Use of sealing rings and sealing locknuts?

[mdshunk]

At what point does a PVC conduit system require the use of sealing rings and sealing locknuts? Outdoors? Washdown environment? Concrete pour? High condensation/ambient humidity environment?

Several areas that I generally install PVC conduit bring this question into my mind. Animal barns, where a barn full of cows or horses causes condensation to drip off everything. Milking parlors, where darn near everything is hosed down. Wastewater treatment areas, where washdown, high ambient humidity, and caustics and acids all play a role. Lastly, concrete pours... where everything that can go wrong will. Also, would a PVC conduit coming out of the SIDE of an outdoor enclosure (such as a meter base) require a sealing ring or sealing locknut? Can a sealing ring or sealing locknut (or both) ever be a substitute for installing a hub?

[Wgoodrich]

PVC terminal adapter is same as a pipe thread. PVC is normally glued together. If an adaption from PVC to metal a metal coupling is used and the pipe threads or the Termnal adapter seals same as a pipe thread. Now understand that any wiring underground is considered as a wet location and must be considered so because metal or plastic that underground conduit will fill with water over time. Not a maybe here. This is why we use wire approved for a wet codition with a "W" in the initials.

If a conduit is entering the sides or bottom of a weather proof box they need not be sealed where they enter this box. Notice in design a weather proof panel is required drip holes to drain the weatherproof panel box.

When entering the top exposed to the weather this entry must be sealed. Again if you use a manufactured hub screwed on there is a lip under the hub making for weather tight and the pipe threads of the PVC conduit seals that conduit. If you do not use a manufacture listed hub for a panel and make your own hole then most commonly you use a listed Meyers hub. This myers hub will normally have rubber o rings to help seal in its designed and is listed for the use of this type installation.

Also be aware when passing through a wall with a strong difference of ambient temperature such as passing from an outside meterbase and an inside panel you are supposed to seal that conduit with duct seal to stop the inrush of cold to hot air creating condensation inside the panel which would eat that panel and cause shock hazard.

Hope this helps

Wg