sealing locknut

[stew]

Had an inspector say that a sealing locknut was not listed for use with a pvc ta. If you use pvc entry into the verticle wall of a 3 r panel is this not ok? He said that a sealing locknut was on listed for rigid steel pipe.I always use a meyers hub on the top of 3r panels but have used sealing locknuts before on the sidewalls and never had anyone tell me this. Any of you inspector types know for sure??

 

[Dennis Alwon]

Unfortunately the inspector is correct. This is from the UL white book

Sealing (Liquid-tight) Locknuts — Sealing locknuts are intended for use with threaded rigid metal conduit and intermediate metal conduit with one sealing locknut in the outside or the inside and either an ordinary locknut or sealing locknut on the inside of the enclosure for wet locations or liquid-tight applications. Sealing locknuts may also be used with Listed wet location or liquid-tight fittings where so marked on the fitting carton and used on the inside of the enclosure.

 

[stew]

thanks did not know that. How about the use of an o ring for this? Guess i still have a bit of a problem with this as we use of course steel locknuts on plastic fittings. I dont know it just seems like a sealing locknut would be ok but now I see otherwise. The good thing about this particular install was that the only thing above the opening was the feed thru lugs and just barely. when the lugs were removed the code was met!(we were going to remove prior to inspection them but forgot)

 

[Dennis Alwon]

thanks did not know that. How about the use of an o ring for this? Guess i still have a bit of a problem with this as we use of course steel locknuts on plastic fittings. I dont know it just seems like a sealing locknut would be ok but now I see otherwise. The good thing about this particular install was that the only thing above the opening was the feed thru lugs and just barely. when the lugs were removed the code was met!(we were going to remove prior to inspection them but forgot)

Personally I cannot imagine why a sealing locknut would not work with PVC. I have used them and have not had trouble with it. The same is true , BTW, for hubs and plastic fittings.

"O" rings don't come up in the search of the white book so I am not sure but I suspect it cannot be any better than a sealing locknut.

This is why I stay below the buss and I don't have this issue at all.

 

[pete m.]

Unless I am mistaken, if you use the factory pre-punched KO's in 3R equipment then no sealing lock-nuts or hubs would be necessary.

Pete

 

[Dennis Alwon]

Unless I am mistaken, if you use the factory pre-punched KO's in 3R equipment then no sealing lock-nuts or hubs would be necessary.

Pete

True but they are always below the buss.

 

[pete m.]

True but they are always below the buss.

Agreed .

So, to the OP are you utilizing factory pre-punched KO's?

Pete

 

[Dennis Alwon]

Agreed .

So, to the OP are you utilizing factory pre-punched KO's?

Pete

I see the problem. I assumed he was above the buss but if he is not then a sealing locknut is not req.

From his second post it does look like the feed thru lugs were the problem.

 

[renosteinke]

There are a couple assumptions here - and knowing the 'back story' can help you read between the lines.

The first has to do with the requirements for a 3R enclosure. Contrary to popular belief, these enclosures ARE allowed to have minor amounts of water enter them during the test. It's only required that the water not pool high enough to reach the 'hot' parts.

Therefore, strictly speaking, there's no 'rule' against pipes entering anywhere on the sides. There is, however, a LISTING standard that says 'no FACTORY ko's above the 'hot parts.' This is because of a belief that pre-punched ko's are likely to leak, or be pushed in by playful gremilins.

As for the quote from the UL "White Book:" the speaker was addressing the different types of pipe threads, and where they are used. That is, the difference between the straight thread on EMT fittings and the tapered thread on RMC fittings. What the speaker is saying is that the sealing locknuts are intended for use on the tapered threads - in fact, they probably won't fit on EMT fittings at all. They certainly won't go on very far.

I believe the inspector is trying to do a good job, but that he's reading too much into things.

 

[Dennis Alwon]

Therefore, strictly speaking, there's no 'rule' against pipes entering anywhere on the sides.

Maybe so... but... I do agree if this is on the side of the panel it seems to be a lot to do about nothing.

312.2 Damp and Wet Locations.
In damp or wet locations, surface-type enclosures within the scope of this article shall be placed or equipped so as to prevent moisture or water from entering and accumulating within the cabinet or cutout box, and shall be mounted so there is at least 6-mm (?-in.) airspace between the enclosure and the wall or other supporting surface. Enclosures installed in wet locations shall be weatherproof. For enclosures in wet locations, raceways or cables entering above the level of uninsulated live parts shall use fittings listed for wet locations.
Exception: Nonmetallic enclosures shall be permitted to be installed without the airspace on a concrete, masonry, tile, or similar surface.

 

[stew]

had to make a penetration that had its highest arc at the level of the bottom feed thru lugs. we removed the lugs now and he was happy happy!!

 

[Cow]

I'm glad our inspectors over here don't call us on this. Even though using sealing locknuts on pvc isn't to the letter of the law, there are bigger fish to fry IMO.

I'd almost be willing to bet that using a standard o-ring with an MA wouldn't leave enough threads in the enclosure to get a plastic bushing on. From one problem to another....:roll:

I'd have to find skinny o-rings....

 

[Smart $]

Unfortunately the inspector is correct. This is from the UL white book

Sealing (Liquid-tight) Locknuts — Sealing locknuts are intended for use with threaded rigid metal conduit and intermediate metal conduit with one sealing locknut in the outside or the inside and either an ordinary locknut or sealing locknut on the inside of the enclosure for wet locations or liquid-tight applications. Sealing locknuts may also be used with Listed wet location or liquid-tight fittings where so marked on the fitting carton and used on the inside of the enclosure.

The highlighted sentence structure leaves me asking:

What must be marked on the carton? Listed wet location or liquid-tight fittings, or sealing locknuts may be used with these fittings???

 

[Dennis Alwon]

The highlighted sentence structure leaves me asking:

What must be marked on the carton? Listed wet location or liquid-tight fittings, or sealing locknuts may be used with these fittings???

Sounds to me like the carton must state that the fitting is listed for sealing locknuts.

 

[Dennis Alwon]

Here is something from the carlon site. That seems to answer our problems. But then wouldn't a sealing washer count-- doesn't state that.

 

[kwired]

For enclosures in wet locations, raceways or cables entering above the level of uninsulated live parts shall use fittings listed for wet locations.

Is a PVC male adapter listed for use in wet locations? If so then why can't it enter the side of the panel.

If it can enter the side of the panel who cares if a standard locknut is used vs a sealing locknut? The sealing locknut is simply overkill if this is the case but not a code violation.

It all comes down to is the terminal adapter listed for wet locations?

 

[Dennis Alwon]

Is a PVC male adapter listed for use in wet locations? If so then why can't it enter the side of the panel.

If it can enter the side of the panel who cares if a standard locknut is used vs a sealing locknut? The sealing locknut is simply overkill if this is the case but not a code violation.

It all comes down to is the terminal adapter listed for wet locations?

I think my post above answers your question-- It is not listed for wet location without the sealing washer.

 

[kwired]

Here is something from the carlon site. That seems to answer our problems. But then wouldn't a sealing washer count-- doesn't state that.

Looks like maybe terminal adapter is listed for wet location if using a sealing washer.

Putting a sealing locknut on is not a code violation but not using the sealing washer would be.

 

[Smart $]

I think my post above answers your question-- It is not listed for wet location without the sealing washer.

Not quite.

Basically all PVC, conduit and fittings, are listed for wet locations.

Adding the sealing washer would only be required if the enclosure is required to be waterproof. Waterproof and weather proof are not the same. A 3R enclosure has only a weather-proof rating.