Sealing Lockrings vs Myers Hubs

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ketoe

Member
Meyers Hub Versus sealing lockrings for short nipples between a wireway and manual transfer switch, sealing lockrings are listed for wet locations, does anyone know of a Code issue that could come up with this if done with 6 inch close nipples using sealing lockrings instead of Meyers hub

(Edited Title to reflect thread topic)
 
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mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
If not mistaken sealing lock rings or Meyers hub not required if entry is below electrical terminal connections within the transfer switch or disconnect. May be warranted on the gutter though.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
If not mistaken sealing lock rings or Meyers hub not required if entry is below electrical terminal connections within the transfer switch or disconnect. May be warranted on the gutter though.

That would depend on whether the enclosure listing is NEMA 3 or NEMA 3R. With NEAM 3 it is required everywhere.
 

kwired

Electron manager
Location
NE Nebraska
That would depend on whether the enclosure listing is NEMA 3 or NEMA 3R. With NEAM 3 it is required everywhere.
As well as application conditions.

Use it indoors @ dry location (for whatever reason) and you can connect dry location fittings to it, any side.

There also are NEMA 12 cabinets that say in the instructions for NEMA 3R applications to remove drain screws or drill drain holes or something similar. May be something similar for a true NEMA 3.
 

stickboy1375

Senior Member
Location
Litchfield, CT
I. Installation
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 (¼-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.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
A little clear silicon sealant over the lock rings dose a great job to insure no water enters .
Don

I think that doing this with sealing lock nuts would be compliant. With non-sealing lock nuts not compliant, IF you needed the sealing to be compliant.

UL is pretty clear about how you can close openings in enclosures and maintain the type rating of the enclosure. Sealant is not one of the ways.

In fact, not real long ago we approached UL about doing this very thing and offered to pay them to test it so this method could be added to our UL508a procedure. They told us not to waste our money as it has been tried before and cannot pass the UL tests.
 

kwired

Electron manager
Location
NE Nebraska
I think that doing this with sealing lock nuts would be compliant. With non-sealing lock nuts not compliant, IF you needed the sealing to be compliant.

UL is pretty clear about how you can close openings in enclosures and maintain the type rating of the enclosure. Sealant is not one of the ways.

In fact, not real long ago we approached UL about doing this very thing and offered to pay them to test it so this method could be added to our UL508a procedure. They told us not to waste our money as it has been tried before and cannot pass the UL tests.

Does that apply to all uses of "sealant" or just sealant only as the means of closing an opening?

What I am getting at is something I have done many times and never had it rejected either is to put a bead of silicone around a hole then screw a metal plate over a hole (4x4 flat blanks work great up to 3 inch ko size holes).

I did not read code before this reply, but seem to recall there is no requirement that material used to close an opening be listed, just that it provides a closure that is equivalent to the rating of the enclosure, so if it is a raintight enclosure I fail to see how this method doesn't provide raintightness as well as similar metal thickness and strength of the original enclosure. Have many times used a bolt/nut maybe a washer for smaller holes - especially if not a standard KO size. If outdoors and around grain bins - there are hundreds of rubber gasket(-ed) washer head bolts that were left over from the construction of the bin and usually laying on the ground as the bin construction guys drop them all over the place - they seal pretty well. I always pick several up, otherwise they just eventually get buried in the dirt.
 

jap

Senior Member
Occupation
Electrician
Does that apply to all uses of "sealant" or just sealant only as the means of closing an opening?

What I am getting at is something I have done many times and never had it rejected either is to put a bead of silicone around a hole then screw a metal plate over a hole (4x4 flat blanks work great up to 3 inch ko size holes).

I did not read code before this reply, but seem to recall there is no requirement that material used to close an opening be listed, just that it provides a closure that is equivalent to the rating of the enclosure, so if it is a raintight enclosure I fail to see how this method doesn't provide raintightness as well as similar metal thickness and strength of the original enclosure. Have many times used a bolt/nut maybe a washer for smaller holes - especially if not a standard KO size. If outdoors and around grain bins - there are hundreds of rubber gasket(-ed) washer head bolts that were left over from the construction of the bin and usually laying on the ground as the bin construction guys drop them all over the place - they seal pretty well. I always pick several up, otherwise they just eventually get buried in the dirt.

Whether it's approved by code or not, I've been known to do the exact same things with better results than most of the new fangled design things your supposed to use.

JAP>
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
I was confused on that as well, why would you need a weathertight fitting with a nema 3 cabinet?

I don't think there is "code" it is listing. NEMA 3R is "raintight" designed to allow drainage of water such that it won't accumulate and short out. It is not intended to prevent any water from entering. NEMA 3 is gasketed and sealed to prevent the water from entering in the first place.
 

stickboy1375

Senior Member
Location
Litchfield, CT
I don't think there is "code" it is listing. NEMA 3R is "raintight" designed to allow drainage of water such that it won't accumulate and short out. It is not intended to prevent any water from entering. NEMA 3 is gasketed and sealed to prevent the water from entering in the first place.

Type 3 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.

Type 3R Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.


The ratings look very similar to me, except for the windblown dust part....probably why a Nema 3 has a gasket. :) Nothing to do with water though, IMO.
 
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iwire

Moderator
Staff member
Location
Massachusetts
I don't think there is "code" it is listing. NEMA 3R is "raintight" designed to allow drainage of water such that it won't accumulate and short out. It is not intended to prevent any water from entering. NEMA 3 is gasketed and sealed to prevent the water from entering in the first place.

We will have to remain in disagreement on this. IMO the NEC is clear on this and it applies to any wet location rated equipment.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
The ratings look very similar to me, except for the windblown dust part....probably why a Nema 3 has a gasket. :) Nothing to do with water though, IMO.


If you get a Square D iLine panel it shares dual listings, N3R and N3. Read the instructions, it tells you for NEMA 3R rating, remove the two screws in the bottom of the pan. You can disagree with me all you want. I was just informing you are what is. You can do whatever you want to do.
 

kwired

Electron manager
Location
NE Nebraska
If you get a Square D iLine panel it shares dual listings, N3R and N3. Read the instructions, it tells you for NEMA 3R rating, remove the two screws in the bottom of the pan. You can disagree with me all you want. I was just informing you are what is. You can do whatever you want to do.
Square D panelboard cabinets as I recall are NEMA 12, remove the drain plugs and they are NEMA 3R. They use same series of cabinets for all panelboards including I-Line, NF, NQ...
 

Carultch

Senior Member
Location
Massachusetts
I think that doing this with sealing lock nuts would be compliant. With non-sealing lock nuts not compliant, IF you needed the sealing to be compliant.

UL is pretty clear about how you can close openings in enclosures and maintain the type rating of the enclosure. Sealant is not one of the ways.

In fact, not real long ago we approached UL about doing this very thing and offered to pay them to test it so this method could be added to our UL508a procedure. They told us not to waste our money as it has been tried before and cannot pass the UL tests.

What is the approved way of maintaining the enclosure NEMA rating with PVC conduit? Answer yes or no, for the following.


PVC Male adapter with sealing locknut on the interior
PVC Male adapter with O-ring gasket on the exterior and standard locknut on the interior
PVC Male adapter with Myers hub
PVC Male adapter wtih sealing locknut on exterior (gasket facing enclosure), and standard locknut on interior
 
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