Circuit breaker tester maps to wrong breaker!!


I was trying to map the outlets in my house to the appropriate circuit breakers. In addition to plugging in lamps etc. I was using a tracing tool made by Sperry that you plug into an outlet and it squawks when you position the receiving device over the appropriate breaker.
Almost all circuits in the house map fine - the tool adjusted for sensitivity points to a breaker, I shut it off, lamps go off, all is well.
In my kitchen, ALL GFCI outlets map to THREE!! breakers (all wrong). All the GFCIs are on one breaker which is NOT picked up by the tester. Two other(non GFCI) outlets and the fridge are also on this breaker.
This would suggest something is wrong. Any ideas?
I intend to have a professional electrician look at it but was wondering what the error could be, and the urgency of having it evaluated (have been living here for about 2.5 years and the house has not yet burned down). House is 50+ years and mixture of grounded and ungrounded wiring.
Incidentally, if I was trying to map the breakers with only a radio or lamp I would not have detected what appears to be a problem.
I can be reached at snipped-for-privacy@mail.utexas.edu if you prefer e-mail
Roland
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I don't like being shocked. Have not suffered a good shock for over ten years. Then on a volunteer job, I debugged a strange electrical problem that no one could solve. Got a real good shock. Two circuit's hot wires were tied together in one switch box. Two switches were suppose to control separate circuits. The wireman tied both hot wires together in that box. The 'unexpected' circuit got me real good. A problem compounded by safety grounds not properly tied together in another box.
Just one idea to investigate.
Joe Doe wrote:

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These plug-in circuit tracers are handy enough but I have no doubt there are lots of situations in which they indicate the wrong cables back at the panel, so I'd never trust my life to them. Anything they indicate needs to be verified by other means. For Roland's situation it sounds like the tracer's signal is being induced into other cables; this is pretty common (though three at once is worth bragging about). Probably all the cables are close together somewhere, going through a joist or a sill. In fact, they may be *too* close, for too long a stretch, by current code, but it's hard to know if this is worrisome enough to start tearing up walls.
Now, as to why the signal is not appearing on the right cable, I dunno. But if you *know* that the breaker kills that circuit, then clearly the signal *is* being blocked, so the reason why is really of academic interest only (on a hunch, I'd try it with the fridge unplugged). I would never discourage you from having it checked out, but my gut feeling is that all is ok and the tester is just giving wrong weird results.
As an aside, it's only a matter of time before your toaster and electric frying pan gang up on your fridge and they all knock each other out. If you're going to spring for an electrician, have a dedicated line run to the fridge, and as a side issue have the current circuit checked out.
But J.Doe has stumbled over true evilness. I have some knob-and-tube in my house that I haven't completely figured out yet, and I have a sneaking suspicion that the neutrals, if not the hots, are mixed from different circuits. I have a little inductive tester that's my first tool to check for hot wires; its negative results in low-sensitivty mode (ie, direct contact) are mostly pretty accurate but it gives a lot of false positives owing to induced voltages. I also have a lamp-type device. I test them both on known-live circuits lots before I trust their negative results. Both of these are cheap at most hardware stores. Prior to touching a bare wire, *after* I'm "certain" by all other means that it's cold, I hold it by the insulation and carefully brush it on a neutral or a ground wire. This is a test of last resort; the arc from a hot wire is serious business (the flash could cause vision damage if you're looking at it, and start a fire) but in my own opinion it does rank as slightly more survivable than grabbing it with bare hands with your feet on the ground.
Chip C
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chipc snipped-for-privacy@yahoo.com (Chip C) writes:

Hmmm... I didn't realize that code prevented cables running together. Does this apply to cable bundles in the basement? I always thought that running cables together was a sign of neat workmanship (vs. a scattered spider's web of cabling) rather than against code.
Can you explain what the code says here?
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I routinely do something completely different to confirm before I grab a wire - because I so hate electric shocks. I even brushed the hot wire on safety ground wire. No sparks? Then it should have been dead. Safety grounds were not connected together elsewhere. I was 'had' by a multiple failure. In another case, when the switch was flipped, then two circuit breakers became connected. Flip the breaker, and radio would go silent. Why? Defectively wired switch was not in right position. Change that switch and circuit breaker no long quieted the radio.
That wire tracer is a great tool. It says something is seriously wrong. But no tools by themselves are sufficient information. Other tricks and tools are required to explain the anomaly or to find a wiring defect. The wiring tracing buzzer is reporting something weird. No way around that. The question is now, "Why is it suggesting that three breakers are interconnected". If that question is not answered, then a potentially serious problem still exists.
Even brushing the hot wire on safety ground AND measuring with a volt meter was not sufficient. I still got shocked because it was a multi part problem. If all tools do not agree, keep looking for the problem. My problem? I assumed there was only one fault. Literally got burned by the assumption.
Chip C wrote:

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As I understand it your tester told you that three GFI receptacles are on three circuit breakers, but in reality they are all on one circuit breaker.
I suggest using the lamp or radio to confirm this and stop relying 100% on sensitive instruments that can give false readings under certain circumstances. You could always use the "old timer" method. Put a flasher button in a pigtail socket with a 150 watt bulb. Plug it into the receptacle. Go to the electrical panel and clamp an ammeter over each individual conductor until you find the circuit with the bouncing needle.
John Grabowski http://www.mrelectrician.tv
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That's a lot less house wrecking than plugging in a radio. Turn it up full blast and try breakers till you get the one which turns off the radio.
(meantime, you've reset every computer and clock).
I really like your idea. Might use it sometime.
--

Christopher A. Young
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I have found those sensors less than reliable. With practice you can get better, but there is a little technique to it. I find the safest is the old radio trick, plug it in and when you hear it go off, you got it. Note: always turn it back on to make sure. :-)
Joe Meehan
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