Electrical short

May 20, 2006 14 Replies

I am trying to help a friend find an electric short in an older home. The house is served by two circuits protected by breakers. One of those circuits is shorted. I have removed and isolated every receptacle and switch but not found the cause, what sort of suggestion might you have?



Any thoughts or ideas appreciated,



rog


Have you tried replacing the breaker? They go bad sometimes.

Well, if you have ruled out all the devices, that leaves the wiring. The short must be in the wiring between two devices. Isolate it and replace the bad wiring. Actually though, I would go over the devices once more; they are both more likely and easier to fix.

Thanks for the replies..

I read on line of a device for isolating (finding) shorts in household wiring. Do they work?

I have replaced the breaker and feel pretty confident that devices are OK..

rog

Let's start from the very beginning: how do you know it's a short? What are the symptoms.

Doug, Initially the C/B popped, reset--no avail. Eventually C/B replaced, but still popped. Circuit pegs a clamp on amp meter then pops... removed each switch one at a time as well as all receptacles. Still pops the breaker.. rog

Are you sure you got every device and box disconnected? Also before doing anything drastic I would buy another C/B incase the new one is bad. Did it come factory wrapped or just in a bulk box. Someone could have switched their bad one at the store for a good one. I almost bought someone's old faucet at lowes in a new package.

Yes, indeed, they do. And what about ceiling fixtures with chains and not swtiches? Or things hard-wired like furnaces and water heaters?

I downloaded your newgroup filter thingy. It doesn't do anything; presumably it needs a filter?

It trips with everything disconnected?!

Yep, you've got a short. Never hurts to verify, though, because many people use the term "short" to refer to *anything* electrical that isn't working.

My best guess is that there's one more device on the circuit somewhere that you haven't found yet.

I guess you haven't been following the filtering discussions over at rec.woodworking.

The filter file I provide is an accompaniment to the filter program Nfilter (aka NewsProxy). You need to use them *both* for anything to happen.

But if it pegs the clamp-on ammeter, isn't it most likely a short? A bad circuit breaker would trip with amps below its rating.

Ben Miller

IMHO, I would disconnect the wire off the terminal on the break, and then try closing it. From the other posts, it does seem like the consensus is to rule out the breaker.

later,

tom @

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Sounds like the cable itself is shorted somewhere, possibly crushed by an improperly installed strain relief, cut on the edge of a box with no strain relief or bushing, or it has a nail through it. Charring from a fire or gnawing by rodents could also do it. Another possibility is that it was cut on a steel stud.

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