We recently had a bru-hah-hah between a contractor doing work for us and the consulting engineer who designed the job. The issue was the feeders to an AHU with electric reheat. The unit came in with nameplate ratings different from what was indicated on the plans. All this was on feeders less than 100 amps. The result was the belief for needing one size larger wire for one of the feeders to the unit. Since the unit had 75 degree ratings on its terminations the consultant said we could use the 75 degree ampacity column in the NEC. This would allow for the wire to remain as he sized it. I got to be the good/bad guy to make a call and said let's increase the wire size. This was based on the fact I wasn't sure just what the rating of the terminations at the head end of the feeder was. We were feeding this unit from a 40 year old panel. So I was not sure we didn't have 60 degree termination limitation there. Was this a good call, bad call, or not sure call? And no I did not go and rip of the panel cover off to verify the 40 year old breaker terminations; arc flash hazards you know!
Thanks for your time,
Jim
Thanks for your time,
Jim