Clarification of Nipple Rule...

[vtsoundman]

Have an exterior main service panel connected via 2" diam 18" long nipple to a j-box....Out of the j-box right right into an 2" LB and then 12" into another j-box...

....Service Panel...Nipple(1) ... J-Box(1) ... 2" LB + ~12" of PVC....J-box(2)

Total length via center line from j-box(1) to j-box(2) is right at ~23" - the centerline length includes the LB, fittings, and 12" PVC. I need to use the LB instead of a sweep as it enters a building via concrete wall below j-box(2).

Am I good with the Nipple(2) or is the LB hosing the whole parade?

Code cycle: NEC in CA...

 

[infinity]

Not sure exactly what the question is, sounds like your concerned about the overall length of the nipple-LB-nipple configuration.

 

[vtsoundman]

Not sure exactly what the question is, sounds like your concerned about the overall length of the nipple-LB-nipple configuration.

Sorry if it wasn't clear

The first 18" nipple connects the main service panel to a 18" square NEMA-3R J-Box - so it should be fine.

The second nipple is the concern...

I come out of the 18x18 j-box into an LB then into 12" of PVC into another J-box (NEMA 1 located inside). The total LB+12" of PVC is ~23" -> the question is does the LB negate the application of the nipple rule for connection between the NEMA 3R to NEMA 1 j-box?

 

[infinity]

Yes all pull points start the 24" limitation over again.

 

[vtsoundman]

Yes all pull points start the 24" limitation over again.

Do I need to wire derate (for more higher CCC and fill) for the LB or is this part of the nipple too? Some of the discussions I've read suggested that it is and some have suggested it is not. I think it is part of the nipple...

 

[packersparky]

Yes all pull points start the 24" limitation over again.

That may depend on if the inspector considers and LB a "similar enclosure" to a box or cabinet. Around here they do not consider a LB as a similar enclosure.

Where conduit or tubing nipples having a maximum
length not to exceed 600 mm (24 in.) are installed
between boxes, cabinets, and similar enclosures, the
nipples shall be permitted to be filled to 60 percent of
their total cross-sectional area, and 310.15(B)(3)(a)
adjustment factors need not apply to this condition.

 

[vtsoundman]

That may depend on if the inspector considers and LB a "similar enclosure" to a box or cabinet. Around here they do not consider a LB as a similar enclosure.

Where conduit or tubing nipples having a maximum
length not to exceed 600 mm (24 in.) are installed
between boxes, cabinets, and similar enclosures, the
nipples shall be permitted to be filled to 60 percent of
their total cross-sectional area, and 310.15(B)(3)(a)
adjustment factors need not apply to this condition.

My LB + PVC conduit length is < 24 (between the j-boxes)...so would your inspectors be good? I am having trouble connecting the dots on your post. Thx.

 

[infinity]

My LB + PVC conduit length is < 24 (between the j-boxes)...so would your inspectors be good? I am having trouble connecting the dots on your post. Thx.

You have two nipples (not that it's really germane to the conversation) and their combined length is less than 24" so no derating applies. The part that is germane is the length of each individual nipple that is between the pull points such as the LB. You could have a 24" nipple-LB-24" nipple and still would not need to apply derating.

 

[vtsoundman]

You have two nipples (not that it's really germane to the conversation) and their combined length is less than 24" so no derating applies. The part that is germane is the length of each individual nipple that is between the pull points such as the LB. You could have a 24" nipple-LB-24" nipple and still would not need to apply derating.

Got it...and now I understand. Thx for being pedantic... Do I need to watch the fill for the LB? If so, I'll need to find another soln for making a 90 _into_ the building. Any suggestions? I suppose I could upsize the LB, but at some point this starts to get ridiculous....

 

[infinity]

Got it...and now I understand. Thx for being pedantic... Do I need to watch the fill for the LB? If so, I'll need to find another soln for making a 90 _into_ the building. Any suggestions? I suppose I could upsize the LB, but at some point this starts to get ridiculous....

No fill calculation needed for the LB. LB's have other limitations due to the fact that most standard ones do not have the required 6X internal dimension for an angle pull. You can use the information stamped inside of the LB to see if it's compliant.

 

[vtsoundman]

No fill calculation needed for the LB. LB's have other limitations due to the fact that most standard ones do not have the required 6X internal dimension for an angle pull. You can use the information stamped inside of the LB to see if it's compliant.

Outstanding thx. Largest conductors will likely be #1 copper, so all set for bend radius (then spliced alum SE or XHHW at the inside JBox for the various subs ). I think these are stamped 2/0 or 3/0 (don't recall).