Breakers not tripping

[ampman02]

I have a situation that has stumped me. I'm doing some electrical renovation at my sisters house. The house was built late 70's. Has a GE loadcenter
150 a main breaker. I'm sure the house is not grounded to todays. Anyway the problem is when I was tripping breakers to re-device each room some would trip instantly and some I was just gorilla welding, wouldn't trip at all. By the way the breakers are new. I feel this is a grouding system issue but don't understand why some trip and some dont. Thanks

 

[roger]

Re: Breakers not tripping

Are you trying to burn down your sisters house?

Bolting a circuit to make an OCPD trip is not a good way to do this identifying.


You will not know if you have damaged these conductors within the wall.

You should invest in a cheap circuit tracer or simply plug in a lamp and go by trial and error to find the breaker.

Roger

 

[ampman02]

Re: Breakers not tripping

thanks for the advice. any idea why the breakers that dont trip aren't?

 

[dereckbc]

Re: Breakers not tripping

Originally posted by ampman02:
thanks for the advice. any idea why the breakers that dont trip aren't?

Sure the fault path impedance is too high. Do the circuits habe an EGC installed?

 

[rbalex]

Re: Breakers not tripping

You may want to go to this web page and download a copy of NEMA AB-4. It's free. All you have to do is register.

Read the Introduction and Clause 4.3 carefully. Its very likely that your "crowbar" testing damaged some of the MCCBs.

 

[physis]

Re: Breakers not tripping

I'm not passing judgement or taking sides but a couple of weeks ago a friend of mine called me with a problem. He's a tile guy and he was replacing an exterior lighting fixture. He tripped the breaker with the hot against the box. When he tried to reset the breaker nothin doin. I suggested he probably aggravated an existing condition and my guess was that he got a conductor welded to a box "somewhere". Befor I was able to get my cape on and fly over to rescue everybody he was lucky enough to find the problem in another box. He was very lucky, if it were me I'm sure I'd still be looking for it.

 

[midget]

Re: Breakers not tripping

What do you guys mean by bolting a circuit? And gorilla welding? I'm not fimiliar with these terms. And why is it bad?

 

[iwire]

Re: Breakers not tripping

Originally posted by midget:
What do you guys mean by bolting a circuit? And gorilla welding? I'm not fimiliar with these terms. And why is it bad?

The Term "Bolted Fault" is a term that is often used in describing a firm / permanent connection resulting in a short circuit or ground fault.

If you wire nutted the white and black together at an outlet you would have a "bolted fault".

"Gorilla Welding" I have never heard before but I think we can assume that means taking a hot wire and intentionally touching it to a grounded box resulting in a ground fault.

Done this way it is not a "bolted fault", it would likely be a high impedance fault that may not trip a breaker but will be making sparks as the copper and steel disappear at the connection. This would be the 'welding' part.

The gorilla part describes the person doing this as having no more sense then a gorilla.

 

[midget]

Re: Breakers not tripping

It what situations would the grounded conductor not be a netural? I don't quite understand that. But all the rest of the stuff in your post makes since. What's an EGC?

 

[highkvoltage]

Re: Breakers not tripping

A switched leg or 240V NM circuit(Non metallic conductor also known as romex) that some hack didn't mark with tape to notify others what it was being used for.

 

[electricman2]

Re: Breakers not tripping

EGC E quipment G rounding C onductor.
The grounded conductor of a corner grounded delta system would be one example of a grounded conductor which is not a neutral.

 

[midget]

Re: Breakers not tripping

Originally posted by highkvoltage:
A switched leg or 240V NM circuit(Non metallic conductor also known as romex) that some hack didn't mark with tape to notify others what it was being used for.

Shouldn't they of just used some 3 conductor?

[ December 07, 2004, 08:57 PM: Message edited by: midget ]

 

[George Stolz]

Re: Breakers not tripping

There are many occasions where the white wire can be more useful when used for other things. One of them is commonly called the "farmer switch" which is one of few switching methods detailed in code. Look it up in 200.7.

 

[ryan_618]

Re: Breakers not tripping

I stopped doing that as soon as I saw someone drop an 800 amp main by bolting a couple #12's on a 20 amp circuit. That really is the least of the worries though, the above statements are far more important and should be taken very seriously.