REAL WORLD DC Color Coding for PV

[Zee]

So I go check on a commercial install I built a few years ago.

We had used red use-2 in the array for positive wires.
For negative, we ran white.
So far so good, as white = grounded conductor in this case.
Similarly, red is not green or white or gray, so it can be used per NEC for ungr. conductor.

However, you could not see ANY difference between positive and negative color coding.....
They were all white!
You scratched them they were still white.
Snow white.
WHat happened?
In the case of COLORED insulation, the USE-2 insulation bleaches white within years! Even when under panels.

(The Code that dictates color coding of conductors has been discussed in other threads. So no need to go there.)

Given a choice of many colors, I recommend black as the ungrounded wire for pv systems.
REASON: Black USE-2 does not bleach out and turn white.

Have you folks seen similar?

(Why do thes conductors change color??
I am told it is due to the manufacturing process.
All other colors ( e.g. red USE-2) are made by using bleached white insulation and then adding color. The color bleaches in time.

Black is - I believe originally black. NO bleach.)

 

[jaggedben]

I have seen similar sun bleaching in a couple cases. I seem to recall that one could tell which conductor was which only if one looked on the underside of the conductor where it was not exposed to sunlight. The one I'm thinking of was a five year old system, and yellow and red USE-2 were used for ungrounded conductors.

So yes, non-black USE-2 conductors bleach to white. I think John Wiles (original writer of article 690) has said this to numerous people, that he only trusts black USE-2 to last the life of a solar system. Most of the time that I have done DC systems we used black with a white strip for grounded conductors. (We call it 'candy cane.')

In my opinion someone should also make black USE-2 with a red stripe, if that isn't already available. I have said before that in my opinion the color coding for PV should be: ungrounded pos = red, ungrounded neg = black, grounded = white. And ideally some other marking should be made at home-run connections and other terminations so that bleached conductors can be distinguished.

 

[Zee]

Good input.Now...what happens when UNgr. systems start going in?No white can be used.For color permanence reasons black is preferable.SO... two black conductors?

 

[ggunn]

Good input.Now...what happens when UNgr. systems start going in?No white can be used.For color permanence reasons black is preferable.SO... two black conductors?

Two black conductors is very common.