Conduit Fill vs. LB Fill

[Will Wire]

I recently did a conduit fill calculation for three # 4 THHN, and one # 6 THHN and arrived at 0.2979 cubic inch. According to Chapter 9 tables it will fit in 1" EMT. The 1" LB states maximum fill is three # 4 conductors. NEC 314.28 (A)(3) says I can't exceed the fill of the conduit body if marked. Is my only solution to up size the conduit run, or bush down a larger LB.

Thanks,
Trent

2020 Code Cycle

 

[infinity]

Yes you'll need to oversized the LB. The conduit run can remain the same size as it is you’ll just need to transition from one size to the other.

 

[Will Wire]

Thank You

 

[augie47]

An expensive alternative might be found with a Mogul LB which allow a greater fill.

 

[don_resqcapt19]

Any time you have conductors 4 AWG and larger, you need to be looking at the markings on the conduit bodies. Most times a standard conduit body of the same trade size as the conduit will not be suitable.

 

[Seven-Delta-FortyOne]

Any time you have conductors 4 AWG and larger, you need to be looking at the markings on the conduit bodies. Most times a standard conduit body of the same trade size as the conduit will not be suitable.

Never really thought of that.

Prolly why it’s always so difficult to get 3x3/0 and a #4 into a 2” LB. I’ve been thinking about just going up to 2 1/2” just for easy of pulling.

 

[don_resqcapt19]

Never really thought of that.

Prolly why it’s always so difficult to get 3x3/0 and a #4 into a 2” LB. I’ve been thinking about just going up to 2 1/2” just for easy of pulling.

A 2x4 and a small sledge hammer can work wonders with that

 

[letgomywago]

Never really thought of that.

Prolly why it’s always so difficult to get 3x3/0 and a #4 into a 2” LB. I’ve been thinking about just going up to 2 1/2” just for easy of pulling.

Use a small gutter it'll work slick.

 

[Seven-Delta-FortyOne]

Use a small gutter it'll work slick.

Love gutter.

Been using it more and more for my generator installs.

 

[Eddie702]

I have used gutter and I have bushed LBs most of the time and I don't see anything wrong with either one. As we all know being undersized just gets you in trouble when pulling

 

[qcroanoke]

Love gutter.

Been using it more and more for my generator installs.

We use it too. But lately production has complained it costs more and takes longer to use WW than an LB with reducing bushings.

 

[don_resqcapt19]

I have used gutter and I have bushed LBs most of the time and I don't see anything wrong with either one. As we all know being undersized just gets you in trouble when pulling

While no one ever does it, if the volume of the LB supported by a conduit of a smaller trade size than the LB, exceeds 100 cubic inches, the LB needs independent support.

 

[texie]

I've always been fan of using wireway as an LB with #4 and larger conductors. Works great except when you are outside and the application is vertical.

 

[dkidd]

Use a small gutter it'll work slick.

Wireways are not gutters. see https://forums.mikeholt.com/threads/raceway-gutter-or-wireway.142501/

 

[texie]

Wireways are not gutters. see https://forums.mikeholt.com/threads/raceway-gutter-or-wireway.142501/

True, but in some areas it is slang for a short wireway. But I must admit I'm a stickler for proper NEC terms as I've said here many times.

 

[letgomywago]

Wireways are not gutters. see https://forums.mikeholt.com/threads/raceway-gutter-or-wireway.142501/

You use a gutter like a 4"x2' and punch it like an LB or a T and it gives proper bending space for larger wires without needing a rubber mallet or shoehorn to fit the wires