What is the definition of Sunlight Resistant?

[Brent Larsen]

PV wire is sunlight resistant. How many hours of direct sunlight can sunlight resistant wire take before the insulation breaks down? I can not find a definition for Sunlight Resistant.

 

[Dennis Alwon]

That's a good question. It is sunlight resistant not sunlight proof.

 

[Dennis Alwon]

I do know colors other than black require significant additions of UV stabilizers to make them suitable for the application.

 

[Dennis Alwon]

I also found this but I don't have the UL standards--Not sure that will even give you an answer

For an optional marking of sunlight resistant, the conductors covered by UL 44 and UL 83 are required to meet the requirements of 720-hour carbon-arc or xenon- arc exposure tests.

 

[Brent Larsen]

I also found this but I don't have the UL standards--Not sure that will even give you an answer

I have looked at UL and can't find anything.
Seems I remember that RHW-use 2 was rated as sunlight resistant to 300 hours.
PV wire is supposed to be better, but how much better?

 

[kwired]

I have looked at UL and can't find anything.
Seems I remember that RHW-use 2 was rated as sunlight resistant to 300 hours.
PV wire is supposed to be better, but how much better?

I hope you plan a PV installation to last for more than 300 hours of sunlight exposure

 

[GoldDigger]

The 300 hours of arc is high intensity, many times that of sunlight and much higher in UV content than normal sunlight.
But it would still be nice to know what the actual ratio is.


Tapatalk!

 

[Dennis Alwon]

I have looked at UL and can't find anything.
Seems I remember that RHW-use 2 was rated as sunlight resistant to 300 hours.
PV wire is supposed to be better, but how much better?

There is a 720 hour test and a 300 hour test but that does not mean that the wire is only good for 300 hrs. Not sure what that correlates to.

 

[Dennis Alwon]

If you can decipher this it may help. It came from here but I don't understand it

Measurements in Florida with a pyranometer show that the average one-year deposition of Total Ultraviolet (TUV, 295 - 385 nanometers) at 26 degrees facing south is 275MJ/m^2. If we integrate the energy deposited in a laboratory xenon-arc device for the same bandwidth with an irradiance level (light output) of the lamp set at 0.55 W/m^2/nm, it will take 1,620 hours to deposit the 275MJ/m^2 (using a Borosilicate Type S inner and outer filter). The Sunshine carbon-arc instrument will take about 1,300 hours to deposit an equivalent amount of energy. Again, these values only take into consideration the amount of light deposited on a surface in a selected bandwidth of the total spectrum, without regard for the spectral sensitivity of the material, the temperature range and amount of moisture (in any form) encountered in the different "climates", and the naturally occurring variability in the outdoor test.

 

[Brent Larsen]

If you can decipher this it may help. It came from here but I don't understand it

I can't really decipher it but....
I am running into large utility scale PV power plants that have exposed PV wire string line home runs all over them. When I build PV power plants these conductors are protected from UV radiation. These plants should last for 25 plus years. I can't imagine that PV wire is rated for 25 years of direct sunlight.
I have looked at the manufactures websites for answers and can't find them.

 

[GoldDigger]

If I understand it correctly, it says that the test for UV resistance uses about one quarter of what wire deliberately exposed with no shade and at the worst (for the wire) angle to full Florida sun will get in one year.
Not terribly reassuring.

Tapatalk!

 

[ggunn]

I do know colors other than black require significant additions of UV stabilizers to make them suitable for the application.

FWIW, I attended a John Wiles symposium a couple of years ago where he showed pictures of colored USE-2 wire that had been in the field for a few years which had insulation that was sunbleached and crumbling. His recommendation was to use only black.

 

[kwired]

FWIW, I attended a John Wiles symposium a couple of years ago where he showed pictures of colored USE-2 wire that had been in the field for a few years which had insulation that was sunbleached and crumbling. His recommendation was to use only black.

Now tell that to NEC for applications of say a grounded conductor that is smaller than 4 AWG being used at service weatherheads or similar locations.

 

[ggunn]

Now tell that to NEC for applications of say a grounded conductor that is smaller than 4 AWG being used at service weatherheads or similar locations.

I don't try to tell the NEC nuthin'. I just use all black USE-2 or PV wire conductors in exposed locations. I recommend the same, but it's free advice and worth every penny.