How do you seal PVC entering an enclosure in a wet environment

M

marmathsen

Senior Member
Location
Seattle, Washington ...ish
Occupation
Electrical Contractor
When you have PVC entering some sort of box or other enclosure outside (top or side entry), do you seal the the TA to prevent water intrusion? LFMC and LFNMC connectors both come with sealing O-rings, but PVC TAs don't. Do you buy them separate and install them? My supplier seemed totally confused when I asked for some, and needed to special order them. He sold me sealing lock nuts instead which appear to be designed for RCM and IMC. Do the sealing lock nuts compress against the threads and actually seal out watter? The o-rings compress between the lip of the connector and the enclosure which seems like a better seal.
 
At least one PVC manufacturer has flat sealing rings for their male adapters.
However I would never permit a top entry in to an enclosure for that type of equipment in a wet location. If you are working for me, all entries will be in the bottom, or the lower part of the sides. It is pretty much impossible to keep water out when you have a top entry.
 
I wired a lot of underground vaults for water valves. Enter low via a LB, drill drain hole, then up to J Box. Duct seal in LB
Water gets in via conduit and condensation.
Also used wp wirenuts
 
Meyers Hub? I use them in the industrial world for enclosure entry to keep moisture out of the enclosures.
Use a MA to the meyers hub and should be golden.
 
don_resqcapt19 said:
At least one PVC manufacturer has flat sealing rings for their male adapters.
However I would never permit a top entry in to an enclosure for that type of equipment in a wet location. If you are working for me, all entries will be in the bottom, or the lower part of the sides. It is pretty much impossible to keep water out when you have a top entry.
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Although technically not legit, a TA threaded into a Myers or meter hub seems like a pretty good method. Probably half the overhead services in America have that.
 
Carlon says this on page 178 of their catalog.
Washers-Flat Sealing washers.
Where a waterproof termination is required into any enclosure (metallic or nonmetallic), install the neoprene washer over the threads of a terminal adapter before inserting into the enclosure. Use a standard locknut or threaded bushing to secure the assembly.
Click to expand...
 
Best option would be for a box and top entry would be a box adapter glued into a bell end. This won't work for an enclosure and if you have an enclosure I'd hope you have a meter hub or something and that it'd be a 3r enclosure not a 4x
 
Myers hubs, sealing locknuts, O-rings, etc..... will all help but water is perhaps the most invasive thing on the planet. It will find the slightest crack, hole or gap. Some of the poorest engineered buildings that I have done had their main electric rooms below grade level. They tried pouring concrete walls and I used Link Seals for the cored holes for the conduits but nothing keeps 100% of it out. I remember replacing 90 sections of switchgear at OU Medical Center that had been in operation for only 10 years or so due to water getting in because the main electrical room was below finished grade. Good luck
 
marmathsen said:
When you have PVC entering some sort of box or other enclosure outside (top or side entry), do you seal the the TA to prevent water intrusion? LFMC and LFNMC connectors both come with sealing O-rings, but PVC TAs don't. Do you buy them separate and install them? My supplier seemed totally confused when I asked for some, and needed to special order them. He sold me sealing lock nuts instead which appear to be designed for RCM and IMC. Do the sealing lock nuts compress against the threads and actually seal out watter? The o-rings compress between the lip of the connector and the enclosure which seems like a better seal.
Click to expand...
Article 314 allows us to drill "weep holes" not smaller than 1/8" and not larger than 1/4" for wet location boxes to keep water from accumulating inside the boxes. Electricians took it upon themselves to do this long before this was introduced in the NEC.
 
don_resqcapt19 said:
At least one PVC manufacturer has flat sealing rings for their male adapters.
However I would never permit a top entry in to an enclosure for that type of equipment in a wet location. If you are working for me, all entries will be in the bottom, or the lower part of the sides. It is pretty much impossible to keep water out when you have a top entry.
Click to expand...
So...How do you avoid it? You can't in all cases, such as trying to tie several panels together via a trough. You either put the trough at the bottom or the top. Either way, something has a top entry.
 
VirutalElectrician said:
So...How do you avoid it? You can't in all cases, such as trying to tie several panels together via a trough. You either put the trough at the bottom or the top. Either way, something has a top entry.
Click to expand...
I have no issues with top entries in a wireway, just will not permit top entries in an equipment enclosure. Have often installed wireways that extended beyond the equipment enclosure for that very reason.
 
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