Thread: Hot neutral bar

Had a 1981 house today 200 AMP panel. Panel was full, lots of added circuits. Compressors, welders and an 80 AMP dock service. Would anyone agree that all the doubled and tripled neutrals together might have caused the neutral bar to get hot to the point of discoloring? The ground lug was also triple tapped.

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No, I would not make that assumption.

My first suspicion would be a loose connection at the big lug.
But it would be best not to speculate at all and just say that amateur handiwork is suspected, list the faults, and call for repairs or replacement.

Originally Posted by John Kogel

No, I would not make that assumption.

My first suspicion would be a loose connection at the big lug.
But it would be best not to speculate at all and just say that amateur handiwork is suspected, list the faults, and call for repairs or replacement.

Thats what I did John, the question was more of a curiosity of mine. Thanks for the input.

The cause of that discoloration is that the neutral terminal is not securely attached to the neutral terminal bus (the lug is loos for some reason), OR, or the neutral conductor may be loose in the neutral terminal lug, or may have been loose in the neutral lug at one time and was subsequently corrected.

Originally Posted by Paul Kondzich

Would anyone agree that all the doubled and tripled neutrals together might have caused the neutral bar to get hot to the point of discoloring?

I have seen brand new panels still in the box have similar discoloration so I am guessing it may sometimes be caused by the manufacturing process.

Not a safe assumption. If neutrals were getting hot enough to discolor the bar, then I would expect to see melted and/or blackened insulation.

A loose lug would be my guess from the color. I have heard the electricity traveling the wires in industrial plants immediately with a large draw. The wires move it seems. Over time they should be checked, especially when using industrial welders, as lugs can loosen if not properly torqued.

Originally Posted by Jim Luttrall

I have seen brand new panels still in the box have similar discoloration so I am guessing it may sometimes be caused by the manufacturing process.

This!

Originally Posted by Lon Henderson

Not a safe assumption. If neutrals were getting hot enough to discolor the bar, then I would expect to see melted and/or blackened insulation.

AND this!

That discoloration was NOT caused by heat.

Originally Posted by Speedy Petey

AND this!

That discoloration was NOT caused by heat.

The lug appears to be tarnished as well, but since you are never wrong, it must be a strange coincidence. Ignore it?

It appears that the insulation is expanded, near the lug, to me. My paper ruler (yes I use one on the screen to prevent scratches) shows a size difference when compared to the neighbor wire, also a difference on the wire on the lug as it nears the termination point. This may be due to the depth perception phenomena, since they are so far away from each other.

Originally Posted by Speedy Petey

This!

Originally Posted by Speedy Petey

AND this!

That discoloration was NOT caused by heat.

Wow! You must know All the details related to that installation to be that sure of yourself.

While I, too, have seen SIMILAR looking discoloration on new bus bars ... with SIMILAR ... being the key word, THE PATTERN of the discoloration suggests the cause was heat.

Originally Posted by John Kogel

The lug appears to be tarnished as well, but since you are never wrong, it must be a strange coincidence. Ignore it?

Why be a jerk? I wasn't.
Why not wait for me to be a jerk then you can be a jerk back.

Originally Posted by Jerry Peck

Wow! You must know All the details related to that installation to be that sure of yourself.

Yes I do. That is a pic of my own panel and I know ALL the details.

Originally Posted by Jerry Peck

While I, too, have seen SIMILAR looking discoloration on new bus bars ... with SIMILAR ... being the key word, THE PATTERN of the discoloration suggests the cause was heat.

Jerry, you are usually more on top of these things than most here. I am surprised you see it this way.
IMO and experience I see no signs of over heating in any of the pics shown.

Originally Posted by Richard Skalski

It appears that the insulation is expanded, near the lug, to me.

I see that too, but also look at how distorted the rectangular lug is. I think it's distortion from the wide angle shot.

Originally Posted by Speedy Petey

Why be a jerk? I wasn't.
Why not wait for me to be a jerk then you can be a jerk back.

I knew you could handle it.

Greener inspectors come here to learn. A scorched patch in a panel needs to be checked out.

Originally Posted by Speedy Petey

Yes I do. That is a pic of my own panel and I know ALL the details.


Jerry, you are usually more on top of these things than most here. I am surprised you see it this way.
IMO and experience I see no signs of over heating in any of the pics shown.

Pete,

I was/am referring to the photo in the original post ... NOT the photos you posted.

The photo iusuallyhe original post shows discoloration on the top left corner of the terminal lug, and the discoloration on the neutral bus is greatest at, and appears to originate from under, that lug, the discoloration then spreads out and diminishes from there. There are also what look like could be arc marks below the terminal. All of which indicate to me that heat could be the cause.

Pete, usually you pick up on those things and do not rush to judge the cause, thereby eliminating a viable cause in such an adamant manner.

Okay,

Am I the only one going to question the stupidity of multiple Neutral conductors sharing positions on the bus bar?

Every single one of those doubled up positions must be removed. Think about the increased load being carried by these Neutrals.

Just suppose, the moron connects a 30 amp Neutral and a 15 amp Neutral into the same hole, what is going to happen?

You are allowed to place multiple EGCs into the same hole, but not Neutrals.

The doubled neutrals are not going to carry any more load than a single neutral. In the case of a #10 and a smaller conductor sharing a hole the smaller conductor might not receive the proper torque and be loose and heat up. The return current is not going into the other circuit. It is trying to get back to its source, the transformer.

We have agree to disagree with each other.

How about this, with two Neutrals in the same hole you are sharing the Neutral with 2 or more breakers thus creating unbalanced multiwire branch circuits.

Regardless, the placing of multiple Neutrals into the same hole on the Neutral Busbar is not allowed.

Please refer to NEC 2008 - 408.41, than fail this panel board!

The neutrals are not being shared any more than if they were in two holes in the bus. The current is not leaving one neutral and going into the other one.

The multiple bonding conductors sharing the same terminal including different sizes and type (solid vs. stranded, awg).If drop check for a replacement bug on the N. Suspect a loss of same occured, possibly fault or overheating with close proximity (doesn't BELONG THERE) with unstripped NM cable sheath and paper insulation wrap in midst of grounded & bonding conductors to the R of bars (60C), durring a lightning arrestor or distribution breaker reset or the unexpected resumption of utility power while using an improperly transfered and improperly grounded generator hookup/decoupling 'event'; IOW an objectional current event (on the groundING not the groundED, "side".

Note tracking to L of the bonding terminal - and see the inappropriately present white NM cable sheath and paper insulation to the right of same.
You *might* find discoloration when/if the NM cable sheath inppropriately located, is examined and stripped for appropriate routing.



The sharing of terminal, esp. this terminal, in this manner, is not correct. The smaller (undersized) solid copper conductor is neither stranded, compact stranded, nor is it of a size (too small) allowed for this terminal, and it is one of three in a terminal not rated to be shared with dissimilar conductors (dissimilar as to type - stranded vs. solid -- dissimilar does not just pertain to tinned copper vs. bare copper or copper vs. aluminum, etc.), and not for a conductor of its meager size, nor is it allowed to be shared in a terminal not rated for more than one conductor, and even if rated for two conductors, (certainly not three conductors, esp. one of dissimilar type) and would have to be so marked.

Note the unterminated, uncovered ends, "clipped" cable to the right of the bars:

Jim,

Did you review NEC 2008 - 408.41 yet? If you want I can verify the sane citation in the 2011 edition of code

When you clamp two wires together you are splicing them, just as if you capped them together. How difficult is that to understand? When one Neutral serves 2 breakers it is by definition a multiwire circuit.

The correct way to fix this panel is to add additional Neutral busbars and make the proper connections.

To not flag this panel is to just beg for a serious problem for an unsuspecting owner.

You are not sharing the neutrals. They are simply terminating at the same bus in the panel. Using your analogy that the wires in the same hole are spliced, all the circuits in the panel are sharing a neutral due to the conductivity of the bus.

Originally Posted by Robert Meier

I agree, if the two neutrals in one hole are tight it's electrically no different than being in different holes. Although the NEC has a separate hole for each requirement.

Thank you, I did not think it was hard to understand what I was saying.

Originally Posted by Jim Port

You are not sharing the neutrals. They are simply terminating at the same bus in the panel. Using your analogy that the wires in the same hole are spliced, all the circuits in the panel are sharing a neutral due to the conductivity of the bus.

Jim,

Just to clarify - you are not saying that having two neutrals in the same terminal is okay ... are you?

Originally Posted by Jerry Peck

Pete,

I was/am referring to the photo in the original post ... NOT the photos you posted.

The photo iusuallyhe original post shows discoloration on the top left corner of the terminal lug, and the discoloration on the neutral bus is greatest at, and appears to originate from under, that lug, the discoloration then spreads out and diminishes from there. There are also what look like could be arc marks below the terminal. All of which indicate to me that heat could be the cause.

Pete, usually you pick up on those things and do not rush to judge the cause, thereby eliminating a viable cause in such an adamant manner.

"Pete" didn't post any photos. The OP and later Robert Meier did.

but since "usually you" DON'T "pick up on those things and do" "rush to judge"....

Originally Posted by H.G. Watson, Sr.

"Pete" didn't post any photos. The OP and later Robert Meier did.

but since "usually you" DON'T "pick up on those things and do" "rush to judge"....

Watson, as usual ...
"
since "usually you" DON'T "pick up on those things and do" "rush to judge"....
'

You apparently did not read this post from Pete:

Originally Posted by Speedy Petey

Yes I do. That is a pic of my own panel and I know ALL the details.

Originally Posted by Jerry Peck

Jim,

Just to clarify - you are not saying that having two neutrals in the same terminal is okay ... are you?

No I am not. I am disputing that they are now a shared neutral the way Donald sees it.

Originally Posted by Jim Port

No I am not.

I didn't think you were, just wanted to make sure.

I am disputing that they are now a shared neutral the way Donald sees it.

I agree with you in what you are saying with regard to what Donald said, but I also suspect that Donald is not saying what he means to say, and I suspect that part of the problem is Donald using the term "shared neutral" and what that term means to us.

Originally Posted by Jerry Peck

Watson, as usual ...
"
since "usually you" DON'T "pick up on those things and do" "rush to judge"....
'

You apparently did not read this post from Pete:

Actually, I DID.

As usual, it is only YOU who quite obviously CAN NOT follow the FLOW of one of your many thread-hijacking side conversations!

YOU challenged Pete's earlier statements made about "THAT" panel - (a statement made BEFORE Robert Meier posted ANY photos of a completely different panel). Pete sarcastically responded to your commentary "THAT" panel (that pictured in the OP, the one his first comments which you challenged, were made about) and his statements WERE regarding "THAT picture" to the Original Post panel pictures pictured, were/as his own.

YOUR response

Originally Posted by Jerry Peck

I was/am referring to the photo in the original post ... NOT the photos you posted

Clearly shows it was YOU who were lost! Speedy Pete's commentary including the sarcastic remark regarding ownership was pertaining to THE PHOTOS in the ORIGINAL POST. Robert Meier's photos popped up (cross posting) in the MIDDLE of YOUR challenging interragories.

Pete's subject "that picture" "that" "panel" (pictured in the OP) was established already - by Pete, and he was sarcastically responding and claiming ownership of was the Orignal Posted photos - YOU are the ONLY one who was "confused" as to the subject panel of his remarks, sarcastic response and otherwise.

Originally Posted by H.G. Watson, Sr.

... in the MIDDLE of YOUR challenging interragories.

Talk about describing yourself, sheesh!

... YOU are the ONLY one who was "confused" ...

You are, as is typical for you, confused, argumentative, arrogant, and ... too many other obnoxious things to bother bending everyone's ear with here, we all see what you are like, and your posts only continue to confirm it.

Wow, I had no idea my post created so many responses. I have my email set to notify at every response to post. I got the last one from Mr Watson who was not even the last response. In this case, the buyer supplied the electrician with a copy of my report. The electrician happens to be a friend of mine. He also assumed it was a loose main neutral lug and called the utility to pull the meter. This assumption was looking at the pictures not being on site. When the meter was pulled the main neutral lug was tight. The first four (top to bottom) neutral lugs were loose. He assumes that's where the discoloration came from. He also added he had never in 30 years seen that discoloration out of the box in regards to a panel.

That's very interesting. Because the insulation on the wires isn't melted, it doesn't appear to me that heat is the source of the discoloration. I wonder if free electrons or radical molecules released by microshorting at the loose lugs caused the discoloration.

I have seen a few times when I buy a panel that the bus has a rainbow like discolouration to it. Never though too much about it.