Colored PV Wire & UV Breakdown

[SunFish]

I have been taught that black insulation holds up the best to UV and other colored insulation will degrade quicker, so best practice is to use all black wire on the roof under and around the array and tape the ends for identification. But can't find any actual studies or articles on this subject. For PV systems 690.31(B) allows conductors smaller than #4 to be marked with tape. This leads me to believe this code was instated to allow the use of black insulation on the roof for system longevity.

Some of my colleagues would like to use red (with ungrounded systems) or white (with grounded systems) wire on the roof for easier homerun identification. I've seen colored wire get pretty faded on the roof but it is still identifiable, does the colored insulation get brittle and crack faster over time as compared to black or is this just the color fading that is the concern?

Wondering what others in the industry think about this subject?

 

[ggunn]

I have been taught that black insulation holds up the best to UV and other colored insulation will degrade quicker, so best practice is to use all black wire on the roof under and around the array and tape the ends for identification. But can't find any actual studies or articles on this subject. For PV systems 690.31(B) allows conductors smaller than #4 to be marked with tape. This leads me to believe this code was instated to allow the use of black insulation on the roof for system longevity.

Some of my colleagues would like to use red (with ungrounded systems) or white (with grounded systems) wire on the roof for easier homerun identification. I've seen colored wire get pretty faded on the roof but it is still identifiable, does the colored insulation get brittle and crack faster over time as compared to black or is this just the color fading that is the concern?

Wondering what others in the industry think about this subject?

John Wiles had a lot to say about it in a class I took from him a few years ago. He had pix of red and white USE-2 that had been exposed to sunlight for several years. You could not tell the red from the white (it was all white) and the insulation was cracking and crumbling. He advised us to stick with black and use colored tape to show polarity.

 

[jaggedben]

I've seen it myself: red and yellow USE-2 turned white. And that was in areas not even directly exposed to sunlight. Bad idea.

One thing we used to use, although I haven't seen it lately, was USE-2 with a white stripe. We'd use it for the grounded conductor. It kept things straight during installation, but I don't know how long the marking has lasted.

Tape markings seem to last longer if they are not in direct sun.

 

[Zee]

I've seen it myself: red and yellow USE-2 turned white. And that was in areas not even directly exposed to sunlight. Bad idea.

One thing we used to use, although I haven't seen it lately, was USE-2 with a white stripe. We'd use it for the grounded conductor. It kept things straight during installation, but I don't know how long the marking has lasted.

Tape markings seem to last longer if they are not in direct sun.

I've seen the white stripe factory-painted onto "PV Wire" before. Good idea.

Red will fade to snow white on use-2.... i have seen it too... Will new PV wire behave similarly???? who knows....

 

[GoldDigger]

I've seen the white stripe factory-painted onto "PV Wire" before. Good idea.

Red will fade to snow white on use-2.... i have seen it too... Will new PV wire behave similarly???? who knows....

Reports are that PV wire does the same thing.
But the insulation is thick enough that you can just scrape some surface off to see what the color was. :dunce:

 

[MasterTheNEC]

I have been taught that black insulation holds up the best to UV and other colored insulation will degrade quicker, so best practice is to use all black wire on the roof under and around the array and tape the ends for identification. But can't find any actual studies or articles on this subject. For PV systems 690.31(B) allows conductors smaller than #4 to be marked with tape. This leads me to believe this code was instated to allow the use of black insulation on the roof for system longevity.

Some of my colleagues would like to use red (with ungrounded systems) or white (with grounded systems) wire on the roof for easier homerun identification. I've seen colored wire get pretty faded on the roof but it is still identifiable, does the colored insulation get brittle and crack faster over time as compared to black or is this just the color fading that is the concern?

Wondering what others in the industry think about this subject?

Most of the manufacturers (we do) provide the same level of sunlight-resistant in all colors from and all sizes in terms of PV Wire. Just check the specs on the wire you are intending to use and it will say on the manufacturers specs for that wire if it is sunlight-resistant and at what sizes. For example, some will say 8 AWG and larger is Sunlight- Resistant and it will also be printed on the wires legend as SUN-RES and in our case it applies to all colors of conductors that are listed as Photovoltaic or PV Wire.

 

[GoldDigger]

The standard for Sunlight Resistant, IIRC, involves a lot less than the equivalent of 10 hours a day of direct sunlight.
Also just because two colors meet the same standard does not mean that they perform the same when taken beyond the standard. So YMMV.

 

[MasterTheNEC]

The standard for Sunlight Resistant, IIRC, involves a lot less than the equivalent of 10 hours a day of direct sunlight.
Also just because two colors meet the same standard does not mean that they perform the same when taken beyond the standard. So YMMV.

And a seat belt on a 1960's truck might not be as reliable as one on a 2014 truck either. However, it was compliant at the time of installation. The fact is you have many more choices other than just BLACK that meet Sunlight-Resistant today.

 

[GoldDigger]

And a seat belt on a 1960's truck might not be as reliable as one on a 2014 truck either. However, it was compliant at the time of installation. The fact is you have many more choices other than just BLACK that meet Sunlight-Resistant today.

I do not dispute that. Just pointing out that some will choose, for good reason, to stick to black even with other colors available under code

 

[ggunn]

I do not dispute that. Just pointing out that some will choose, for good reason, to stick to black even with other colors available under code

I know I will.

 

[MasterTheNEC]

I do not dispute that. Just pointing out that some will choose, for good reason, to stick to black even with other colors available under code

Ahhh I understand.

Just as an FYI- For a manufacturer to make such a claim (that all of their colors are sunlight-resistant or from a specific size and up), the testing has to take place in a R & D Lab. The artificial aging process and exposure requirements under UL 4703 that exposes the various colors to a much more stressful condition over a rapid period than would be expected in the installation environments life span. While no manufacturer will make a claim to a life-expectancy, I can assure you that when companies that make Wire and Cable invest 15 million in a dedicated R & D facility, published data actually validated. Due to the nature of PV Wire (Photovoltaic Wire) it has a thicker insulation value than USE-2, RHH, and RHW-2....and is evaluated under UL 4703 direction.

The scope of UL 4703 is : "1.1 This Outline covers single-conductor, insulated and integrally or non-integrally jacketed, sunlight resistant, photovoltaic wire rated 90?C, 105?C, 125?C, or 150?C dry and, 90?C wet, 600, 1000, or 2000 V for interconnection wiring of grounded and ungrounded photovoltaic power systems as described in Wiring Systems, Article 690, and other applicable parts of the National Electrical Code (NEC), NFPA 70."

Before any manufacturer placed such a statement on their wire, it has been truly tested and again those that have multi-million dollar, LEED Platinum facilities dedicated just to this type of testing will feel perfectly confident in making such statements.

So I lean less on "CODE" and express more of a testing process that is used in the past may have limited the protection from sunlight to black insulation now thanks to technology and advanced material compounds have opened the door to a rainbow of possibilities (hmm...thats sounds weird but I said it). and yes...I hear a Skittles Commercial coming on a TC somewhere.

But again I understand and do not wish to sway your opinion.