Results 1 to 13 of 13
  1. #1
    Join Date
    Mar 2007
    Location
    Oregon
    Posts
    2,365

    Default Deep Rainbow Color at Top of Bus Bar

    I see light rainbowing from time to time and have been told by seveal electricians that it's not a concern. This was a much deeper color than I've seen and it was only on one leg. The other side was bright silver.

    I wrote it up as a possible loose breaker to bus bar connection and to have it looked into further. The panel is from a 1978 house - GE split bus.

    Do you guys call the rainbow color when it's really deep like this?

    Similar Threads:
    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    OREP Insurance

  2. #2
    Join Date
    Mar 2007
    Location
    Garland, TX
    Posts
    652

    Default Re: Deep Rainbow Color at Top of Bus Bar

    According to the National Fire Protection Assoc. (NFPA), fuse terminals and fuse clips should also be examined for discoloration caused by heat from poor contact or corrosion. Early detection of overheating is possible through the use of infrared examination. If evidence of overheating exists, the cause should be determined.

    I use an IR thermometer to evaluate for heat and also check for stored chemicals.

    I note what's observed and move on...

    badair http://www.adairinspection.com Garland, TX 75042
    Commercial-Residential-Construction-EIFS-Stucco-ACMV-Infrared Thermography
    life is the random lottery of events followed by numerous narrow escapes...accept the good

  3. #3
    Join Date
    Mar 2007
    Location
    Oregon
    Posts
    2,365

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Quote Originally Posted by BARRY ADAIR View Post
    I note what's observed and move on...
    Just curious.... we have to make a recommendation so what do you say?

    Also, with an IR thermometer isn't just testing the day you're there pretty limiting?

    There were some other things in the panel (double taps) so I just told them to investigate the cause, particularly a loose breaker to bus connection.


  4. #4
    Join Date
    Apr 2009
    Location
    NY State
    Posts
    443

    Default Re: Deep Rainbow Color at Top of Bus Bar

    I have seen that on a LOT of panels, with no ill effects.
    I will honestly admit I don't know what causes it, but I truly don't think it is overheating.


  5. #5
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Deep Rainbow Color at Top of Bus Bar

    I don't see what you are describing in those photos, but if it what I have seen, it is the plating on the bus bars during manufacture, nothing wrong though, just the way it turned out.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  6. #6
    Join Date
    Mar 2007
    Location
    Oregon
    Posts
    2,365

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Here's a picture with the area circled... the pictures really didn't come out good. The one pictured is a deep rainbow color while the other side is completely bright silver. That difference is what got me thinking. I've seen rainbowing many times but never anything close to this deep and rich a color.

    Attached Files Attached Files

  7. #7
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Quote Originally Posted by Matt Fellman View Post
    Here's a picture with the area circled... the pictures really didn't come out good. The one pictured is a deep rainbow color while the other side is completely bright silver. That difference is what got me thinking. I've seen rainbowing many times but never anything close to this deep and rich a color.
    That could be from overheating as that is directly below where that bus bar is tapped off the main breakers, could be a loose or poor connection at the breaker terminals or at the bolted connection at the bus.

    Now that I see what you were referring to, if you look at the first photo at 400x zoom you will see what looks to be overheating around that bolt at the bus bar.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  8. #8
    Join Date
    Mar 2007
    Location
    Oregon
    Posts
    2,365

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Yep.... around the bolt is the first thing that caught my eye but the picture didn't really come out, hence the one from the side.

    I talked it through with the buyer and he seemed to grasp the problem. I told him the first thing I'd do (or have an electrician do) is pull the breakers and check the connections and go from there.


  9. #9
    Join Date
    Mar 2007
    Location
    Garland, TX
    Posts
    652

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Quote Originally Posted by Matt Fellman View Post
    Just curious.... we have to make a recommendation so what do you say?
    The inspector observed XXXX (pic of perceived problem) and observed/didn't observe a temperature rise (pic of IR temp at perceived problem at time of inspection, all we can do) I advise further investigation by a qualified electrician to assure proper function or make any necessary repairs/replacements required.

    Also, with an IR thermometer isn't just testing the day you're there pretty limiting? No more limited than the rest of our inspection. I've not found an electrical defect that repairs itself and anything that is questionable would have to be further evaluated by the qualified electrician for a conclusive answer as to the cause.

    There were some other things in the panel (double taps) so I just told them to investigate the cause, particularly a loose breaker to bus connection.
    Good call!
    i try to keep it simple

    Last edited by BARRY ADAIR; 08-18-2009 at 06:11 AM.
    badair http://www.adairinspection.com Garland, TX 75042
    Commercial-Residential-Construction-EIFS-Stucco-ACMV-Infrared Thermography
    life is the random lottery of events followed by numerous narrow escapes...accept the good

  10. #10
    Tony Dolce's Avatar
    Tony Dolce Guest

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Anytime you see a discoloration as described always know it is excessive heat on the buss bar. The source of the heat can be a variety of different things from a breaker not making up properly to the buss to a loose connection of the buss or over amping the buss. It should always be investigated. Ever heat up a piece of metal with a torch or solder a copper plumbing joint, same thing it changes color.
    Tony Dolce
    Meade Electric
    Phoenix electrician affordable repairs and installations electrical service in Phoenix


  11. #11
    Join Date
    Apr 2009
    Location
    NY State
    Posts
    443

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Quote Originally Posted by Tony Dolce View Post
    Anytime you see a discoloration as described always know it is excessive heat on the buss bar.
    This is not at all true. I have seen similar discoloration in relatively new equipment and it was NOT from heat.

    Just replace the word "always" above with "sometimes".

    Last edited by Speedy Petey; 08-20-2009 at 04:31 PM. Reason: typo

  12. #12
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Quote Originally Posted by Tony Dolce View Post
    Anytime you see a discoloration as described always know it is excessive heat on the buss bar.
    Quote Originally Posted by Speedy Petey View Post
    This is not at all true. I have seen similar discoloration in relatively new equipment and it was NOT from heat.

    Just replace the work "always" above with "sometimes".
    Peter,

    I agree with you. I have seen what could be described as a rainbow effect on brand new equipment which has NEVER been energized. Even out-of-the-box.

    I think that statement is mis-leading in that it could likely cause a false determination of the cause.

    I would re-word that statement to this: 'Anytime you see a discoloration as described always LOOK FOR EVIDENCE OF excessive heat on the buss bar.'

    In the photo shown, that evidence is the darker, much darker, area right at and right around the bolted connection.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  13. #13
    John Steinke's Avatar
    John Steinke Guest

    Default Re: Deep Rainbow Color at Top of Bus Bar

    Absent other signs - damaged breaker connection, a measured high temperature, etc., I wouldn't worry about it.

    I have two reasons. Firse, many panels have those colorings fresh from the box. It seems that there is heat generated at different points of the manufacturing process. Also, the metal may have some corrosion-resistant treatment (such as 'clear irridite' or others) that show such a rainbow effect when there are variations in the thickness of the coating. I have seen differences of even a millionth of an inch result in a dramatically different appearance.


Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •