Oxidized conductors

[Marc M]

Any of you guys seen oxidation on some conductors but not all? I suppose if it is oxidation.
(BTW, i did see the disco grnd)

[Scott Patterson]

Any of you guys seen oxidation on some conductors but not all? I suppose if it is oxidation.
(BTW, i did see the disco grnd)

I have seen it on some copper conductors and then in the same box some were still clean and shinny copper color. I have no earthly idea why or how it happens. My guess is that the line might have a thin layer of oil (from hands) or grime on it that it offering some protection.

Looking at what you have in your picture looks like it has been exposed to hydrogen sulfide or another sulphur based product. Can you say Chinese drywall! :)

[Jim Luttrall]

Do you have Chinese drywall in your area, salt water, chlorine? That looks like some kind of environmental contamination to me. Looks like the discoloration is more pronounced the lower you look in the cabinet.

[Marc M]

I didnt think that we had CD out here in california. Yea, it was weird that only a few have it and others didnt. I thought it looked like the oxidation went all the way to the top?

[Jim Port]

I see that when the conductors have gotten wet.

[Jim Luttrall]

I didnt think that we had CD out here in california. Yea, it was weird that only a few have it and others didnt. I thought it looked like the oxidation went all the way to the top?
It just looks more pronounce the further you go down as the ones terminating in the higher terminals are shiny.

[Scott Patterson]

I didnt think that we had CD out here in california. Yea, it was weird that only a few have it and others didnt. I thought it looked like the oxidation went all the way to the top?

If you have or had 84-Lumber, Home Depot, Lowe's or Wicks Lumber stores you can have problematic drywall. They all had the opportunity to get and stock it at some time.

[Gunnar Alquist]

I didnt think that we had CD out here in california.

Marc,

Yes, some areas of CA did get Chinese drywall. Since you did not post your location more specifically, I cannot give you more specific info.

[James Bohac]

I inspected a home last week with Chinese drywall. Copper looked just like your photo. The copper stub outs beneath the sinks were also black as well as the copper attached to several receptacles. When I looked at the back of the drywall above the garage, I found CHINA and Knauf faintly printed on two separate sheets of drywall. It was nice to find the smoking gun!

[bob smit]

These are over heated neutral conductors because;
The tandem breakers are your clue.
The multi-wire branch circuits are your other clue.
Unless each line conductor of a 3-wire circuit is on a different 'leg', there will not be any balancing of the neutral.
Therefore, the multi-wire circuit neutral would carry the full load of 2 line conductors.
Note: line conductor terminology proper is, 'ungrounded conductor'.

[Rick Souter]

What is the age of the home?
Chinese drywall hasn't been around forever.
Think it was imported from as early as 2001 to 2007
R

[Gary DeWitt]

These are over heated neutral conductors because;
The tandem breakers are your clue.
The multi-wire branch circuits are your other clue.
Unless each line conductor of a 3-wire circuit is on a different 'leg', there will not be any balancing of the neutral.
Therefore, the multi-wire circuit neutral would carry the full load of 2 line conductors.
Note: line conductor terminology proper is, 'ungrounded conductor'.

Bob, I'm new to electrical inspection and would like to know how you came to this conclusion from the photos posted. Not a challenge, just want to know how to spot overload without the obvious sign of melted insulation and without tracing circuits? I do understand the concept of multi-wire circuits and how they work.
Thanks in advance.

[Jim Port]

Bob was probably basing that on all the black and red conductors on the breakers.

[Daniel Mummey]

Oxidation occurs mostly when those conductors (wires) take on more than their fair amount of electron flow, and heat does that. They still look in "fair" condition from picture.

[bob smit]

Correct Daniel M. Copper (CU) oxidizes at higher temps more quickly and is precipitated by I squared R losses in the form of thermal radiation.
Simply put, more current flow at the relatively low voltage of 120 V nominal, results in greater heat produced, thus more oxidation.

The color of the neutral terminations are what concerned me. The pics did not allow us to see the line or breaker terminations.

The 2-reds & 2-black per breaker arrangement is what U would want to see in support of the idea that a multi-wire branch circuit is on different lines thus balancing the neutral. However, one would have to trace each pair of red/black to make sure. We also see just some of the panel breakers.
I'm curious just how many tandem or twin breakers this panel is listed for?

[bob smit]

I just revisited the pics and noticed the grounding conductors....must have tunnel vision today. Now I see the 'atmosphere issue' the previous posts were relating to. oops

I would have to agree that we may have a combination of old and new circuits.
I still don't like the color of the N conductors and I see one of the grounding conductors not connected.