Roof/Attic Ambient Temperature Adjustment 2008

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Minuteman

Minuteman

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2008 310.15(A)(2) Exception No.5 (3)(c)Conduits Exposed to sunlight on Rooftops. Where conductors or cables are installed in conduits exposed to direct sunlight on or above rooftops, the adjustments shown in Table 310.15(B)(2)(c) shall be added to the outdoor temperature to determine the applicable ambient temperature for applications of correction factors in Table 310.16 and Table 310.18.
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310.15(A)(2) Exception No.5 (3)(c) the FPN says: "One source for the average ambient temperature in various locations is the ASHRAE handbook - Fundamentals."

My question. Why suggest ONE source and not nail something down as a standard. For all we know, some AHJ could use his trick knee as a source for determining the average ambient temperature. Why didn't the CMP just put the answer in the book rather than leave things so arbitrary?
 
I work in multiple jurisdictions (as I am sure others do as well) and I can see potential problems.



Inspector: We use 195* as our rooftop average ambient temperature.

Me: Where did you get that from? The jurisdiction 2 miles away uses 160* from the ASHRAE Handbook.

Inspector: Oh, well, we use Poor Richard's Almanac.



:-?

Edit: spelling
 
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90.5 (C) last sentence: Fine print notes are informational only and are not enforceable as requirements of this Code.
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I kinda gathered that from 310.15(A)(2) Exception No.5 (3)(c) FPN, when it said "One source". But I did not know until now that FPN's are informational only and not enforceable. Hmmm??? :wink:
 
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