Parallel conductors

[lauraj]

Purely theoretical question here:

If you are installing isolated phase parallel conductors in conduit as permitted by 300.3(B)(1) exception into a metal bottomed enclosure, you have to cut a slot between the conduits per 300.20(B).

What about the metal locknut? Does that act as an inductive choke?

 

[iwire]

Re: Parallel conductors

The two times I have been directly involved in isolated phase arraignments as described in 300.20(B) Exception we did not use lock nuts.

I can not imagine using that exception in combination with metal bottomed enclosures.

The exception only applies to underground conductors which IMO suggests open bottomed switchgear will be the only option.

 

[jbwhite]

Re: Parallel conductors

300.3 (B)(1) specifies nonmetalic conduit. so get nonmetalic lock nuts.

 

[roger]

Re: Parallel conductors

I agree with Iwire, the times I have done this type of underground installation, it has always been in open bottom gear.

In a metal bottom enclosure you could use aluminum locknuts or a PVC chase nipple into a coupling for a couple of options.

Roger

 

[ryan_618]

Re: Parallel conductors

I agree with Roger's agreeing with Iwire.

To elaborate on what Roger said regarding aluminum locknuts, you could use any locknut that is non-ferrous (no iron).

 

[hurk27]

Re: Parallel conductors

Bob I'm a little confused?

 

[iwire]

Re: Parallel conductors

Originally posted by hurk27:
Bob I'm a little confused?

I meant to reference 300.3(B)(1) exception.

 

[pierre]

Re: Parallel conductors

I also have installed this type of installation, but never to a metal bottom enclosure.
I guess I would probably have cut the bottom out of that enclosure.
I would also look at the installation instructions for that enclosure, sometimes you will see it says "top feed only". We have just such a scenario from a fair sized job here. The pipes are already installed underground, and I was reading the installation instructions for the equipment and it says "top feed only".
What a surprise... they were not happy I found that.