necnotevenclose
Senior Member
Between ambient temp and voltage drop my process has been to calculate ambient temp first than look at voltage drop than based on the two values go with largest size? Is that correct?
I do temperature derating,with rooftop adder if applicable and conduit fill if applicable, then voltage drop, and take the larger of the two.Between ambient temp and voltage drop my process has been to calculate ambient temp first than look at voltage drop than based on the two values go with largest size? Is that correct?
I may not have been unambiguous with my answer. In no particular order, I decide what the minimum wire size would be from a required ampacity perspective taking into account the deratings for ambient temperature, elevation from roof, and conduit fill, whichever are applicable. I also calculate what the minimum wire size would be from an allowed voltage drop perspective. After I have done those two calculations, I pick whichever is the larger of the two results. Sometimes ampacity wins, sometimes voltage drop wins.I don’t quite understand the question, or the first reply. You don’t derate on the basis of voltage drop, and voltage drop is not a function of ampacity.
For solar work there are two sources I use. Weather.com will give you the highest average high and record low temps for a given zip code, and there are ASRAE climate data sites (http://www.solarabcs.org/about/publications/reports/expedited-permit/map/index.html) available. I compare the two sources for the location I am dealing with, and I usually opt for a conservative course of action.I'm curious: what do you base your ambient temperature on?