Avoiding electrocution while doing DIY stuff around the home

Factual Questions
1

After two electricians did some electrical work at my house, I noticed that one of my new floodlights wasn’t working. Curious, I flipped off the wall switch, removed the cover on the electrical box and started to investigate by first untightening the two (or three) connected white neutrals.

For reasons I don’t understand, I got shocked by the neutral wires due to some wiring screwup. The shock wasn’t bad, but I’d like to avoid an encore performance.

I’ve been told that turning off the electricity at the wall switch isn’t safe enough and that the entire breaker must be flipped, which can be a pain. I’ve seen advertised on TV these pen-shaped electrical devices that allow you to point the tip at a X-mas tree bulbs, and a chirp will tell you if it’s working.

Long story short, I’m looking for a dumbed-down, fool-proof device for testing electrical wires around lighting fixtures and wall sockets. What device is recommended, in this instance?

[Yes, I promise to flip off the breaker from now on, but I want added insurance.]

2

Wearing rubber soled shoes helps, as does using a wooden step ladder.

In my day electricians screwdrivers were common, basically a small insulated screwdriver with a light coil in it. It has a contact on the top, which you touch, if the handle lights up then you have a live wire. Best to test it out before embarking on a job.

3

Let me add: I know “multitesters” exist, but don’t know how to use one properly.

I do own a neon voltage tester, but it requires one to connect two leads–one black and one red–to the electrical receptacle in question.

Basically, I’m looking for a device I can simply point at exposed wiring and see if it’s hot. Having to actually touch a small electrical lead to a possibly hot wire skeeves me, probably because I was shocked by 240 volts DC as a kid–and on a wet tile floor.

Distance is good.

4

This is what you need. It says something about metal contacts in the product description, but it’s actually a non-contact sensor. Get it anywhere close to a hot wire, even with no current, and it will beep and flash when you push the button. If anything, it’s a bit conservative; I’ve had it react to the voltage in the circuit on the neighboring breaker to the one I’ve shut off.

For an upgrade, this one senses current and voltage.

5

That would be a non-contact voltage tester. The cheap ones cost about ten bucks, and the good ones that will last longer than the batteries it’s packaged with cost about $20-25.

You should be able to find them at any hardware store’s electrical department.

6

The latter device tests “current and voltage.” Does that mean it tells me that I’ve got a live wire AND what voltage that wire is?

7

Looks like that one can tell you if current is flowing in a wire, in addition to whether or not it’s merely live.

As for what the voltage is - in a house, you really only have two choices. zero (ground or neutral wires, or a de-energized line) or 120 volts on live wires. Anything in between is a problem, probably caused by a bad connection.

If you really want to know the exact voltage, you’d need a voltmeter.

8

To address one point of the OP:

There are basically two ways to wire a light fixture controlled by a wall switch:

-Run power to the switch, then up to the fixture. In this case the switch controls the hot line, and when the switch is off, the fixture box is not hot.

-Run power to the light fixture, and a “control” line to the switch. Hot needs to go to switch, and then come back from the switch to the lamp. This means that BOTH the white and black wire on the switch circuit are hot, and there is no neutral.

Because it is much easier, and usually uses less wire, to feed a series of fixtures with one branch, the second method is by far the most common.

9

What happened was your neutral was being shared by another consumer / circuit. If you break the circuit between a consumer and the electrical box, you run a real risk of a neutral shock.
look at it this way


 Electrical panel <---(white wire)----[light fixture 1]<------(white wire)--[light fixture 2]

If light fixture 2 is on, and you disconnect the white wires from light fixture 1, light fixture 2 will go out, as it has lost its ground. If you are grounded, and you touch the white wire that leads to fixture 2 you are supplying the ground path. A shock results. If you grab the wire that leads straight back to the panel there is no shock hazard assuming that the panel is wired and grounded properly. Just touching a shared neutral can can give you a shock if you are grounded, even if every thing is connected.
Note that the second fixture could be on a separate supply, so turning off the breaker for the fixture you are working on is not always a guarantee of safety. (ask me how I know this)
As far as this being a screw up, I don’t know. Shared neutrals were OK when my house was built, I have no idea if they still are. When I rewired my garage a few months ago, I did not share any neutrals between circuits. I got lit once from a neutral shock, that was enough for me.

10

I get a little bit nervous when people who don’t know how to use a multimeter do their own wiring.

A multimeter is simple. If you want to measure voltage, just remember that you measure voltage between two points. Between one prong and the other of an electrical outlet should be 120 volts. If you are poking around inside a box, put one probe from the meter on the box and touch everything else in the box with the other probe. You can also check every wire to every other wire. If they all aren’t zero, it ain’t safe to touch.

If you want to measure current, remember that you are measuring current through a point, so you have to break the circuit and use the meter to complete the circuit again. All of the current will go THROUGH the meter, so make sure the meter’s circuit can handle the current that you are trying to measure.

If you want to measure the resistance, just remember that the meter measures resistance by putting a voltage across its probes then measures the current that results. You can’t measure resistance on an energized circuit.

A few more words of advice.

Go down to ye ol local library and read every book you can find about DIY home wiring. Check out a copy of the national electric code and study it. Don’t just learn the rules, but try to figure out why the rules are what they are.

If you don’t understand something, ask here. There’s lots of folks here who understand electricity and will gladly answer your questions or point you in the right direction.

Always touch stuff with one hand and one hand only. The reason for this is that an electric shock through your hand and out your foot may hurt like a sonofabitch, but it’s probably not going to kill you. A shock that goes from hand to hand though crosses your heart, and has a chance of throwing your heart rhythm out of whack and killing you.

I personally shut off the breaker, check for live voltage, and still treat the wires like they could be live anyway. Don’t touch bare metal, always use insulated tools, etc.

11

I’d agree with this. It really sounds like you don’t know enough about wiring to do this safely. Don’t risk it!

Besides, you said this problem started after two electricians did work at your home. So call them, and tell them this. They should come out and fix it for you at no charge.

12

My “wiring” is no more extensive than: black to black, white to white, bare to bare wire. :wink:

13

Not necessarily that simple. I’ve seen a lot of botched home wiring. For examples, not using a proper wire nut to join wires, or using a wire nut but not making a good mechanical connection between the two wires first.

Always, always turn off the breaker first. Then use at least one of those little voltage testers with the incandescent bulb to make sure your circuit is truly dead. test the wires not just against each other, but each one against the ground to make sure there isn’t a floating ground that’s live.

When working with dangerous voltages, we were taught to always probe with one hand behind your back, to make sure you weren’t inadvertantely touching a ground with one hand and a live wire with the other.

Personally, when I’m working with house wiring I turn off the breaker, flip the switch on and off to make sure the fixture isn’t working, then for good measure I test the wires with a voltage tester. And I never, ever touch bare wire with my hands. I use insulated electrician’s pliers to twist wires together, and insulated cutters to strip them.

It sounds like overkill, but that way if I ever forget any one of those steps I probably still won’t kill myself.

House wiring can be a bit counter-intuitive, so don’t assume you understand the circuit just by looking at the color of the wires. Get a good book on simple house wiring, or find a good web site, and study it until you really understand what’s going on before you start mucking with things. You don’t want to kill yourself, or create a fire hazard, or cause other annoying electrical problems.

14

Good advice here.

One point I’d add is if there’s even the smallest chance that someone else may have access to the electrical panel, you need to tag it with something that says “Work in progress! Do not change the position of any circuit breaker without consulting …”.

15

I will remember this post, and all of the others. I can afford an electrician, but enjoy the satisfaction of the DIY. That said, it seems I’ve been taking a few risks and will henceforth do everything by the book–after reading the good book on wiring.

Many thanks to all.

16

Not so much. Oh, it’ll prevent you from conducting directly to the earth, but you can easily be grounded against something else, and if that path is from one arm to another (say, you’re holding a plumbing pipe to steady yourself while messing with a circuit on the other) even a 110VAC line can potentially be fatal. (Not likely, unless you’ve got a heart condition, but it has happened.)

To the OP: dude, just shut off the circuit at the breaker. With rare exceptions, you don’t need a live circuit to do work, and the “pain” that it takes to turn it off and on is nothing compared to the literal pain of being knocked on your ass and sent to the e.r.

Stranger

17

Here in Bogotá, some electricians don’t seem to care about codes, if there are any. Sometimes I find wiring that is all the same color and one must really use testers to know what each wire is doing and where it is going. This kind of wiring is very dangerous. I try to avoid doing anything when I find all one color and I just call another electrician. I think they do this when they don’t have all the right colors to do the job. Saves them time going to find a white or black or red wire. Go figure!

18

This is all good advice. But I have a question.

I’ve been shocked by 110v probably a dozen times or so. It’s certainly not pleasant. But it never knocked me on my ass or sent me to the E.R. either.

Isn’t the danger (to a person) of household current a bit overstated? Fire, is of course a different matter

And as Stranger said. Just cut the main breaker. Yeah, you will have to reset all the clocks, but it’s worth it.

19

After reading the responses, I’m a bit, um, shocked at the unknown risks I’ve taken. Again, I can easily afford a professional, I just like the satisfaction of, um, … narrowly escaping electrocution, I suppose. :wink: That said, a “professional” (apprentice, actually) caused my last two shocks, as described in my OP.

A good 10 years ago, I wired up a new fixture in a bedroom closet. I traced the line to my attic, turned off the breaker, and commenced wiring. Whoops. Wrong breaker. The 110 v. jolt wasn’t bad at all–rather wimpy, actually–so I figured I could (a) trudge down three stories or (b) just be very careful. I got zapped twice again and being sweaty from the attic’s heat didn’t help. Again, the shocks seemed minor–nothing like what I’ve been hit with by a car’s alternator or an electric fence (low amperage both, of course), and nothing close to the 240 DC childhood jolt I mentioned in my OP.

In retrospect, these uninformed, knuckle-dragging stunts have been pretty dumb. Not until now did I realize that getting zapped while being grounded is even more dangerous–and that bit about getting shocked from one hand via the heart to the other hand is an eye-opener.

Time to get a Black & Decker book on wiring.

20

110VAC isn’t especially dangerous (either from the voltage or 60Hz frequency) and a healthy person can generally tolerate it. If you have your foot in a pool of water, or you get a potential across your chest, though, it can cause a heart arrhythmia that could be fatal. It’s not as risky as 220VAC and it’s not going to do the kind of physical damage that 440VAC or higher voltages will do, but it is definitely a hazard.

Stranger