Splicing of 350MCM cable in pull box/ junction box

[D!NNy]

I have 350MCM 600V THHN cable pulled in a 3" rmc conduit via a Pull box / junction box
Ambiance is ocean area (corrosive)

Based on 314.28
Straight pull
- with out splicing min length of JB/PB is 24"
- with splicing min length of JB/PB is 18"

JB/PB of 18" * 18" * 8" is already purchased

options for splcing:
1. PDB, however per 314.28 (E) 2, min manufacturer recommended size is 24". also

Are there any other options for splicing that code compliance, UL rated, and can use the 18" boxes .

3M has this product: https://rexel-cdn.com/Products/3M/5304.pdf?i=6AA11246-243B-4660-B2EB-A5F7A2BB1A63
Polaris has this product : https://rexel-cdn.com/Products/NSITork/ISR-500.pdf?i=CAD229D7-9F3E-4A4B-AD3E-D4714BC888A9

Thanks for the help in advance

 

[don_resqcapt19]

While the code permits a smaller enclosure where splicing, it is my opinion that it really needs to be larger than what is required for a straight pull without a splice.

You may be able to fit compression sleeves with heat shrink insulation in the 18x18" box, but you don't have a lot of room to work with.

 

[buffalonymann]

I have 350MCM 600V THHN cable pulled in a 3" rmc conduit via a Pull box / junction box
Ambiance is ocean area (corrosive)

Based on 314.28
Straight pull
- with out splicing min length of JB/PB is 24"
- with splicing min length of JB/PB is 18"

JB/PB of 18" * 18" * 8" is already purchased

options for splcing:
1. PDB, however per 314.28 (E) 2, min manufacturer recommended size is 24". also

Are there any other options for splicing that code compliance, UL rated, and can use the 18" boxes .

3M has this product: https://rexel-cdn.com/Products/3M/5304.pdf?i=6AA11246-243B-4660-B2EB-A5F7A2BB1A63
Polaris has this product : https://rexel-cdn.com/Products/NSITork/ISR-500.pdf?i=CAD229D7-9F3E-4A4B-AD3E-D4714BC888A9

Thanks for the help in advance

manufacturer's recommendations do not carry the same weight as manufacturer's requirements.

 

[Ingenieur]

where did you get the mfg rec min 24" from?

314.28.E.2 applies to a power distribution block
what you are doing is splicing, 1 cable in and 1 out, no taps or distribution

the polaris pg 1 isr look like a good choice

 

[sameguy]

I found going the minimum often takes longer for the men and the"savings" is eaten by the labor.

 

[Cow]

I would never use an 18" box for splicing 350's. #2's yes, 350's a BIG no!

Over here we'd be using 24+" min and depending on the chosen splicing method and available space, more than likely larger than that. I don't know any electricians that like beating their hands up on the side of the box forcing oversized wires in too-small-of-a-box.