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Comment by dhosek | Hacker News Reader

A few years back, we hired an electrician to do some relatively small things for us—things I could do like replacing light switches with timer switches and the like, but didn’t have time to do. The thing that really blew me away was when I asked him if he wanted me to shut off the power at the breaker box and he said no and did all the work with live current in the wires. Yes, I know, gloves, rubber soled shoes, he was fine, but it still was somewhat terrifying to watch.

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I know some electricians who would call this man an idiot. PPE is for when a hazard cannot be avoided, which in this case it could easily have been avoided. Though of course the safety culture and laws differ from place to place.

Shut off the breaker? Oh, don't worry about that. If I need it shut, I will just touch the stripped end of this white wire, to the stripped end of this black one! Saves a walk to the breaker! But would you be a dear and reset it for me?

From the perspective of many electricians, "high voltage" doesn't happen until ~600v.

that's medium voltage. High voltage is over 15kV. Low voltage is usually 50V or less, at least in MEP electrical parlance. So there's a gap from 50V-600V that doesn't really have a clear name

In Europe anything below 10kV is low voltage because 10kV is what feeds the 380V 3-phase distribution transformers that then feed single 230V phases to residential/office.

Have done this too (and am not a professional electrician either) --- you use insulated tools and make sure you stay out of the way of any possible current paths.

Why not just shut off the breaker though? What’s the harm in that?

Live feedback without additional expensive and buggy test tools. May be marginal, but if you are trying to guarantee a certain income/payrate, it’s easy to take shortcuts in a system you’re comfortable in.

For effect. You want the client to feel that they got their money's worth and it wasn't something they could have done themselves.

Other devices on the same circuit that I didn't want to disturb.

Like what? A deep freeze? Genuinely curious. If this were commercial it would make more sense.

How do you know it’s installed right without putting power through the thing? You’re going to turn the breaker off an on for every single switch? NOPE!

Flipping the breaker for each circuit as you start and finish working on it sounds eminently reasonable

It’s more terrifying to see anyone point a metal tool toward an open breaker panel.

Not an electrician, but I did some when younger. And did it unknowingly at least once, when the other guy on the job cut power to the wrong circuit. My father would do it routinely.

Critical caveats: Residential 120V/15A, familiar wiring, dry wood frame buildings, proper equipment, and we knew what we were doing. If you can't tick all 5 of those boxes, my advice is that you hire an electrician to do the work.

Also the fault current is really low at these locations. My electrician shorted 2 wires together in my garage to avoid having to go back to the panel and shut it off. Try that right by a big substation at 480V and you would not be doing great.

You are correct that 120V/15A has very little potential for arcing that would be directly dangerous to you, and I've also known an electrician or two who used that method.

But I really wouldn't recommend doing that. There's a wide and complex canyon of consequences between "that little blue arc won't hurt me" and "triggering a fault current will not damage anything, anywhere, either short- or long-term".

> Yes, I know, gloves, rubber soled shoes, he was fine, but it still was somewhat terrifying to watch.

What gloves? For 110V? Bah!

Unless you’re a complete idiot and try to cut both wires at once with a conductive cutter, nothing happens when you snip them one by one.

And selection bias means we don’t see those guys around for long.

1. you can definitely get electrocuted snipping a single wire with insulated ppe, just brushing up against a wall can form a circuit.

2. You are thinking of survivorship bias, selection bias is a different thing.

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