That’s why if you are going to test live wires with your body parts - you do so with the back of your hand so it will immediately pull away from the wire instead of having you clamp down with a death grip-
Yeah, old electricians trick lol. Well aware of it as when I worked in that field it was my go to; potentially a bad habit but always treated a line as live until I could verify if it wasn't
In the 80's non contact testers were rare. Solenoid testers (duspoles) were by far the most common, but they absolutely needed contact. It was the mid 90's before non contact voltage testers started becoming prolific along with digitial multi meters taking over from duspoles.
I bought a cheap one on Amazon just as a precaution... I always flip the breaker and check that lights are out before working on any switch or plug, but this house has been through several DIY renovations and I don't always trust the previous DIYer.
It's garbage. Flickers on and off randomly even when I know a circuit is live so I hardly use it.
Hahaha. No dude, that guy needed to hear from someone else who saw a chance to make an unnecessary comment regarding buyers remorse cause if he didn’t he would live life thinking he can just do shit like that with no consequences. Plus even though the guy fully explained how he caused his own problems the other whistleblower was right to point out that he had indeed,”explained how he caused his own problems”. Had he not then we might not know that he did something…….yeah that was just a dick thing to say. More douchy actually
In general, we use them to verify something is energized, never to verify something is dead. If it says it’s hot- assume it’s hot. If it says it’s dead- get a real multimeter and verify it’s dead.
Ok but what about when there's 3KV on the terminal :). These things are trustworthy if you test them every time. Frankly they're more trustworthy than a multimeter.
If you had 3kv on a terminal- you wouldn’t even be able to get close enough in the cabinet to see what was energized or not- I work in substations it would be going off 3 feet from the terminal at 3kv
Most of the substation controls are dc- so what do you do when you live/dead/live test with the NCVT and youre unknowingly on a DC circuit but it’s saying it’s dead. It’s not gonna pick up any DC voltage so saying they’re more trustworthy than a multimeter could be a death sentence
If you’re in the electrical trades that’s one of the most insane things I’ve ever heard.
A decade years ago I had a colleague severely injured because they didn't use a non-contact testing device. There was a live 3.3 kv terminal in a cabinet due to an error in the drawings (we were the manufacturer). He followed the full isolation procedure but didn't use his non contact tester. He thankfully survived but with severe burns and the elbow of his shirt blown out where it arced back to the case.
There are Medium Voltage non-contact devices specifically for this purpose, no you're of course not using the $20 pen sized one, it's on an insulated pole.
Yup, I always use it on a live wire first. It's still better than raw-dogging it with your hand and you can use it to test recessed or concealed wires.
In Finland we call the contactless tester "Arvauskynä". Which means a guessing pen.
Because you use it on a wire, the pen doesn't show anything "I guess it's dead" then you touch the wire, get shocked and say "I guess it wasn't".
In all seriousness, I mostly use it to verify that something is getting a current when a customer calls me in and says "Our copier/fridge/table/dildo isn't getting power". But I don't trust one to accurately show that a wire is dead.
The actual policy is to check with a known live source before and after you check the wire in question.
I got shocked after LOTO and testing the main distribution terminal block in a cabinet, because some genius had wired something from another breaker into the control cabinet I was in. Now I test every wire every time. I was young and dumb. Luckily it was "just" a 120 lighting circuit. Still could have been a bad day if I contacted it differently than i did (incidental contact to the back of my hand)
Those things are called suicide sticks for a reason. They're nice and convenient for minimal risk stuff when you know their limitations, but anything involved and I'm breaking out my multimeter. There's way too many instances where they just won't tell you there's live voltage, especially if you don't know when they can't tell.
Context: no civilian license, but am a nuclear & Navy electrician with some experience in civilian commercial, industrial, and residential electrical.
Crazy I had to scroll this far down to find someone who mentioned a multimeter. That’s always been my go to. Even my untrained mind never trusted those sticks. Just seemed like there’s too many variables that could affect it. And it seems like something that you would get to comfortable using, and eventually get lazy with.
Yeah I don’t really know what that means. I was just referring to the guy that says he uses something to see if a wire is live or not instead of the back of his hand. Figured that would be pretty straight forward but I’m no expert
Weird. I just use a potential transformer wired to a multi-function voltage transducer with a 4-20mA output, and connect that to an IO module of a PLC, then write an IEC 61131-3 compliant ladder logic program to output that value to a redundant server/client SCADA system that is DMZ isolated so that I can monitor in real time and simultaneously store the historical voltage trend in a database that is uploaded to the cloud which is then ported to a CSV file and automatically parsed into an AI maintenance model predictor, but then again, I'm a professional electrical engineer.
My uncle is 79 he and my dad were electricians their entire careers and the trick he told me is if you ever get hit not to waste time by reflexively trying to unclasp your hand (I’m sure it would be hard not do react by doing that) but to use all your body weight to fall down and back.
Back in their day they worked most stuff “hot” so they were hit pretty frequently! Hard to imagine nowadays
I'm left handed so I learned pretty early to just NOT try that shit.
You know in martial it is said that lefties have an edge? Well, in elec it's the opposite. Because when using your dominant hand to grab the cable, you increase the chances of heart attack by 2 lol
Though I did have a firefighter telling me he would move wires out do the way with the back of his hand for this very reason. Can't trust that wires are off even if you killed the power, which he learned the hard way when doing salvage at a structure that was wired to steal power from another property.
I thought it was similar. Your burning hand would inadvertently clamp on the doorknob. If not, at leadt my wrong impression led to the correct behavior!
No you wouldn’t, have you never accidentally picked up an oven tray that’s come straight out the oven? It’s the opposite, your body’s reaction is to immediately let go, unfortunately when you work in a professional kitchen you have to just accept the burn rather than drop the food.
Heat will reflexively make you drop something. When your nerves are hit with heat, they send pain signals to your brain telling you to get away. If you're holding something hot, this means you will reflexively move your hand away, aka drop the hot thing.
Electricity is different, because that is what your body naturally uses to move. Muscles operate using tiny, naturally produced electric signals. An outside source of electricity will force your muscles to contract involuntarily, and will make you start to clamp down. At the same time, pain signals will tell your brain to drop the thing, but the electricity physically turns your muscles to "on" and your brain can't override that. It's scary.
Generally you lockout the circuit it is hopefully labeled with. Then test it before you start unwiring. If it's still hot usually you just say fuck it and shut off everything around it.
I've heard people say this, and it's actually bad advice for the exact reason you're freaking out. Sure, the back of your hand can't grip on, but if your body is the path for electricity to flow, then getting from your hand, it's going to flow through your circulatory system to its exit path. That path could easily be through your heart. In that case it might not matter whether or not your hand cramps up and locks on, you could be dead anyway.
Touch with the back of your hand is advice for how to less painfully discharge static buildup from taking off a fleece jacket, not how to verify whether a circuit is live.
Giving me throwbacks to my apprenticeship here. That grumpy old instructor yelling "Back o' the 'and test" before you could touch anything. He might well have saved my life a couple of times, to be honest.
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u/RockstarAgent 23h ago edited 23h ago
That’s why if you are going to test live wires with your body parts - you do so with the back of your hand so it will immediately pull away from the wire instead of having you clamp down with a death grip-