Q&A / 

Electrical Shock Touching Light Fixture

William Roberts from Orlando, Florida (FL) wrote to me:

"I have a three way switched light - like the example in your garden shed video.

Both switches work correctly,  but if I touch the light fixture when the light is on, I get shocked.

What would be the cause of that?"

Well William, that's easy. The fixture is becoming energized by the electric current in the circuit. I put that video you watched below for you.

You gave a clue to the source of the problem when you said this only happens when the light is ON.

Here's what's going on.

When you have an alternating current circuit in the OFF situation where NO CURRENT is flowing, the white or neutral wire is the same as the bare ground wire. This means you can touch the white wire and not get shocked.

But, when you have current flowing in the circuit, a light on, the toaster coils glowing red, the wet-dry vacuum on, the computer on, etc., the white wire in the circuit becomes ENERGIZED. The HOT part of the electricity starts to move back and forth along the white wire.

This is why it's called alternating current.  The alternating current in your home cycles at 60 times per second. The electrons in the black and white wires move back and forth along the wires about two feet or so constantly reversing direction - 60 times per second. If the current was direct, the electrons would march from one end of the wire to another like water flows through your garden hose.

I discovered  that white wires in a circuit can become energized 35 years ago when I grabbed onto what I thought was a SAFE bare end of a bunch of white wires and was thrown from the ladder by the vigorous JOLT of the alternating current. Had the circuit breaker been turned OFF, I could have touched the white wires and nothing happened.

You need to locate where a nicked or bare part of the white wires in the fixture is touching the metal of the fixture.

If you were to get shocked touching the fixture all the time - even when the light is OFF - that means the black, or HOT, wire is what's touching the metal in the fixture.

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4 Responses to Electrical Shock Touching Light Fixture

  1. I thought you should switch the hot (black) wire for this reason. The light hot line should be switched on and off. The black wire from the circuit breaker should go to the common of one of the switches, the light hot goes to the common of the other switch. the 2 poles of the switches connect to eachother . The only white wire that would be live would be going to a(nother) light switch. In that case a piece of black tape should be wrapped around the white wire to indicate it could be hot.

  2. Dear Tim,

    I have to disagree with your conclusion; if the writer got shocked while he was standing on the ground, pavement, etc. and touched the body of the fixture, this means that the body of the fixture was not grounded per NEC. If it was, as soon as the light was turned ON, the black wire would be shorted to ground, tripping the breaker.
    Also, even though the white wire (neutral) is carrying current, unless it is an extremely long circuit, it is effectively at ground potential, and you will not be shocked – no more so than if you touched the same neutral wire where it is bonded to the panel ground bus.

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