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CallMeVilla 01-16-2014 08:10 AM

Dead Circuit Tracing
OK, what is the best way to trace a dead residential circuit?

One outlet in the garage is dead. No power leg registering on a non-contact device and a plug-in detector. A GFCI in the nearby downstairs bathroom is also dead. No power leg registering. Every breaker has been flipped and tested ... none power either of the outlets.

Logically, I would suspect a bad outlet or wire between the garage and the main (thinking that circuit loops to the bathroom GFCI). However, I do not see another outlet!

Thoughts? Process? Testing devices I don't have? :hide:

nealtw 01-16-2014 08:56 AM

The gfci is the only unit that power goes thru ,that would be my first suspect, did you tighten screws at the breaker. After that I would map the breakers so you know what controls what and how many outlets you might find on a circuit and what might be in the same area. It's common not to have the bathroom light on the gfci but it might be on the same circuit, so you might look for a loose wire there. Check the house for rodent damage,

bud16415 01-16-2014 09:04 AM

There are a number of tone generators that should work for this on the market. Most are intended for use with low voltage phone and computer cables etc. it is my understanding they work fine also on power wiring such as you have but the line must MUST! be dead. 120V will fry the tester.

The better unites can see thru drywall etc. and when you get back to the panel or sub panel or other wire points the probe will pick up the tone and tell you that you have the right conductor.

I don’t own one but I’m sure someone will recommend one and the best method of using it. I have seen them used.

Here is the fluke model

CallMeVilla 01-16-2014 09:13 AM

1 Attachment(s)
Thanks guys .... I do have a tone and probe device and that will be my next step AFTER checking all screws. While GFCIs can go bad, it is rare in a relatively new house in California. The presence of the 2nd outlet being dead is a clue that there is a more probable issue somewhere else.

I will report back on how I solved this one ...

JoeD 01-16-2014 11:58 AM

Look for another GFCI outside or in another bathroom or the basement. They put all that stuff on one circuit many years ago. Someone could have added the bathroom GFCI and not really needed it because there is another protecting the circuit.

Wuzzat? 01-16-2014 12:36 PM

Pull the load center cover and check with a real meter that the breaker is actually putting out 120v but be careful of arc flash.

A dead circuit could mean the hot is open, the neutral is open or both are open and these cases can be checked out individually. This will give you a clue as to what kind of problem you have.
A tripped GFCI would give you the last case.

Wuzzat? 01-18-2014 08:57 AM


Originally Posted by CallMeVilla (Post 98649)
One outlet in the garage is dead.
A GFCI in the nearby downstairs bathroom is also dead.

Another choice:

Because of phantom voltages possibly fooling an electronic ohmmeter turn off all breakers.
BTW, I use an incand. bulb/battery continuity tester once power is off because it puts some decent current through the connections.

At least one of the three conductors in the cable entering one of the boxes almost certainly eventually goes to the load center hot, neutral or ground, so,
using an ohmmeter and a helper, completely disconnect this two outlet segment from each other and from the load center hot, neutral and ground and from whatever it's feeding downstream.

Then restore continuity between the two outlets (but check that the hot, neutral and ground for these two are wired correctly to the short slot, the long slot and the round hole).

Then run a new cable from the load center or some other convenient pickoff point to the GFCI.

There's an assumption in this procedure. Do you see what it is?

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