# burned panel lugs



## backstay (Feb 3, 2011)

RICK BOYD said:


> why would the lugs burn up under a correctly installed breaker ?
> 
> this is a pic of a general switch brand ,
> but I saw a challenger brand do the same thing.
> ...


Continuous high or over current will do that.


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## Jeff Henry (Sep 8, 2011)

backstay said:


> Continuous high or over current will do that.


If so does that mean the breaker didn't trip when it should have?


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## EC2253 (Mar 7, 2008)

That's from an arc caused by bad connection to the bus typical with that style breaker


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## BuzzKill (Oct 27, 2008)

EC2253 said:


> That's from an arc caused by bad connection to the bus typical with that style breaker


yeah that seems like a classic case of super high impedance on that bus from a poor connection.


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## BuzzKill (Oct 27, 2008)

EC2253 said:


> That's from an arc caused by bad connection to the bus typical with that style breaker


yeppers!


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## Jeff Henry (Sep 8, 2011)

BuzzKill said:


> yeppers!


Thats a scary avatar you have.


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## BuzzKill (Oct 27, 2008)

Jeff Henry said:


> Thats a scary avatar you have.


He won "ugliest dog in the world!"


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## Jeff Henry (Sep 8, 2011)

BuzzKill said:


> He won "ugliest dog in the world!"


So that is a picture of a real dog?


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## BuzzKill (Oct 27, 2008)

Jeff Henry said:


> So that is a picture of a real dog?


yeppers!:thumbsup:


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## backstay (Feb 3, 2011)

Jeff Henry said:


> If so does that mean the breaker didn't trip when it should have?


No, high current say 90% of rating will cause metal fatigue in the breaker over a long time. The clips will get loose and cause even more current from voltage drop across it. Once the connection gets loose it will start to arc. Usually the breaker will be tripping in this case, but it gets reset many times before it gets to this point.


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## Shockdoc (Mar 4, 2010)

Cheap garbage panel.


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## backstay (Feb 3, 2011)

Shockdoc said:


> Cheap garbage panel.


I agree, here's one that had the same problem.


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## Zog (Apr 15, 2009)

backstay said:


> No, high current say 90% of rating will cause metal fatigue in the breaker over a long time.


UL 489 requires the breaker to not have a rise of >50C at the terminal connection at 100% rated current for an indefinite time. 



backstay said:


> Once the connection gets loose it will start to arc. Usually the breaker will be tripping in this case, but it gets reset many times before it gets to this point.


How would arcing cause the breaker to trip?

For a MCCB that has a thermal element a poor connection will cause heating (I^2R) that will radiate to the thermal element and cause a premature trip.


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## backstay (Feb 3, 2011)

Zog said:


> UL 489 requires the breaker to not have a rise of >50C at the terminal connection at 100% rated current for an indefinite time.
> 
> 
> 
> ...


I didn't mean the arcing caused it to trip. Heat from the bad connection will cause tripping. I don't know what the rise at his terminals was, but 20 years of 90% current will defeat that breaker, indefinite or not.


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## RICK BOYD (Mar 10, 2008)

How would arcing cause the breaker to trip?

For a MCCB that has a thermal element a poor connection will cause heating (I^2R) that will radiate to the thermal element and cause a premature trip.[/quote]



look at the burn marks on the main, there was some heat in there !


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## Meadow (Jan 14, 2011)

Poor enginering, some old brands simply never were up to there listed ratings. Look at FPE for example.


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## backstay (Feb 3, 2011)

....


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