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The typical color of most types of electrical conduit is dark gray.

I plan to run some kind of conduit along the edge of a flat roof to install security cameras, and I'm already worried about the heat radiating from the black roof not being good for the cables.

Will painting the conduit white help it absorb less heat from the sunlight directly in the conduit itself? Even if it is less heat, will it be enough to make a difference? Or am I worrying about nothing and it will be fine?

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  • Ideally you'd route the conduit so its out of the sun and out of the rain as much as possible.
    – Criggie
    May 13 '20 at 5:03
  • What is it in contact with? Or is it supported on posts acrosd the middle of the roof? Ie shortest run?
    – Solar Mike
    May 13 '20 at 6:54
  • @SolarMike. Sorry I didn't elaborate. I had just written the linked question so I didn't think to put more info here. It would be resting on the surface of the roof as close to the edge as possible or (where possible) screwed to the wall of the taller party of the building about an inch or two above the roof surface. There is a picture at the other question in the link above.
    – Moshe Katz
    May 13 '20 at 12:39
  • While the original question for the following answer was for plumbing PVC and UV light, the answer still applies to electrical PVC and may be helpful in your decision of whether or not to paint it: diy.stackexchange.com/a/18349 May 13 '20 at 13:52
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Elevating the conduit 7/8” or more off the roof surface will be more effective than painting but yes white is the least heat absorbing color. Why 7/8” elevation? That is what code requires or a temperature adder is used when derating the wire; with 7/8” elevation, the adder is not required. This is located in section 310.15(A)(3)(c), "Raceways and Cables Exposed to Sunlight on Rooftops".

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The heat radiated from a black roof will be less than radiated from any other colour of roof (because other colours reflect more light).

You haven't said what type of cable you plan to use, but it will probably be fine.

Conduit may be is hard to water-proof. use damp resistant cable.

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  • 2
    We did an experiment once about plate colors and insulation in the sun to explain how solar thermal panels worked. Panels of white metal, red, blue and black, then no insulation behind, with insulation and no glass cover and with glass cover. All could be touched and all had a temperature display. Black, insulated & covered got the hottest by some 18 degrees - white remained the coolest.
    – Solar Mike
    May 13 '20 at 6:53
  • How is that experiment in any way relevant to heat radiated from the roof?
    – Jasen
    May 13 '20 at 11:52
  • Because the OP makes it clear that the conduit will be in contact with the roof...
    – Solar Mike
    May 13 '20 at 13:18
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    Jasen, black roofs are the hottest surface they don’t reflect heat like white but absorb the heat and the roof temp can be much hotter than the ambient temperature this is why code requires a 7/8” elevation or a temp adder to de rate the wire.
    – Ed Beal
    May 13 '20 at 13:28
  • Radiate and reflect are not the same thing at all. Black absorbs and radiates very effectively.
    – Ecnerwal
    May 13 '20 at 19:33

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