Voltage Drop Factors:

[SJRibsman]

Hello, I have recentl aquired an Electrician's Calculations Manual from the library, and I am at the chapter on Voltage Drop. The question I have concerns the 2KIL, divided by the CM. As I recall the K (constant) was 1.93 for cu. and 3,18 for al. The book shows 11 and 18 for al.

 

[Gregg Harris]

Hello, I have recentl aquired an Electrician's Calculations Manual from the library, and I am at the chapter on Voltage Drop. The question I have concerns the 2KIL, divided by the CM. As I recall the K (constant) was 1.93 for cu. and 3,18 for al. The book shows 11 and 18 for al.

Recheck your # from chapter 9 in NEC Table # 8

11 and 18 are correct K at 77-121 degrees F

 

[Mouser]

To find the exact "K" = cm x Ohms per foot. But normally we use 12.9 for copper and 21.2 for aluminum @75 degrees.