derating conductors

Status
Not open for further replies.
S

sbm53l

New member
On a 120/240Volt, single phase system, are how many 2- wire circuits (#12 THHN) with a #12 equipt. ground can be pulled in a 3/4" E.M.T. without derating?
 
sbm53l said:
On a 120/240Volt, single phase system, are how many 2- wire circuits (#12 THHN) with a #12 equipt. ground can be pulled in a 3/4" E.M.T. without derating?
Click to expand...

One 2-wire circuit.

Now if you asked how many 20 amp two wire circuits you can place in that 3/4" before derating will normally become a problem my answer is four 2-wire circuits.
 
Last edited:
bob,
I know you get tired of me.....

The "four" answer I can understand...
the "one", I can't... "two" and above yes
enlighten me, please
 
I think this is what Bob was saying: One 2-wire circuit has two current-carrying conductors. No derating needed. A pair of 2-wire circuits will have four current-carrying conductors. Derate to 80%.

The question was worded in the context of how many circuits you can have, before you have to derate. So "one" is the answer.
 
It doesn't make any difference until you get to 9 #12 wires.

90? column #12 is good for 30 a.

table 310.15(B) (2)(a) 9 wires multiply 30 X .70 = 21

asterisk on #14, 12, and 10 240.4D ..... 20 amp max for #12

It's a long way to get there but it doesn't make any difference for #12 until 9.

I guess unless it's a motor circuit.:) ...(yes, I like cans of worms.)
 
realolman said:
It doesn't make any difference until you get to 9 #12 wires.

90? column #12 is good for 30 a.

table 310.15(B) (2)(a) 9 wires multiply 30 X .70 = 21

asterisk on #14, 12, and 10 240.4D ..... 20 amp max for #12

It's a long way to get there but it doesn't make any difference for #12 until 9.

I guess unless it's a motor circuit.:) ...(yes, I like cans of worms.)
Click to expand...


Actually "9 #12 wires" is misleading. I'm guessing that you meant 9 CCC's. The total number of conductors is irrelevant for derating purposes.
 
Status
Not open for further replies.
Top