ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
dsk 3
Recent Posts
Windows 7 update problem
by ampherder. 06/21/17 07:01 AM
Norwegian power?
by dsk. 06/19/17 03:40 PM
Anyone ever take a Furnas A14D drum sw apart?
by gfretwell. 06/17/17 08:14 PM
Mains supply in GDR
by dsk. 06/15/17 04:02 PM
Any UL 508 experts out there?
by sparkyinak. 06/07/17 05:49 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
238,129 Are you busy
173,294 Re: Forum
166,180 Need opinion
Who's Online Now
0 registered members (), 65 guests, and 12 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#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

Work Gear for Electricians and the Trades

#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

Life is tough, Life is tougher when you are stupid

#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: 1,326
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: 9,083
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: 1,326
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: 4,259
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.




Member Spotlight
Vlado
Vlado
Croatia
Posts: 28
Joined: February 2011
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.016s Queries: 15 (0.003s) Memory: 0.7931 MB (Peak: 0.9592 MB) Zlib enabled. Server Time: 2017-06-23 01:33:38 UTC