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#180482 - 08/27/08 03:25 PM NEMA 3R enclosure  
sudsy4  Offline
Member
Joined: Apr 2002
Posts: 32
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


Bill

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#180484 - 08/27/08 04:11 PM Re: NEMA 3R enclosure [Re: sudsy4]  
wire_twister  Offline
Member
Joined: Jul 2007
Posts: 265
Georgia USA
If you use a myers hub.


Jimmy

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#180485 - 08/27/08 05:56 PM Re: NEMA 3R enclosure [Re: wire_twister]  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
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.


#180487 - 08/27/08 06:18 PM Re: NEMA 3R enclosure [Re: renosteinke]  
sparkyinak  Offline
Member
Joined: Jul 2007
Posts: 1,327
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.


"Live Awesome!" - Kevin Carosa

#180495 - 08/27/08 09:30 PM Re: NEMA 3R enclosure [Re: sparkyinak]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,124
Estero,Fl,usa
Don't we go in the back of meter cans all the time? I don't remember any special fitting.


Greg Fretwell

#180498 - 08/27/08 11:00 PM Re: NEMA 3R enclosure [Re: gfretwell]  
sparkyinak  Offline
Member
Joined: Jul 2007
Posts: 1,327
Alaska
The special fittings were for "field expediant" holes not factory KO's


"Live Awesome!" - Kevin Carosa

#180542 - 08/29/08 11:57 AM Re: NEMA 3R enclosure [Re: sparkyinak]  
JValdes  Offline
Member
Joined: Jun 2007
Posts: 301
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.


#180545 - 08/29/08 01:39 PM Re: NEMA 3R enclosure [Re: JValdes]  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,262
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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