Are LB’s legal

[Dsg319]

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I just seen these online searching. Pretty noice

 

[don_resqcapt19]

Its interesting in the case of PVC I don't know of any conduit bodies like that the mogul kind or whatever you can get with rigid.

Yeah a common 2" example is a single phase feeder with 4/0, 4/0, 2/0, and a #4 aluminum XHHW-2 conductors pulled in, thats less than the max permitted XHHW-2 in CH9 C11, so the LB does not need to have 12" between entries.

But then 314.28(A)(3) goes on to say:

For other conductor sizes and combinations, the total permitted crosssectional 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.

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That is for a very specific type of LB and not the standard one.  That is the type covered in the second paragraph and is why I said to look at the third paragraph.  Not sure how large they make these in, but this is the only type permitted for the full wire fill of the conduit trade size.  
The third paragraph applies to standard LBs, and they will be marked for the maximum number and size of conductors that they have been listed for.  You can calculate for other combinations based on not exceeding the area of the specified number and size of conductors.
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[Dsg319]

The bad thing is the inspector has no say on how I get my wire in the pipe, and, He also won't be there to help when is shorts out and we have to replace everything.

Jap>

You mean you weren’t required to megger the wires after you beat them in lol?

 

[jap]

You mean you weren’t required to megger the wires after you beat them in lol?

Not a requirement an inspector's going to make me do.

Jap.

 

[don_resqcapt19]

they have 2 different types of lb not sure if either makes any difference for bend radius
one sold as a service LB
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and more typical lb
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The issue is not a bend radius, but the distance between the two conduit entries

 

[LarryFine]

The issue is not a bend radius, but the distance between the two conduit entries

Right. The difference between those two LB styles is having to make a hole for the hub or not.

 

[PaulEd]

LB, LR, LL​	Source: 2012 UL 514B Table 40 P121​	​	​	​
XHHW Wire​	XHHW in2​	Max Fill in2​	LB Trade Size​	Max Qty​
4​	0.0814​	0.2442​	1”​	3​
2​	0.1146​	0.3438​	1-1/4”​	3​
1/0​	0.1825​	0.5475​	1-1/2”​	3​
3/0​	0.2642​	0.7926​	2”​	3​
300​	0.4536​	1.3608​	2-1/2”​	3​
400​	0.5782​	1.7346​	3”​	3​
500​	0.6984​	2.0952​	3-1/2”​	3​

Where can one find this chart and similar ones?

 

[infinity]

Where can one find this chart and similar ones?

According to the chart the reference is here:

Source: 2012 UL 514B Table 40 P121

 

[PaulEd]

According to the chart the reference is here:

Source: 2012 UL 514B Table 40 P121

I see.

Forgive me but is there an online version to search this? I’m not familiar with how to search the UL book

 

[kwired]

One of those details is that if the conduit body has a volume of over 100 in^3, then it will not qualify to be supported by the conduit itself under 314.23(E), so independent support will be required. Looks like a 2-1/2" LB exceeds 100 in^3?

Cheers, Wayne

See the exception afterwards, there is 5 pretty commonly used raceway types this doesn't apply to. For the most part you can't do it with flexible raceway types.

 

[wwhitney]

See the exception afterwards, there is 5 pretty commonly used raceway types this doesn't apply to.

Yes, the exception applies when "the trade size of the conduit body is not larger than the largest trade size of the conduit or tubing" But my comment was in reference to upsizing the conduit body larger than the connected conduit. Which means the exception no longer applies.

So a 3" IMC/RMC/PVC/EMT conduit body connected to 3" conduit/tubing does not need other means of support, per the exception. But If you use that 3" conduit body with 2" or 2.5" conduit/tubing, then the conduit no longer qualifies as the means of support.

Cheers, Wayne

 

[kwired]

Yes, the exception applies when "the trade size of the conduit body is not larger than the largest trade size of the conduit or tubing" But my comment was in reference to upsizing the conduit body larger than the connected conduit. Which means the exception no longer applies.

So a 3" IMC/RMC/PVC/EMT conduit body connected to 3" conduit/tubing does not need other means of support, per the exception. But If you use that 3" conduit body with 2" or 2.5" conduit/tubing, then the conduit no longer qualifies as the means of support.

Cheers, Wayne

After reading carefully I think I agree with you. This likely would beat least 1.25 maybe even 1.5 inch or larger before you start getting volumes over 100 cubic inches.

I guess to get around the additional support rule you maybe need to reduce before reaching the conduit body - say a short piece of 3 inch on each side of the 3 inch conduit body with support method on those pieces then reduce to 2.5 or 2 inch beyond there?

Most inspectors (there's always some that don't have a clue on reality) likely let you get away with the reducer at the conduit body, especially with say GRC and a malleable iron conduit body. This about as stupid as the support rule for a short length of 19-36 inches that kind of came around not so long ago. If you have a 4 inch GRC 30 inches long between two cabinets, NEC thinks it needs support other then at the terminations. Reality says it isn't going anywhere without also damaging the cabinets it is attached to. Any strap you put on it to meet code is in reality being supported by the conduit more so than the strap is supporting the conduit.