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#15951 - 11/02/02 07:01 PM Why corrosion on only one of 2 busbars?
Charlie Offline
Junior Member

Registered: 11/02/02
Posts: 5
On a Siemens 200A load center there is very extensive white corrosion on one side, from where the hot wire originally connects, all the way to the bottom of the right bus. Every breaker has this white powder, and the main breaker seems to have an internal problem on that side, so that power is intermittent. Does this suggest any kind of underlying problem that should be addressed in the system?

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#15952 - 11/02/02 07:21 PM Re: Why corrosion on only one of 2 busbars?
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
Charlie,

If I had to guess from the information given I would say that there has been water coming in the panel, possibly coming in on the service cable. Is this in the Basement? Any signs of rust on the bottom of the panel?

Bill

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#15953 - 11/03/02 04:55 AM Re: Why corrosion on only one of 2 busbars?
jes Offline
Member

Registered: 07/12/02
Posts: 103
Loc: CT
I second Bill's assessment based on the info given. How balanced is the load bere? (Right side bus have more??) Where is the panel located, how is it fed,? Also, how old is this installation and are there any photos?

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#15954 - 11/03/02 07:28 AM Re: Why corrosion on only one of 2 busbars?
Charlie Offline
Junior Member

Registered: 11/02/02
Posts: 5
Load appears to be balanced. Three different brand breakers have been used. Challenger breakers show considerable corrosion, might have come from earlier panel. Some rust in the bottom. Basement installation, right above where gas pipe enters house. Grounded to that pipe. I just don't get the complete difference between right and left bus: one extreme white corosion and the other none.

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#15955 - 11/03/02 08:02 AM Re: Why corrosion on only one of 2 busbars?
electric-ed Offline
Member

Registered: 07/08/02
Posts: 184
Loc: Canada
Is there a chance that the bus in question has been replaced, at some time in the past, with one made of a different metal?

Ed

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#15956 - 11/03/02 09:57 AM Re: Why corrosion on only one of 2 busbars?
Charlie Offline
Junior Member

Registered: 11/02/02
Posts: 5
It looks to be the original bus. I wondered about a manufacturing lot defect in the plating process. But I even have this corrosion above the main breaker where the service lines comes in. That's not part of the bus.

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#15957 - 11/03/02 02:34 PM Re: Why corrosion on only one of 2 busbars?
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
It may be a good idea to take careful, comparitve bus-to-load-terminal millivolt-drop tests of individual circuit breaker poles and associated current readings with a high-quality, suitably overvoltage-protected multimeter.

[See http://ecmweb.com/ac/december_2000/index.htm "Testing Contact Quality on Live Motor Starters"]

Besides having questionable conductivity, corrosion leftovers can also initiate tracking over otherwise insulated surfaces and break down, causing a messy, knuckle-singeing bus-side fault.

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#15958 - 11/03/02 03:45 PM Re: Why corrosion on only one of 2 busbars?
harold endean Offline
Member

Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
What is the humidity in the basement? Is it damp? Or a dry basement? A Damp basement can be almost as bad as water coming in through the service cable. By the way, Is a Challenger breaker allowed in a Siemans ITE panel?

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#15959 - 11/03/02 04:08 PM Re: Why corrosion on only one of 2 busbars?
Charlie Offline
Junior Member

Registered: 11/02/02
Posts: 5
It's relatively dry, but it does have fieldstone walls. Concrete floor. I guess I shy away from the general environment as the cause because of the different behavior of the two busbars. And I don't know enough about the corrosion products or reactions to know if a little corrosion actually accelerates the corrosion process.

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#15960 - 11/03/02 04:10 PM Re: Why corrosion on only one of 2 busbars?
Charlie Offline
Junior Member

Registered: 11/02/02
Posts: 5
I tried to access the link from Bjarney but it does not seem to be available.

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