CodeQuandary
Member
- Location
- Washington DC
I was looking at the current Code Graphic of the day, which is on Raceways & Cables exposed to sunlight on roofs, Ambient Temperature Adjustments.
It involves #6 THWN-2 in conduit 3/4" above a roof.
First: It announces an ambient temperature of 105F. In the informational note on 310.15(B)(3)(c) it suggests a source for ambient temperatures is the ASHRAE Fundamentals Handbook... but what am I supposed to take from that (I'm looking at it now)? Is it one of the Cooling Dry Bulb temperatures in the "Design Conditions for Specific Locations" table (.4%? 1%? 2%?)? Or something else?
Second: from table 310.15(B)(3)(c) the conduit position requires a temperature correction adder of 40F. So 105F + 40F is 145F. But then from the Table 310.15(B)(2)(a), a temp of 145F with THWN-2 (a 90C conductor), I get a correction factor of .65, but the graphic calls out .58 (which would be the correction factor for 150-158F).
I don't mean to be picky, but I'm hoping to take my ICC E3 exam soon, so details matter -- is this just a typo or am I missing something?
Thanks!
Keith
It involves #6 THWN-2 in conduit 3/4" above a roof.
First: It announces an ambient temperature of 105F. In the informational note on 310.15(B)(3)(c) it suggests a source for ambient temperatures is the ASHRAE Fundamentals Handbook... but what am I supposed to take from that (I'm looking at it now)? Is it one of the Cooling Dry Bulb temperatures in the "Design Conditions for Specific Locations" table (.4%? 1%? 2%?)? Or something else?
Second: from table 310.15(B)(3)(c) the conduit position requires a temperature correction adder of 40F. So 105F + 40F is 145F. But then from the Table 310.15(B)(2)(a), a temp of 145F with THWN-2 (a 90C conductor), I get a correction factor of .65, but the graphic calls out .58 (which would be the correction factor for 150-158F).
I don't mean to be picky, but I'm hoping to take my ICC E3 exam soon, so details matter -- is this just a typo or am I missing something?
Thanks!
Keith