SER cable leaving large plastic junction box - bushing/clamp?

[megalo]

I am planning on splicing the individual conductors going out to my detached garage (in conduit) to a 2-2-2-4 SER cable to run through the basement, as the basement is mostly finished and I can't run conduit through it.

Does the SE cable need to be protected when it exits the plastic junction box? If so, do I use a bushing or clamp? From what I understand, using a metal clamp on a plastic (and thus, ungrounded) box requires the clamp to be bonded somehow.

Thanks!

 

[pattenp]

Personalty I think it's a stretch to require a metal clamp to be bonded if used on a plastic box; why don't metal staples need to be bonded? Anyway, I would use a bushing on the box and staple the SE to a framing member within a foot of the box.

 

[megalo]

The county electrical chief did say that they won't require the clamp to be bonded.

I guess I need to figure out where to get a big *** clamp or bushing - that 2-2-2-4 SER is not thin.

 

[pattenp]

If that's the case then get a plastic threaded adapter for the box and use a large NM clamp screwed into the threaded adapter.

The county electrical chief did say that they won't require the clamp to be bonded.

I guess I need to figure out where to get a big *** clamp or bushing - that 2-2-2-4 SER is not thin.

 

[Falcon67]

Where my 2-2-2-4 exits a 6" box into the house eve/attic, I just used a 2" bushing. Drilled the top of the box and glued it in.

 

[Aceman]

Use an 1.5" metal Romex connector. Like what Pattenp posted, except bigger.

 

[pattenp]

Yeah, I used a picture of a 1/2" clamp, but hey.. I did say a large NM clamp.

Use an 1.5" metal Romex connector. Like what Pattenp posted, except bigger.

 

[megalo]

On a somewhat-related-but-not-really question - I'm using 2" conduit to run the individual conductors. The panel I bought for the garage (Square D QO 100 amp) only has a 2" knockout, not the 2.5" for the OD of the 2" conduit.

Is it common practice to cut a larger hole in the electrical box?

 

[Alchymist]

On a somewhat-related-but-not-really question - I'm using 2" conduit to run the individual conductors. The panel I bought for the garage (Square D QO 100 amp) only has a 2" knockout, not the 2.5" for the OD of the 2" conduit.

Is it common practice to cut a larger hole in the electrical box?

That's why electricians have knockout punches.

 

[megalo]

That's why electricians have knockout punches.

Ah, that looks good - but a bit expensive for a one-time-use thing.

Wonder how poorly my hole saw will handle sheet metal...

 

[ishiboo]

They make larger clamps for use with SE/SER. I had to splice my service entrance in a 8x8 plastic junction box and used those clamps.

 

[Falcon67]

On a somewhat-related-but-not-really question - I'm using 2" conduit to run the individual conductors. The panel I bought for the garage (Square D QO 100 amp) only has a 2" knockout, not the 2.5" for the OD of the 2" conduit.

Is it common practice to cut a larger hole in the electrical box?

Mine has a 2" knockout, just use a 2" threaded end for the conduit.

 

[megalo]

I forgot to mention that I am coming straight into the back of the box (lower right corner in your picture). Those knockouts aren't quite big enough.

Which leads to another question - the wall is built with 2x4s, so it's only 3.5" thick, which is the same as the box. This leaves no room to put the male threaded adapter in that hole. The stub on the LB is only ~1.5" further out on the outside of the wall. I could come straight into the box with a short segment of conduit, but I wouldn't be able to secure it like that threaded adapter is. Am I SOL?

 

[Alchymist]

Put the adapter in the box, cut the siding to fit around it, short piece of conduit to LB, caulk. LB can stand away from the siding slightly.

 

[Aceman]

Google "pvc box adapter"

It'll slip right through the KO and into the LB.

 

[megalo]

I'll take a look and see how far the male adapter will protrude, since it's easy to remove from the box without cutting something.

 

[Falcon67]

Get an LB with a thread, then thread the 2" end in from the panel side into the LB. You could probably cut some of the conduit end of the adapter off to give more room in the box. Also note that to get your box flush with any interior wall covering, you will need to pull it out about 1/2", so you will have 1/2' behind the box to the siding. You could also LB into the wall below the box, then turn up into the bottom of the box.

 

[megalo]

Haven't seen a threaded LB yet.

I thought about putting an LB in the wall, but the 2" LBs are huge and will stick out a fair amount (and I'd have to leave the back of the LB accessible).