Ambient Temperature & rooftop work ?

pipe_bender

Senior Member
Location
Boston
Occupation
Electrician
The NEC has had some changes on ambient temperature correction over the past cycles and I see some old topics on it, nothing is called out if I am more than 3/4" above the roof under the 2023 NEC, but how do you determine the ambient temperature above flat commercial roof? What about a panel-board on a roof with breakers?
Say three roofs roofs Boston, Denver and Dallas do you just look up a ASHRAE table for the city?
 
Correct... the ASHRAE is the base you use.
(Note: If can use XHHW-2 you don;'t have to use that adjustment)
 
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