follow instructions or NEC

[Ponchik]

Based on 314.16(C)(1) conduit body conductor fill is based on the conduit fill of the conduit that is attached to that conduit body.

Example: 1" EMT conduit has a maximum of allowance (4) #4 THHN conductors. Based on the instruction of the conduit body manufacturer it allows maximum (3) #4 conductors.

Two questions:
1. Do I follow the NEC or the manufacturer or ask the AHJ?

2. If the manufacturer says maximum (3) #4 does that mean I can NOT install (10) #12s? Or it means the total volume of the conductors can not exceed the equivalent volume of (3) #4 conductors?

Thanks

 

[infinity]

Conduit bodies need to follow the same 6X and 8X rules for junction boxes when the conductors are #4 or larger. So if you were pulling #12 AWG conductors then you could just follow the fill for the raceway attached to it. If the conduit body doesn't meet then 6X or 8X sizing then you must follow what the manufacturer has printed on the inside of the conduit body.

There was a change in the 2017 NEC to allow you to use the equivalent fill when calculating sizes and combinations that differ from what's printed inside of the conduit body. If the AHJ follows the letter of the NEC then there is no need to ask.

 

[Ponchik]

Thanks. I need to study what you said.

 

[don_resqcapt19]

Based on 314.16(C)(1) conduit body conductor fill is based on the conduit fill of the conduit that is attached to that conduit body.

...

The rules in 314.16 are for conductor sizes #6 and smaller. You need to look to 314.28 for conductors #4 and larger. For the conduit body, you need to look at 314.28(A)(3) and you need to understand that the conduit bodies discussed in the second paragraph do not apply to standard conduit bodies. That paragraph applies only to this type of conduit body:

The last paragraph applies to standard and mogul type conduit bodies

 

[kwired]

Conduit bodies need to follow the same 6X and 8X rules for junction boxes when the conductors are #4 or larger. So if you were pulling #12 AWG conductors then you could just follow the fill for the raceway attached to it. If the conduit body doesn't meet then 6X or 8X sizing then you must follow what the manufacturer has printed on the inside of the conduit body.

There was a change in the 2017 NEC to allow you to use the equivalent fill when calculating sizes and combinations that differ from what's printed inside of the conduit body. If the AHJ follows the letter of the NEC then there is no need to ask.

Why did they put in a new rule that actually makes sense?

Of course most conduit bodies and conflicting conductor combinations that seem to be relatively common still won't be marked for what we would like, and won't physically be large enough to meet the 6X or 8X rules either, so for most instances nothing has really changed:happyno:

 

[infinity]

Why did they put in a new rule that actually makes sense?

Of course most conduit bodies and conflicting conductor combinations that seem to be relatively common still won't be marked for what we would like, and won't physically be large enough to meet the 6X or 8X rules either, so for most instances nothing has really changed:happyno:

Well it's changed in the sense that if it doesn't meet the 6X or 8X rule and it says Max 3-#4/0 conductors and you want to pull in 4-#2's now you can.