[klyrs]

Alternative lessons:

1. Save your progress to disk periodically -- for a genetic algorithm, that will be the seeds passed to the next generation. That way, you'll only lose one generation if you need to unplug your box. As a programmer who does any amount of research, this is a superpower. Godliness is achieved when you automatically commit this data, summary metrics, and the code that generates it into a git repo.

2. Invest in a UPS. If you need to do a project that will take longer than your UPS will last, you can just move the box & UPS onto another circuit.

But, yes, be careful with electricity. Lessons from my grandpa, who survived all of his live-circuit edits and died of lung cancer:

3. Wear rubber-soled boots.

4. Keep one hand behind your back.

5. Use rubber-handled tools and do not touch the metal bits.

6. If a ladder is necessary, it should be non-conductive.

7. Equip your child with a 2x4 and give them the instructions to pry you away from the source of electricity with that, and to not touch you under any circumstances.

[segfaultbuserr]

You missed the most important safety precaution.

0. Get a non-contact voltage tester. Always assume mains wiring is dangerous, unless it has been checked. And always assume the voltage tester is lying to you, unless you've verified it at a known live wire at the beginning of your work.

The final event that led to the accident was,

> so I figured that if I instead just turn off the lights, then even without flipping the breaker for that room

If a non-contact voltage tester was used, it could be prevented.

Turning off the light switch without flipping the breaker can be safe if there's no energized wires nearby and no miswiring.

[janzer]

Also of note is that in some regions it is apparently common to run the power to the fixture itself, then extend down to the switch. Which means there will always be hot wires at the fixture unless the circuit is shut off.

My experience with this comes from people who were from the southern US and who found it very weird and even at first insisted it was "wrong" to run the power to the switch then to the fixture. My theory on where this comes from is that this is a result of most homes in that area being built on slabs and so the power feeds are generally run through the ceiling. Whereas locally most buildings have basement/crawl spaces so the power feeds are generally in the floor then run up the wall to the switch and extend from there to the fixtures.

[wankeler]

Standard approach in UK too, though power to switch us increasingly common to support smart switches that need a neutral.

[nucleardog]

Addendum to your point zero—test against a known live wire before _and_ after if you want to be really cautious. It’s possible the tester failed after your initial test, but before you checked the wire you actually wanted to test.

For example, imagine some batteries on the verge of death. They may keep enough charge initially to test right after being turned on but quickly die before you get to the actual wire under test.

[klyrs]

Hmmm... this sounds suspiciously close to "good" advice. I'm sure my grandpa would have done a spark test with the shaft of a screwdriver.

Personally, I take a radically different approach to household wiring: hire folks who know better than gramps.

[segfaultbuserr]

I'm not sure why you would think that my suggestion is "suspiciously good". Your suggestions included rubber boot or keeping one hand behind your back, which are what a grandpa would tell you as precautions when working on a potential live circuit. And my suggestion to double check whether a circuit is really dead before working under such a "deadly" assumption is arguably more important.

> Personally, I take a radically different approach to household wiring: hire folks who know better than gramps.

I never suggested otherwise. In a qualified household wiring, all switches are correctly wired, thus turning off a light switch and touching an exposed wire is as safe as turning off the breaker. And there won't be hidden junctions in the walls waiting to be burned up. And a single earth leakage doesn't kill the power of an entire home... - these properties are what you definitely want.

My point is not to assume anything while working on an existing system. I test live voltage even before I replace a lightbulb - you don't have to mess up the entire wiring of your house, a single miswired light socket can be just as dangerous. Fortunately, so far I've never encountered a single case where the light socket is live after opening the light switch, nor a single case where the metal thread of the light socket is live, which gives me confidence that the wiring at my home was probably in compliance. I simply don't assume.

[klyrs]

> I'm not sure why you would think that my suggestion is "suspiciously good".

With comedic intent. I don't want to give folks the impression that grandpa's advice was good.

[heelix]

I remember being in the attic with my Grandfather. He touched a bare wire and said something like 'wooee - That was 220.' I figure I've drawn heavy out of the luck bag already in my life with electricity.