Wire fill in Conduit, Conduit Bodies and Fittings

[FredAPX]

I'm trying to rationalize some of the rules to wire size and conduit fill. According to the NEC, I can run 12 #14 AWG THHN conductors through a 1/2 EMT conduit, yet can only run 2 #14 AWG THHN conductors through most 1/2 Condulet LB's. The cross section and volume (open air) of a section of 1/2" conduit is far less than that of a 1/2" condulet body. So how does the NEC explain the difference?

 

[infinity]

I can run 12 #14 AWG THHN conductors through a 1/2 EMT conduit, yet can only run 2 #14 AWG THHN conductors through most 1/2 Condulet LB's.

Where did you find the only 2-#14's in the LB limit? You can install the same 12-#14's conductors in the LB.

 

[FredAPX]

I was going by the NEC 314.16 and 314.28. It states 2 cubic inches per 14 AWG wire passing through the body. The body of the device states 4.24 cubic inches of volume, therefor only two 14 AWG conductors (2 cubic inches per conductor x 2 conductors = 4 cubic inches) are permitted. This doesn't make any sense.

 

[infinity]

I was going by the NEC 314.16 and 314.28. It states 2 cubic inches per 14 AWG wire passing through the body. The body of the device states 4.24 cubic inches of volume, therefor only two 14 AWG conductors (2 cubic inches per conductor x 2 conductors = 4 cubic inches) are permitted. This doesn't make any sense.

It doesn't make sense because you're reading it incorrectly. It says when there are splices within the conduit body the 2 cu inch per conductor rule applies.

 

[FredAPX]

Thank you Infinity. I realize that much of the code is poorly written at best, and could be made much clearer. It's very rare that I need to use conduit bodies and I'm just trying to not get burned by misreading the code. Thank you so much for your time!

 

[infinity]

Thank you Infinity. I realize that much of the code is poorly written at best, and could be made much clearer. It's very rare that I need to use conduit bodies and I'm just trying to not get burned by misreading the code. Thank you so much for your time!

 

[infinity]

You're welcome. For conductors #6 and smaller the fill without splices is the same as the permitted number of conductors in the raceway. Once you get to #4 and larger conductors that changes and is based on the 6X and 8X pull box rules.

 

[FredAPX]

Thanks again ROB!