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Posted By: Electric Eagle Breakers that don't trip/ Fire hazard - 05/29/03 12:03 AM
Why is it that a breaker would hold with a dead short on it?

Recently we had a customer with a lightning strike. One circuit would not reset. I went on the troubleshoot with a helper. After taking a look around and unplugging everything on the circuit, I tried to close the breaker and it tripped. It was an old Westinghouse breaker, so just for kicks I replaced it with a new Seimens breaker and went in search of the problem. I took appart what I thought was the first j-box(switch) and told the helper to go reset the breaker. He did and came back saying it held, but was buzzing. I IMMEDIATELY went to the panel to turn it off. As I got there another breaker on the same phase tripped, but this circuit wasn't buzzing anymore and was still on. The wire was smoking. We traced the wire through the attic and found the wire melted throughout the circuit. We found one section where the wire was burned in half, thus why the breaker wasn't buzzing anymore.

This incedent scared me pretty bad. It made me tell everyone in the company to turn off a breaker if it buzzes. We rewired the entire circuit and all is well there, but it could've been very bad.

Today I tried to turn on a breaker on a new installation(15 amp GE). The breaker buzzed, but didn't trip. I had to turn it off. Someone had a ground touching a screw on a receptacle. Why aren't these breakers working???????

[This message has been edited by Electric Eagle (edited 05-28-2003).]
This type of problem should be brought to the attention of the testing agency.

On a humorous note, perhaps this equipment was designed by those who designed the following products?

[Linked Image from joetedesco.com]
[Linked Image from joetedesco.com]
Posted By: CRW Re: Breakers that don't trip/ Fire hazard - 05/29/03 02:52 AM
maybe it wasn't really a "dead short", but instead an arcing fault--not enough steady current to trip the breaker.
Posted By: Redsy Re: Breakers that don't trip/ Fire hazard - 05/29/03 11:04 AM
As CRW said, it sounds like a high resistance fault. Next time, try to get a meter on it.
Posted By: Active 1 Re: Breakers that don't trip/ Fire hazard - 05/29/03 03:15 PM
Maybe a poor ground path with high resistance not alowing enough current in the short to trip the breaker.

With EMT it could be loose lock nuts and set screws.
Posted By: sparky Re: Breakers that don't trip/ Fire hazard - 05/29/03 10:53 PM
Breaker 'hum' is a curious thing, the fact that noise is produced as a byproduct of load....
Other than motor starts i would also side with CRW.
Posted By: Gwz Re: Breakers that don't trip/ Fire hazard - 05/29/03 11:03 PM
By the replies, I guess it is not possible to have a defective CB.
Posted By: sparky Re: Breakers that don't trip/ Fire hazard - 05/30/03 12:19 AM
better chance than a defective fuse Glenn
GEE JOE,

Are you saying that maybe one of those red handled type breakers have a problem with tripping? LOL I have seen that problem first hand before. I shorted out a circuit, burnt a locknut and screw driver tip, but the breaker held. It did not trip. I have heard of one job in the past few years of inspecting where that type of circuit breaker panel actuall caused the fire in the building. That was the word of one of the people who went in after the he fire to clean out the building.
Posted By: Scott35 Re: Breakers that don't trip/ Fire hazard - 06/01/03 03:12 AM
The non-trip situation may have been from numerous factors.

<OL TYPE=1>

[*] Load current stayed within the tolerance of the unit's trip characteristics - like not exceeding 20 amps on a 20 amp breaker, or rising briefly to only about 40 amps, then dropping back to 20 amps,
[*} Arc fault - as mentioned by others,

[*] Faulty unit or fried contacts,

[*] exceeded the AIC of the unit - highly unlikely in Residential or without a corresponding explosion of the frame!

[*] The parallel circuitry result of two branch circuits originating from the same line / phase allowed divided current levels to flow across each breaker - so each frame only saw ½ the current level flowing.
</OL>

Just thinking and typing outloud! [Linked Image]

Now if the situation was on the above mentioned and shown FPE equipment, or possibly on Zinsco type P / FP equipment, that is the exception [Linked Image]

No need to use trip-free type breakers if using FPE or Zinsco FP/Ps! They came factory stock as trip-free!
[Linked Image]

It's been a long time since I have flamed out towards FPE and Zinsco!

BTW, not all of the FPE or Zinsco line is like this. Only certain devices are the ones with the "Sucks For Overload / Overcurrent Protection" characteristics! Unfortunately, the ones that suck were very commonly used, which is why everyone in the trade makes so much fun of them.

Scott
Thanks for the replies. On the second situation I described, the ground was touching a "hot" screw. It was not wrapped around it, but just touching, so I guess it could've been not touching enough. It was good enough to make the wire very hot in about 2 seconds.

All I can say is that a Cutler Hammer CH breaker or Sq D QO breaker, they would've tripped instantly.
Posted By: derater Re: Breakers that don't trip/ Fire hazard - 06/03/03 11:26 PM
Had what may be a typical situation with the Fed Pac stuff today.Regular cust. said a tennant got a shock from their microwave;first check of receptacle looked good which made me look elsewhere;thought it was feeding through the plumbing since the sink set off the tic tracer-but no, a thorough look found a tiny nick on the hot coming into metal box;grounded ok,and by rights,and correct me if I'm wrong here,should trip the &%@@**# breaker.When I'd backtracked and remetered I could get 120v from plate cover screw to sink.Makes me shudder.
Posted By: sparky Re: Breakers that don't trip/ Fire hazard - 06/04/03 12:14 AM
I just refer my customers to the 'net, and sites like this FPE one

Let them decide for themselves....
Posted By: C-H Re: Breakers that don't trip/ Fire hazard - 06/04/03 12:10 PM
Scott35,
Quote

3. exceeded the AIC of the unit - highly unlikely in Residential or without a corresponding explosion of the frame!

What if lightning struck the electrical system and went down the branch circuit?
its something some one needs to develop,, an MCB tester,, we have meters for everything else but no way of testing an MCB
Posted By: Bjarney Re: Breakers that don't trip/ Fire hazard - 06/05/03 07:46 PM
There are gizmos for circuit-breaker testing, but they are large, heavy {and pricey.} The basic idea of forcing current through a breaker [or fuse?¿?;-)] is simple, but the technique gets a bit complicated.
http://www.phenixtech.com/products/Circuit_Breaker/index.php http://www.phenixtech.com/products/Circuit_Breaker/brochures/30105-HC1-HC2-PORTABLES.pdf
Posted By: Bjarney Re: Breakers that don't trip/ Fire hazard - 06/12/03 10:02 PM
The first, fourth and fifth images posted at http://www.inspect-ny.com/fpe/fpefire.htm do not look like the classical FPE “stab-lok” products, but may be Square-D QO-series components.
http://www.inspect-ny.com/fpe/Burnup.jpg looks a lot like “QOU” breakers marketed for OEM use. OEM Circuit Breaker Catalog

Looks like the faces [single-width handle and window of multipole QO-series circuit beakers] pictures in these links. http://www.inspect-ny.com/fpe/HeaterBrkr.jpg and http://www.inspect-ny.com/fpe/Close2.jpg

Are the first, fourth and fifth images of FPE or Square-D stuff?

(Long URL edited by Webmaster)

[This message has been edited by Webmaster (edited 06-12-2003).]
Posted By: PCBelarge Re: Breakers that don't trip/ Fire hazard - 06/13/03 05:38 PM
Faulty breakers do occur, but if I am reading this correctly, he did say a GE breaker (not that they don't fail). In my experience, I have seen more 'high impedance return fault current paths' than faulty breakers.
As already mentioned in this post, but what seems to virtually be ignored is this type of situation. I also believe that a 'high impedance return fault current path' poses one of the greatest risks for us in the field.

Why? It is basically invisible!!! I also believe there is an increase in this situation for several reasons, installations are getting older, and more people today are performing "electrical installations'who really have not got a clue.

When I am at a job and a ground fault of some kind occurs and it does not trip the overcurrent device, it makes me very nervous for my safety, and anybody else for that matter.
How many times have we seen a loose locknut, screw backed out or missing, a ground splice not made, or the conductor broken under the wirenut? Too many!!!

One last thing....If you read the electrical accident reports, you will see the ages in general are older, I believe this is because we get too comfortable and one day it is going to.....

Be Safe

Pierre
Posted By: mlk682 Re: Breakers that don't trip/ Fire hazard - 06/14/03 12:18 AM
Is there a possibility that a shared nuetral condition existed or exists? Maybe the nuetrals got tied together in a switch location? That would explain the other breaker tripping on the same phase? Like your posts on here Eagle, I bet your business does well, Keep up the good work
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