Conduit Fill

[PaulNolan]

Hello Everyone,
I need some assistance in determining the number of #10 thhn conductors in a 2 inch emt longer than 24 inches.
20 will be current carrying.
Table C1
63 #10 THHN in 2 inch EMT
Table 310.15.(B)(3)(a)
derate by 50%
32 #10 THHN conductors
I think I missed a step
Any help would be appreciated
Thank You
Paul

 

[infinity]

Hello Everyone,
I need some assistance in determining the number of #10 thhn conductors in a 2 inch emt longer than 24 inches.
20 will be current carrying.
Table C1
63 #10 THHN in 2 inch EMT
Table 310.15.(B)(3)(a)
derate by 50%
32 #10 THHN conductors
I think I missed a step
Any help would be appreciated
Thank You
Paul

The number permitted represents 40% conduit fill. Not sure what you mean with the other information.

Welcome to the Forum.

 

[Ingenieur]

Hello Everyone,
I need some assistance in determining the number of #10 thhn conductors in a 2 inch emt longer than 24 inches.
20 will be current carrying.
Table C1
63 #10 THHN in 2 inch EMT
Table 310.15.(B)(3)(a)
derate by 50%
32 #10 THHN conductors
I think I missed a step
Any help would be appreciated
Thank You
Paul

you do not derate the fill
you still have 63 conductors
but their ampacity is derated by 50%
so if the selected ampacity is 35 A, it is derated to 17.5 A
so for a continuous load you can load them to 17.5/1.25 = 14 A

 

[Smart $]

you do not derate the fill
you still have 63 conductors
but their ampacity is derated by 50%
so if the selected ampacity is 35 A, it is derated to 17.5 A
so for a continuous load you can load them to 17.5/1.25 = 14 A

Ampacity determined by derating is not factored 125% for continuous loads. In short, you only factor continuous loads 125% when determining the minimum size for the termination temperature limitation.

 

[Ingenieur]

Ampacity determined by derating is not factored 125% for continuous loads. In short, you only factor continuous loads 125% when determining the minimum size for the termination temperature limitation.

I have no idea what info you are trying to convey :?

 

[Smart $]

I have no idea what info you are trying to convey :?

Look at 210.19(A)(1) 2014 or 2017.

(a) is where you determine the minimum size wire with terminal temperature limitations considerations using the 60°C column or 75°C column (latter mostly). This determination factors continuous loads 125%. Let's call this sizing for the equipment termination enclosures.

(b) is where you determine whether the minimum size wire has an ampacity not less than the calculated load after the application of adjustment and correction factors. Note this determination does not require factoring for continuous loads and can use the 90°C column if the wire is so rated. Let's call this sizing for the condition(s) of use between equipment enclosures.

Your application of continuous load factoring above is errant because the 'location' you are applying it to is between equipment enclosures where you need only apply adjustment and correction factors, no factoring for continuous loads.

 

[Ingenieur]

Look at 210.19(A)(1) 2014 or 2017.

(a) is where you determine the minimum size wire with terminal temperature limitations considerations using the 60°C column or 75°C column (latter mostly). This determination factors continuous loads 125%. Let's call this sizing for the equipment termination enclosures.

(b) is where you determine whether the minimum size wire has an ampacity not less than the calculated load after the application of adjustment and correction factors. Note this determination does not require factoring for continuous loads and can use the 90°C column if the wire is so rated. Let's call this sizing for the condition(s) of use between equipment enclosures.

Your application of continuous load factoring above is errant because the 'location' you are applying it to is between equipment enclosures where you need only apply adjustment and correction factors, no factoring for continuous loads.

:? Still

 

[Smart $]

:? Still

One day it may sink in. :huh:





Perhaps not. :slaphead: