Re: Was going to say the same thing
> power must originate FROM the box, not the light fixture!
Never saw that in NEC. It is quite normal to run power to a lamp fixture, then go on to a switch. There is even a note about doing this in pre-made cable: neither conductor is the 'neutral' so you mark the white with black (since the 1980s).
> two phase pool filter pump motor on a pair of single 120 volt phases
In days of fuses, that's the only way you could do it. I worked a school building that was all fuses on KNIFE SWITCHES. The white wires become redundant but that's not unsafe. --- ah, that was all 3-phase, except the kitchen range, which was a 230V split fed from 2/3 of a 208V 3-phase feed. Converting from fuses to breakers took over 80 years, but was a simple 1-for-1 change.
Yeah, box-less twist splices in hidden spaces, bathroom fluorescent started better if you touched it (no ground), lampcord run through floor "temporarily" (both my uncle and me). My parents house, the clothes dryer had been tapped -ahead- of the main fuse.
> electrical wiring in commercial construction (in the US in recent electrical code at least) is protected by metallic conduit.
Iron conduit goes WAY back, to the first electrical fires in NYC and Chicago. Places where your mistakes will have huge consequences: commercial/industrial but also side-by-side residential. Conduit starts from Gas Pipe (why the fittings are threaded) though thinwall has taken over all but the most violent situations.
> the 7200W hob was connected to the wall socket using a poundland kind of plug, instead of being directly connected to a junction box.
?? In the US it is normal to use a very large plug on 30A, 40A, and 50A appliances, particularly if they need to be moved for cleaning. No, not a "poundland" item, the plug is $20 or more.
> too important to use the kettle in the kitchen and brought their own kettle into the office ...with the inevitable fuse blowing results.
That same school building was wired for candles. Maybe one power outlet per room, and maybe 20 rooms on a hallway fuse. When electric kettles got common, the profs liked a spot of tea between classes (so, all the same time). They could use two in one hallway, the third would simmer for a few seconds and then the fuse failed. This was "solved" with resettable circuit breakers. In locked cabinets, but the locks soon "broke". When young they would hold three kettles for just long enough but a fourth forced a walkaround to reduce the load and then a reset. After a while that was not needed: these were the notorious (low price) Federal Pacific breakers which stopped breaking if tripped too often. I've seen that panel too hot to hold, the smell of old cloth insulation charring...
> use their reciprocating saw to cut through its own power cord.
That's not even exciting. I had a friend, every time I went over I brought the black tape and patched-up his tool cords.
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My "Ooops!" story is: needed to bring network coax(!) into the conference room, through a foot of soft masonry. Picked a spot outside the very wide door trim. I checked both sides of the wall noting a telephone cable tacked to the molding. Nevertheless I drilled the cable dead-center (I'm so talented?). 50-pair cable. Not only knocked-out most of the phones in the building, it soon turned out that splicing the damage did not fix them all. (This phone system so old that there were fuses in a locked closet.)