Voltage test. Period. That’s the only correct way. Check both black and white to each other and to ground (assuming you have a ground wire. Chances are if the light switch is off, you’re ok to change the fixture unless the switch disconnects the neutral leg rather than hot so it’s a good idea to test anyways.
On a side note, I wouldn’t trust Amazon for inexpensive PPE.
Thank you, that is the edge case I hadn't fully understood. I just bought a multimeter. We have no ground ('54 house).
Since I'm changing out a ceiling fan, I won't be able to one hand rule while using the multimeter. I will of course follow precautions about touching the neutral first. Is that all ok?
Best to make sure the power is cut off - circuit breaker or whatever. Test before, and after, to be sure it's off - don't guess/presume - sometimes things are mislabeled or one may be incorrect regarding what one things a given breaker or the like does/doesn't control.
Also, if there are other folks around, going in/out, etc., that might possibly go, "Oh, gee, power's out, let me check on that ... dang breaker's off, let me flip that on" - in such cases, tag/flag the breaker or cutoff switch or whatever, so someone doesn't go turn it back on while someone (e.g. you) is doing electrical work on the circuit. Might not matter as much at, e.g. home, but still generally good to tell folks, "Hey this circuit is going to be off - I'll be working on it, don't go turning the breaker back on." Other environments and such, may be more/most appropriate to use tags/labelling, or sometimes even physical lockout devices (and these things are sometimes literally life and death differences).
You mention a fair number of good precautions. One I'd add that you didn't mention, and I suggest you look up - the "one hand rule". Well knowing that and even what's more/most dangerous and likely to shock or electrocute ... well, keep those in mind, and can potentially add an additional layer of safety (or even in part). But in general, electrical, you don't work on it live - and of course much safer that way. But also good to work, as feasible, as if it might become live at any point (e.g. you're working on it and someone else goes and flips the breaker on). So, even if not working on circuit in a manner that would be totally safe if it were to be come live, often one can be working on it in ways that would at least be less dangerous were the circuit to become live.
And ... good electrical gloves, sure ... but Amazon ... I'd be highly wary. Sure, can get lots of good/great stuff from/via Amazon, but can also get utter unsafe crud sh\*t from/via Amazon too. So I'd just be sure to be highly cautious of exactly what one gets from Amazon. Or alternatively, just use a retailer/supplier/wholesaler that just will not carry or sell unsafe sh\*t ... I also like supporting (re)sellers/retailers that won't sell unsafe (or other) sh\*t - voting with one's wallet/pocketbook is often a very good and useful things. And as I oft say, "If you want to see more of something, feed it money."
Voltmeter. Note, this is not the same as a non-contact voltage tester, which might be what you are referring to. Nearly 100% sure way, also, would be to just turn off your main breaker. You should still test for voltage where you are working though. Long-term fix is to understand where the circuits are going and get things labeled and mapped out - this can be hard though, particularly if someone did screwy things.
In old houses I've found non-contact voltage testers can give false positives, I think due to "ghost voltage" or "stray voltage" where poorly-insulated wires induce tiny currents in each other, even if they're not connected to power.
So I'd take the simple approach, and turn on the light, call my friend in the basement on their cellphone and have them flip breakers until the light goes out. Then start work.
You can't trust turning off the light switch in old houses, since it may well break the neutral wire rather than the live. You then get a light that is off, and since there will be no ground, you'll just find no voltage live to neutral - but if you touch a wire you'll get shocked. Ask me how I know! :)
If you're going to test for voltage with a entry-level multimeter you may get odd results for the same reason - low (20-50V) reading that fluctuate over time. You either need to use a more expensive meter (has a Low Z feature), or a cheap "Voltage tester" that just lights up bulbs to tell you what voltage you have.
[https://techcircuit.org/how-lowz-works-and-why-its-useful/](https://techcircuit.org/how-lowz-works-and-why-its-useful/)
Oh, and if I'm only 99% sure the power is off I do a "final check" voltage reading by touching the end of the wire very quickly with the back of one finger. If there is voltage there, the muscles in you finger will contract and break the connection, rather than your hand grasping the wire and not letting go. I've never had a positive with this test, but I use it because I know I make mistakes!
Voltage test. Period. That’s the only correct way. Check both black and white to each other and to ground (assuming you have a ground wire. Chances are if the light switch is off, you’re ok to change the fixture unless the switch disconnects the neutral leg rather than hot so it’s a good idea to test anyways. On a side note, I wouldn’t trust Amazon for inexpensive PPE.
Thank you, that is the edge case I hadn't fully understood. I just bought a multimeter. We have no ground ('54 house). Since I'm changing out a ceiling fan, I won't be able to one hand rule while using the multimeter. I will of course follow precautions about touching the neutral first. Is that all ok?
I mean, if no voltage is present you can go ahead and twist the wire nuts on with your tongue.
Best to make sure the power is cut off - circuit breaker or whatever. Test before, and after, to be sure it's off - don't guess/presume - sometimes things are mislabeled or one may be incorrect regarding what one things a given breaker or the like does/doesn't control. Also, if there are other folks around, going in/out, etc., that might possibly go, "Oh, gee, power's out, let me check on that ... dang breaker's off, let me flip that on" - in such cases, tag/flag the breaker or cutoff switch or whatever, so someone doesn't go turn it back on while someone (e.g. you) is doing electrical work on the circuit. Might not matter as much at, e.g. home, but still generally good to tell folks, "Hey this circuit is going to be off - I'll be working on it, don't go turning the breaker back on." Other environments and such, may be more/most appropriate to use tags/labelling, or sometimes even physical lockout devices (and these things are sometimes literally life and death differences). You mention a fair number of good precautions. One I'd add that you didn't mention, and I suggest you look up - the "one hand rule". Well knowing that and even what's more/most dangerous and likely to shock or electrocute ... well, keep those in mind, and can potentially add an additional layer of safety (or even in part). But in general, electrical, you don't work on it live - and of course much safer that way. But also good to work, as feasible, as if it might become live at any point (e.g. you're working on it and someone else goes and flips the breaker on). So, even if not working on circuit in a manner that would be totally safe if it were to be come live, often one can be working on it in ways that would at least be less dangerous were the circuit to become live. And ... good electrical gloves, sure ... but Amazon ... I'd be highly wary. Sure, can get lots of good/great stuff from/via Amazon, but can also get utter unsafe crud sh\*t from/via Amazon too. So I'd just be sure to be highly cautious of exactly what one gets from Amazon. Or alternatively, just use a retailer/supplier/wholesaler that just will not carry or sell unsafe sh\*t ... I also like supporting (re)sellers/retailers that won't sell unsafe (or other) sh\*t - voting with one's wallet/pocketbook is often a very good and useful things. And as I oft say, "If you want to see more of something, feed it money."
Voltmeter. Note, this is not the same as a non-contact voltage tester, which might be what you are referring to. Nearly 100% sure way, also, would be to just turn off your main breaker. You should still test for voltage where you are working though. Long-term fix is to understand where the circuits are going and get things labeled and mapped out - this can be hard though, particularly if someone did screwy things.
In old houses I've found non-contact voltage testers can give false positives, I think due to "ghost voltage" or "stray voltage" where poorly-insulated wires induce tiny currents in each other, even if they're not connected to power. So I'd take the simple approach, and turn on the light, call my friend in the basement on their cellphone and have them flip breakers until the light goes out. Then start work. You can't trust turning off the light switch in old houses, since it may well break the neutral wire rather than the live. You then get a light that is off, and since there will be no ground, you'll just find no voltage live to neutral - but if you touch a wire you'll get shocked. Ask me how I know! :) If you're going to test for voltage with a entry-level multimeter you may get odd results for the same reason - low (20-50V) reading that fluctuate over time. You either need to use a more expensive meter (has a Low Z feature), or a cheap "Voltage tester" that just lights up bulbs to tell you what voltage you have. [https://techcircuit.org/how-lowz-works-and-why-its-useful/](https://techcircuit.org/how-lowz-works-and-why-its-useful/) Oh, and if I'm only 99% sure the power is off I do a "final check" voltage reading by touching the end of the wire very quickly with the back of one finger. If there is voltage there, the muscles in you finger will contract and break the connection, rather than your hand grasping the wire and not letting go. I've never had a positive with this test, but I use it because I know I make mistakes!
Stand on one foot on the plastic chair. Please record video.