Overheated breaker panel stabs

[AntonLargiader]

While doing some work in my older (15+ years) 200A QO main panel I found this:



There's no indication that the breakers that were in that spot are overheated so it might be old damage. Searching for anything about overheated stabs brings up pages of FPE info but nothing about repairing a QO panel.

Common? How bad? Can I replace those stabs, move them to the bottom, use them as is, brush them lightly? For now I moved those double breakers down and put some 15A breakers there.

I have a permit open for my other work so I could replace the panel but I really don't see it as necessary. Worst case I skip those stabs.

 

[barnjunkie]

It appears that it overheated due to a bad connection and continued to arc creating the carbon residue. You really can't file or sand away the pitting that is most likely causing the bad connection. I think you would be better off to skip using the affected stabs or replace the panel.

 

[alfredeneuman]

You could buy the smallest QO panel available, and use the stabs for replacement.

Under no circumstances use abrasives such as emery cloth, or brushes to clean the pitting.
The stabs have a VERY thin electroplating of zinc as an interface to the breakers and you'll damage it.

 

[Bert_]

That bus really isn't too bad, usually by the time you find it they are a lot farther gone. You could probably get by using those spaces for lightly loaded circuits. Seems like this is a somewhat common problem with QO stuff.

If you have or can find a scrap panel you could swap the fingers.

 

[barnjunkie]

If you have or can find a scrap panel you could swap the fingers.

I wouldn't tell the inspector that you did this.

 

[mm08822]

It looks like the righthand side breaker(s) had the issue and lefthand side was ok. Is it a 2p breaker or 2 1P cb's that were plugged in on the right? and what size(s)?
Any idea of the actual load running thru the righthand breaker(s)?

May be able to replace the righthand breaker(s) if they show the same (or worse) connection issues.
I'd be tempted to further investigate the remaining quality of those stabs with some electrical contact cleaner and only a pencil eraser used to clean up. Obviously done with the main off.

As for changing out the stabs with others, I would really want to do it first on an old panel to check torque values and if any conductive paste was used or even locktight. The connecting bolt may be a one time use and has very low holding torque upon re-use.

You could also move the new breaker(s) to unused stabs and put two blanks in the cover and just move on from there.

I would check all breaker/stab connections while I am in there. If there are more in same condition, maybe time to consider new panel.

 

[wyliesdiesels]

IIRCC those are field replaceable. But u would need the exact listed part for replacement and you would also need a properly calibrated torque wrench with the correct value to properly torque them.

 

[AntonLargiader]

After I posted that I had a vague recollection of replacing a breaker there some years ago for this issue. The one that was there today was for the downstairs outdoor unit, and the contacts on it look fine.

The smaller QO panel that I am currently replacing does not have those same fingers. If I find an old panel with those fingers I will salvage them and swap them out. I think anything I do will be better than what is there. In the meantime, I think I can just put 15A circuits on those stabs.

From a pedantic side I agree with the correct torque and all of that, but it's not that different than any other bolted electrical connection. I don't torque every breaker, and the finger is actually a much simpler connection. Nothing to crush in the middle. In motorcycle repair we have standard torques for such connections based on the thread size.

 

[Mr_fixit]

Is this what you need?

 

[sberry]

I had a QO do it not too long ago.

 

[AntonLargiader]

Is this what you need?

The look the same as what I have, but without part numbers or direct comparison I can't say for sure. But they appear to be the same parts that are damaged in my panel.

Did you remove them yourself? If so, what do you remember about their mounting? Super-tight, any compound applied, etc?

 

[Mr_fixit]

Yes I removed them from a new panel myself. no, not super tight. no compound. I'd suggest you judge how tight when removing your old ones, if you decide to replace them. I would . It's only a 1/4" head screw. They're yours for the price of shipping if you want them - I would think that would be about 4 bucks. From all the square d panels I've taken apart, I've see two types. one is as in the first pictures, from about a 20 year old or so ( new) panel, or they used a thinner version , in newer stuff, like in this last pictures. You have the older style. These pictures show old and new type side by side.

 

[zmaxmotorsports]

See if you can still find a qo panel with the same model # and amount of spaces and just swap the guts out,would save you a lot of reworking if the panel is buried in a wall.

 

[sberry]

How about skip a space? Seems that would be easier?

 

[6t7gto]

pe·dan·tic1
/pəˈdan(t)ik/
adjective
of or like a pedant:
synonyms: overscrupulous, scrupulous, precise, exact, perfectionist;

 

[wyliesdiesels]

pe·dan·tic1
/pəˈdan(t)ik/
adjective
of or like a pedant:
synonyms: overscrupulous, scrupulous, precise, exact, perfectionist;

Huh??

 

[sberry]

It means if there is a harder way to do it or more fukkin around someone will find it.

 

[lakeroadster]

It means if there is a harder way to do it or more fukkin around someone will find it.

Agreed

Kill the power to the panel, remove the old ones, replace them... and move on.

or better yet...

How about skip a space? Seems that would be easier?

 

[AntonLargiader]

I'll replace them when I can. For now I have 15A breakers there. The panel will still be pretty full so I don't want to have to skip them. I think that space was an oven before.

Mr. Fixit, if I can't round up a few locally I'll take you up on your offer. Thanks!

 

[bjcouche]

If you have unused spaces at the bottom of your panel, then I would remove the bad stabs and throw them out. Then remove stabs from the bottom and install them in the vacant spaces. It then looks less obvious that there was ever a problem. It's common for panels to have more knockouts on the bottom than actual stabs behind them. They often use the same panel cover for different guts. But then you were offered replacement parts for the cost of shipping, so my OCD would make me buy those. I would even be sure to get the exact same type, whether the shiny or dull one pictured.... There might be a difference between one being plated copper and plated aluminum parts.... QO used different parts depending on year made and panel size, cost, etc.
Brian