Circuit breaker trips


Old 01-18-11, 06:53 PM
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Join Date: Mar 2009
Location: Michigan
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Circuit breaker trips

I have a circuit breaker that keeps "tripping".

It's marked on the service panel box as lighting upstairs. I replaced the circuit breaker. This wasn't the problem. It's not an overload.

I had all items unplugged from this circuit. In my opinion it's obviously a short. Not being an electrician, I had an electrician check it out. He removed all switches, wall plugs and overhead lights and found no loose wire or shorts. He said the short is in the walls.

He said to find the short he would have to run a new circuit from the box outside the house (in conduit) into the upstairs. Then go from outlet to outlet till he finds the short.

My question is: is this the way you find a short in the walls and would it cost $1,500.00 (his estimate)?

The house was switched from fuses to 100 amp breakers 20 years ago. The house was built 1930.

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Old 01-18-11, 07:03 PM
Tolyn Ironhand's Avatar
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One way to find a short is to install a lamp holder (a light bulb socket with two wires coming off of it) and wire it in series in the circuit between the short and the breaker. The light will burn very bright. Then you start taking apart (or put together as the case may be) the circuit devices (labeling as required) until the light goes out. When the light goes out you have found your short.

If you have an accessible attic you may want to have a look see in case you have any critters chewing on any wires. Also, have you hung any thing on the walls lately?
Old 01-18-11, 07:59 PM
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Join Date: Mar 2009
Location: Michigan
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Thank you for your reply Tolyn. There wasn't any nails pounded in the walls lately. and critters chewing is always a possibility. Your other idea seems simpler than his suggestion. I'll mention it to him.
Old 01-19-11, 09:40 AM
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Given the age of the house and that this is for lighting, is this a knob and tube circuit (K&T)? K&T wiring is mostly copper wires with fiber or rubber insulation (often with bare spots) mounted on ceramic studs and insulator tubes. Perhaps you know if it's there or have seen some in the basement or attic?

If it is K&T the chance of a short is much higher as all you would need to have is something fall across the exposed conductors.

Last edited by ibpooks; 01-20-11 at 11:05 AM. Reason: clarified k&T
Old 01-20-11, 05:49 AM
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Join Date: Mar 2009
Location: Michigan
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Thank you for your reply ibpooks. I haven't seen the knob and tube circuits. I'll have the electrican check it out.

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