Is the inside of conduit ran indoors a wet location?

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Buck Parrish

Buck Parrish

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I heard some guys arguing on another forum about it. Got me to thinking. The question is not about under the slab, we all know that's a wet location.

For example, If you have 2 inch or 3/4 EMT ran on racks above, inside a dry building. Is the inside of that conduit a wet location? Would you be required to pull THWN ?
Somebody said it is a wet location due to temperture changes and condensation.

What say you?
 
Buck Parrish said:
I heard some guys arguing on another forum about it. Got me to thinking. The question is not about under the slab, we all know that's a wet location.

For example, If you have 2 inch or 3/4 EMT ran on racks above, inside a dry building. Is the inside of that conduit a wet location? Would you be required to pull THWN ?
Somebody said it is a wet location due to temperture changes and condensation.

What say you?
Click to expand...
No.
 
Buck Parrish said:
I heard some guys arguing on another forum about it. Got me to thinking. The question is not about under the slab, we all know that's a wet location.

For example, If you have 2 inch or 3/4 EMT ran on racks above, inside a dry building. Is the inside of that conduit a wet location? Would you be required to pull THWN ?
Somebody said it is a wet location due to temperture changes and condensation.

What say you?
Click to expand...

Come on Buck-- you knew that.. that guy has no basis for his statement... Just listen to "C'est Moi". He is a great guy...lol Yes that's me...hahaha
 
It is possible to have condensation inside interior conduits , under the right conditions, but it’s not the norm.

Penatrations onto a walk in cooler or freezer can experience this problem. But the fix is not water resistant wiring. The solution is to seal the interior of the conduit with duct seal around the wiring at the boundary, to prevent passage of air at great temperature and humidity variations.

I have also seen this happen in roof and wall penetrations where the building normally operates at a different static atmospheric pressure than the outside. Such as a wood mill or other facility where there is a large dust collector or exhaust fan to serve a process performed inside. The fix is sealing the inside of the conduit to prevent free air exchange, not wet location rated wire.

Many times where this condition is mild, not a great difference of pressure or temperature, I will seal the conduit with a small piece of plastic bag stuffed inside the conduit at the boundary location. It makes it easier to remove for future changes when required, but performs the same function with readily available materials.
 
MTW said:
Many times where this condition is mild, not a great difference of pressure or temperature, I will seal the conduit with a small piece of plastic bag stuffed inside the conduit at the boundary location.
Click to expand...
That was you?! 😲



:sneaky:
 
By Article 100 definition it is not a wet location. If it were considered wet then the boxes and fittings would also need to be rated for wet locations.

Location, Wet. Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject
to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.
Click to expand...
 
LarryFine said:
"Inside a conduit" is not a location. The conductors are in whatever location the conduit is.
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Well there is this..............
(B) Wet Locations. The interior of enclosures or raceways
installed underground shall be considered to be a wet location.
Insulated conductors and cables installed in these enclosures
or raceways in underground installations shall comply with
310.10(C) .
Click to expand...

and this................
300.9 Raceways in Wet Locations Above grade. Where raceways
are installed in wet locations above grade, the interior of
these raceways shall be considered to be a wet location. Insulated
conductors and cables installed in raceways in wet locations
above grade shall comply with 310.10(C).
 
It is a wet location, if the inside area where the raceway is installed, is a wet location, for example car wash facilities, parts of may industrial facilities, or other areas subject to wash downs.
 
Little Bill said:
Well there is this..............


and this................
300.9 Raceways in Wet Locations Above grade. Where raceways
are installed in wet locations above grade, the interior of
these raceways shall be considered to be a wet location. Insulated
conductors and cables installed in raceways in wet locations
above grade shall comply with 310.10(C).
Click to expand...
To me, those are saying that the presence of the conduit does not alter that these are wet locations
 
LarryFine said:
To me, those are saying that the presence of the conduit does not alter that these are wet locations
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That may be true but it clearly says "shall be considered a wet location". I was just pointing out they can be a wet location as opposed to your statement that they can't be a location.
 
LarryFine said:
To me, those are saying that the presence of the conduit does not alter that these are wet locations
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The code change that resulted in the addition of 300.9 was made because many code users insisted that the interior of a conduit installed in a wet location was not wet. The change makes it clear that where the outside of a raceway is in a wet location, the inside of that raceway is also a wet location.
 
don_resqcapt19 said:
The code change that resulted in the addition of 300.9 was made because many code users insisted that the interior of a conduit installed in a wet location was not wet. The change makes it clear that where the outside of a raceway is in a wet location, the inside of that raceway is also a wet location.
Click to expand...
Exactamundo, and well said. (y)
 
But is the interior of a conduit installed in a damp location (e.g. some regions under a covered porch) itself a dry location? I didn't find anything in the NEC that contradicts that idea. : - )

Cheers, Wayne
 
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