Service panel_bent busbar tab

[70runner]

Completed a ground mount solar install last week, waiting for local Permission to Operate approval. Hadn't used the 240v circuit in the garage (welder, 2 post lift) during 3 week install. Went to use lift today, pushed power button...nada. 240v circuit DPST breaker not tripped, one 120v leg checked ok, the other no voltage. Checked couple other DP breakers on panel, all normal 240vac. Hmmmmm.

Bad breaker? Off panel continuity check was proper. Decided to swap it out anyway with known good one from another slot on panel. Same results. While I was swapping breakers noticed one of the corresponding busbar tabs looked bent, middle tab in pic. Having replaced a couple Zinsco panels, the tab discoloration reminded me of some of the Zinsco busbars I've seen. Perhaps some arcing residue?


Used screwdriver to pry tab back into correct position and cleaned it with wire brush. Remounted orig breaker, watching carefully that tab stayed in place. Solved the problem, 120v on both legs. As the solar installers did some work with the panel, my theory is they may have bent the tab or the tab could have already been pushed in and they pushed it in far enough to lose connection to that 120v leg.

Question for the electricians among us, how often do you see this sort of problem, bent busbar tabs?

 

[sparky 1971]

I don't recall ever seeing one bent like that, but I've seen plenty of them cooked, some worse, some not as bad as what you have. That's why bare aluminum bus panels ****. All you did was delay it happening again when you cleaned it up. Do you have another space or two open so you can move the breakers off of that tab?

 

[Norcal]

Crouse-Hinds Panel?

 

[wyliesdiesels]

Completed a ground mount solar install last week, waiting for local Permission to Operate approval. Hadn't used the 240v circuit in the garage (welder, 2 post lift) during 3 week install. Went to use lift today, pushed power button...nada. 240v circuit DPST breaker not tripped, one 120v leg checked ok, the other no voltage. Checked couple other DP breakers on panel, all normal 240vac. Hmmmmm.

Bad breaker? Off panel continuity check was proper. Decided to swap it out anyway with known good one from another slot on panel. Same results. While I was swapping breakers noticed one of the corresponding busbar tabs looked bent, middle tab in pic. Having replaced a couple Zinsco panels, the tab discoloration reminded me of some of the Zinsco busbars I've seen. Perhaps some arcing residue?


Used screwdriver to pry tab back into correct position and cleaned it with wire brush. Remounted orig breaker, watching carefully that tab stayed in place. Solved the problem, 120v on both legs. As the solar installers did some work with the panel, my theory is they may have bent the tab or the tab could have already been pushed in and they pushed it in far enough to lose connection to that 120v leg.

Question for the electricians among us, how often do you see this sort of problem, bent busbar tabs?

This was a bad idea to do.

If there were any coatings on it, you removed some or all of it with a wire brush.

Furthermore, when the stabs get cooked like that, pitting occurs which causes poor contact with the breaker.

As said above, youre just delaying the inevitable of it happening again.

The stab should be removed from service

 

[70runner]

Crouse-Hinds Panel?

Not sure, it's orig panel for house built in 1980.

I don't recall ever seeing one bent like that, but I've seen plenty of them cooked, some worse, some not as bad as what you have. That's why bare aluminum bus panels ****. All you did was delay it happening again when you cleaned it up. Do you have another space or two open so you can move the breakers off of that tab?

Yea, the panel is a 1980s relic. I'm just happy it isn't a Zinsco like the 2 subs. Thought about relocating, unfortunately the cable runs don't reach for either breaker on that tab. Suppose I could extend the runs with wire nuts though.

This was a bad idea to do.

If there were any coatings on it, you removed some or all of it with a wire brush.

Furthermore, when the stabs get cooked like that, pitting occurs which causes poor contact with the breaker.

As said above, youre just delaying the inevitable of it happening again.

The stab should be removed from service

That's what I'm gathering per sparky above. Wouldn't be my first bad idea. Plan to wirenut some extensions so I can relocate the two breakers. Is there a code limit on #wirenuts in a panel? Appreciate the responses.

 

[wyliesdiesels]

Not sure, it's orig panel for house built in 1980.

Yea, the panel is a 1980s relic. I'm just happy it isn't a Zinsco like the 2 subs. Thought about relocating, unfortunately the cable runs don't reach for either breaker on that tab. Suppose I could extend the runs with wire nuts though.

That's what I'm gathering per sparky above. Wouldn't be my first bad idea. Plan to wirenut some extensions so I can relocate the two breakers. Is there a code limit on #wirenuts in a panel? Appreciate the responses.

there is no code prohibition on wire nuts in a panel...

 

[sparky 1971]

Not sure, it's orig panel for house built in 1980.

Yea, the panel is a 1980s relic. I'm just happy it isn't a Zinsco like the 2 subs. Thought about relocating, unfortunately the cable runs don't reach for either breaker on that tab. Suppose I could extend the runs with wire nuts though.

You can put as many wire nuts as you want to in there. It wouldn't hurt to get a new breaker while you're at it.

 

[Jim greengo]

You can put as many wire nuts as you want to in there. It wouldn't hurt to get a new breaker while you're at it.

And a new panel to put it in,while you're at it.

 

[mike93lx]

40ish years is a good run. Plan for a replacement sooner than later

 

[alfredeneuman]

If there were any coatings on it, you removed some or all of it with a wire brush.

There is a thin (20-30 microns thick) zinc electroplating on the bus as an interface to the breakers. Any abrasives used will remove this...even fine steel wool

 

[sparky 1971]

I was unaware of any coatings outside of Square D's tin. 20 microns isn't enough to amount to anything. Installing the breaker probably scrapes most if it off.

 

[nadogail]

Probably time for a service upgrade with a new panel.

 

[alfredeneuman]

was unaware of any coatings outside of Square D's tin. 20 microns isn't enough to amount to anything. Installing the breaker probably scrapes most if it off.

You're right (as usual) it is tin on the aluminum and as far I know it's on all brands.
Either zinc or copper sulfate is used to prepare the surface for the tin.

 

[sparky 1971]

You're right (as usual) it is tin on the aluminum and as far I know it's on all brands.
Either zinc or copper sulfate is used to prepare the surface for the tin.

I wasn't trying to be a smart ***. I honestly thought Square D was the only manufacturer that coated. The tin coating they use is really shiny, almost chrome like in appearance. The other brands are more like bare aluminum in appearance, so a zinc coating made sense, to me at least. Regardless, if it's only 20-30 microns thick, the breaker will still probably scrape most of it off. There have been a couple of times in the Post Corona days that I've had to use an aluminum bus panel that wasn't a Square D (Siemems). Thinking that was bare aluminum, I coated all of the bus tabs with a thin layer of No-Alox.

 

[alfredeneuman]

The tin can have either a shiny or matte surface.
I didn't think you being a smart ***...far from.

 

[mike93lx]

You're right (as usual)

Let's not let him think he's that good...

 

[sparky 1971]

Let's not let him think he's that good...

Don't worry. What I know, I know well, but am willing to admit there is a whole lot I don't know because I haven't done it. You'll notice there are a lot of threads I stay out of. Sometimes it's because the question has already been answered and I have nothing to add, other times, I just don't know.

 

[hobby-shop]

I don't recall ever seeing one bent like that, but I've seen plenty of them cooked, some worse, some not as bad as what you have. That's why bare aluminum bus panels ****. All you did was delay it happening again when you cleaned it up. Do you have another space or two open so you can move the breakers off of that tab?