Watertight vs Submersible Conduit

[kalql8]

I am reviewing a submittal that requires a NEMA 6P control panel. The location is in a flood plain, and has the potential to flood. My question is: The conduit and fitting that will be attached need to be similarly made, that is, submersible, not just watertight. The submitter has pointed out that the conduit will be WATERTIGHT (emphasis by submitter). Is this different than submersible? Is the submitter trying to state what he will be supplying, and relying on my ignorance of a fine point in a definition?

 

[davidbeach]

The control panel will need to have submersible fittings, you can't count on the conduit system. The NEC makes the assumption that anything installed below grade can be full of water. So, your "submersible" conduit will probably have water in it at some point. Far easier to seal around the cables as they enter, or use a water-tight bulkhead, than to try to keep a conduit system "submersible".

 

[IRstuff]

Elimination of water eliminates all sorts of problems. I had water coming into my house because the conduits were not watertight, and the other end was uphill of my end, resulting in a net gradient for the water that got in. VERY annoying.

TTFN
faq731-376

 

[davidbeach]

Back in the day, when I was still engineering underground conduit systems, I always assumed the conduit would be full of water. If that water could flow somewhere to cause problems, there would be provisions made to intercept and divert the water. For instance, switchgear for a medium voltage service installed 3 floors below grade sat on a drained pit, with the conduits entering the pit rather than the top of the gear. There is some water flow in the service conduits most of the year, but no water damage to anything.

Assume that the conduits are watertight, and will remain watertight forever, and you will be disappointed at some point. Assume that there will always be water in the conduits and design the system to keep water away from things that can be damaged by the water and you'll have far fewer problems over the life of the installation.

 

[ScottyUK]

You will probably find it easier to use cable glands than conduit to keep water out. Over here cable glands are readily available to IP67 or IP68, and some are rated to IP69 which is designed for washdown applications using pressure washers. Sorry I'm not sure what the US equivalent standard is.

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If we learn from our mistakes I'm getting a great education!

 

[waross]

Submersible will keep water out. Water tight will keep water in.
Tongue in cheek but you get the idea.


Bill
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"Why not the best?"
Jimmy Carter