Technical > Home Improvement > 4 volts on a 120v service? (Resolved - kind of)

4 volts on a 120v service? (Resolved - kind of)

Re: 4 volts on a 120v service?

reply to psafux
Since receptacles have power you know the breaker is delivering power (assuming switch is on same circuit). So either there is an open somewhere between the receptacle you tested and the switch feed or you may have a ground fault receptacle somewhere in the system that has tripped.

Bathroom receptacle should be on GFI protected circuits unless you home is very old. In some cases lights are on the same circuit sometimes a different one. This can be accomplished either with a ground fault breaker or receptacle. If it is a receptacle it needs to be wired such that if it trips all receptacles in room get turned off.

Are you sure receptacles with power is on same circuit as switch? Need to trace wiring from switch - should run to nearest receptacle.

If you are handy it is not too hard to do. Just be careful - 120 volts can kill. Personally rather then messing with a multimeter I use a little neon light tester. Easier then using a meter. A ground fault outlet tester is also handy. Verifies receptacles are wired correctly and has a GFI trip button to test GFI.

/tom

reply to psafux
Phantom current is what you are seeing.

reply to Raphion
Thanks guys, ill check that out.

Raphion: I could not get more than 4v out of several different ways of testing. I don't recall anymore if I tried hot to ground, I think so> Ill do more tomorrow.

The house was built in the early 30's, still has some 2 prong outlets :P We have been upgrading and bringing up to code as we go!

Tschmidt: Thanks for the detailed reply. I assume the switch and outlet are wired together. When the circuit breaker was turned off, everything went dead in the bathroom. All outlets, the vanity lights, I could not get 4v on the switch any longer.

--
Yes. the cat in my avatar is indeed mine.

thanks for the reply. I have turned off every other breaker, short of the MAIN, and everything in the bathroom remained on, and 4 volts still registered at the switch in question.

Breaker #15 is the only circuit that turned off the bathroom in its entirety.

If I understand what you are saying, this would have ruled that out ?

Also - this morning I tested hot-ground, hot-neutral and both registered 4 volts. I am testing the wire not the terminal on the switch.
--
Yes. the cat in my avatar is indeed mine.

reply to psafux
Sounds like you've got an "open" between the upstream power source, and the switch. I'd suggest pulling upstream recepticles, and checking the connections.

GFCI could be suspect; or check for burned/loose terminals, espically "backstabs"

Work carefull, breaker off... Don't assume something's dead, until you test it.

Laz

reply to psafux

reply to LazMan
Lazman - thanks. i will check that out, I haven't pulled that outlet out yet, but i was thinking about it. Will do that over the weekend.

And oohhhhhhh don't worry, I will NOT work with live power :P When I was a child, I grabbed my dads screwdriver and stuck it into the light socket in the garage. fortunately I had grabbed a wooden handled driver :P Been extremely cautious ever since!
--
Yes. the cat in my avatar is indeed mine.

reply to psafux
did some more testing this morning.

on the switch, tested hot to ground again - 4 volts
on the switch, tested hot to neutral again - 4 volts

pulled the outlet out, there is only hot & neutral going the outlet (no ground, no other wires going anywhere else).

There does not appear to be any continuity between the switch and the outlet (multimeter registered infinity between the two). So the same circuit breaker controls both but they are not wired together it seems.

The electrical wires in the basement are a jungle, should be fun!
--
Yes. the cat in my avatar is indeed mine.

reply to psafux
Digital multi-meters are not the best tool for troubleshooting line voltage house wiring, as you can see, you're getting (false) readings when there is no power on a circuit.

What you need is a tester designed for voltage and a continuity testing like this:

»www.mytoolstore.com/ideal/ide05-12.html

This is one tester we used on my job at a large northeast electric utility company, for systems operating up to 600 volts.

Safety Reminder: Always prove your tester on a known live circuit prior to AND after every use!
--
~Help Find a Cure for Cancer~
~Proud Member of Team Discovery ~

Re: 4 volts on a 120v service?�

Re: 4 volts on a 120v service?

it definitely sounds like an open neutral. You wouldn't get a reading of anything besides phantom voltage on hot to ground with that outlet since you also commented that there is no ground wire going to that outlet.

Putting aside that it sucks not having that ground (I'll assume it is old, no retrofitted wiring else its also a code violation), i would start hunting down where that neutral has come loose.

reply to psafux

Re: 4 volts on a 120v service? (Resolved - kind of)

It's frustrating but you are probably pretty close to getting it solved.

One more thing to try before calling an electrician. In the same J-box redo the hot wire. If the gods-of-electricity shine on you that may be all you need to do to fix the problem.

/tom