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#180482 - 08/27/08 12:25 PM NEMA 3R enclosure
sudsy4 Offline
Member

Registered: 04/24/02
Posts: 32
Loc: Elizabeth,PA USA
Can I come thru a wall into the back of a NEMA 3R enclosure mounted on the wall and maintain the 3R rating?

Thanks
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#180484 - 08/27/08 01:11 PM Re: NEMA 3R enclosure [Re: sudsy4]
wire_twister Offline
Member

Registered: 07/25/07
Posts: 265
Loc: Georgia USA
If you use a myers hub.
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#180485 - 08/27/08 02:56 PM Re: NEMA 3R enclosure [Re: wire_twister]
renosteinke Offline
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Registered: 01/22/05
Posts: 5300
Loc: Blue Collar Country
To answer that, you need to understand how the enclosures are tested.

For the NEMA-3R test, a driving rain is sent onto the enclosure at about a 15 degree angle. At the end of the test, there cannot be a 'significant' amount of water in the enclosure.

In addition, there is a rule that factory KO 'pre-punches' cannot be located higher than the lowest energized part.

Some understand the latter rule to mean that ANY opening made above the lowest energized part has use a Myers' hub. I'm not convinced of that logic for vertical faces, though I agree when the opening is on the top face. (After all, snow and water can accumulate on the top).

For openings on protected faces - like the back - I have a bit of trouble imagining how any significant amount of water can ever reach the opening - let alone enter it.

Remember ... NEMA-3R is essentially a glorified umbrella; it's not intended to protect a directed water source, such as a hose stream.

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#180487 - 08/27/08 03:18 PM Re: NEMA 3R enclosure [Re: renosteinke]
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1286
Loc: Alaska
I agree with Reno. The hole on top of some 3R's enclosures has that up rolled lip to prevent wat to get into the enclosure.
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#180495 - 08/27/08 06:30 PM Re: NEMA 3R enclosure [Re: sparkyinak]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
Don't we go in the back of meter cans all the time? I don't remember any special fitting.
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#180498 - 08/27/08 08:00 PM Re: NEMA 3R enclosure [Re: gfretwell]
sparkyinak Offline
Member

Registered: 07/08/07
Posts: 1286
Loc: Alaska
The special fittings were for "field expediant" holes not factory KO's
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#180542 - 08/29/08 08:57 AM Re: NEMA 3R enclosure [Re: sparkyinak]
JValdes Offline
Member

Registered: 06/03/07
Posts: 308
Loc: South Carolina
You can use a nipple or conduit in the back bottom factory KO and maintain the rating. If its a concentric KO, and you have any rings left you must bond with a bonding bushing. Not required with PVC of course.

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#180545 - 08/29/08 10:39 AM Re: NEMA 3R enclosure [Re: JValdes]
electure Offline

Member

Registered: 12/24/00
Posts: 4225
Loc: Fullerton, CA USA
 Quote:
If its a concentric KO, and you have any rings left you must bond with a bonding bushing


JV, Unless it's service equipment (or you really blow out the concentric KO's), they're not required on systems for under 250 volts to ground.

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