Wireway

[Bill WWW]

Hello,

Just a quick question on wireway I cant seem to find the answer on.

NEC 376.22(B) says if there are over 30 wires inside wire-way you must comply with 310.15(B)(3)(a)
310.15(B)(3)(a) states that if conductors are not spaced at lengths over 24” then you must de-rate them according to the table.

If I have a huge wireway, and bundle groups of 30 or less wires and maintain spacing between each bundle, it appears I will not have to de-rate? What type of spacing would be required?

Thanks in advance for any help.

 

[Smart $]

Once you go over 30 conductors at a wireway cross section, you derate to the table. Bundling and spacing offers no "reprieve" because the wires are inside a raceway.

 

[Bill WWW]

376.22(B) says nothing about derating, and doesn't refer you to T310.15(B)(3)(a), it says to refer to 310.15(B)(3)(a) (not the table)

If you refer to 310.15(B)(3)(a) it clearly states you must follow T310.15(B)(3)(a) only if conductors are ran longer than 24" without spacing. If I put space between the conductors, I see no reason to refer to the table.

 

[wwhitney]

If you refer to 310.15(B)(3)(a) it clearly states you must follow T310.15(B)(3)(a) only if conductors are ran longer than 24" without spacing. If I put space between the conductors, I see no reason to refer to the table.

Actually, 310.15(B)(3)(a) lists two different situations where derating applies: "where the number of current-carrying conductors in a raceway or cable exceeds three" OR "where single conductors or multiconductor cables are installed without maintaining spacing . . ." A wireway with over 30 conductors falls under the first of those clauses (376.2 indicates a wireway is a raceway), so avoiding the second clause doesn't help you.

Cheers, Wayne

 

[iwire]

Actually, 310.15(B)(3)(a) lists two different situations where derating applies: "where the number of current-carrying conductors in a raceway or cable exceeds three" OR "where single conductors or multiconductor cables are installed without maintaining spacing . . ." A wireway with over 30 conductors falls under the first of those clauses (376.2 indicates a wireway is a raceway), so avoiding the second clause doesn't help you.

I agree.

 

[iwire]

Hello,

Just a quick question on wireway I cant seem to find the answer on.

NEC 376.22(B) says if there are over 30 wires inside wire-way you must comply with 310.15(B)(3)(a)
310.15(B)(3)(a) states that if conductors are not spaced at lengths over 24” then you must de-rate them according to the table.

If I have a huge wireway, and bundle groups of 30 or less wires and maintain spacing between each bundle, it appears I will not have to de-rate? What type of spacing would be required?

Thanks in advance for any help.

Are the conductors running with the wireway or perpendicular to the wireway?