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weatherproof connection of pvc conduit to exterior metal boxes

weatherproof connection of pvc conduit to exterior metal boxes

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Old 02-04-17, 10:41 PM
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weatherproof connection of pvc conduit to exterior metal boxes

I am running 3/4" pvc conduit underground to a pump controller box located outdoors, and from there back underground in 1 1/2" pvc to sump pumps. The pump control box is either pvc or possibly polycarbonate. It requires i drill my own holes for conduit. i also need to connect to a metal waterproof box with threaded openings. How do I make a water tight connection from the pvc to these boxes?

I cannot find a male threaded connector (terminal adapter) with a gasket or o-ring. You can get these for liquid-tight (flexible) and EMT, but there doesn't appear to be an equivalent for pvc. I've scoured the web with no success. An electrician suggested a male connector and apply silicone. Someone else suggested I buy an o-ring. I'm not sure these approaches will pass inspection, so at the moment my plan is to transitiion to liquid-tight using a bunch of adapters, but surely since pvc is intended for outdoors, there must be a better way. Any suggestions?
 
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Old 02-04-17, 10:53 PM
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Welcome to the forums.

If the connections are at the bottom of the box..... no need to seal as the water won't travel up.
 
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Old 02-05-17, 07:16 AM
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You could a PVC bulkhead fitting. They are usually used when connecting to tanks, but will work fine for this as they include a rubber seal. You can get ones intended to solvent weld to the pipe, or ones that are threaded to make to a male threaded adapter that is then solvent welded to the pipe.
 
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Old 02-05-17, 10:18 AM
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I cannot find a male threaded connector (terminal adapter) with a gasket or o-ring.
Like PJ said, if the conduit enters the bottom you don't need a sealing fitting. For the top or sides I like Myers Hubs (or equivalent).

http://www.cooperindustries.com/cont...b-brochure.pdf
 
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Old 02-06-17, 12:16 AM
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Thank you Pete, Paul and Casualjoe for your suggestions. I've looked into these and once I started searching on Meyers Hubs I have learned quite a lot. It's surprising that there isn't a clear consensus. For what it's worth, here's what I've found:
1) Meyers hub is only listed (approved) for rigid conduit, but people say inspectors might accept it with a pvc male terminal adapter. Apparently Meyers hub is pipe thread and pvc is straight thread
2) Some people say that you get a better seal if you use a rigid metal conduit nipple to connect the meyers hub to a female pvc adapter. Not sure if rigid metal to pvc is considered water tight. And again, threads compatible?
3) Some people say you can use a sealing locknut, although it is only listed for rigid metal conduit, so an inspector could fail that
4) Arlington Industries claims their exterior receptacle boxes will seal water tight directly to ordinary pvc terminal adapters
No consensus as to what is UL listed or code approved!

Lastly, bulkhead connectors seem to be hard to find locally and they're expensive (they're rated for fluids and high pressures). Seeing as you can't use regular plumbing pvd for electrical, would these be rated for electrical cocnnections?

Your point about entering the box from below will solve most of my problems!

Arthur
 
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Old 02-06-17, 12:23 AM
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I just discovered that Carlon makes neoprene washers specifically to seal male terminal adapters
https://s3.amazonaws.com/cesco-conte...7-Brochure.pdf
 
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Old 02-06-17, 04:42 AM
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Never had anyone question using Myers Hubs for other electrical fittings although it specs. for Ridgid conduit, threads on electrical fittings would be standard,I would bet if you contacted Myers they would agree,probably just haven't updated the specs.
Geo
 
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Old 02-07-17, 05:08 PM
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Your point about entering the box from below will solve most of my problems!
As far as I know, you can also by code enter the sides with a typical rigid conduit with locknuts/bushings or EMT connectors (or anywhere else you have concentric knockouts), but I always preferred the Myers hub to be sure it is raintight.
 
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