Question on 312.5(C)

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SmithBuilt

Senior Member
Location
Foothills of NC
I need to use emt for protection of romex as it comes out of the bottom of a panel. the emt would be about 5' long in order to go thru the floor. Would this violate 312.5(C)?

There is an exception for the conduit to be used out of the top of the panel.

I know I could box and junction at the end, but would rather not.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I would have to agree with Ron, however I have never understood why we go into the top but not into the bottom. I have actually done this installation for years not knowing it wasn't legal and I have never been hit on it.

I would love to know why it is not acceptable.
 

dnem

Senior Member
Location
Ohio
Dennis Alwon said:
I would have to agree with Ron, however I have never understood why we go into the top but not into the bottom. I have actually done this installation for years not knowing it wasn't legal and I have never been hit on it.

I would love to know why it is not acceptable.

Our continuing ed gave the reason that heat from multiple cables in a single conduit can escape up thru the open top of the pipe when above the panel. . That's the reason for the 10foot limit. . But when the pipe is below the panel the heat rises into the panel and so is not allowed.

One of Mike Holts videos shows a panel of electrical industry guys pooled from various backgrounds and areas of the country. . The consensus among his panel was that the surface-mounted specification of 312.5(C)X is not enforced by inspectors. . Recessed panels with recessed pipe stubs coming out of the top is common practice and commonly accepted daily in many places thruout the country.

David
 
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dnem

Senior Member
Location
Ohio
SmithBuilt said:
I can't strip the romex because there are no markings on the individual wires, correct?

Yeah, you have problems when you strip the sheath off Romex
310.11 Marking
In our department, the only sheathless Romex we accept is pieces run thru residential whips, as in liquidtite AC unit whips. . An extra piece from the branch circuit run to the outside disconnect can be stripped to get rid of the paper in the Romex jacket and then pushed thru the liquidtite whip. . The inspector may or may not say something about it.

David
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
dnem said:
heat from multiple cables in a single conduit can escape up thru the open top of the pipe when above the panel.

I can buy into this but how do you explain 312.5(C)(d) ? If the conduit is sealed how does the heat escape ?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I just came back from a long walk off a short pier and I was thinking. Unusual for me, but nonetheless, I was thinking.

If I stub a pipe down from the panel into a crawl space put a junction box on it and run thhn wire in the conduit spliced below to NM cable. Is this not legal??? Certainly it is... It is also the same heat situation as a pipe stubbed down with romex in it. Heat travels up in both cases. Yeah? or Nay?
 

dnem

Senior Member
Location
Ohio
Dennis Alwon said:
I just came back from a long walk off a short pier and I was thinking. Unusual for me, but nonetheless, I was thinking.

If I stub a pipe down from the panel into a crawl space put a junction box on it and run thhn wire in the conduit spliced below to NM cable. Is this not legal??? Certainly it is... It is also the same heat situation as a pipe stubbed down with romex in it. Heat travels up in both cases. Yeah? or Nay?

Altho the 10foot piece in 312.5(C)X doesn?t have to be terminated in a box at its top end just like other short raceway sections [300.10X1 + 300.18(A)X], its common to limit the length to 2feet which allows different wirefill. . If you were running the conduit to a jbox, the odds are much lower that you would be able to get that jbox mounted within 2 feet. . If you go over the 2feet limit of Chapter9Tables NotetoTables(4), then 334.80, T310.16, + T310.15(B)(2)(a) become more restrictive than 240.4(D) for 14 + 12gauge wire after you get more than 9 wires in the pipe.

But if you can get the jbox under the panel within 2feet or run multiple HR pipes with each having no more than 9 CCC, then your idea would work.

Side note: When you go over the 2foot mark, on a 120/240 single phase residential, T310.15(B)(2)(a) counts 14/2 the same as 14/3 and 12/2 the same as 12/3 because the neutral doesn?t count as a CCC when all hot conductors of the system are present in the run in question. . So you?re better off running Romex multis for HRs.

David
 
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