While troubleshooting a dead GFCI receptacle in my bathroom I discovered that a nearby light switch plate's screws have 120 volts coming out of them. The GFCI was reading 1.5v from hot to ground on itself, with breaker flipped off and I wanted to see if grounding it somewhere else would change this. I tried the sink faucet, still 1.5v, and then tried the switch plate screw...120v. Was very surprised by this. To be sure, I tried the screw to a sink faucet and a different outlet's ground and still had 120v. What can cause this?

I have never been shocked by the screws, thankfully. I will flip the breaker for the light circuit later and have a look to see what is going on. I imagine the ground and hot wires are crossed behind the switch plate, but thought I'd ask here and see if any warning alarms go off or any bits of advice are given. Thanks.

A bit more information. The 120v is coming from the screws regardless of the switch position and the lights behind the switch have always functioned properly.


My guess, since everything works fine still, is that the ground to this circuit is disconnected somewhere and the hot or possibly a loose "disconnected" hot from another circuit is touching the switch yoke or box.

If your ground were in working order and connected properly to the box or device, the breaker would have long since tripped. I don't know what mess is going on with the hot or some energized wire, but this will be a problem within it.

  • 1
    This was pretty much it. The switch had been replaced at some point before I bought the house. When replaced, it was shoved so hard into the box that the bracket the ground screw goes into, had punctured a hot wire's jacket. Specifically, a hot wire feeding the switch. The hole was pretty small, but it had a corner of the ground screw bracket nested nicely inside. Guess the last guy decided it would be easier to take the ground wire off of the screw instead of figuring out why the new switch kept flipping his breaker. – zerpsed Feb 20 '16 at 17:56
  • Ouch, good thing you caught it before something else for a zap. – TFK Feb 20 '16 at 18:15

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