Conduit Inside Conduit

[ryangittens]

In order to satisfy 690.31(B) can you put PVC inside PVC to separate the DC and AC wiring?

Is there any code that says you cannot put conduit in conduit?


Thanks!

 

[Strathead]

In order to satisfy 690.31(B) can you put PVC inside PVC to separate the DC and AC wiring?

Is there any code that says you cannot put conduit in conduit?


Thanks!

It isn't uncommon to put ENT inside large conduit. It is called innerduct then. As such you could certainly put two conduits inside a conduit and run AC in one and DC in the other. As far as specfically what you ask, I will defer to those more expert than me.

 

[JFletcher]

I would think that putting a stick of rigid PVC inside of a larger stick of rigid PVC would not be code compliant, one for strapping and securing and for conduit supporting other conduit. ENT and innerduct look a lot of like, however they may have different listings.

 

[petersonra]

I would think that putting a stick of rigid PVC inside of a larger stick of rigid PVC would not be code compliant, one for strapping and securing and for conduit supporting other conduit. ENT and innerduct look a lot of like, however they may have different listings.

IMO if you put PVC conduit inside another conduit it is not conduit anymore. It is some kind of a long sleeve. But I would be more inclined to use something flexible like smurf tubing.

 

[Strathead]

I am going to self correct. I thought Innerduct was ENT with a factory installed string. It isn't. ENT is Polypropylene and Innerduct is HDPE, which means no PVC glue fittings. Which raises another question. Code 770.12 mentions Innerduct, but I can't find a definition or an article 300 section that defines Innerduct. Why does the code use a term that needs defining, but isn't defined?

 

[pv_n00b]

Is the conduit listed for that use? If not then I can't see how that would be acceptable. I don't know of anything in the NEC that says you specifically can't do this. I can't say this is something I would try, if I have to run two conduits anyway why not just run them side by side?

 

[kwired]

If using "typical raceway" you will terminate into cabinets, boxes, etc, where you still have both types of circuits entering the enclosure from essentially the same position.

If using a "sleeve" you can have multiple wiring methods contained within. Said sleeve doesn't even need to be something that is otherwise listed as a raceway.

Securing and supporting - you are allowed to fish wiring methods into structures or portions of them - a sleeve fits into this description.

 

[Fulthrotl]

If using a "sleeve" you can have multiple wiring methods contained within. Said sleeve doesn't even need to be something that is otherwise listed as a raceway.

yup. anything outside a raceway, is a sleeve the raceway goes thru.

4" pvc, or 2" square steel tubing, it's a sleeve.

 

[Strathead]

Is the conduit listed for that use? If not then I can't see how that would be acceptable. I don't know of anything in the NEC that says you specifically can't do this. I can't say this is something I would try, if I have to run two conduits anyway why not just run them side by side?

If the code doesn't prohibit something then it is allowed. That is the way it is.

 

[ptonsparky]

If the code doesn't prohibit something then it is allowed. That is the way it is.

FWIW, I agree with you, but not all do.

 

[kwired]

How do you comply with 300.18(A) with the inner raceway?

 

[pv_n00b]

yup. anything outside a raceway, is a sleeve the raceway goes thru.

4" pvc, or 2" square steel tubing, it's a sleeve.

So in the OPs case, they could run two conduits inside a larger conduit to separate the AC from DC circuits. In that case, the outer conduit is just a sleeve and needs no listing for use. But if they wanted to run just two conduits nested together with circuits in the smaller and larger conduit then the outer one would still be considered conduit and not a sleeve. Does that about sum it up?

 

[pv_n00b]

If the code doesn't prohibit something then it is allowed. That is the way it is.

True, as long as the listing also allows it or does not prohibit it. That's the way it really is.

 

[NTesla76]

I just noticed that in the 2017 index it mentions Innerduct and refers you to 770.12, but 770.12 is no longer there. The definition is there in Article 100.

 

[gadfly56]

So in the OPs case, they could run two conduits inside a larger conduit to separate the AC from DC circuits. In that case, the outer conduit is just a sleeve and needs no listing for use. But if they wanted to run just two conduits nested together with circuits in the smaller and larger conduit then the outer one would still be considered conduit and not a sleeve. Does that about sum it up?

It certainly sounds logical, although I can't see anyone actually doing that.

 

[ggunn]

In order to satisfy 690.31(B) can you put PVC inside PVC to separate the DC and AC wiring?

Is there any code that says you cannot put conduit in conduit?


Thanks!

If you're going to run two conduits anyway why does one need to be inside the other? Why make it hard on yourself?

 

[TurboSolar]

Maybe they ran one pipe and realized they needed to separate ac and dc after they ran that one pipe. I had a situation where we piped a commercial job for microinverters so only needed one pipe for ac and then the plans changed to an inverter so we needed to do something similar to what he is asking to separate dc and ac without having to dig up the concrete.