roblsmith3
Member
- Location
- Cary, NC USA
I know I know, that this has been posted before but to be honest it was never answered, merely tiptoed around! I'll give more specifics......we have a 300' run of AC conductors in a 1.5" EMT on a flat roof mounted about 3.5" off the roof with rubber roof blocks. The project is located near Charlotte, NC and we are on the 2014 NEC.....so the temp difference in extremes is ~135 degrees Fahrenheit. According to chart 352.44, the change would be 5.48 in/100 ft x EMT multiplier of .2 equals 1.1" per 100 ft. Since this is a 300' run, that would be a movement of 3.3" total. Now, considering it is a PITA to bend 1.5" conduit to avoid using expansion joints and the cost of each expansion joint is about $150/piece. Are they really necessary? What is another way to go about this without bending or using the joints? I had heard using LFMC would also work but I do not know if that is code compliant. Thanks and look forward to the wise elders of the forum to bring me some clarity!:?