Breaker in sub panel charring at the buss connection

[Mr. Live Wire]

Any Idea why a breaker in a residential 120/240v panel would have charring on the bus bar and breaker contacts ?
It's a 2pole 50 amp breaker that is fed from inverter
All other breakers in sub are fine and are older than the now damaged breaker that was installed with the solar system. It is an old zinsco panel but all other components look in tact. Just wondering if it's a coincidence the breaker burnt up or could something in the system be causing a breakdown.

 

[Hedges]

Zinsco is a known fire hazard, if the model I'm thinking it must be replaced.

PV supplies continuous current longer and closer to limits than typical loads, so that could be the reason.

 

[jmjack]

Any Idea why a breaker in a residential 120/240v panel would have charring on the bus bar and breaker contacts ?
It's a 2pole 50 amp breaker that is fed from inverter
All other breakers in sub are fine and are older than the now damaged breaker that was installed with the solar system. It is an old zinsco panel but all other components look in tact. Just wondering if it's a coincidence the breaker burnt up or could something in the system be causing a breakdown.

I would have a qualified electrician check your entire panel and get a recommendation if the panel is safe to use and if using a back-fed breaker to power the panel is a good option for this panel. The breaker connection to the bus bar was never a good design and I have seen breakers pop loose just taking off the panel cover.

You are probably aware but if not Zinsco panels were recalled due to safety concerns-

"While Zinsco too was part of a major recall and lawsuit, the company no longer exists. Thousands of homes around the country may still have these malfunctioning and known hazardous electrical panels installed. Zinsco panels were quite popular during the 1970’s. The circuits have been reported to not “trip” when necessary and actually melt the circuits instead of safely shutting the power off. Even with an overloaded circuit, Zinsco electrical panels have been known to not trip causing fires due to the excessive heat."

My guess, your back-fed breaker is not making good contact and could be arcing due to the loose connection and amperage going through it.

 

[Mr. Live Wire]

Main and sub

 

[Mr. Live Wire]

Ever see a split bolt in a panel before lol

 

[Nobodybusiness]

Ever see a split bolt in a panel before lol

A split bolt with no Rubber or electrical tape on it either.

 

[rodrick]

Hey at least it’s a ground

 

[Nobodybusiness]

Hey at least it’s a ground

Todays inspectors would be apoplectic about it.

 

[Supervstech]

True enough but todays inspectors would be apoplectic about it.

Nah… split bolts are commonplace. Completely acceptable.

 

[Supervstech]

Main and sub

Where do you live? Here in NC, all outdoor meterbase Zinsco panels can be replaced for free by duke energy.

 

[Nobodybusiness]

Nah… split bolts are commonplace. Completely acceptable.

Only time I have seen a Split bolt without rubber and vinyl tape used was on a ground rod.

In a panel, gutter or meter pan had to have Rubber and Vinyl tape.

That is why I used Polaris connectors because the AHJ would not allow split bolts without rubber layer and then vinyl layer.

 

[Supervstech]

Hey at least it’s a ground

No… it isn’t… it is on the neutral conductor… it is grounded… and it’s at the main panel, so I suppose it is ok… that RED conductor connected to it is a big Nono going to the neutral bar… looking further, it appears to be the sub panel neutral feeder… not ok to be uninsulated.

 

[Mike 134]

As others have said breaker was not making good contact with the bus bars.
I'd guess it was a used breaker since they have not been made for 50ish years.

 

[Rednecktek]

As others have said breaker was not making good contact with the bus bars.
I'd guess it was a used breaker since they have not been made for 50ish years.

There are companies that make aftermarket compatible breakers for those panels, I've had to replace a few before. Replace that breaker ASAP.

 

[SparkyJJO]

I know it is expense, but personally I'd rip that Zinsco out ASAP.

 

[Supervstech]

As others have said breaker was not making good contact with the bus bars.
I'd guess it was a used breaker since they have not been made for 50ish years.

Looking at the sub, the gray breakers are modern safe replacement breakers, the 30 is an ancient original… at a MINIMUM I would remove the 30, and install a replacement breaker.

 

[Hedges]

Just upgrade the panel already!

It has 70A to its busbars and 100A to a sub panel.
You could put in a panel with 175A or larger main breaker to support at least the same load.
I like 225A busbar, 200A main breaker. You can have a 100A branch breaker to replacement sub panel (125A if wire gauge sufficient)
That will support up to 70A PV breaker under 120% rule.

If you do that, make plans for battery backup and protected loads panel.