What makes a NEMA 3 rating on an electrical box.

[69gp]

Looking to see what makes a NEMA 3R box rating. I am old school and whenever I entered a NEMA 3 box or enclosure it was with a sealing ring on the outside or a Myers hub. We just had a project built and the specification said that all conduits entering outdoor enclosures must be by Myers Hubs. Great thats what we wanted. Well that not what we got. Contractor just used sealing locknuts on the inside of the NEMA 3R trough. 2 conduits had no sealing locknuts. There were no sealing O rings on the outside of the trough. To me this is a poor installation since the sealing locknut is on the inside. This will allow the knockout to rust from the outside in. I know that the answer will be just slap some silicone on it and call it a day. I did try and find installation instructions on the NEMA site but could not locate them. Does anyone have a link or can direct me to where I could find installation instructions.

 

[don_resqcapt19]

The sealing lock nuts have the same watertight rating as the conduit hub, so no issue other than the contract documents were not complied with.
I never use anything other that standard locknuts on the bottom entries of a 3R enclosure, since 3R enclosures are required to have drain holes on the bottom.
The UL Guide Information for Conduit Fittings (DWTT) says this about the sealing locknuts.

Sealing (Liquid-tight) Locknuts — Sealing locknuts are intended for use with threaded rigid metal conduit and intermediate metal conduit with one sealing locknut on 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 certified wet location or liquid-tight fittings where so marked on the fitting carton and used on the inside of the enclosure.

 

[hbiss]

You don't need WP connectors on the bottom of an enclosure. Those connectors alone are all you need. And what's that cotton candy stuff? And what's with those ground wires?

-Hal

 

[jim dungar]

NEMA/Type 3R enclosures are not water tight. They are allowed have water enter them as long as it is below any energized parts.

 

[69gp]

Sorry about this I should have explained a little better. I dont have an issue with the conduits comming up to the bottom of the trough. The ones I am concerend with enter through the side. Red arrow are side entrance green is from the bottom

 

[don_resqcapt19]

Sorry about this I should have explained a little better. I dont have an issue with the conduits comming up to the bottom of the trough. The ones I am concerend with enter through the side. Red arrow are side entrance green is from the bottom

Assuming there are no exposed live parts in the wireway, side entries do not need to be sealed. Insulated wire is not exposed live parts.

 

[tom baker]

You don't need WP connectors on the bottom of an enclosure. Those connectors alone are all you need. And what's that cotton candy stuff? And what's with those ground wires?

-Hal

The pink is expanding foam which is not listed for that use. Duct seal is

 

[69gp]

Assuming there are no exposed live parts in the wireway, side entries do not need to be sealed. Insulated wire is not exposed live parts.

My concern is that these are 3" conduits with the seal on the inside. once water gets on the bare metal it will start to rust.

 

[hbiss]

once water gets on the bare metal it will start to rust.

NEMA 3R enclosures are not watertight. So, either from moisture getting in or from condensation, those locknuts will develop some rust. But it will be a very, very long time before they are compromised. That spray foam in the ends of that conduit will do nothing. You might want to drill a few weep holes in the bottom of that trough just in case moisture accumulates.

-Hal

 

[electrofelon]

Assuming there are no exposed live parts in the wireway, side entries do not need to be sealed. Insulated wire is not exposed live parts.

NEMA/Type 3R enclosures are not water tight. They are allowed have water enter them as long as it is below any energized parts.

A few comments and questions:

First, we need to know which article to look at. The "below energized parts" phrase seems to be only for article 312 equipment. You also have to look at the raceway article

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 (1 ∕4-in.) airspace between the enclosure and the wall or other supporting surface. Enclosures installed in wet locations shall be weather‐ proof. For enclosures in wet locations, raceways or cables entering above the level of uninsulated live parts shall use fittings listed for wet locations.

Here is what article 314 says:

314.15 Damp or Wet Locations. In damp or wet locations, boxes, conduit bodies, outlet box hoods, and fittings shall be placed or equipped so as to prevent moisture from entering or accumulating within the box, conduit body, or fitting. Boxes, conduit bodies, outlet box hoods, and fittings installed in wet locations shall be listed for use in wet locations. Approved drainage openings not smaller than 3 mm (1 ∕8 in.) and not larger than 6 mm (1 ∕4 in.) in diameter shall be permitted to be installed in the field in boxes or conduit bodies listed for use in damp or wet locations. For installation of listed drain fittings, larger openings are permitted to be installed in the field in accordance with manufacturer’s instructions

and here is the applicable part of article 376 for metal wireways:

376.10 Uses Permitted. The use of metal wireways shall be permitted as follows: (1) For exposed work. (2) In any hazardous (classified) location, as permitted by other articles in this Code. (3) In wet locations where wireways are listed for the purpose.

And here is what article 352 (PVC) and 358 (EMT) says (I know there is no EMT in the OP's install but putting this in for completeness on the topic)

352.10 uses permitted..........(D) Wet Locations. PVC conduit shall be permitted in portions of dairies, laundries, canneries, or other wet locations, and in locations where walls are frequently washed, the entire conduit system, including boxes and fittings used therewith, shall be installed and equipped so as to prevent water from entering the conduit. All supports, bolts, straps, screws, and so forth, shall be of corrosion-resistant materials or be protected against corrosion by approved corrosion-resistant materials.

358.42 Couplings and Connectors. Couplings and connectors used with EMT shall be made up tight. Where buried in masonry or concrete, they shall be concretetight type. Where installed in wet locations, they shall comply with 314.15.

So for a a metal wireway install, Where do we need weather resistant/raintight/watertight fittings? For PVC, it seems particularly arguable about what entry locations would result in "Water entering the conduit". For EMT it seems we need them even on the bottom, unless we claim that is not a wet location? The final piece is what do the instructions of the wireway say? Does the listing or instructions offer any guidance? Just looking at the NEC, i am not seeing any restriction of putting a regular PVC TA right in the top of a 3R wireway.

 

[LarryFine]

"Approved drainage openings not smaller than 3 mm (1 ∕8 in.) and not larger than 6 mm (1 ∕4 in.) in diameter shall be permitted to be installed in the field in boxes or conduit bodies listed for use in damp or wet locations."

I have never thought of it as "installing" a hole. Who stocks those?

 

[jim dungar]

First, we need to know which article to look at.

Actually you need to look at the construction and listing requirements for Type 3R 'weather-proof' enclosures.

 

[69gp]

All thanks for your replies. For clarification the foam does 2 things. This is a polywater product approved for sealing conduits. Since all this work is outside it prevents mice and rodents from using the conduit to go from transformers to cabinets and enclosures. The main reason it is done is because the conduits are buried. We are in the northeast and during the winter the feeders will heat up during the day since this is a solar site and cool off at night where it will create condensation. A lot of it. And as we all know this leads to corrosion and damaged equipment.

 

[electrofelon]

Actually you need to look at the construction and listing requirements for Type 3R 'weather-proof' enclosures.

Exactly, and I said this exact thing in my previous post. Do you know what they say about this issue?

 

[jim dungar]

Exactly, and I said this exact thing in my previous post. Do you know what they say about this issue?

Field openings must be sealed to be equivalent to the original enclosure construction.

Type 3R listing allows for water entry, and exit, below energized parts.

 

[electrofelon]

Field openings must be sealed to be equivalent to the original enclosure construction.

Type 3R listing allows for water entry, and exit, below energized parts.

Okay interesting, so the listing uses the same above/below live parts phrase as in article 312. So say I have no spices, or fully insulated splices, then I can come into the top of a 3r wire way with nothing beyond a PVC TA and be compliant?

 

[jim dungar]

Okay interesting, so the listing uses the same above/below live parts phrase as in article 312. So say I have no spices, or fully insulated splices, then I can come into the top of a 3r wire way with nothing beyond a PVC TA and be compliant?

Did you miss the requirement to return the enclosure to an equivalent construction? The top of the enclosure needs be 'water tight' or it is no longer a 3R enclosure, regardless if the are energized parts or not.

 

[electrofelon]

Did you miss the requirement to return the enclosure to an equivalent construction? The top of the enclosure needs be 'water tight' or it is no longer a 3R enclosure, regardless if the are energized parts or not.

Okay I guess that makes sense, although your two statements in post 15 seems to be contradictory in the case of there being no exposed live parts.

 

[jim dungar]

Okay I guess that makes sense, although your two statements in post 15 seems to be contradictory in the case of there being no exposed live parts.

Let me try again.
A 3R enclosure needs to have 'water tight' entries on its top, or else it is not a 3R.
A 3R enclosure does not need 'water tight' entries anywhere else, unless they are above energized components.

 

[electrofelon]

Let me try again.
A 3R enclosure needs to have 'water tight' entries on its top, or else it is not a 3R.
A 3R enclosure does not need 'water tight' entries anywhere else, unless they are above energized components.

Okay thanks. Where exactly is this information found?