tracking power feed short to switch

120v household line.  Feed line suddenly lost power.  Tenant reports no heavy usage at the time - says she just finished a shower so possible condensation/steam issue caused the short.  one gfci in bathroom works fine, no load on gfci just a direct 12-3 yellow feed line into gfci no load out (appears only bathroom is on bathroom circuit breaker).  Double switch box is the problem - first switch controls bathroom fan and shower light.  Second switch controls vanity light.  Seems main power feed from the "wall" is dead (tested with volt meter and main feed line to switch box is dead).  No other outlets or switches seem to be on bathroom breaker (all other outlets & switches in apartment work)

I have a few options to get power to the switch box - but my question is how best to track the short in the line?  AFAIKnow, since gfci works, energizing from the breaker side will tell me know more than i know now.  Is cutting sheetrock the only sure way to track the short location?  I would try looking for lower resistance but only the gfci and the double switch seem to be on the circuit.  Any suggestions i appreciate - thank for taking time to read my post

Gfci?

Murdoch GFCI is ground fault circuit interrupter (RCD).

You have the breaker tripped on the bathroom lights, therefore there is a fault at the fan, shower light or vanity light.

If there is no load out on the gfci then it is not doing anything, possibly you have missed the load out.

Check the wiring at the fan, shower light and vanity light.

Perhaps measure resistance (with the breaker off) at the switch from switched hot to neutral (or ground) to see which of fan/shower light or vanity light is the problem.

Very low resistance being the faulty part.

This forum is primarily UK based so some variants may be present in our answers.

^^

Thanks.

Wonder what country the op is from

United States  I'd guess  ...120V  feed  etc    and gfci's    :C .  They use the terms "Ground " and "Hotwire "  I believe .

And you trace the fault using an insulation resistance tester. No doubt you have a different name for that the other side of the pond as well?

Most American electricians don't know what a test set is.

As I am ignorant about this ( and many other electrical things). What are the standard tests that the Americans perform on circuits?

serious question

kerching said:

As I am ignorant about this ( and many other electrical things). What are the standard tests that the Americans perform on circuits?

serious question

Click to expand...

I'm sure Tony can fill in more info on this, but, as far as I know, none.

They wire to code fire it up and f*** off.

No dead testing is done to confirm polarity or cable/connection resistances.

No live testing is done to prove that ADS will occur as required to prevent fire or electric shock.

Another reason IMHO we don't need AFDD's?AFCI's as much as they are needed in the USA.

kerching said:

As I am ignorant about this ( and many other electrical things). What are the standard tests that the Americans perform on circuits?

serious question

Click to expand...

I’ll quote a moderator on an American site. “We work to code so an installation doesn’t need testing.” “Turn on, if there’s no bang or smoke, it’s good to go.” When I posted a copy of an EICR all hell broke out.

It started as a simple question about testing a new installation, it went on to become a blazing row. I did have some back up, there are some US electricians that do carry out dead tests, the majority don’t.

Tony S said:

I’ll quote a moderator on an American site. “We work to code so an installation doesn’t need testing.” “Turn on, if there’s no bang or smoke, it’s good to go.” When I posted a copy of an EICR all hell broke out.

It started as a simple question about testing a new installation, it went on to become a blazing row. I did have some back up, there are some US electricians that do carry out dead tests, the majority don’t.

Click to expand...

Is it wrong that I have deliberately installed faults on some circuits, just to push the point my jobs over here need testing. 

Note: Nobody was in risk of danger, and no damage was caused. 

Also caught some of them using the non contact testers to prove dead, that was quickly barred on my jobs too.

We used to do that with apprentices to teach them how to find a fault. I can’t see anything wrong with adult training when they need it!

Like it Rob!

If the kit is going into the IEC market place, e.g. Europe, then the tests have to be done for the Tech File anyway...

Sidewinder said:

Like it Rob!

If the kit is going into the IEC market place, e.g. Europe, then the tests have to be done for the Tech File anyway...

Click to expand...

Agreed, which they are for CE compliance and everything that goes along with that. 

The kits UL and OSHA complient that we use on the US jobs. However, getting the "electricians" to follow testing for field cabling was a pain in the ass to begin with. 

If it's to c :slap ode it doesn't need testing?!.....brilliant, we need that here 

kerching said:

If it's to c :slap ode it doesn't need testing?!.....brilliant, we need that here 

Click to expand...

Do you want AFDD;s as mandatory? That's what started it  :happybunny:

Tony S said:

Do you want AFDD;s as mandatory? That's what started it  :happybunny:

Click to expand...

Ah, NO!

I retract my statement