Circuit breaker is off but tester shows current in receptacle?

Question

I am planning on adding an additional receptacle to the circuit in a bedroom that currently only has one. I turned off the breaker for the circuit and no appliances or lights work but my tester shows that there is current in both sides of the receptacle. This doesn't seem right and I'm not quite sure how to proceed. The tester I'm using is a simple non-contact probe so that could be the problem.

My apartment is old and is a mix of k**b and tube and some updated circuitry but I don't know the specifics. The receptacle I'm working with is not grounded and is part of the circuit that covers two bedrooms, a bathroom and a single receptacle in the kitchen.

Why would the tester beep when the breaker is off and what should i be looking for now?

Thanks

Answer 1

As previously stated someone could have rewired that particular circuit and because you said the apartment is old it may also have a short that is bleeding into the circuit. Last but not least that circuit may be wired to a different breaker/fuse in addition to the one you are aware of.

Answer 2

You had better trace the circuit to find the proper circuit breaker, and disconnect it. (Special tool)  The tester is telling you the circuit is hot!

Answer 3

Non-Contact tester are not 100% dependable; that is one reason they are nick-named "stupid-sticks". Sometimes just swinging one like a baseball bat will generate enough static electricity to start it singing like a bird.

Try a "wiggy" or a multi-meter to be sure that the circuit is hot; the multi-meter will also give you an actual voltage reading. You have more than likely encountered a "shared neutral", and the neutral is carrying the unbalanced current from another circuit. It could also be that at some time in the past, the conductors got tied into another circuit; and this receptacle is receiving energy from more than one circuit.

If you have too much trouble, call in a qualified, licensed electrical contractor.

**************************************...

Now that you've provided alittle more info; let me first say "DO NOT shut off the main breaker/disconnect if it will shut down anything in the store! If your tinkering causes any additional problems that effect the store, you're liable.

Also, the store may be on a 3-phase service that you are tapped off of. Call the landlord, as this sounds like a  mixed use rental property, only a licensed electrician is allowed to do ANY work on it. That applies to just about every state in the union; including the People's Republic of Chicago.

Answer 4

Those testers work off of frequency.

If you bump the tester on anything it will beep.

Keep in mind it will beep constantly when voltage is present.

Try it at another good location.

I often check mine by bumping it on my hand and it will beep and lets me know when it's working.

Turn off all power if your not sure before working on it.

Answer 5

I recently bought a cheap non-contact tester and found it to be completely worthless.  I went back to the supplier and exchanged it (along with some more money) for a Fluke non-contact tester, which works fine.

If you don't have any other testers, you can plug something in to the outlet in question, like a lamp, and see if it works.  Although I can't tell what exactly is going on from here, I would test the tester first.

Answer 6

This is never good under any circumstances. Most likely reason is bleed back from Electric Stove or hot water heater.

Do not take a chance have it checked out by someone that knows this stuff!

This is not a small thing you need to get it checked out big time!

Answer 7

Don't trust a non contact sensor to tell if you have voltage or current at a location because they do not work the same.  You need a multimeter to test this as you are testing for actual voltage and you may only be reading a 60 cycle hum that is induced into your probe.  It will not tell you if there is any voltage present.  

Answer 8

I believe another possibility is that the circuit you're working on shares a neutral with another circuit.  Finding the other circuit is tricky if you don't know what you're looking for.  It wouldn't have to be this way, but many times when this is done, the circuits that share a neutral are right above/below each other in the panel.  If it was me, I'd start by shutting off the adjacent circuits in the panel to see if voltage was still detected on the circuit I was working on.  If that still didn't work, I'd keep shutting off breakers until voltage was no longer detected.

Answer 9

It MAY be that folks in the past mixed up the wires or you could have some stray voltage tricking your tester into thinking the receptacle is hot when it isn't.  Best thing that comes to mind is get a VOM (volt-ohm meter) and check for voltage at the receptacle going to a known, good ground .  You may need to run a wire from the vicinity of the receptacle to a good, known ground.  You're solving a mystery so awareness and thoughtfulness count.