Conduit threading

[don_resqcapt19]

We install pipe to keep water from coming in

I don't think so...if that was the case, then conduit couplings would have tapered threads to make them water tight. Tapered threads would also improve the fault return path via the conduit.
Don

 

[steve66]

I don't see anything in the electrical code that prevents you from putting pipe dope on your conduit couplings. Of course, you may get some funny looks from the other trades

Don & Paul:

I hope you didn't think I was serious I knew Paul wasn't really suggesting we put gaskets on threaded couplings and connectors.

But I don't think I have ever seen anybody address Paul's point - why do EMT connectors have to be raintight when threaded couplings don't?

Steve

 

[don_resqcapt19]

Steve,

But I don't think I have ever seen anybody address Paul's point - why do EMT connectors have to be raintight when threaded couplings don't?

I have made a number of comments on that subject, even to the extent of calling the new UL listing "bogus". It is my opinion that the old compression type EMT couplings that are no longer listed as water tight are more water tight than is a threaded coupling.
Don

 

[Nick]

Case in point,
We did a 12KV feeder a couple of years back. The 5" aluminum conduit ran across a roof then vertical down the outside wall into a tap enclosure in a basement. All fittings were threaded and made up tight. During the first major rain storm water leaked through one of the couplings down the inside of the conduit and caused one phase to flash over.

 

[LarryFine]

Nick, I always drill a 1/8" hole in exterior fittings (LB's, etc.) at the lowest point for water to drain.

 

[hillbilly]

Nick, I always drill a 1/8" hole in exterior fittings (LB's, etc.) at the lowest point for water to drain.

I've done that too, more times than I can count. It's part of building a system that will stay, rather than just working out of the book. Speaking of the book, I've sometimes wondered (if in some strange way) this practice is a violation.
steve

 

[LarryFine]

. . . I've sometimes wondered (if in some strange way) this practice is a violation.

I'd say it's not only not a violation, it's required:

[quote='02 NEC]225.22 Raceways on Exterior Surfaces of Buildings or Other Structures. Raceways on exterior surfaces of buildings or other structures shall be raintight and arranged to drain.[/quote]

 

[Smart $]

At power plants and refineries that I've done weather-exposed installations, we use "drain plugs" at the lowest point in runs.

http://www.stahl.de/input/ex/rohrinstallation/12000007_en.pdf