Wireway or Rectangular Box

[e57]

This is one that has always perplexed me....

376.23(B) Metallic Wireways Used as Pullboxes.
From commentary of the '02 code

Section 376.23(B) was added to the 2002 Code to ensure adequate space for conductors in other raceways as they enter a wireway. Where wireways are used as pull boxes, the same minimum dimension requirements associated with raceway entries of pull boxes apply.

I assume it is implied that the practice is sanctioned - And my interpetation has always been travel in the enclosure as a raceway - then it's a raceway - i.e. going from one skinny end to another.... Other interpetations have been the same as the 35 conductor rule for derating - I try to straddle both interpetations.

 

[quogueelectric]

Mr. Cow [notice the respect I am showing since meeting you :grin:]

One can lead a cow to water, but but you cant always make him drink. I missed my horse race for this so you guys rate high on the food chain in my book. I only follow 3 races each year. That everything in moderation thing.
I got hung up in traffic from Lodi NJ visiting Mark32 he did me a solid on a wire closeout to clear inventory. He is a good guy.

Alright I will blow all the respect by asking the question that is begging to be asked here. What is the primary ampacity differences between a wireway and a box??
I remember years ago there was a 30 wire cross sectional rule that nobody either enforced an or took into consideration yet I havent seen it in the book recently so I believe it has been removed.
By me almost everyone ran 2-4 2" pipes up to a trough above the panel and brought all mc cables into the trough ran the odd ckts down the left side even ckts down the right side.
Trade practice yet not to code. Back to the grind tomorrow. It was a good weekend. Nice to meet everyone.

 

[Pierre C Belarge]

376.22 Number of Conductors.

This is the section where you will find your 'lost' requirement for ampacity adjustment, based on the number of current carrying conductors.

 

[Rockyd]

I'll bet that it says the same thing in 362.22. Looks like a "cut and paste" piece of verbage to me

 

[don_resqcapt19]

Pierre,
Given the exception to 310.15(A)(2), I think that it would be a rare installation where the size of the box was large enough to have an effect on the ampacity of the conductors that are installed in the box.

 

[Pierre C Belarge]

Don
Not to break chops, but I am not sure what you are trying to say???

 

[Smart $]

Don
Not to break chops, but I am not sure what you are trying to say???

Say you have a 1'x1'x4' trough where in at least one cross-sectional area there are more than 30 conductors entering and leaving the volume through various conduits. If less than 10% of each of those circuits' length is in that cross-sectional area, the 310.15(A)(2) exception allows you to use the higher-rated adjacent ampacity, perhaps derated for in the conduit, for the circuit... thus making a derating in the "wireway" a moot point under such a circumstance.