How would you recommend people working on their own house implement anything more than turning off the circuit breaker? (I'm not doing anything electrical in general, but sometimes small fixes are necessary for home owners.)
You can and should use a test light or DVOM to verify the power is out.
You can and should treat the wires as if they were "hot" anyhow. You should keep a wire nut on the hot wire. Don't actually put any of the wires in your teeth.
Now. You could do all that, but what I do at home is carry a lot of insurance and work "hot". I don't care about 120V or even 240V. I make sure what I'm touching one arm at a time with no ground path through my heart. Don't stand in water. Simply just don't touch the hot wire. I learned to work hot on a piecework job that payed by units completed and that was about 1000% more if you could work hot. And, you can, if you manage the risk. If you mess up 99% chance you'll say "OW" and NOT do that again. I wouldn't play Russian roulette with 1:6 odds. But 1:100 (die from) x 1:100 (mistake) x 10 hours per year (occasional fixes), fine not worth the bother. Far more chance of dying falling off the ladder than electrocution. DON'T stand on rolly chairs.
Now at an uncontrolled job-site, where I'm payed by the hour, 2000 hours/year? NEVER. It's a lot different when you are a company of one vs. many. I know what I'm doing, and while I make mistakes, I can guess how often. If you have more than 0 co-workers, you cannot trust or predict their mistakes.
https://www.amazon.com/dp/B004J173I8/ref=twister_B007NAGJJG?...
Personally, I just lock the panel.
If your panel can't be locked a big piece of masking tape across the door, holding it shut, with "NOPE. call <you>" written with a sharpie should do the job. :)
FWIW, the first photograph in that WP article with the tagged panel is one of mine... from close to 15 years ago.
If you want to get fancier or if others are going to need to access the fuse box while you're working, you can get "lock dogs" which let you lock individual circuit breakers. Then you just lock off the one for the circuit you're working on.
- Switch off (at circuit breaker)
- Prevent switching on (lock the breaker)
- Check voltage free (multimeter cleared for 230V/120V operation with long, isolated test leads)
- Ground and short (put a plug into the socket connecting earth, live and neutral, you can DIY that at home safely by cutting open an unused cord and soldering all three wires together)
- Cover nearby powered equipment
Hmm. Given that breakers in the US don’t disconnect the neutral, grounding the neutral can introduce potentially unpleasant stray currents.
On the flip side, as far as I can tell, it’s entirely possible for a code-compliant installation to give you a moderate zap if you touch the neutral with the breaker off: if you have a long feeder to the panel, and someone turns on a big, single-phase load on a different breaker, the voltage drop on the feeder neutral could zap you. Imagine a 50A inrush current a across 1 ohm. That’s 50V for a few cycles.
(From experience, 50V AC won't kill you unless you are standing in a bathtub and covered yourself in conductive gel, you'll just get some minor pain in most cases)
Hmm. Are phase-to-neutral loads permitted? If so, does this mean that the building and ground are allowed to carry neutral currents? This seems like a bad idea.
I’m not an electrician, but I’ve seen enough problems caused by “objectionable current” (the US code name for currents through what is supposed to be ground even in the absence of a fault) that I think that neutral should be treated as a hot wire whose voltage to ground just happens to be quite low. This would involve all breakers switching the neutral as well as having a reliable mechanism to detect neutral-to-ground faults.
Newer US GFCI devices are supposed to detect neutral-to-ground faults, so that’s a start, but I don’t think any of them will actually disconnect the neutral if such a fault is detected. They do this by inductively coupling a low voltage 120 Hz common mode waveform on hot + neutral, or maybe just on neutral. It’s a cute trick.
We use the TN-C-S system, wherein before the GFCI you have 3-phase with a PEN that is shorted to ground when it enters the building, then it is split into PE and N wires. The GFCI is 3-phase with only 1 phase being put into the building (usually, though multiple phases aren't uncommon in larger housings). The PE wire is connected to the heating system and various other ground potential points (either to provide ground or obtain ground potential). The N wire is shorted to PE before entering the socket (or the socket itself shorts these two). Once it leaves a socket the entire thing becomes unpolarized, so to speak, so devices after the socket can't short PE and N without polarized plugs.
This avoids problems with the inrush since the inrush voltage against ground will be grounded away shortly after entering the socket (and trip your breakers). It also means that it's less likely that a single broken wire results in the entire GFCI becoming useless, though if neutral is broken it can become somewhat dangerous (but the device stops working).
Shorting the neutral to ground as well as hot has the benefit that under fault conditions the neutral wire can become electrically hot and if there's a miswired circuit that has current passing through it shorting it to ground would prevent a shock hazard from forming when you disconnect the neutral wire.
In the Real World, you’ll just tell your wife/kids/roommates “Hey don’t touch the fuse panel until I’m done doing this thing” and it’s not an issue.
https://youtu.be/fUAIBZKeK74 For the Dateline Special.
Tell the other inhabitants what you're doing and tape over the breaker with a note saying to see you before it's turned on.
Sure you could stick a padlock clasp on the breaker box but when your job-site has a number of people you can count on one hand a note will have 99.99999% of the same benefit and if they're trying to recklessly kill you all a lock does is buy a little time.