Hello,
There is an example in 2008 NEC for load calculations(page 93, 210.20):
25A continuous, 60?, four current carrying conductors in a race way...
over current: 25x1.25=31.25, so next size is 35A.
conductor size: here is where I am confused; First, he calculates "minimum" conductor size (25x1.25=31.25, next size 8AWG, 40A).
But then he uses the actual load (25A) to find the "derated" ampacity due to four conductors in a conduit which 31.25 (25/0.8). What was the point of this? He already found the minimum conductor size in step 2 (#8AWG). Did he want to make sure 25/0.8=31.25 is not greater than 40A (#8AWG)?
Thanks
There is an example in 2008 NEC for load calculations(page 93, 210.20):
25A continuous, 60?, four current carrying conductors in a race way...
over current: 25x1.25=31.25, so next size is 35A.
conductor size: here is where I am confused; First, he calculates "minimum" conductor size (25x1.25=31.25, next size 8AWG, 40A).
But then he uses the actual load (25A) to find the "derated" ampacity due to four conductors in a conduit which 31.25 (25/0.8). What was the point of this? He already found the minimum conductor size in step 2 (#8AWG). Did he want to make sure 25/0.8=31.25 is not greater than 40A (#8AWG)?
Thanks