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stumped on a short circuit

Posted by genetic (My Page) on
Mon, Mar 31, 14 at 22:29

I've got a breaker that keeps popping. The 15-amp circuit in the basement consists of several light fixtures and outlets. None of the outlets have devices plugged in, and I don't think any outlets are controlled by switches. There's a set of switches for a bathroom (call it A), a set of 2 3-way switches for fixtures on the stairs (call it B), and a switch for 2 more fixtures (call it C). With everything turned off, the breaker does not trip immediately when resetting it. It takes a combo of at least any 2 of switching A, B, and C on to cause it to trip. Usually it trips immediately after turning on the second switch, but sometimes it can take 5-10 minutes. Early on, I tested the breaker and it read 120V. I have replaced all switches B and C. Switches on A read at 120 V. Fixtures on B and C read 120 V in each socket. All the outlets are fine (grounding included) with testing via neon tester. It seems like a question of wattage load but we're not anywhere near 1800W. Could the breaker have gone bad since I tested it, considering the countless times I've tripped it trying to troubleshoot it?

Follow-Up Postings:

RE: stumped on a short circuit

You haven't tested the breaker. Breakers don't trip because of voltage and measuring voltage at the breaker (even if defective) will always typically read zero (of off/tripped) or 120V.

A clamp on ammeter at the breaker can tell you just what the circuit is pulling.

RE: stumped on a short circuit

You don't say if this is a new circuit, sounds like you may have 2 feeds to that circuit, unless of course you have a faulty fixture. Are the 3 way switches wired properly, with power to the common"blk" screw, and on the other switch, common,"blk" screw to the lights blk wire, and the other two wires from the 14/3 as runners from one switch to the other. Of course you can wire it with pwr and lights from the same side, but we'll stop here for now.Just a thought

RE: stumped on a short circuit

Any back stabbed outlets?

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