Exposed Conduits in Pools

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Sparky1981

Sparky1981

PE
Location
Denver, CO
Occupation
Electrical/Lighting Engineer
I have designed many pools in my past. Recently I have been confronted with my standard spec that calls for Rigid Steel Conduit for natatoriums. In the 2020 NEC 680.14 makes it clear this meets code. However I am wondering about longevity. Is this the best solution? Does anybody else have experience with pools that would not recommend rigid steel? Are there case studies? I have searched for a bit and am coming up pretty dry so figured I would pick the brains on the forum. The contractor suggested EMT or PVC. EMT is a clear no from me. PVC I would only reject based on look (painted rigid steel would look better than PVC), but if the rigid steel is not expected to perform for a few decades then I may consider changing my spec.
 
I had to look up natatorium... I just say "indoor swimming pool", I didn't know there was a word for that. (y)

Assuming the presence of chlorine, bromine, acids etc., galvanized RMC or IMC is probably not going to last much more than a decade, but per 680.14 it is allowed (EMT by the way is not). You could use SS RMC conduit if money is no object, but that's fairly uncommon. Most people use PVC and you can paint PVC conduit with latex paint by the way. It only has to be grey when you install it so that the inspector knows it's conduit. Once it's inspected, you can make it pink, blue, rainbow, whatever.
 
masterinbama said:
Rigid Aluminum.

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When I did some work at a fertilizer plant that used chlorine, aluminum conduit was banned. It reacts and forms what looks like mold on the aluminum (aluminum oxide), which eventually stops further corrosion, but looks like crap. If you clean it off, it just forms again and if you keep cleaning it, eventually you have removed most of the aluminum.
masterinbama said:
Or robroy

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Robroy (coated conduit) is what we used, but it looks ugly for something like a swimming pool and I'm pretty sure paint won't stick to it.
 
I've done a lot of work for YMCAs with nadatoriums. RMC is definitely the best choice. It holds up well and they always paint it to make it blend in. PVC gets broken too easily. Life guards hit it with the poles for their flags, starting platforms, etc. It will sag when their ventilation system gets rusted out and the temperature swings etc. RMC will last 30+ yeas if they paint it (and they always do).
 
Random musing here: I wonder if you could enhance the longevity by adding more zinc to the equation.

Pull in a zinc wire to act as a sacrificial anode with respect to internal moisture and use spray on zinc to reinforce weak points at joints prior to painting.

Jon
 
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