Help 200 amp service

[new-master]

Does anyone have any good reason why this 200 amp service the main breaker did not trip or the service cable caught on fire any good reason or good explanation on why this would happen without tripping the main 200 amp breaker

 

[LarryFine]

Welcome to the forum.

It looks like heat from the terminal, not overload.

 

[Dennis Alwon]

Yes, it's Cutler Hammer. We had a load of those breakers failing that were installed in the 80's or 90's. Some don't kill the power when you shut it off. Others the handle will not stay when switched off- it pops back. I don't know why CH has not had a law suit with these breakers. We have replaced over 10 and I bet there are a ton more out there. I know of others who have had the same issue.

 

[gene6]

If thats a service breaker it is 'up stream' from the cable, those terminals are the supply side of the breaker, unlike feeders and branch circuits. Probably an issue with the oxidation / termination of the aluminum wire.

 

[infinity]

I agree with Larry it looks like the terminal wasn't torqued properly and the black conductor overheated.

 

[new-master]

If thats a service breaker it is 'up stream' from the cable, those terminals are the supply side of the breaker, unlike feeders and branch circuits. Probably an issue with the oxidation / termination of the aluminum wire.

It did not have any DEOX/Noalax on the aluminum terminations to the main breaker


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[Strathead]

Yes ditto. Loose connection.

 

[new-master]

I agree with Larry it looks like the terminal wasn't torqued properly and the black conductor overheated.

Either to lose or over-tighten
I thought that could be one of the reasons the lug actually melted like butter


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[new-master]

Yes, it's Cutler Hammer. We had a load of those breakers failing that were installed in the 80's or 90's. Some don't kill the power when you shut it off. Others the handle will not stay when switched off- it pops back. I don't know why CH has not had a law suit with these breakers. We have replaced over 10 and I bet there are a ton more out there. I know of others who have had the same issue.

I’m in new electrician so all of this feedback means a lot to me. Thank you guys


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[tom baker]

It did not have any DEOX/Noalax on the aluminum terminations to the main breaker


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Noalox is typically not required unless the installations require. But it’s easier just to use it and not get comments. Know what the code and UL requires and win those bar bets

 

[infinity]

Like Tom stated anti-oxidant paste is not required and won't help with a terminal that is not properly tightened.

 

[gene6]

Noalox is typically not required unless the installations require. But it’s easier just to use it and not get comments. Know what the code and UL requires and win those bar bets

Is oxygen not gas that has a deteriorating effect on aluminum?

 

[retirede]

Is oxygen not gas that has a deteriorating effect on aluminum?

Aluminum oxidizes. So does copper. So does steel. So does…..

 

[gene6]

Aluminum oxidizes. So does copper. So does steel. So does…..

And are all those oxide films the same conductivity ?

 

[hillbilly1]

Yes, it's Cutler Hammer. We had a load of those breakers failing that were installed in the 80's or 90's. Some don't kill the power when you shut it off. Others the handle will not stay when switched off- it pops back. I don't know why CH has not had a law suit with these breakers. We have replaced over 10 and I bet there are a ton more out there. I know of others who have had the same issue.

That reminds me, I need to check my mom’s, hers is that vintage.

 

[roger]

In true forum spirit we have to nitpick things beyond the actual topic. There is a squeeze type flex connector on the lower black NM and I have looked for awhile and do not see a main bonding jumper, not saying it's not there but I can't find it.

 

[hillbilly1]

In true forum spirit we have to nitpick things beyond the actual topic. There is a squeeze type flex connector on the lower black NM and I have looked for awhile and do not see a main bonding jumper, not saying it's not there but I can't find it.

It’s there, just hard to see.

 

[rc/retired]

In true forum spirit we have to nitpick things beyond the actual topic. There is a squeeze type flex connector on the lower black NM and I have looked for awhile and do not see a main bonding jumper, not saying it's not there but I can't find it.

The main bonding jumper is a strap that runs under the main breaker. Almost in line with the switch.

Ron

 

[hillbilly1]

The main bonding jumper is a strap that runs under the main breaker. Almost in line with the switch.

Ron

CH uses a finger that attaches to that strap and the neutral bar.

 

[roger]

It’s there, just hard to see.

I figured it was there, I was missing it.