Derating

[wireperson]

I need to relocate an electric dryer ckt to the kitchen , everything is run in EMT, the electric stove is run in a 1" EMT over head (2 hots 1 neutral #8 )ending on a deep 1900 box , I was thinking in using the same conduit to run my 3# 10 for the dryer + ground passing through the 1900 box then from there to the dryer outlet, my concern is the derating of the wires and box fill on the 1900 box , anything on the NEC that doesn't let me do this? ideas?

 

[quinn77]

first id start with ampacity.table 310.15(B)(2)(a) dictates an adjustment factor of 80% of conductor rating. what kind of insulation is present?
if the ampacity is sufficient for nameplate load...move on to box and conduit fill calc.

 

[infinity]

Depending on the OCPD on the #8's derating might be an issue since you have 4 CCC's. With a 1" EMT conduit fill shouldn't be an issue. The box fill looks good too.

 

[wireperson]

ok , here it is again .
conduit #1 emt , 2 # 6 tw + 1 #8 neutral tw . feeding an outlet for an electric stove (11.5 kw) ,on a 40A federal pacific OCPD .
want to :
pull 2 hots #10 thhn +neutral #10 thhn + #10 ground on a 30A OCDP f or an electric dryer (2160 W)

the stove outlet box uses a deep 1900 box. I'm planing on passing through this outlet box to go to the new dryer outlet.

I hope it's more clear now . . . thanks in advance

 

[ceb58]

Should not be an issue. The #6 is rated for 75amp 90deg colm
The #10 rated at 40amp
You will be in the 4-6 ccc range so 80%
75amp*.80= 60amp your on a 40amp OCD
40amp * .80= 32amp on a 30amp OCP

40A federal pacific OCPD .

I would be more concerned with it being a FP. Probably wouldn't trip with a 100amp load on it.

 

[jumper]

Should not be an issue. The #6 is rated for 75amp 90deg colm
The #10 rated at 40amp
You will be in the 4-6 ccc range so 80%
75amp*.80= 60amp your on a 40amp OCD
40amp * .80= 32amp on a 30amp OCP



I would be more concerned with it being a FP. Probably wouldn't trip with a 100amp load on it.

Isn"t #6 TW 55 amps? Assuming CU.

AL is 40 amps.

 

[Jim W in Tampa]

assuming thhn your fine but as already mentioned you used a very filthy word FEDERAL PACIFIC not sure about everyone but i am not hungry enough to install anything on a FPE just too much liability

 

[ceb58]

Isn"t #6 TW 55 amps? Assuming CU.

AL is 40 amps.

You are correct 55amps. My bad. Still 55amp * .80 = 44amp
He is still good on 40amp OCP

But this is assuming copper conductors. Another missing part of the puzzle.

 

[jumper]

2 # 6 tw + 1 #8 neutral tw . feeding an outlet for an electric stove (11.5 kw) ,on a 40A federal pacific OCPD .

Are these AL or CU?

 

[wireperson]

Are these AL or CU?

Cu , what about the range , its a 11.5 kw = 48A ? isn't that an issue?

 

[Jim W in Tampa]

Cu , what about the range , its a 11.5 kw = 48A ? isn't that an issue?

Its on a 40 amp breaker so wires protected. Seriously dought it would ever be at full 11.5
but is a point if inspector wanted to push it

 

[jumper]

Cu , what about the range , its a 11.5 kw = 48A ? isn't that an issue?

Here a good thread on this subject. Better than any answer I can give.

http://forums.mikeholt.com/showthread.php?t=120095