Murray Panel burned up

Status
Not open for further replies.
S

sd4524

Senior Member
Location
Southern California
016.jpg018.jpg017.jpg015.jpg


Here are some pics from Thursday. This Murray/ Home Depot brand panel was installed 3 years ago when the homeowner remodeled the kitchen. I could not move any of the 3 main lugs with my allen wrench, even the burned one. After de-energizing, I put my hand on the burned lug and it snapped right off. Obviously, an installer error of over tightening but I can't believe how chintsy those 2 screws are that hold the lug to the main bus.
I checked at home depot and I see that the new Murray design on those lugs has changed to something that looks more sturdy.
 
This could happen to any panel. It doesn't have to be Murry (which BTW I believe is owned by Siemens). Doesn't look like there was any anti-oxident used either. There could have been some arcing at the lugs that caused the melt down. Nice pics.
 
It looks like the screw that held the terminal to the bus was not tight when the conductor was installed. It appears that the heat originated at the lug to bus connection and not the conductor to lug connection.
 
What is horizontal busbar about above the line side meter jaws? It appears to be tying the two jaws together. Something just doesn't look right but there is probably more to it than one can see in photo.
 
Murray Panel burned up

kwired
What is horizontal busbar about above the line side meter jaws? It appears to be tying the two jaws together. Something just doesn't look right but there is probably more to it than one can see in photo.

kwired- The bar that you speak of must be an insulator, otherwise, we know there would be a phase to phase short, and probably an explosion.

I agree with the other folks, there more than likely was a loose connection.
 
kwired said:
What is horizontal busbar about above the line side meter jaws? It appears to be tying the two jaws together. Something just doesn't look right but there is probably more to it than one can see in photo.
Click to expand...

I saw that also
I also agree with Don, how many times has a lug turned slightly when torquing the conductor down.
I thought de-ox was only needed with AL?
 
Gac66610 said:
I saw that also
I also agree with Don, how many times has a lug turned slightly when torquing the conductor down.
I thought de-ox was only needed with AL?
Click to expand...

Anti oxidation compound is not needed for todays aluminum conductor alloys. Many people like to use it anyway primarily out of habit. It certainly doesn't hurt to use it.


I looked again and the horizontal bar earlier mentioned maybe is an insulator.
 
sd4524 said:
After de-energizing, I put my hand on the burned lug and it snapped right off. Obviously, an installer error of over tightening .
Click to expand...


I have seen several lugs that were burned like that on different brands of panel. Normally not torqued in the first place (loose connection). It could be over tightened but it's hard to over tighten without breaking the lug off. A torque wrench is the answer. That's about the only way to tighen to the correct value.

The fact that it broke off doesn't mean anything other than it got really hot and stressed the metal. I have replaced a few where the lugs were burned completely away. The do get "hot'.
 
Gac66610 said:
I thought de-ox was only needed with AL?
Click to expand...
It's not required. But when you remove the locking parts of the lugs inside a meter enclosure there's always a drop of that grease applied to the back of each lug. I've seen too many main breaker lugs and meter enclosure lugs burn up so I adoped the slogan for Frank's Hot Sauce "I put that Sh*T on everything".
 
I'm not a fan of screwed lug design. I've seen it on SquareD 200A disconnects with one screw (~10-32) tapped into the back of each neutral lug. The only explanation I can think of for an electrical engineer to spec that kind of joint is planned obsolescence. Embarrassing.
 
growler said:
I have seen several lugs that were burned like that on different brands of panel. Normally not torqued in the first place (loose connection). It could be over tightened but it's hard to over tighten without breaking the lug off. A torque wrench is the answer. That's about the only way to tighen to the correct value.

The fact that it broke off doesn't mean anything other than it got really hot and stressed the metal. I have replaced a few where the lugs were burned completely away. The do get "hot'.
Click to expand...

If you would be there at the right time that whole lug was likely glowing at some time. At this point it is usually still working to some degree - we usually get called after things quit working and what is in the picture in this thread is what we find.
 
Anytime that there is heating at a connection things go down from there. From my experience with breakers the heating and cooling cycle causes the termination to loosen farther which results in more heating. The heat also conducts itself through the copper and can affect springs which hold contacts closed. In the illustrations here look at the contacts to the left where the stab goes and notice the discoloration. This may be an indication that stab connection may have been compromised by the heating which could eventually fail.
 
Is ITE actually calling that panel a Murray? I know ITE purchased Murray but I thought they dropped the name, here that would be a ITE Siemens meter main service panel, although not a common one but even the main are ITE Siemens, but I agree with Don most likely a loss in connection between the lug and buss bar not a un common failure since Siemens stopped using bevel washers
 
kwired said:
What is horizontal busbar about above the line side meter jaws? It appears to be tying the two jaws together. Something just doesn't look right but there is probably more to it than one can see in photo.
Click to expand...
That thing bugs me also, it's definitely not an insulator. Looks like a solid bar across the line, with the right side slightly elevated.
 
Status
Not open for further replies.
Top