Romex in plenum?

[TRAVIS LATIOLAIS]

I wired a house that was off the ground(no slab). I ran all my HR's under the house, because ther was no attic(none).I did not realize that the underneath of the house was one big plenum. All of the underneath perimitter is sealed off with cinder blocks. Inspector is the one that caught it, and said, I cant run wires in what is now a plenum. He rejected my inspection. Any one know the code reference, or a possible solution to problem? Any help would be greatly appreciated. Thanks

 

[ActionDave]

Ask the inspector where he thinks you should run the wires and for a code reference, then call his boss and ask if he shares the same opinion.

 

[jumper]

I have seen the HVAC guys "pan the joists" and it is legal to cross it in parallel. But a crawl space as a plenum in resi?

 

[Ponchik]

based on NEC 2008
300.22 talks about wiring in plenum spaces which doesn't list NM cable as a listed wiring method for plenum. But you may stretch 300.22(C) exception and see if it will fly for your installation.

 

[Ponchik]

I have seen the HVAC guys "pan the joists" and it is legal to cross it in parallel. But a crawl space as a plenum in resi?

you meant cross it in perpendicular?

 

[Sierrasparky]

Hey Travis , welcome to the forum! Where are you located?

The inspector is letting a crawl space with a dirt area , possible rodent, bugs and stuff be a plenum for envrionmental air?
sounds very unusual to me not to some code.

 

[steve66]

Is it possible the inspector is misunderstanding the term "plenum"? I think the NEC defines "plenum" a little differently than most people use the term. The NEC also has "other spaces used for enviromential air", but NM cable wouldn't be allowed in these either.

So are you saying there is a furnace or air handling unit that pushes air into the crawl space, and the air then comes up into the occupied space? Or are you saying the return air passes through the crawl space? If either of those apply, I don't think NM cable is allowed, but cable with a metal covering (FMC, AC, or MC) might be allowed.

In short, what makes you and the inspector think this is a plenum?

 

[Jon456]

One solution is to place all the home runs in EMT. Electrical conduit is allowed in plenums.

 

[ActionDave]

That would work but, I would rather have the truck that delivers the EMT park on my chest than run it in a crawl space. I have done it. It was awful.

He needs to talk to inspector. If it is run through a stud or joist bay covered over with metal, like the tinners sometimes do then the inspector is correct, but I can't see an entire crawl space considered a dedicated environmental air space.

 

[Jon456]

If you don't like EMT, how about running the NM in non-jacketed flexible metallic conduit ?

 

[hillbilly1]

Hey Travis , welcome to the forum! Where are you located?

The inspector is letting a crawl space with a dirt area , possible rodent, bugs and stuff be a plenum for envrionmental air?
sounds very unusual to me not to some code.

Yeah, looks like the HVAC contractor would have failed their inspection upon doing this, I would think they would have a code preventing this, we are not the only ones that have regulations!

 

[growler]

All of the underneath perimitter is sealed off with cinder blocks. Inspector is the one that caught it, and said, I cant run wires in what is now a plenum. He rejected my inspection. Any one know the code reference, or a possible solution to problem? Any help would be greatly appreciated. Thanks

I don't know what the levels of Radon gas are in that area but I would asssume that Radon remediation wouldn't include circulating the air through the house.

I really think the whole idea is not to breath this gas.

I would question the use of a crawl space as a plenum.

 

[dana1028]

I wired a house that was off the ground(no slab). I ran all my HR's under the house, because ther was no attic(none).I did not realize that the underneath of the house was one big plenum. All of the underneath perimitter is sealed off with cinder blocks. Inspector is the one that caught it, and said, I cant run wires in what is now a plenum. He rejected my inspection. Any one know the code reference, or a possible solution to problem? Any help would be greatly appreciated. Thanks

I would be very surprised if this crawl space qualifies as a plenum per the energy codes [either Federal or state]. The energy codes spell out the exact materials/enclosures, etc. for plenums and such a design is highly suspicious.

Like others have said, check with the AHJ to see if this 'plenum' meets the federal or state energy regulations for a plenum.

 

[dpeter]

Melodie home builders in Indiana did this for their return air as well as wood foundations and was code compliant. I do not recall seeing any wiring in the crawl space but that wasn't the reason I was down there. Also, they are no longer in buisiness.

 

[dana1028]

Melodie home builders in Indiana did this for their return air as well as wood foundations and was code compliant. I do not recall seeing any wiring in the crawl space but that wasn't the reason I was down there. Also, they are no longer in buisiness.

Passing a final inspection by an inspector does not make an installation code compliant [really not trying to be argumentative]. Exposed wood is not allowed to be part of a plenum [sheet metal, duct board, etc. are materials that completely seal the 'plenum' space and thus meet the requirements for a plenum. I have seen lots of installations that pass an inspection due to lack of energy code requirements - that is the point I'm trying to make for the OP. You can call it a plenum but if it is in violation of the energy code then it is not a plenum - given the OPs situation I would certainly want this avenue checked before I started rewiring.

 

[Sierrasparky]

Passing a final inspection by an inspector does not make an installation code compliant [really not trying to be argumentative]. Exposed wood is not allowed to be part of a plenum [sheet metal, duct board, etc. are materials that completely seal the 'plenum' space and thus meet the requirements for a plenum. I have seen lots of installations that pass an inspection due to lack of energy code requirements - that is the point I'm trying to make for the OP. You can call it a plenum but if it is in violation of the energy code then it is not a plenum - given the OPs situation I would certainly want this avenue checked before I started rewiring.

I can't belief this is a code compliant plenum either !

 

[TRAVIS LATIOLAIS]

Hey guys, thanks for your response. Steve66 is right. Airhandling unit pushes air underneath house, which is sealed around perimitter with cinder blocks, and insulation (plenum). The air then comes up into occupied space through 6inch squares cut in floor (no duct). Inspector said to re- run wires in mc cable, but thats not in my resi bid. I am meeting with contractor next week, and will keep you all updated. On a side note, inspector said he only seen this once, and it was 12 years ago. I have been doing electrical work for 10 yrs, and never seen such a thing. I thought you couldnt use wood(floor joist) for a plenum!

 

[Sierrasparky]

I would not want it that way in my house.
Is there bare dirt below?

 

[dana1028]

I thought you couldnt use wood(floor joist) for a plenum!

You can't - you might want to take a look at the energy code requirements [all call your state energy dept.] and check this out. I know our state has its own energy code but each state's energy code must comply with the federal regulations. Our code does not permit exposed wood in any duct/plenum space.

 

[Dennis Alwon]

Years ago they used to pan the joists rather than run a duct. You can traverse it but you could not run parallel in the space. I have seen one house where the entire crawl space, dirt floor, was used as a cold air return. I am sure it is not legal anymore. Think of the mold in some crawls as well as other things.