Mogul LB's

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Bowhunter

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Does anyone know of a code requirement that requires a mogul LB to be used on an Electric service?

Example: Can I pit 3 #3's in an inch and a quarter LB?
314.28 (A) (3) seems to say I can if I'm within the 40 percent fill of Ch. 9 Table #1. And if I'm not then it has to be stamped inside the LB what size wire and How many is OK.

Anybody got some references for me?

As an old wireman I know it's best to use what we used to call a service LB for ease of pulling and so small chance of damaging the cable. However, I'm looking for the proper code references.

Jim
 
LB conduit bodies need to comply with the same 6X dimension that would apply to a box with an angle pull. So for 1.25" raceway you would need a conduit body with a minimum of 7.5" between entries. The conductor size/amount inside of the conduit body may also be used. Take a look at 314.28(A).
 
The problem being that 314.28 for conductors #4 or larger requires that the conduit body meet the dimensions in (A)(1) and (A)(2) or not exceed the maximum number of conductors marked in the conduit body.
My chart shows an 1-1/4 form 47 allowing (3) #3s so it would seem you would not need a mogul LB but you should check the actual marking.
 
One problem with conduit bodies is they have tables/charts or even markings on the body, but it is very limited and doesn't come close to covering all the possible conductor combinations that may be installed in it. You may have one that simply says max 3-2/0 AWG conductors, what does that mean if installing #4 or #1 or combinations of different sizes?:(
 
kwired said:
One problem with conduit bodies is they have tables/charts or even markings on the body, but it is very limited and doesn't come close to covering all the possible conductor combinations that may be installed in it. You may have one that simply says max 3-2/0 AWG conductors, what does that mean if installing #4 or #1 or combinations of different sizes?:(
Click to expand...
Under the current code, it means those other combinations are not permitted. I have submitted a public input to say that all of the combinations listed in the manufacturer's instructions shall be permitted.
 
Bowhunter said:
...
Example: Can I pit 3 #3's in an inch and a quarter LB?
314.28 (A) (3) seems to say I can if I'm within the 40 percent fill of Ch. 9 Table #1. And if I'm not then it has to be stamped inside the LB what size wire and How many is OK. ...
Jim
Click to expand...
The new wording in the 2014 NEC that is cited above, does not apply to standard LBs. It only applies to this type of LB

The intent is that the wire bending radius in this type of LB is not less than the minimum bending radius permitted in Chapter 9, Table 2 for the conduit of the same trade size as the conduit body.
The 6x rule applies to standard types of LBs, however the last part of 314.28(A)(3) permits the installation of larger conductors where the conduit body is marked with the maximum number and maximum size of conductors that are permitted to be installed in the conduit body.
 
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