Does last 5' feeder to roof equipment exempts from 310.15(B)(3)(c)?

[alanchang1019]

When sizing feeder for roof equipment, our office design standard is:

ALL CONDUIT RUNS SHOWN ON THE ROOF SHALL BE RUN BELOW THE CEILING SPACE WHERE AMBIENT TEMPERATURE WILL BE BELOW 86? F. FINAL CONNECTIONS TO THE ROOF EQUIPMENT IS LIMITED TO 5'-0' OF DIRECT SOLAR EXPOSURE.

Do we need to comply with 310.15(B)(3)(c) circular raceways exposed to sun light on roof for the last 5' feeder to roof equipment? Is there any code section says this can exempt from 310.15(B)(3)(c)?

 

[Dennis Alwon]

IMO art 310.15(A)(2) could exempt you

(2) Selection of Ampacity. Where more than one ampacity
applies for a given circuit length, the lowest value shall be
used.
Exception: Where two different ampacities apply to adjacent
portions of a circuit, the higher ampacity shall be permitted to
be used beyond the point of transition, a distance equal to 3.0
m (10 ft) or 10 percent of the circuit length figured at the
higher ampacity, whichever is less.

 

[infinity]

What about 310.15(A)(2)Ex:

310.15(A)(2)Selection of Ampacity. Where more than one ampacity
applies for a given circuit length, the lowest value shall be
used.
Exception: Where two different ampacities apply to adjacent
portions of a circuit, the higher ampacity shall be permitted to
be used beyond the point of transition, a distance equal to 3.0
m (10 ft) or 10 percent of the circuit length figured at the
higher ampacity, whichever is less.

 

[Dennis Alwon]

What about 310.15(A)(2)Ex:

Yeah what about it.

 

[Smart $]

Yeah what about it.

It's fine where the adjacent higher ampacity portion of the circuit is 111% or greater compared to length of the exposed portion (i.e. the exposed portion is not more than 10% of the adjacent portion).

...

 

[alanchang1019]

Thanks everyone, this is really help.

So in my case, conduits on roof should always be less than 5'. As long as the feeder below roof is longer than 50', art 310.15(A)(2) can exempt it.

 

[Dennis Alwon]

Thanks everyone, this is really help.

So in my case, conduits on roof should always be less than 5'. As long as the feeder below roof is longer than 50', art 310.15(A)(2) can exempt it.

That's the way I see it but it can never be more than 10'

 

[Smart $]

It's fine where the adjacent higher ampacity portion of the circuit is 111% or greater compared to length of the exposed portion (i.e. the exposed portion is not more than 10% of the adjacent portion).

...

Thanks everyone, this is really help.

So in my case, conduits on roof should always be less than 5'. As long as the feeder below roof is longer than 50', art 310.15(A)(2) can exempt it.

Hmmm... now that I think about it, should have said 10 times.