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Joined: Apr 2002
Posts: 32
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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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Joined: Jul 2007
Posts: 265
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Jimmy
Life is tough, Life is tougher when you are stupid
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Joined: Jan 2005
Posts: 5,445 Likes: 3
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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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Joined: Jul 2007
Posts: 1,335
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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
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Joined: Jul 2004
Posts: 9,928 Likes: 34
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Don't we go in the back of meter cans all the time? I don't remember any special fitting.
Greg Fretwell
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Joined: Jul 2007
Posts: 1,335
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The special fittings were for "field expediant" holes not factory KO's
"Live Awesome!" - Kevin Carosa
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Joined: Jun 2007
Posts: 301
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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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Joined: Dec 2000
Posts: 4,294
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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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Posts: 4,116
Joined: October 2000
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