conduit exposed to sunlight

[don_resqcapt19]

The study used for this code rule indicated that the temperature rise applies to all types of raceways. It appears that the code rule should say "raceways" and not "conduit".

 

[kwired]

Raceway.​

An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.​

Perhaps the available data, based on the tests, was only for conduits, so extending it to all raceways would not have been supported by data. ​

Perhaps you are correct, keep in mind this is located within article 310 - Conductors for general wiring, and would not include some wiring methods like busbars, underfloor raceways and the like, by their intended purpose would not be installed on a rooftop. The remaining conduits and tubings you would think have enough similarities that they should have been included as well as cable assemblies - after all it is conductors for general wiring that is being addressed - I still think it was a mistake or not thought out well enough before the final wording was selected.

 

[macmikeman]

I still think it was a mistake or not thought out well enough before the final wording was selected.

Thats almost something we can say we agree on....

Here is another macmikeman point of view. I say the real problem from running conduits across roofs is how many times I find them separated at the couplings from having a less than dynamic support method. Not talking about the top notch jobs where channel iron beams are supporting strut racks, I mean the standard 4"x4" unsecured wood every ten or so feet. And also lots of times these supports end up causing roof leak problems given enough time. Or the wind blows the whole thing around a few feet. Yes the code addresses the support issues, but not the leak issues since it is the electrical code not the roof code. Yet damage is damage.

 

[weressl]

The study used for this code rule indicated that the temperature rise applies to all types of raceways. It appears that the code rule should say "raceways" and not "conduit".

The study did not draw that conclusion, it specifically stated conduits as the base of the study and suggests - but not supported by empirical data - that the results are applicable to all conduit and tube type raceways.


"Since all the conduits showed the same qualitative193
effects, for simplicity, only the results of the EMT experiments 194
are reported here".

The major gap of the study seems to be that it was done with UNLOADED conductors, eg. the samples were duds, not connected to a circuit and the thermal effect of current is not taken into effect.

"All the conductors were electrically unloaded."

If that is the ONLY data that was used for 310.15(B)(2)(c) ruling, then it is on a very weak basis. Granted, something had to be done, but it appears to be a half-hearted effort.





​

​