couldn't get anything done myself. I told my boss but he said I had to just deal with it. Well I did, and I quit. I'm at the point in my career that I don't have to put up with their BS. I put up with it for years, and now I don't have to, and I'm not going to. It's not worth the years off my life that it was taking.

      1. A.P. Veening Silver badge

        How did your boss react to your solution of the problem?

        1. Rich 11 Silver badge

          Do we give a shit what the boss thought?

          1. A.P. Veening Silver badge

            His reaction might cause us enjoyment (Schadenfreude).

      2. MachDiamond Silver badge

        " Even when on the phone they'd come over and tap me on the shoulder until I answered."

        --------Hmmm, I'm not sure, you should ask the supervisor/manager.

        Either that or give them a wrong answer if you wouldn't be in the line of fire from the shrapnel. The same thing you'd do if asked to train your replacement after being made redundant.

      3. ChrisC Silver badge

        "Even when on the phone they'd come over and tap me on the shoulder until I answered"

        Unless the co-worker was genuinely unable to understand why their intrusion, not just into your overall working zone, but specifically into your personal space, and specifically specifically actually engaging in unwanted physical contact, was an no-no, then this 100% should have been something your employer took seriously. And given the way your boss actually responded here, it sounds like getting outta there ASAP was probably the best move you could have made regardless of what prompted it, because if that's their response to something like this, what other workplace issues might they be equally dismissive of.

    4. TheMaskedMan Silver badge

      "This means that I have to start from the beginning, or sit for a long while staring into space wondering where I was before the interruption."

      Sounds about right. I recall reading some research a few years ago (can't remember where, unfortunately) which suggests that a programmer who is interrupted while deep in concentration can take up to 15 minutes to get back in the zone once the interruption is dealt with. The same presumably applies to writers, composers and a whole bunch of others. There's a lot to be said for coding through the night, while normal people sleep!

      1. BenDwire Silver badge

        Amen, Brother. Add PCB design to that list.

        Long before COVID normalised such things, I used to take a day out of the office and worked from home if I had a tricky circuit board to lay out. The truth is I would sit up half of the night getting it done with zero distractions, then spend the next morning catching up with my sleep. My closest collegues knew not to ring me before lunch, even if it was urgent...

      2. MachDiamond Silver badge

        "There's a lot to be said for coding through the night, while normal people sleep!"

        When I had a manufacturing company, I would get a lot of my work done after 5pm. At that point I could ignore the phone, faxes, email (eventually) and people knocking on the door. I was also the chief design engineer which was something almost impossible to do during the day.

    5. Muscleguy

      Yes, Saturday morning in the charity shop. I had to log our first big delivery of Xmas cards (I know, I know). The delivery note and the delivery were at strong variance. One type of card should have had 10 packs, it had 40. Some were completely absent, others short, some like the first had extra.

      I was sitting with the sheet and my phone calculator adding the columns up, I got interrupted twice, so had to start again. So many 10's and 8's. I eventually got it down in time for the end of my shift. Boxes of cards some put in any old way. It was be methodical or don't bother. Why they gave the job to me.

      Oh yes some cards were three in this box, two in this one, three in that one. I was running sub totals on the sheet.

    6. MachDiamond Silver badge

      "This means that I have to start from the beginning, or sit for a long while staring into space wondering where I was before the interruption."

      This is also why working in an office can be inefficient depending on the sort of work you do and how much outside input you need.

      I love the line from a Nik Kershaw song, "I'm sick and tired of answering the call of Alexander Graham Bells's invention". It made me stop and think and come to the conclusion that a ringing phone can be ignored (or a text, etc). At the time I had a phone answering machine so if it was important, the caller could leave a message. If they didn't leave a message it wasn't important and likely spam.

      I hated it when I got into a flow designing something and a coworker would bother me with a question they could have found the answer to elsewhere. It was 10 minutes or more before I could get back to the same level of concentration. At the end of the working day I'd make notes to help me get started the next morning or I'd effectively knock off when I hit a natural stopping point and fiddle around filling out my work journal or a bit of documentation.

      1. spuck

        My office whiteboard is the place I put down things I think of while the day goes on, for me to remember tomorrow morning what was important today.

        +1 for your epiphany of being able to ignore a ringing phone. My dad will never let a ringing phone interrupt him. His motto is: "I got it for my convenience, not theirs."

        I'm If it's important, they will leave a message or try again. I've had to learn that lesson again now that everything is instant messages and Slack...

        1. MachDiamond Silver badge

          "My dad will never let a ringing phone interrupt him. His motto is: "I got it for my convenience, not theirs.""


  8. TimMaher Silver badge

    What is the worst sound in a server room?

    No sound at all. Bah boom!

    (How often have I posted that here?)

  9. Ian Johnston Silver badge

    The idea of holding in a breaker to stop it doing its job reminds me of the old southern US steamboat ballad "Jim Bludso" which mentions "A (no longer used racial epithet) squat on her safety valve".

    1. Muscleguy

      My Pa used to be a mechanical engineer for NZ Rail. They had a problem with the drivers putting their lunch tins or a brick on the dead man's switch they had to keep a foot on.

  10. Korev Silver badge

    Did the WAP phones support Hans-free?

  11. IJD

    Not an unplugging story, but an idiot student story with very much the same effect...

    The heavy electrical engineering lab at Cambridge had a massive paired 3ph AC motor-generator set used for efficiency measurements -- the kind of thing where each one is maybe 4' diameter and 6' long, can't remember the exact power figure but at least 1MW each springs to mind. The idea was to use the motor to power the generator with both connected to the mains, which therefore only has to supply a few percent of the power -- for example 1MW into the motor and 950kW back out of the generator means only 50kW net load.

    All fine until some numpty student had a bright idea while running the test -- "Hey, I wonder what happens if I reverse the field coil polarity?"

    <dumph> all the lights and lab equipment go out. As does the whole of the engineering labs. As -- so I was told -- did a large part of East Cambridge.

    Cue Bill -- the guy who ran the lab -- running into the room screaming "Which one of you f*cking morons reversed the field coils?!?!?"

    1. DJV Silver badge

      Your student wasn't called Jon Pertwee, was he? Or was that only for neutron flow polarity?

      1. IJD

        He was a fellow student, not one of mine. And no, it wasn't me, but even after 45 years or so I'm not going to name him just in case he's still around in the industry... ;-)

    2. ChrisC Silver badge

      Ah, the electrical engineering labs, full of weird ancient looking pieces of grey metal-clad kit controlled with bakelite knobs, just begging to do you a serious injury if you so much as look at them in the wrong way...

      As an E&EE graduate whos career path has taken me entirely down the "electronics" side of my degree, I'm not in the least bit sad about having left the "electrical and..." side well behind me as I walked out the faculty doors for the last time, though my time there has left me with a lifelong healthy level of respect for anyone with the right mindset to make a living out of working on that side of the subject.

      1. Sam not the Viking Silver badge

        And realistic reckoning on 'earthing'.

        1. BenDwire Silver badge

          Or 'Well Grounded' as some might say :-)

      2. Death Boffin

        Going south rapidly

        The electronics side can have a lot of excitement too. A 30kV 100mA magnetron supply failing provides plenty of fireworks.

      3. NXM Silver badge

        electrical avoidance

        My old power lecturer (whose stories, as I've mentioned previously, always started with 'When I used to work for the SWEB') used to say that if you didn't know where the root 3 goes, you shouldn't be doing power engineering.

        So I didn't, and concentrated on digital electronics. The world of power engineering was safe as a result.

        1. H in The Hague

          Re: electrical avoidance

          "if you didn't know where the root 3 goes, you shouldn't be doing power engineering."

          Root 3 I can cope with. It was root -1 that always put me off electrical engineering. Imaginary numbers being ... well a bit beyond my imagination.

    3. spuck

      I bet the lesson didn't need to be taught again!

    4. Martin Summers

      I was always taught that reversing the polarity would get you out of trouble.

      1. Anonymous Coward
        Anonymous Coward

        Ah, the Star Trek lesson.

  12. chivo243 Silver badge

    Was this in The Netherlands?

    He could have been Tweede Hans!

  13. aerogems Silver badge

    Sounds like BOFH material

    This story sounds like it'd be good inspiration for a BOFH story or two. I can think of at least two different ways to go with it.

    1: Simon sends the PFY in to perform a similar task, but the PFY just starts disconnecting everything in sequence and if someone comes to investigate then obviously it was being actively used, and then maybe finds a way to extort some cash out of fixing it.

    2: They start disconnecting things under the pretense of "fire safety" or "preventive maintenance" and then extort a "expedite" fee out of different departments to make sure to test their stuff first, then they just spend the day drinking in the server room, or using the opportunity to mine systems for any incriminating information they could use for a future bender.

  14. Boris the Cockroach Silver badge

    The distraction

    in my game can be ........ expensive

    As it all too easy to be deep in thought staring at the computer screen as you build the mental model of what you are doing vs the physical model of the clamps/robot arms/tooling trying to hold said mental model and some idiot demands your attention with a trivial thing that they could have solved for themselves, thus the mental model disappears while you deal with the trivial.. then with the person, and try to get your mind back to where it was.

    However you've forgoten clamp B and decide to send the tool straight through it thus releasing the part from the fixture with the result the part gets stuck on the tool, spins upto 6500 rpm before making a rapid exit from said machine, flying across our carpark, into the neighbouring unit's car park and imbedding itself in their front door.....

  15. MachDiamond Silver badge

    Tabla Rasa

    I've often found it better to completely tear out the old and install the new rather than trying to use something existing "to save time/money". A couple of buildings I leased had the old 25pr cabling for a 1A2 phone system that nobody bothered to remove long after it was deprecated. One place was using pairs for this and that and I have to admit that in those cases it might have been more expedient to do that than run new cabling. I just asked for early entry to the building to get power and low voltage stuff all installed and ripped out the previous old wiring. When we made our big move over a weekend, the phones, computers and machinery all worked right away. A bit of forethought and planning goes a long way.

    1. phuzz Silver badge

      Re: Tabla Rasa

      So you prefer to take the sensible, forward-thinking, approach to problems? Clearly not management material!

      1. MachDiamond Silver badge

        Re: Tabla Rasa

        "So you prefer to take the sensible, forward-thinking, approach to problems? Clearly not management material!"

        I prefer to work for a living. Odd of me, maybe.

        The non-technical person/bean counter will think, "Hey there's some wiring already there, why can't we use that and save some time/money?" Somebody who's been to a few rodeos will start backing away slowly and figuring out a way to get all the work done when management isn't looking.

  16. DS999 Silver badge

    I'm surprised his work went that well

    I would have assumed it would be impossible to dislodge all the old unused cables without tugging loose cables that were in use all too often, so having only one unplanned outage during the entire win is a huge win in my book!

  17. Richard 12 Silver badge

    The timeline doesn't add up

    It's not been possible to "hold in" a circuit breaker for a very, very long time.

    Post 1920s or so they were only for military and similar operations where risking a fire is considered acceptable due to the risk of (eg) being fired upon.

    It is rather unlikely that a civilian WAP install in 1999 would have anything like that.

    Fusewire was still in use, though one would hope any sparky who survived their apprenticeship would refuse to do the screwdriver bypass and suggest unplugging some of the load instead.

    1. katrinab Silver badge

      Re: The timeline doesn't add up

      My residential circuit breaker can be "held in", and I do need to hold it in for about a second after a power outage because the initial in-rush current of all my stuff is more than it is rated for.

  18. Anonymous Coward
    Anonymous Coward

    what kind of

    Crappy breaker doesn't pop if you hold the button?

  19. Anonymous Coward
    Anonymous Coward

    we used to run a sound system on a fairground ride (the sound system took a lot more power than the ride) and the inrush current of the amp powering up was on the limit of the breaker, this meant that depending on what part of the sine wave the mains was at when you switched the amp on it would either start up perfectly or trip out the entire ride, if it tripped you could usually get it running on the third reset (as each attempt charged the capacitors in the amp a bit more until there was little to no inrush current).

    if it stayed powered for more than 0.5 seconds it would stay on for the rest of the day.

    1. Anonymous Coward
      Anonymous Coward

      A buddy of mine and I built a railgun for a high school physics project. (No, I am not making this up, and I have photos to prove it.) We built a capacitor bank out of electrolytic caps harvested from used disposable cameras, soldered to two rails. (Not the launch rails.) Power was a bridge rectifier with DC side to rails and AC side to an extension cord, plugged into the wall at 120V. Sometimes the first plugging-in would trip the breaker from the inrush current, but the second would hold since the caps were partly charged.

      Apparently we soldered on exactly one backwards; when he powered it up the first time, it blew its lid with a couple-foot jet of flame. 150 caps, 150 uF each, 120V is a LOT of power.

      (First attempt spot-welded the ball bearing to the launch rails, which were made from copper grounding rod. We sanded the chrome off the ball bearings for future tries.)

  20. Elongated Muskrat Silver badge

    This doesn't sound real

    A server room with windows? Pull the other one...

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