Crawl space NM cable

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nizak

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I haven’t wired a new home in many years that had a crawl space.

Floor is poured concrete, area is not heated.

My question . Is this considered a damp area and would require UF type cables for all wiring down there?

All wiring will be run through bored holes in floor joists.

Thanks
 
I have never seen UF run thru a crawl space although many of them are soaking wet. In new construction the crawl should be bone dry.
 
You should ask your local AHJ. Some localities see attics and crawls as damp locations, like under a covered porch or deck
 
LarryFine said:
Not because of leaks, but because it exposed to outdoor air. Fog moving through the attic venting, for example.
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If so, with my open windows in the house proper, it is also a damp area and NM should never be allowed unless home is totally closed with no outside air allowed entry. Old homes witout proper insulation that has excessive air infiltration through walls also make space inside walls a damp area by this criteria.
 
nizak said:
I haven’t wired a new home in many years that had a crawl space.

Floor is poured concrete, area is not heated.

My question . Is this considered a damp area and would require UF type cables for all wiring down there?

All wiring will be run through bored holes in floor joists.

Thanks
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The floor is poured concrete over some sort of decking with joists under? Like a slab?
Sounds unusual.
 
nizak said:
I haven’t wired a new home in many years that had a crawl space.

Floor is poured concrete, area is not heated.

My question . Is this considered a damp area and would require UF type cables for all wiring down there?

All wiring will be run through bored holes in floor joists.

Thanks
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A lot of states did not adopt the "bored holes" in a crawl space requirement.
 
I see no reason why you couldn't run nm in a crawl space.
Just like someone else mentioned check the AHJ. Check to see if you're in a flood zone.
FWIW:
I'm assuming the wiring in mention is for the crawl space area or maybe floor receptacles?

I typically run my wires for each floor overhead for the most part.
 
If it is truly damp down there mold issues are likely going to be a problem.

There is a difference between high humidity and damp. Condensing humidity can turn into damp conditions, but typical attic or crawlspace doesn't have much for condensing situations.
 
LarryFine said:
Not because of leaks, but because it exposed to outdoor air. Fog moving through the attic venting, for example.
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Ha, I have been in thousands of attics and have never seen fog moving thru. I hope you were being facetious. I can honestly say I have never seen any moisture in attics unless there is a leak which doesn't fit the bill for damp location.

I don't understand why we use NM-B instead of NM-C. Certainly they could price them the same or close to it. NM-C will handle damp locations and all these questions would be a non issue
 
Lots of houses locally in my area are built up on post and pier with a sort of criss cross fence skirt ( I forgot the actual word for this, but I'm 66, so be it.) Anyway, here we have inspectors who insist that makes it a damp location, so when rewiring one of these when you run nm down there you run the gauntlet of which inspector is going to make you change that to uf cables. One guy who hasn't retired yet says any cables outside of the tyveck are to be uf since it clearly states "indoor use" on the plastic wrap of rolls of nm cables, and hence must be used only "indoors".





edit to add- Lattice - it just popped into the noggin
 
macmikeman said:
Lots of houses locally in my area are built up on post and pier with a sort of criss cross fence skirt ( I forgot the actual word for this, but I'm 66, so be it.) Anyway, here we have inspectors who insist that makes it a damp location, so when rewiring one of these when you run nm down there you run the gauntlet of which inspector is going to make you change that to uf cables. One guy who hasn't retired yet says any cables outside of the tyveck are to be uf since it clearly states "indoor use" on the plastic wrap of rolls of nm cables, and hence must be used only "indoors".





edit to add- Lattice - it just popped into the noggin
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I would agree that lattice will not make the space dry. That would be a damp location just as something on a screen porch would be considered damp. (I don't mean inside the walls)
 
Dennis Alwon said:
Ha, I have been in thousands of attics and have never seen fog moving thru. I hope you were being facetious.
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No, I'm just saying that that is the rational used by nearby counties that consider such spaces to not be dry locations.

Likewise, some counties allow copper tubing for natural gas, and some allow compression instead of flare connections.
 
LarryFine said:
Likewise, some counties allow copper tubing for natural gas
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I believe the problem with copper tubing for natural gas was the same as it was with galvanized: if the sulfur content of the natural gas is high enough, sulfides of copper (or zinc) would form, which would flake off. I don't know all the gas codes across the country, but I think most systems are now low enough sulfur that copper is allowed.

Cheers, Wayne
 
Dennis Alwon said:
I don't understand why we use NM-B instead of NM-C. Certainly they could price them the same or close to it. NM-C will handle damp locations and all these questions would be a non issue
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Dennis have you ever seen NM-C? I have never seen it for sale, I have seen some 1970's era stuff that had an insulated green wire like MC (or tray cable) and did not have the paper wrap, which I thought might be NM-C but I chalk that stuff up there with XHHN
 
I have never seen NM-C that I was aware of but I thought it was more like NM-B than UF. I got that from this blurb

Type NM cable is defined as insulated conductors enclosed within an overall nonmetallic jacket, while Type NMC is insulated conductors enclosed within an overall corrosion-resistant nonmetallic jacket. The only difference between the two definitions is that NMC is corrosion-resistant and NM cable is not
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