derating

[corey75]

how do you derate
according to annex c table c1 you can have 9 thhn 12's in a 1/2 and 16 thhn 12's in a 3/4 but do you have to derate cause of more than 3 current carring conductors on 310.15(B)(2)(a)
My question is when all the derating is done how many 12's and 10's can you put in 1/2 and 3/4 EMT

 

[iwire]

Re: derating

Corey, You have two separate issues here, how many will fit and after that you would have to derate if more then 3 current carrying conductors by using Table 310.16 and Table 310.15(B)(2)(a)

For a good description of Derating go here
Derating Conductors

[ March 15, 2003, 12:53 PM: Message edited by: iwire ]

 

[daverz]

Re: derating

Derating has nothing to do with the number of conductors permitted in a conduit.

The maximum number of conductors permitted in a conduit does not change under various conditions.

Derating...First, select the allowable ampacity based on conductor (insulation) type.

Second, apply any needed correction factors based on ambient temperature.

Last, adjust (derate) based on the number of conductors in a conduit.

 

[dereckbc]

Re: derating

Take iwire advice and click on the link. The 5 step process is a no brainer, no fail approach.