SER to USE Junction

[patrickcronin]

I am transitioning 4/0, 4/0, 4/0, 2/0 AL from SER cable in a crawlspace to the same sized USE cable at the exterior for 200A service to an auxiliary building.

I plan to make the junction outside of the home in a NM junction box.

My questions:

1. Does the SER cable need to come out of the crawlspace in an LB to enter the junction box from the side (assumes an 18" x 18" x 6" box) to accommodate the radius requirements?

2. If so, what size LB is sufficient for this size cable?

3. Or, can the SER cable enter the box from the rear (6" depth)?

The real question is what is the best, safest method to make this splice?

I am thinking that keeping the splice on the exterior of the building would be better than a splice in the crawlspace but again, that's merely an assumption.

Thank you all in advance for your insight on this issue,

Pat

 

[electrofelon]

I am transitioning 4/0, 4/0, 4/0, 2/0 AL from SER cable in a crawlspace to the same sized USE cable at the exterior for 200A service to an auxiliary building.

I plan to make the junction outside of the home in a NM junction box.

My questions:

1. Does the SER cable need to come out of the crawlspace in an LB to enter the junction box from the side (assumes an 18" x 18" x 6" box) to accommodate the radius requirements?

2. If so, what size LB is sufficient for this size cable?

3. Or, can the SER cable enter the box from the rear (6" depth)?

The real question is what is the best, safest method to make this splice?

I am thinking that keeping the splice on the exterior of the building would be better than a splice in the crawlspace but again, that's merely an assumption.

Thank you all in advance for your insight on this issue,

Pat

I would just come in the back of the box using a clamp connector. see 314.28(A)(2) for sizing. Because of the removable cover, you will be fine with that depth.

For splices, polaris type connectors are real nice, but kinda spendy. Set screw butt mechanical splices are probably the cheapest, but take some more time. I usually use the latter because I'm cheap.

 

[LarryFine]

There's also the split-bolt option.

 

[electricman2]

I'm with electrofelon. Set screw butt connector. Wrap with cambric and 33. Makes a neat splice

 

[kwired]

I am transitioning 4/0, 4/0, 4/0, 2/0 AL from SER cable in a crawlspace to the same sized USE cable at the exterior for 200A service to an auxiliary building.

I plan to make the junction outside of the home in a NM junction box.

My questions:

1. Does the SER cable need to come out of the crawlspace in an LB to enter the junction box from the side (assumes an 18" x 18" x 6" box) to accommodate the radius requirements?

2. If so, what size LB is sufficient for this size cable?

3. Or, can the SER cable enter the box from the rear (6" depth)?

The real question is what is the best, safest method to make this splice?

I am thinking that keeping the splice on the exterior of the building would be better than a splice in the crawlspace but again, that's merely an assumption.

Thank you all in advance for your insight on this issue,

Pat

Does the USE have other ratings (like RHW)? If not it can not enter the building and you must make your splice box on the exterior.

If it has other ratings and is allowed inside, you possibly can make it look a little nicer/slimmer on the exterior by putting a conduit body on outside and then entering and putting your splice box inside.

Butt style set screw splicers need more room to work with as they have conductors entering opposing ends, plus you need to insulate them.

Polaris and others like them can have entry ports on same end instead of opposing ends - might be easier to work with managing how to route conductors in the box. They are already insulated, but usually a little pricey.

If you already have crimp tools, cheap way is parallel groove taps (H taps), you can spend a little labor insulating them or they make snap on covers for them. They are still about cheapest way (if you already have crimping tool for them) and make a very good irreversible splice. Bad news is you will be cutting them off rather than taking them apart if you ever need to open the connection. I'd probably make leads a little long if possible so that you can at least reinstall a Polaris style connector if you ever need to open the connection down the road.

There are also split bolts, needs insulated, and terminal block type assemblies that can be used also.

 

[patrickcronin]

A big thanks to all of you responders.

Ordered a 16" x 16" x 10" NM J box. USE enters in a 2.5" conduit so this sizing should keep everyone happy. Will bring the SER in the back of the box from the crawlspace. The 10" depth should give plenty of room for the bend.

Again, thanks!

Pat