We are looking at the material to specify for connection to electrical equipment with a NEMA 6 (IP67) rating. The possibility exists the equipment will be submerged. Per the manufacturer, the equipment has a threaded fitting, but no factory potted cable. The length we have for the raceway that could be under water is in excess of 100'. I don't want to specify sch. 40 or 80 PVC because it could still let water in. I was looking at a continuous length of liquidtight flexible metal conduit but could not find a NEMA rating. I was then looking at some type of flexible cord but it would be less protected. I am concerned with water getting into the raceway then into the equipment plus the rating of the raceway. Looking for some suggestions for this connection.
NEMA 6 or greater submerged raceway
- Thread starter mjmike
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
how would a pvc pipe that is solvent welded at every joint allow water in?
personally, I think you are asking for something not required. if it is just water using conductors designed for water resistance (such as THWN) in any raceway under the water is probably adequate.
maybe just regualr fitting with a seal near the equipment to keep water from backing up onto the equipment.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I do not believe any raceway is "rated" for submergence.
You can get conductors that are suitable for being in water though.
I don't see how a properly joined solvent welded PVC fitting can ever come apart. The solvent welding process makes it all but impossible. It is all one mass when you are done. Granted, poor workmanship might result in a joint that is defective, but that is not a problem with the raceway.
- Location
- Illinois
- Occupation
- retired electrician
I always thought that too until I had a discussion about that on another forum. He told me to try it and I was very surprised how little force it takes to break a solvent welded PVC conduit joint. There is really very little bonding or welding between the two pieces...just a thin film.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
With PVC plumbing pipe (extensive irrigation systems) I have had three broken joints and every one of them, by the color of the separated pipe, had no primer and almost no cement.
The proper cement type must be applied liberally and the pipe twisted as it is bottomed out in the socket.
The proper cement type must be applied liberally and the pipe twisted as it is bottomed out in the socket.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Another thing to consider is the bouyant force on the conduit once it's submerged. A hundred feet of PVC is going to generate a heck of a lot of lift depending on diameter. Even if the supports don't tear loose, you might break the pipe.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
Unless the water temperature varies a good deal, expansion joints are probably not needed.
I would concerned that the threaded connections would leak.
I would concerned that the threaded connections would leak.
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