Occasional arcing at hot lug in main panel

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Old 11-29-10, 01:37 PM
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Occasional arcing at hot lug in main panel

My lights have been blinking occasionally over the last month since I bought this house. It only happens a few times per day but it happens on all lighting circuits simultaneously. Yesterday, I opened the main panel to figure out why.

I noticed some arcing below and to the side of the main hot lug on the right (200 amp service) when a big load starts up like the furnace or a vacuum cleaner. You can see in the photos how it has melted a bit of the plastic behind the lug. I don't know how long this has been going on prior to the month that I've owned the house.

It does not appear there is any anti-oxidizing Noalox type compound on the aluminum wire feeding either of the main lugs. Shouldn't the electrician who installed this box 20+ years ago have used it on the main cables feeding the panel?

Is the lack of compound on that connection the likely reason for the arcing I'm seeing?








 
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Old 11-29-10, 01:45 PM
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Yes to all your questions. You need to get an electrician out there to clean the connections, apply compound as needed and torque the lugs back down as needed.

The meter may need to be pulled (normally no charge) unless there is some sort of cutoff upstream. DO NOT DO NOT DO NOT try this yourself....
 
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Old 11-29-10, 01:55 PM
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At least don't do it yourself unless you get the power company to pull the meter. Most power companies will do this for free or a small fee while you make the repair. Don't pull the meter yourself or attempt a live repair.

With the meter secured, disassemble the three lugs (hot,hot and neutral) and scrub them up with emory paper or a wire brush. Cut back the burned end of the wire and shine it up with emory paper. Apply no-ox and reassemble and torque the lugs to spec. No-ox is not "required" with aluminum alloy wires, but I consider it an unsatisfactory install without it.

If there is any visible heat damage to the main breaker it should be replaced, but from the picture it looks okay. The neutral connection actually looks like it may be worse than one of the hots.

When you're all done with that, pack the conduit opening with duct seal to keep out moisture and have the power company do a reconnect. Ask the technician to inspect the lugs in the meter can too as they may be in the same shape as these in the panel. He can probably tighten them up for you if they seem loose.
 
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Old 11-29-10, 02:35 PM
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Good info from everyone. I would just add that from the looks of the threads sticking out past the lug that it was never properly tightened.
 
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Old 11-30-10, 01:29 PM
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Thanks for the help. I had an electrician come out today and look at this. He pulled the meter and then looked at the panel. He said the lug nuts turn somewhat freely (all 3 of them, both hots and the neutral). He said the black plastic behind the that one hot lug is somewhat crumbly. He said the panel should be replaced and wants 2K to do the job. Does that sound right?

Why not just put some compound on the wires, reconnect them to the lugs and tighten them to the proper torque?

The panel is a Siemens I-T-E Indoor Load Center, catalog number G1224MB1200.
 
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Old 11-30-10, 01:58 PM
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I don't think you will have a problem with that panel. The main breakers don't get any activity, so with no movement in the area, it won't crumble. No further heat and it will be fine. Keep an eye on it occasionally.
 
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Old 11-30-10, 02:05 PM
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For a one to one change out that seams a bit high, but labor costs vary greatly across the country. I would get a 2nd opinion (or third).

Looking just at your pictures I could see the plastic behind the lug is melted a little. If the lug were to touch the steel behind you would get quite a fireworks show! Without looking at it my self its hard to say but I lean towards paste, tighten and call it good.
 
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Old 11-30-10, 04:02 PM
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I have some more details from the electrician. He said two of the three lugs turn freely but the one where I saw the arcing seems frozen when he tries to turn it. He thinks it might be fused to the black plastic backing. That's why he is suggesting an entire new panel.

The price has gone to almost 3K as he now says it needs to be moved to the basement as it's currently on the wall where there are two steps going to the side door of the house (he says NEC won't allow a panel on a stairway, even though there are just two stairs).

Is it possible to find the black plastic backing and attached lugs for this panel so I can avoid replacing and relocating the panel?



 

Last edited by fromhollywood; 11-30-10 at 04:42 PM.
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Old 11-30-10, 05:51 PM
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He is correct about not having a panel on a stairway. Was this stairway there when the panel was installed? You also need to have 30" in front and 36" out clearance in front of the panel.
You might be able to find replacement "guts" for that panel. Search by the catalog number G1224MB1200
 
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Old 11-30-10, 06:00 PM
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Yes, the stairway was there when the panel was installed.

I've searched for that ITE Siemens catalog number but nothing comes up. I've called local electrical parts houses but they only stock new stuff.

If I could just find an old panel box that matched this one, or just the black plastic backing, I'd avoid having a 3K+ job.
 
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Old 11-30-10, 06:25 PM
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I would go along with panel replacement and relocating it too, but I would definitely get another estimate and maybe two. To just change a panel shouldn't be nearly as high as he quoted. His price even seems high for a complete service replacement. What you have is obviously an obsolete aluminum bus panel. Ask for a copper bus panel this time.
 
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Old 11-30-10, 06:25 PM
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Could the landing for the door be extended so the steps were beyond the panel? You only need 30" and the panel doesn't need to be centered. If the steps started just after the panel and you had a flat floor (stair landing) space of 30 or more inches on the other side and 36" in front that would be OK.
 
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Old 11-30-10, 06:56 PM
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Good idea but there isn't a way to extend the landing. I'm told it's ok to leave where it is if I can fix it but having to install a new one requires me to meet new codes.

What I need to solve the issue and not have to install a new panel is the black plastic backing (which apparently has the lugs permanently attached). Anyone have any ideas on where I could find this? The panel is an ITE Siemens G1224MB1200. The black plastic behind the breakers has these numbers stamped on it:

9810
731 093

Thanks for any ideas.
 

Last edited by fromhollywood; 11-30-10 at 08:02 PM.
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Old 11-30-10, 07:55 PM
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$2K for just a panel replacement seems quite high to me. It's probably $200 - $300 in materials, and presuming the meter pan and cabling is up to snuff, I can't imagine it's more than ~2 hours of work.

Also... if we're assuming the original panel installation was allowed/permitted, a simple replacement due to damage should not require relocation of the panel. It should just be a simple swap out (and a good opportunity to get a panel with more spaces for future circuits).

Just my opinion...
 
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Old 12-01-10, 03:37 AM
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Once you replace the breaker box you have no choice but get it up to the code and unforeally your electrician is correct it can not be on stairway unless you are on the landing spot.

3K to get new loadcentre and relocated that is a questionable price any chance can you take a photo of stairway what you are refering so I may have better idea.

The last house I dealt with it they did have a breaker box on stairway and I end up move it to diffrent location so it took me a little while to move quite few circuits. { it was in half way of 9 step riser stairway }

Merci.
Marc
 
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Old 12-01-10, 10:07 AM
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That looks like a standard Siemens box. I'm thinking you could leave the old one as-is, strip out the guts leaving only the metal. Buy a new 200A Siemens panel and transplant everything from the new box into the old one. That would save quite a bit of labor, and you wouldn't be installing a new panel just repairing the old one.

You could buy a 200A main breaker panel kit from Lowe's, etc and hold up the tub to your old panel in place to see if the screw holes match up. It looks just like the modern design to me.

Also when I looked at your picture again, are the wires on the top right column burned also? The heavier gauge black wires on the double-pole breaker look damaged.
 
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Old 12-01-10, 12:13 PM
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I've asked the electrician to hold-off doing anything until I can find a better solution than just ripping everything out and relocating with a new panel. I don't think that's the most creative solution. So, as it stands, the meter is disconnected from the panel so no electricity in the house.

Is there a way to free a stuck lug? This one on the right won't seem to budge (according to the electrician). I'm not about to try pouring Liquid Wrench on-top of a main breaker! Is there some electrician's product or tool to freeing a stuck lug nut? I'll bet it is stuck to the melted plastic behind but I won't know until I can get it off.

If I do need to pull it all out, I like the idea of taking a new Siemens guts and putting it into this can. I'm hoping that would be considered a fix and not require having to relocate the panel.

Those wires on the top right that look burned are a 100 amp circuit that feeds a subpanel in the basement. They look dark because whoever installed that circuit did it right and used anti-oxidant compound.
 
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Old 12-01-10, 12:26 PM
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Originally Posted by fromhollywood View Post
Liquid Wrench...Is there some electrician's product or tool to freeing a stuck lug nut?
Liquid wrench or similar penetrating lube with a breaker bar and socket wrench; sometimes tapping on the joint with a hammer while you apply pressure will help too. I would also probably try my 18V impact driver before giving up. Use some shop towels as drapes and try not to get oil on everything. The lug could be permanently seized if there was enough thermal expansion though. If you do get it moving, you can use the Noalox grease as a lubricant on the lug threads to keep it from seizing as bad again. It works very similar to thread compounds like Loctite (blue).

add: BTW, there's no way that melted plastic is strong enough to stand up to even moderate wrenching force. The lug is almost certainly seized metal-to-metal from the heat, but you might be able to break it loose with lube.
 

Last edited by ibpooks; 12-01-10 at 12:56 PM.
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Old 12-01-10, 12:28 PM
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Originally Posted by fromhollywood View Post
I've asked the electrician to hold-off doing anything until I can find a better solution than just ripping everything out and relocating with a new panel.
...
If I do need to pull it all out, I like the idea of taking a new Siemens guts and putting it into this can. I'm hoping that would be considered a fix and not require having to relocate the panel.
...
Start calling electricians or work on getting a referral. You want somebody who primarily does rehab and code compliance work. i.e. somebody who knows all the rules, most of the inspectors' hang-ups, and somebody who advertises in areas with older housing stock.

I have nothing to offer but my opinion, but if only internal components are being replaced, you stand a better chance of getting it approved by the inspector.

***edit***
Oh, and since you're only doing repair work, there is a minute chance that a permit may not be required. For example I replaced most of my water piping without adding or removing any fixtures. The plumbing inspector told me I did not need a permit for that work.
 
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Old 12-10-11, 04:42 PM
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So what ever happened?

I've seen Siemens panels like the one pictured. They were widely sold 15-20 years ago.

Siemens has the parts and they can be ordered through a distributor.

You may have to call Siemens directly to get the part numbers. I know you can get replacement lugs and lug stabs. Not sure about the plastic backing.
 
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