burnt bussing

[sethas]

What is the standard for replacing a breaker in a panel that has a burnt buss bar?

Are there any legal or code issues that you can think of that prohibit this?

My standard practice, as I was taught, was to remove the damaged breaker, and give an estimate to replace the panel or service. I have never just installed another breaker, even if there was a space available that was undamaged.

The company I currently work for does this, and has for years. If the buss bar is not completely burnt through, they will install another breaker at the next available location. They will even order buss bar through the supply house, take it to a metal shop, and have new custom bussing made.

Does this seem legal? Or even right?

 

[weressl]

What is the standard for replacing a breaker in a panel that has a burnt buss bar?

Are there any legal or code issues that you can think of that prohibit this?

My standard practice, as I was taught, was to remove the damaged breaker, and give an estimate to replace the panel or service. I have never just installed another breaker, even if there was a space available that was undamaged.

The company I currently work for does this, and has for years. If the buss bar is not completely burnt through, they will install another breaker at the next available location. They will even order buss bar through the supply house, take it to a metal shop, and have new custom bussing made.

Does this seem legal? Or even right?

Neither.

The burn through reduces the cross sectional area of the bus, therefore the current carrying capability is reduced to the downstream breakers. (Not to mention that the adjacent areas should be investigated for residues and developing thermal damage due to conducted heat from the burnthrough point.) So if the bus/insulator assembly is not replaced, I would also consider relocating all downstream breakers and potentially some of the upstream also.

Custom busing will void the listing of the panel, unless the shop is listed as an authorized repair shop. The later is highly doubtful.

 

[charlietuna]

Of course it's wrong because the panel looses it's UL rating. First thing to think about is WHY(?) this happened ? What is the load and how much amperage does it draw ? Is the conductor and breaker matched to the load ? This isn't easy since most of the time the actual cause does not operate all the time ? What degree of damage is there to the bus where it can remain "in service" until new "factory parts" or the entire panel is found, or is it "so" bad it must be taken "out of service". The breaker without doubt should be replaced - while being moved to the same bus arrangement, but in a new position. Blank off the original space and make note inside the panel that these spaces cannot be used due to being damaged. Many panel busses are supported by plastic, and if the bus problem is close by the support, the bus may not be supported. Many commercial buildings try to cut costs by using loadcenters where panelboards should be installed and they just don't stand up to the loads. We found a panelboard serving a large doctor's office that the entire top 15 breakers were loose on all three phases - apparently not assembled properly from the factory ? Use caution- we never know whats behind the breakers....................

 

[sethas]

that was always my understanding, "the panel loses its UL listing".

First. Is there any paperwork to support that assumption. To make sure I am not making things up.

Second. If the panel is in this failed state, and loses its UL listing. Would it be wrong to assume that we are allowed to move a breaker upstream or downstream. We should not even be allowed to be working in the panel at that point. It is no longer a listed item, and would therefore need to be replace.

I have a emailed SQD and Cutler-Hammer on this subject. I'll let you know what they have to say.

 

[charlietuna]

If you asked the manufacturer--they would say Shut it down and (order)buy a new one.
An inspector wouldn't want to stick his neck out and want it replaced.

The owner wants it operating, but with minimal expense.

I have always looked how bad it was and made that recommendation to the owner. If they wanted me to attempt something risky--i would refuse the job. And ask them to get someone else. I had an elevator contractor call me to a high rise condo (30+ stories) to check some power problems that were driving his equipment crazy. We quickly found a problem on the elevator equipment(6 cars) feeder breaker's attachment to the bus . He contacted the building's chief engineer, who in turn called the building's management group who told us to leave it alone. The temperature rise was greater than 60 degrees on the breaker and we knew it was close to failing. We closed everything --very carefully! Panel blew up that night causing a nasty fire - the building had to run on one elevator for four days while parts were ordered -- tenants were not happy !

Nothing can be changed in a panel unless it is designed FOR that panel by it's manufacturer---thats what i've been taught !

 

[wireguru]

If you asked the manufacturer--they would say Shut it down and (order)buy a new one.
An inspector wouldn't want to stick his neck out and want it replaced.

The owner wants it operating, but with minimal expense.

I have always looked how bad it was and made that recommendation to the owner. If they wanted me to attempt something risky--i would refuse the job. And ask them to get someone else. I had an elevator contractor call me to a high rise condo (30+ stories) to check some power problems that were driving his equipment crazy. We quickly found a problem on the elevator equipment(6 cars) feeder breaker's attachment to the bus . He contacted the building's chief engineer, who in turn called the building's management group who told us to leave it alone. The temperature rise was greater than 60 degrees on the breaker and we knew it was close to failing. We closed everything --very carefully! Panel blew up that night causing a nasty fire - the building had to run on one elevator for four days while parts were ordered -- tenants were not happy !

Nothing can be changed in a panel unless it is designed FOR that panel by it's manufacturer---thats what i've been taught !

maybe that was allowed to happen intentionally so insurance would pay for it, whereas the repair would have been out of pocket.

 

[RICK NAPIER]

I have always required a replacement. I will let them swap out the bus from a new panel if it is available.

 

[macmikeman]

110.3 and 110.12 (B) both probably should be considered when either just moving to a new breaker spot, or custom replacement of the buss metal as another poster described.

 

[charlietuna]

maybe that was allowed to happen intentionally so insurance would pay for it, whereas the repair would have been out of pocket.

Well, they did call us in the morning, asking for pricing? Pricing? I immeadiately needed to distance myself from this management group. The fact that the elevator contractor had to call me (as a favor) when his responsibility stoped at the car disconnects. But he had just installed some VFD's and he was worried about the warentee on the equipment. He knows us from other buildings in the area. If the building(with six cars) treats his elevator contractor this way -- i didn't want to get involved.

 

[Cow]

If the buss finger is the only part burned off, we just put a new breaker in another spot. Why replace a panel for one bad breaker position? Unless they need every available space, I wouldn't feel good about telling a customer they needed new guts or a panel.

On the other hand, if it's part of the main buss that feeds the other slots that's damaged, then it's time to look for replacement guts or another panel.

 

[220/221]

Does this seem legal? Or even right?

As opposed to say.....leaving the customer without his AC in the summer?


Of course it's legal and it's right thing to do. I don't need a rocket scientist to visit the site and survey the damage. I am experienced enough to make that call.

I do tell them (in writing on the invoice) that the panel must be replaced and that this is a temp repair. I also note/date it with a sharpie on the deadfront.


As far as replacing the guts (bussing) That's a whole nother thread. I'd do it in a heartbeat if it makes sense but usually it's almost as easy to simply replace the whole panel.

 

[bjp_ne_elec]

So I need to make sure I understand. If the breaker stab was burnt, due to a loose connection, then the panel has lost it's UL rating? I don't have any question, in my mind, if there is actually impact to the main buss - but what if it's just isolated to a single stab?

 

[charlietuna]

From the original post---"BUS FINGER' was not mentioned --only "bus". If a bus finger was damaged with no damage to the connecting main bus --certainly that UL listed part can be replaced.

 

[bradleyelectric]

We have an electric panel with obvious damage. How about we let the customer in on the fact that we are the expert and that the panel needs to be changed. That is how we make a living isn't it? I have never seen a panel that had bus damage and not had the owner let me change it. I would not be comfortable discussing other options and would let the customer know that.

 

[Ohmy]

If the buss finger is the only part burned off, we just put a new breaker in another spot. Why replace a panel for one bad breaker position? Unless they need every available space, I wouldn't feel good about telling a customer they needed new guts or a panel.

On the other hand, if it's part of the main buss that feeds the other slots that's damaged, then it's time to look for replacement guts or another panel.

Generally, the whole buss is compromised when you get a section of it hot enough to burn. We always replace. I don't even like leaving them overnight.

 

[macmikeman]

Generally, the whole buss is compromised when you get a section of it hot enough to burn.

Not saying I disagree, but what is the method used to determine the statement?

 

[~Shado~]

Not saying I disagree, but what is the method used to determine the statement?

Perhaps your how healthy your bank acccount is at the time?

 

[macmikeman]

Perhaps your how healthy your bank acccount is at the time?

:grin:Yeah that works for me as well.

 

[Ohmy]

Not saying I disagree, but what is the method used to determine the statement?

I take the buss bar out and megg it. Then I do a tinsel strength test. Then I put it in a factory stamp to make sure it has not warped.

I get your point though. Generally, we see a little warping of the bar, discoloration from the heat, melted plastic studs or holds where the bar attaches. Sometimes on commercial panels the bars hold up better but we do mainly residential.