# Breaker won't trip on a full short



## Tomer (Jan 22, 2018)

During a troubleshooting job for some outed lights and outlets at an old house I discovered that the branch circuit won't trip even with a full short (Hot to ground).

Is there any way to test all the other breakers in the panel other than disconnecting them from the circuit and then shorting them?


----------



## HackWork (Oct 2, 2009)

There is another thread on a very similar topic going on right now.

What you are doing is not a valid test. There is no way for you to test a breaker yourself, and its not worth having a pro do it for a $3.25 residential breaker. 

The reason why the breaker isn't tripping is probably because there are not-so-great connections made up along the circuit, and the resistance is too high to allow enough current to flow to trip the OCPD. Or the ground isn't a low (enough) resistance path back to the source. Both are typical in old houses.

Hell, your ground is probably made up of the metal sheath of old BX cable without a bonding strip, which isn't a compliant EGC because its known for being high resistance.


----------



## Bird dog (Oct 27, 2015)

HackWork said:


> There is another thread on a very similar topic going on right now.
> 
> What you are doing is not a valid test. There is no way for you to test a breaker yourself, and its not worth having a pro do it for a $3.25 residential breaker.
> 
> ...


Hax made some great points. If you had a bolted fault and the breaker didn't trip there would be heat, sparks, flame or smoke IMO.


----------



## joebanana (Dec 21, 2010)

Tomer said:


> During a troubleshooting job for some outed lights and outlets at an old house I discovered that the branch circuit won't trip even with a full short (Hot to ground).
> 
> Is there any way to test all the other breakers in the panel other than disconnecting them from the circuit and then shorting them?


What type of panel? Zinsco? FPE? About the only tests you could do are V/D, and leakage, otherwise you need a test bench.


----------



## mitch65 (Mar 26, 2015)

sounds like old FPE. Panel main or primary on the service transformer will trip first.


----------



## JRaef (Mar 23, 2009)

Like Hack said, THINKING you are giving it a direct short to ground it not a valid test. RESISTANCE of the connection to ground becomes a crucial element in whether or not the breaker trips instantly or not. In fact it can be so much that the breaker may NEVER trip before something catches on fire. 

This by the way is EXACTLY why the code added *Arc* Fault Circuit Interrupter technology. If you can see an arc, there IS resistance, and that resistance WILL interfere with the tripping time of the breaker.


----------



## HackWork (Oct 2, 2009)

I know some people will get on my case about this, but below you will see my old method for identifying circuits :whistling2:

Even with that shorted plug making a solid short circuit, there have been many instances in which the breaker did not trip. Sometimes the lights dimmed (if they were on the same circuit). Other times you heard a buzzing sound, I believe that was the wire vibrating. This would happen either from the place I was shorting being so far from the panel, or just lots of splices with poor connections.


----------



## Tomer (Jan 22, 2018)

An old FPE it is.









I'm sure it was a direct short to the ground. Initially I shorted between hot wire and the box while working on the outlet. Later to double check. I directly shorted the breaker itself with the neutral bar in the panel.
Sparks light, mild short explosion ensued for the second till I pulled away the wire connecting the 2. Breaker didn't trip.

There might be an issue with the homes ground itself, but to my understanding if the short occurred in the panel as well with heat a flash, sparks and a mild explosion then the breaker is defective. If so, then how the hell do I test all the other breakers? or should I just change all of them? And could there be an issue with the ground besides the defective breaker?


Where could I read up about V/D, and leakage, or bench testing?


Where's that other thread?

I'm attaching pics for reference


----------



## HackWork (Oct 2, 2009)

What you did was dangerous. Shorting out a breaker in an open panel by touching (welding) the neutral bar. 

FPE is "replace on sight". They are known not to trip. Like I said earlier, there are no tests for you to do, you just replace the breaker. In your situation with an FPE panel, you replace the whole panel as well.


----------



## Tomer (Jan 22, 2018)

*Pic links*

can't post pics apparently because I haven't posted enough posts on the forum yet. Not sure how to go around this either than put in the time and posts :biggrin:


----------



## frenchelectrican (Mar 15, 2007)

Tomer said:


> An old FPE it is.
> 
> 
> I'm sure it was a direct short to the ground. Initially I shorted between hot wire and the box while working on the outlet. Later to double check. I directly shorted the breaker itself with the neutral bar in the panel.
> ...



I am sorry to be harsh but what you did when you test the breaker in the panel that is pretty much bonehead move and it is dangerous and you will get hurt very fast with arc blast., ( basically a uncontrolled welding .)

Trust me I have see aftermath of arc blast damage. 

FPE breaker ( USA verison ) is not safe at all and I would just replace it quick no question asked ., if the customer get little stubborn or you want to find out more just goggle up FPE breaker failures and you will be suprised what the situation of that.


----------



## frenchelectrican (Mar 15, 2007)

Tomer said:


> can't post pics apparently because I haven't posted enough posts on the forum yet. Not sure how to go around this either than put in the time and posts :biggrin:


Tomer .,

You have to post at least 10 to 20 to get the photo attachment to work properly.


----------



## Tomer (Jan 22, 2018)

So replace all the breakers in the panel? Or just replace all the panel to a new and improved one?


----------



## frenchelectrican (Mar 15, 2007)

Tomer said:


> So replace all the breakers in the panel? Or just replace all the panel to a new and improved one?


Just get a new panel and new breakers and be done with it.

That what I would do it quick especally with USFPE or other oddball breakers which they are no longer avaiable.


----------



## Zog (Apr 15, 2009)

Besides being a invalid and dangerous test this method may destroy the breaker. Breakers designed to UL 489 standards are only required (And therefore designed) to interrupt rated short circuit current twice, yes twice. Important to keep this in mind.


----------



## Zog (Apr 15, 2009)

Refer to ANSI/NETA MTS or NEMA AB 4 to learn about approved test methods of MCCB's. But, as mentioned, no one will do hundreds of dollars worth of testing on a $20 breaker. When in doubt, replace.


----------



## Tomer (Jan 22, 2018)

*Good point*



Zog said:


> Besides being a invalid and dangerous test this method may destroy the breaker. Breakers designed to UL 489 standards are only required (And therefore designed) to interrupt rated short circuit current twice, yes twice. Important to keep this in mind.


Now that is a (Damn) good point. Thanks


----------



## GeneC (Aug 28, 2017)

Hey man you seem young and ambitious, but what you did at the panel was just off the hook. I'm a cranky old man now and I never did what you did, I used to short outlets like Hack back in the day, But FPE in older homes is junk. I would do as others have said and replace the whole panel, It's a no brainer considering the prices now. I used to have an old FPE panel that I changed out and in a controlled shop purposely shorted breakers some tripped and some melted the insulation off wires and melted without tripping. I used it to sell upgrades and service changes back in the old days. Did with a big generator so as not to trip main. The test equipment you mentioned is not worth the investment unless you work on very large mains where breakers can cost well over $5,000 at that point you become a testing company. just change it all, don't try to be a hero. If your are old enough to remember pushmatic breakers and prior to that just fuses, or knob and tube then we can talk more. Listen to what the others have posted also. Blind ambition will get you hurt.


----------



## JRaef (Mar 23, 2009)

> "I'm a cranky old man now and I never did what you did, I used to short outlets like Hack back in the day,"


As the saying goes; 

*There are old electricians 
and there are bold electricians, 
but there are no old bold electricians.*


----------



## JRaef (Mar 23, 2009)

As to the FPE panel,
Deserved or not (it's actually debatable), there are a number of insurance carriers and AHJs that will INSIST on replacing the entire panel. Besides the anecdotal evidence of "not tripping", there was documentation of the lack of quality control on the bus connections, leading to fires. If you are doing work for a homeowner, you can look at this as an opportunity to "sell up" to doing a complete change-out to a shiny new modern breaker panel. Have them check with their insurance carrier, they might find that once it is brought up, the insurance company may insist on it.
http://www.harrylevineinsurance.com/certain-electrical-panels-ineligible-insurance/
http://wiseinsurancegroup.com/home-insurance-and-federal-pacific-electric-panels/
https://inspectapedia.com/fpe/FPE_Panel_Home_Buyer_Advice.php

If this is your own panel, then shame on you for posting a DIY question... :vs_whistle::wink:


----------



## brian john (Mar 11, 2007)

HackWork said:


> What you did was dangerous. Shorting out a breaker in an open panel by touching (welding) the neutral bar.
> 
> FPE is "replace on sight". They are known not to trip. Like I said earlier, there are no tests for you to do, you just replace the breaker. In your situation with an FPE panel, you replace the whole panel as well.


There are test *BUT*

It is expensive
Not worth the cost

And as you noted replace.

I would try to verify the ground resistance with a DMM, not the ultimate test but in lieu of an expensive meter.


----------



## Signal1 (Feb 10, 2016)

Tomer said:


> An old FPE it is.
> 
> 
> 
> ...


That's nuts.:001_huh:

As stated the normal and cost effective solution here is to replace the panel and breakers.
Also check or re-terminate the GE if needed.


----------



## chicken steve (Mar 22, 2011)

Zog said:


> Besides being a invalid and dangerous test this method may destroy the breaker. Breakers designed to UL 489 standards are only required (And therefore designed) to interrupt rated short circuit current twice, yes twice. Important to keep this in mind.



UL 489 & ANSI C37

Am i reading this right? >> 2.3X's ocpd rating. IE~20A x 2.3=46A?

~CS~


----------



## JRaef (Mar 23, 2009)

chicken steve said:


> UL 489 & ANSI C37
> 
> Am i reading this right? >> 2.3X's ocpd rating. IE~20A x 2.3=46A?
> 
> ~CS~


Well, you're not reading it right as it would apply to a *UL489 listed breaker*, no. 

That statement applies to an ANSI C37 listed POWER BREAKER, i.e. what you would see in SWITCHGEAR, not Panelboards. Different animal. 

That entire paper is comparing the two standards to point out to potential buyers of Switchgear why they DON'T want to use less expensive Panelboards as their main distribution system. That typically only applies to large facilities, but over time, Panelboards and Switchboards (the "lighter" spec) have been making incursions into what was traditionally reserved for SwitchGEAR.

In a nutshell, Switchgear is used to supply the ENTIRE facility, then down stream of that, you feed local Switchboards and then (or) Panelboards. You WANT any faults to clear as CLOSE to the fault as possible, so you coordinate the trip settings to do so. That means the closest breaker or fuse SHOULD clear first, ie the Panelboard feeder, then if not, the NEXT one up the line does, ie the panelboard MAIN or Switchboard feeder and if still not, THEN the Switchgear breaker. But that then has to be able to hold in for LONGER than you would allow that Panelboard breaker, which means it must be built stronger because by the time IT tries to clear the fault, the situation is a LOT worse. So when that ANSI C37 breaker DOES have to clear a fault, the magnetic forces are held in check, whereas that would turn a UL489 breaker into a bomb.


----------



## HackWork (Oct 2, 2009)

brian john said:


> There are test *BUT*
> 
> It is expensive
> Not worth the cost


The key part of what I said to the OP is: "there are no tests *for you to do*".

"*There is no way for you to test a breaker yourself*, and its not worth having a pro do it for a $3.25 residential breaker."


----------



## Wiresmith (Feb 9, 2013)

Tomer said:


> During a troubleshooting job for some outed lights and outlets at an old house I discovered that the branch circuit won't trip even with a full short (Hot to ground).
> 
> Is there any way to test all the other breakers in the panel other than disconnecting them from the circuit and then shorting them?


directly wire to the load of the breaker a large enough load(any equipment that will operate on the voltage)(preferably variable load), use an amp clamp and run the load past the trip setting. what is the trip setting?


----------



## brian john (Mar 11, 2007)

hd13 said:


> directly wire to the load of the breaker a large enough load(any equipment that will operate on the voltage)(preferably variable load), use an amp clamp and run the load past the trip setting. what is the trip setting?


For a 20 amp circuit, you would need a minimum 60 amp load for long time trip. For an instantaneous trip, you would need to bump a load up to 300 amps.


----------



## chicken steve (Mar 22, 2011)

JRaef said:


> Well, you're not reading it right as it would apply to a *UL489 listed breaker*, no.
> 
> That statement applies to an ANSI C37 listed POWER BREAKER, i.e. what you would see in SWITCHGEAR, not Panelboards. Different animal.
> 
> ...


I'm _obviously _not as adept at reading these technical reports as you JR

I get the jist of Eframes & RK fusing better AIC and why they're front line equipment

I don't understand resi mini breaker _mag trip_ ratings , it all seems nefarious , and the closer to poco xformers i get, nervous
:vs_OMG:
~CS~


----------



## JRaef (Mar 23, 2009)

chicken steve said:


> ...
> I don't understand resi mini breaker _mag trip_ ratings , it all seems nefarious , and the closer to poco xformers i get, nervous
> :vs_OMG:
> ~CS~


We all should get nervouser as we get closer to the source... :vs_whistle:


----------



## Tomer (Jan 22, 2018)

*All's well that ends well*

Sold the customer on changing the panel. Resisted the pressure to cut corners and filing with the city and getting electric company to pull the meter.

GeneC. Youngish I guess, 32, Hungry yes with and ex wife and 3 kids to feed and educate life's no walk in the park. Then again you want to stay alive and healthy in order to keep on providing.

hd13 & brian john aren't the mechanism's that make a breaker trip when overloaded and when short circuited different mechanisms? if yes then why would making sure it trips when overloaded let me know that it would trip when shorted? of course if a 20amp breaker doesn't trip on a 300amp load immediately then the question is moot.

JRaef
Not my own panel. Don't even own a panel I rent


----------



## Tomer (Jan 22, 2018)

As a random side note. For some reason it seems that the way they do electricity in the USA is so much more dangerous pricey and complicated then from where I originally learned my trade. But that's a whole new thread isn't it...


----------



## brian john (Mar 11, 2007)

Tomer said:


> S
> hd13 & brian john aren't the mechanism's that make a breaker trip when overloaded and when short circuited different mechanisms? if yes then why would making sure it trips when overloaded let me know that it would trip when shorted? of course if a 20amp breaker doesn't trip on a 300amp load immediately then the question is moot.


A modeled case circuit breaker (typical CB) is a thermal, magnetic device. Two separate features, I think it was mentioned the two type of test to check the trip of this style CB. Thermal is generally tested at 300% or 600% of rated current and magnetic is tested at pickup by bumping the current up in steps until you reach the pickup point. Additionally we megger the CB and verify the contact resistance with a Doctor/DLRO/Micro-ohm Meter.


----------



## Wiresmith (Feb 9, 2013)

brian john said:


> For a 20 amp circuit, you would need a minimum 60 amp load for long time trip. For an instantaneous trip, you would need to bump a load up to 300 amps.


something like 2 big motors in parallel, using inrush current


----------



## brian john (Mar 11, 2007)

hd13 said:


> something like 2 big motors in parallel, using inrush current


More like a resistive load and a Variac, so you can control current.


----------



## frenchelectrican (Mar 15, 2007)

brian john said:


> More like a resistive load and a Variac, so you can control current.


Sometime I used the load banks to check the timing of tripping the breaker.


----------



## eddy current (Feb 28, 2009)

Check this out. Overload and a short in slow mo. https://m.youtube.com/watch?v=wGFnooeA6Iw&feature=youtu.be


----------



## RICK BOYD (Mar 10, 2008)

R & R that "fire box" FPE = flames produced electrically .


----------

