Condulet Fill

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augie47

augie47

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Location
Tennessee
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State Electrical Inspector (Retired)
Sometimes I feel like I'm the only inspector in the world trying to enforce
NEC 314.28 and the manufacturers' tables on conduit fittings.
Daily I see LB's with more conductiors than their ratings.(LB67 2" with 3-3/0 for example). The contractors and supply houses in this area act dumbfounded when you point out the violation. Do you guys enforce this/ see it enforced ???
 
augie47 said:
Sometimes I feel like I'm the only inspector in the world trying to enforce
NEC 314.28 and the manufacturers' tables on conduit fittings.
Daily I see LB's with more conductiors than their ratings.(LB67 2" with 3-3/0 for example). The contractors and supply houses in this area act dumbfounded when you point out the violation. Do you guys enforce this/ see it enforced ???
Click to expand...

I am not sure about the only inspector in the world enforcing 314.28, but you are the only inspector in Tennessee enforcing it. :grin:
 
I know that it's written into the code but it seems to me that many of these violations really aren't a problem. Most of the time the installer was able to install the conductors into the conduit body without any damage to the conductor. You have to wonder if the manufacturer is being overly cautious when rating the conduit body fill.
 
Rob,
Maybe so, but if they don't mark it you have to comply with 314.28(A)(2) which would require an even larger fitting.
 
I just looked at an OZ Gedney LB67, it is very short (length), and it says it is only good for three 1/0's. I don't see how someone could cram three 3/0's into it without damaging the wires. I say good for you, you are doing the right thing.
 
don_resqcapt19 said:
Rob,
Maybe so, but if they don't mark it you have to comply with 314.28(A)(2) which would require an even larger fitting.
Click to expand...


True, but I have seen much larger undamaged conductors installed in LB condulets than allowed by the manufacturer's listing. Obviously a 3.5" C condulet with (5)-600 kcmils would be a problem, an LB maybe not.
 
Isn't there not just a fill concern, but also a bending raduis concern as well?

I see the following guidelines:
Under 600V, can't find any requirement, but Southwire wire manufacturer recommends bending radius is minimum 4X conductor O.D.
Over 600V, nonshielded, bending radius is minimum 8X conductor O.D. (300.34)
Over 600V, shielded, bending radius is minimum 12X conductor O.D. (300.34)
SE and USE cable or conductor, bending radius is minimum 5X conductor O.D. (338.24)

A Crouse-Hinds LB67 has a bend radius is 2.9" so any conductor that requires a larger bend radius shouldn't be put in the LB67 as well. If your use is less than 600V and your 3/0 is THHN/THWN, it has an O.D. of 0.584". Using the 4x guideline, the recommended bending radius is 2.34", so it appears OK from a bending radius standpoint.

However, if it were SE or USE, it would appear to be exceeding the 2.9" as listed by C-H.

Kent
 
Pierre C Belarge said:
Is the trough (or whatever some may call the enclosure) properly sized as per 314.28?
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8?8?36. Two 4" conduits, angle pull. I'm cool.

Business here is OK if you don't build houses. I know other parts of Fla are hurting worse than us. (so far)
 
Yesterday we up sized an 1-1/2" EMT LB to a 2" because it was only rated for (3) 1/0 conductors. We were running (4) 1/0 conductors and we didn't want to take a chance failing the work. An 1-1/2" emt run could handle 5 conductors.
 
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