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#43538 10/16/04 02:26 AM
Joined: Aug 2001
Posts: 545
A
aldav53 Offline OP
Member
When adding a circuit with NM in a finished home that is run through the attic then dropping the from the eve area straight down to the panel with an LB. Can this be run in pipe for mechanical protection? It would seem dumb to put in a WP box and have to splice it with THHN just for the short foot or two of EMT.


The Golden Rule - "The man with the gold makes the rule"
#43539 10/16/04 08:39 AM
Joined: Apr 2004
Posts: 201
Member
Not and meet the requirements of the Code. A provision was added to permit the stovepipe installation for surface mount panelboards but not when they are flush mount. How do you clamp the cable where it enters the panelboard? [Linked Image]

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Charlie Eldridge, Indianapolis, Utility Power Guy

[This message has been edited by CharlieE (edited 10-16-2004).]


Charlie Eldridge, Indianapolis Utility Power Guy
#43540 10/16/04 11:02 AM
Joined: Apr 2002
Posts: 156
K
Member
This has always driven me nuts. Seems to be a stupid rule. What hazards could there be? Heat....then derate? How would you clamp THHN? What is romex but glorified THHN anyways. Once you strip the outer sheating you are left with THHN no.....except you have a bare ground.

#43541 10/16/04 12:26 PM
Joined: Oct 2001
Posts: 597
E
Member
Aldav53,

Is this a generic question, or do you have a specific installation in mind?
  • Is the panel flush or surface?
  • Is the location interior or exterior?
  • Is mechanical protection actually needed, i.e., how are the other branch circuits entering the panel?


Al Hildenbrand
#43542 10/16/04 12:27 PM
Joined: Aug 2001
Posts: 545
A
aldav53 Offline OP
Member
You wouldn't need to strap the THHN because it only runs from the panel, through the emt, then ends at the junction box, so just strap the emt.


The Golden Rule - "The man with the gold makes the rule"
#43543 10/16/04 12:56 PM
Joined: Apr 2002
Posts: 914
E
Member
Quote
314.15 (B) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, listed surface metal or nonmetallic raceway, or other means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, listed surface metal or nonmetallic raceway, or other metal pipe extending at least 150 mm (6 in.) above the floor.

Maybe I'm not understanding the question. If the question is can you run NM in conduit, the answer is yes you can. It seems the other obstacle is securing the cable within 12" of where it enters the panel. I really don't think this is an issue if it is stapled just before it enters the conduit. the purpose of securing it 12" from the panel is to prevent it from being pulled out, I think the conduit will serve that function. If you had an inspector wanting a connection at the panel, you could use several diferent options inside the panel to keep it from pulling out.

#43544 10/16/04 02:17 PM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
They do make a romex to EMT connector. They look cheesy though. That would be considered support, as long as the conduit is supported.

Normally, I would leave an extra length, enough to make it into and be terminated in the panel. Bring it into a box with a few other romex, strip them all, ground them all there, and pull my extra long conductors into the panel. I have to do that for a lot of panels, as here below 8', romex is considered subject to physical damage. (Unlike a lot of other places in the country.)


Mark Heller
"Well - I oughta....." -Jackie Gleason
#43545 10/16/04 02:54 PM
Joined: Mar 2001
Posts: 93
M
Member
The biggest problem I see with conduit chases between the attic directly into the top of the panel, is that condensation forms inside the conduit at the point between the unheated attic, and the heated interior of the building. Of course the water drips directly on top of the breakers, and runs down the back through the bussing. I've seen several completely destroyed panels caused by this. Depending on the temperature difference, the condensation can form so fast that it almost runs in a steady stream. Duxseal helps very little.

#43546 10/16/04 03:08 PM
Joined: Dec 2002
Posts: 228
J
Member
Can you just run the EMT a few inches short, into a ridgid coupling with an NM clamp threaded into the coupling on the inside of the panel to clamp it? Just an idea

Jim

#43547 10/16/04 09:54 PM
Joined: Aug 2001
Posts: 545
A
aldav53 Offline OP
Member
To clear up confusion:
It is an outdoor surface mount panel (used mostly in AZ) the pipe will come out of the top of the panel and LB into the attic (through the soffit). So there is no need for staples. You can barely get into the attic to staple anyway.
From there the circuit runs over to and down a finised wall to a box.

As far as condensation, all the circuits are run down the wall and into the back of the panel. Thats how there all done in AZ. So if condensation were a problem, then all the houses here are wrong.


The Golden Rule - "The man with the gold makes the rule"
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