Change 314.28(A)(3)

[infinity]

Does this finally clear up installing more than three conductors in conduit bodies which are marked with a specific size?

For example:

LB says "3-#2 AWG conductors" I can use 4-#4 conductors when the calculations proves that the 4-#4's have a cross sectional area less than or equal to 3-#2 XHHW conductors.

314.28(A)(3) Where the permitted combinations of conductors for which
the box or conduit body has been listed are less than the maxi‐
mum conduit or tubing fill permitted by Table 1 of Chapter 9,
the box or conduit body shall be permanently marked with the
maximum number and maximum size of conductors permit‐
ted. For other conductor sizes and combinations, the total
cross-sectional area of the fill shall not exceed the cross-
sectional area of the conductors specified in the marking,
based on the type of conductor identified as part of the product listing.
Informational Note: Unless otherwise specified, the applicable
product standards evaluate the fill markings covered here based
on conductors with Type XHHW insulation.

 

[iwire]

Does this finally clear up installing more than three conductors in conduit bodies which are marked with a specific size?

For example:

LB says "3-#2 AWG conductors" I can use 4-#4 conductors when the calculations proves that the 4-#4's have a cross sectional area less than or equal to 3-#2 XHHW conductors.

IMO yes

 

[infinity]

IMO yes

Finally.

 

[iwire]

Finally.

About clarity in the NEC or me being agreeable?

 

[infinity]

About clarity in the NEC or me being agreeable?

The former, the latter happens more often than you think.

 

[Dennis Alwon]

I have always assumed we could do that with the conduit bodies but it is good seeing it in writing.

 

[GoldDigger]

I have always assumed we could do that with the conduit bodies but it is good seeing it in writing.

And it looks like the new wording is intended to indicate that the maximum size number is still absolute. You cannot use one conductor of the same cross section as the (for example) three conductors mentioned in the box limit.
It is not 100% clear, but hopefully there will be no argument about that?

 

[infinity]

And it looks like the new wording is intended to indicate that the maximum size number is still absolute. You cannot use one conductor of the same cross section as the (for example) three conductors mentioned in the box limit.
It is not 100% clear, but hopefully there will be no argument about that?

So you're saying that you cannot pull in one large conductor that is equivalent in area to three smaller conductors?

 

[GoldDigger]

So you're saying that you cannot pull in one large conductor that is equivalent in area to three smaller conductors?

Not if bending radius was a factor in the original determination.
As long as you are not pulling through the special case for two or three conductors jamming would not play any role.

mobile

 

[Carultch]

Does this finally clear up installing more than three conductors in conduit bodies which are marked with a specific size?

For example:

LB says "3-#2 AWG conductors" I can use 4-#4 conductors when the calculations proves that the 4-#4's have a cross sectional area less than or equal to 3-#2 XHHW conductors.

I'm glad to see some consistency and a calculation method that allows you to adapt the fill rating to your situation, but what I still wonder is why conduit bodies don't come with the capacity for their corresponding conduit size's capacity by design?

It doesn't make sense that a 2" L-body is too small to fit the typical application of a 2" conduit, and instead have to resize with reducing bushings.

 

[iwire]

I still wonder is why conduit bodies don't come with the capacity for their corresponding conduit size's capacity by design?

They do come that way if you order larger, more expensive conduit bodies such as these

http://www.cooperindustries.com/con...nhazardous/mogul_bodies_coversandgaskets.html

 

[Dennis Alwon]

I would not think you can go larger even if the larger conductor is equivalent in area, I assume the largest conductor would be the conductor that is marked on the LB and any combination of conductors that are smaller than the largest allow would be fine if it is equivalent in area.

This makes total sense. I wouldn't want to try and pull in a pair of 350 kcm's in a 2" lb even if the area was less.

 

[infinity]

I would not think you can go larger even if the larger conductor is equivalent in area, I assume the largest conductor would be the conductor that is marked on the LB and any combination of conductors that are smaller than the largest allow would be fine if it is equivalent in area.

This makes total sense. I wouldn't want to try and pull in a pair of 350 kcm's in a 2" lb even if the area was less.

I agree but I'm not seeing where that's spelled out in the new requirement.

. For other conductor sizes and combinations, the total
cross-sectional area of the fill shall not exceed the cross-
sectional area of the conductors specified in the marking,
based on the type of conductor identified as part of the product listing.
Informational Note: Unless otherwise specified, the applicable
product standards evaluate the fill markings covered here based
on conductors with Type XHHW insulation.