If there are wires in a conduit on a roof, what is the best way to prevent them from over heating? Let's take out the variables of wire size & wire insulation, & focus on good techniques to prevent general overheating from good old Mother Nature.
The Code will err on the safe side, so if you are following the Code, you probably will not have to deal with other types of cooling, however I have thought of this:
1. You can paint your conduit white to reflect sunlight
2. You can keep wiring in the shade
3. You can put your conduit where there is good airflow.
4. You can put the conduit over a cooler roof, such as a white roof or a living roof.
5. You can keep your white roof clean and reflective.
The Code calls for accounting for greater than 3 current carrying conductors in conduit, wires in sunlight over a roof and high ambient temperatures.
We can find these Code variables in 310.15(B)(2)(a), 310.15(B)(3)(a) and 310.15(B)(3)(c).