NEC 314.28 junction box size for 4 AWG SOOW Cord

[Jpflex]

I’m kind of confused here. Normally you size the junction box at 6 times the conduit trade size and add the sum of those below for angled runs or size the box to 8 times the conduit trade size for straight pulls


However I am installing a plastic junction box where # 4 AWG SOOW Cord will be entering from the bottom splicing inside and exiting adjacent to the first at the bottom for a u bend

The cable entering is not a conduit so would I base the size of the junction box based on the size of any conduit that if installed would hold the SOOW cord or 4 of #4 AWG conductors?

Or #4 AWG x 6 = 24 inch box is obviously not right because the jacketed SOOW Cord is not a conduit?

 

[don_resqcapt19]

314.28(A)(2) ...
When transposing cable size into raceway size in 314.28(A)⁠(1) and (A)(2), the minimum metric designator (trade size) raceway required for the number and size of conductors in the cable shall be used.

 

[Jpflex]

314.28(A)(2) ...
When transposing cable size into raceway size in 314.28(A)⁠(1) and (A)(2), the minimum metric designator (trade size) raceway required for the number and size of conductors in the cable shall be used.

SOOW cord conductors are not labeled as THHN nor have writing on their individual insulation but if I use the table 5 of chapter 9 I can fit 2 hots, 1 neutral and 1 ground or 4 of # 4 THHN conductors into a 1 inch EMT conduit

Therefore do I calculate 1” EMT conduit x 6 = 6 inch box minimum?

 

[don_resqcapt19]

SOOW cord conductors are not labeled as THHN nor have writing on their individual insulation but if I use the table 5 of chapter 9 I can fit 2 hots, 1 neutral and 1 ground or 4 of # 4 THHN conductors into a 1 inch EMT conduit

Therefore do I calculate 1” EMT conduit x 6 = 6 inch box minimum?

SOOW will be bigger than THHN...I would look at RHW or look at the OD of the cable and use that under the single conductor column. I find the sized in 314.28 to be small and would tend to use the OD for this calculation.

 

[jaggedben]

Jpflex, I'm a bit confused. Are you pulling SOOW cable through a box? Or splicing two pieces together in it? (I can't imagine why you would do the first one, but then why mention straight pulls or u-pulls?)

If splicing...
Honestly, unless I was worried about having to argue such a fine point with the AHJ, I would just go by the tables for THHN. Because SOOW conductors are more flexible than THHN and will be just as easy to work into the box, probably easier.

 

[Dsg319]

8”x 8” x 4” box.


No calculation just know I could get my hands in there and get it done easy lol.

 

[Jpflex]

Jpflex, I'm a bit confused. Are you pulling SOOW cable through a box? Or splicing two pieces together in it? (I can't imagine why you would do the first one, but then why mention straight pulls or u-pulls?)

If splicing...
Honestly, unless I was worried about having to argue such a fine point with the AHJ, I would just go by the tables for THHN. Because SOOW conductors are more flexible than THHN and will be just as easy to work into the box, probably easier.

I have a trailer that was fed from two separate sub panels. Each sub breaker panel was fed from a # 4 AWG SOOW cord good for 54 amperes after ambient temperature derating.

These SOOW feeder cords terminated into a 50 ampere 3 prong male 120 volt connector, each breaker panel had its own 120 volt 50 ampere supply their own outdoor receptacle such as for trailers and campers

What the previous installer decided to do was jump both A and B phase buses together within each breaker panel and feed both buses with 1 phase and neutral to neutral buss for a 120 volt breaker panel instead of utilizing the 240 volt panel option

My outside trailer receptacle is 240 volts at 50 amperes with a neutral 4 prong 4 wire so I wanted to install a junction box where I could remove the jumper between busses and feed 2 phases to each panel buss for 240 volt phase to phase or 120 volts phase to neutral with one SOOW cord instead of 2 cords at 120 volts which I do not have receptacles

 

[jaggedben]

Ugh, I still don't understand what you are doing, or if it's okay in general. But at least it sounds like you are splicing the cable in the box, not pulling it through. So, what I said before about the box.

 

[Jpflex]

Technically they didn’t violate code by terminating two wires on one lug because they used one wire going through connector with insulation removed, in order to jump busses

I’m doing a lot of box calculations etc only because I’m preparing for journeyman testing licensing soon and want to make sure I’m working to code regardless if wires will fit outside of code

 

[jaggedben]

Yeah what they did is ... not terrible. But I don't understand what you want to do instead.

 

[jaggedben]

For example I think it would be a code violation to splice two separate 120V cables together in a box to get a 240V feed. If that's what you're proposing.

 

[Jpflex]

Ugh, I still don't understand what you are doing. But at least it sounds like you are splicing the cable in the box, not pulling it through. So, what I said before about the box.

I will be splicing.

What happened is that the two panels feeding this trailer were not supplied by two hots and a neutral plus ground as typical

Instead they were fed by only 3 wires, 1 hot one neutral and one ground

So for me to make this work feed from one receptacle I need to make a junction box where feeders can split into both panel boxes

 

[Jpflex]

Yeah what they did is ... not terrible. But I don't understand what you want to do instead.

Yes I know what was done was not bad, but it just didn’t fit the application we have here.

I noticed the two sub panels do not have a main breaker. I was thinking of installing a small 2 pole 50 ampere breaker panel upstream of the two breaker panels to be code compliant

Or can the 50 ampere breaker for the outside receptacle that feeds these panels cover the panel over current OCPD requirements for panels?

 

[Jpflex]

For example I think it would be a code violation to splice two separate 120V cables together in a box to get a 240V feed. If that's what you're proposing.

I would not splice two cables together in a box to get 240 volt feed in that aspect

However , what I’m saying is taking one single 4 AWG SOOW cord that will be fed /plugged into one outside 2 pole 50 ampere receptacle to feed this junction box where each phase A and B will be spliced here so that one # 4 AWG SOOW cord can split into two ends to feed each sub panel as two 120/240 sub panel for this trailer

 

[Jpflex]

I would not splice two cables together in a box to get 240 volt feed in that aspect

However , what I’m saying is taking one single 4 AWG SOOW cord that will be fed /plugged into one outside 2 pole 50 ampere receptacle to feed this junction box where each phase A and B will be spliced here so that one # 4 AWG SOOW cord can split into two ends to feed each sub panel as two 120/240 sub panel for this trailer

For example I think it would be a code violation to splice two separate 120V cables together in a box to get a 240V feed. If that's what you're proposing.

Heres a picture as it’s quite simple

 

[Jpflex]

Is it code compliant to splice the load side wires of a small main breaker box (not by terminating two wires on the same load side breaker lug), in order to branch two feeders out for two sub panels that were not supplied with a main breaker within each sub panel?

 

[Jpflex]

Here’s a picture of what I mean for above question

 

[jaggedben]

If you're splitting a feeder to feed two panels then I believe each panel needs a main breaker so it's individually protected. But otherwise it's fine.

 

[wwhitney]

If you're splitting a feeder to feed two panels then I believe each panel needs a main breaker so it's individually protected.

If the OCPD protecting the feeder is small enough to protect the busbars of each panel, then 408.36 is satisfied. I see no other general reason that each panel would need to be individually protected.

Cheers, Wayne

 

[Jpflex]

If you're splitting a feeder to feed two panels then I believe each panel needs a main breaker so it's individually protected. But otherwise it's fine.

The two panels were originally without a main breaker so they were relying on 20 ampere branch circuit breakers and the 50 ampere breaker to the out slide receptacle feeding these

I’m out of space to add 2 of 2 pole breakers for each sub panel so I have 1 of 50 ampere 2 pole GFCI breaker supplying these two small breaker panels