Thread: multiple NM cables entering panel enclosure through one fitting

I was looking through my November/December issue of IAEI News (the International Association of Electrical Inspector magazine) again and saw this that I was going to post and had forgotten to do so.

I hope this answers the questions of other HIs who disagreed with what I stated, and those questions of a "professional" electrician who also questioned it.

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That is a very good picture. Here is a code reference how to do it correctly. This is from Article 312.5


(C) Cables.

Where cable is used, each cable shall be secured
to the cabinet, cutout box, or meter socket enclosure.

Exception: Cables with entirely nonmetallic sheaths shall
be permitted to enter the top of a surface-mounted enclosure
through one or more nonflexible raceways not less
than 450 mm (18 in.) and not more than 3.0 m (10 ft) in
length, provided all of the following conditions are met:
(a) Each cable is fastened within 300 mm (12 in.),
measured along the sheath, of the outer end of the raceway.
(b) The raceway extends directly above the enclosure
and does not penetrate a structural ceiling.
(c) A fitting is provided on each end of the raceway to
protect the cable(s) from abrasion and the fittings remain
accessible after installation.
(d) The raceway is sealed or plugged at the outer end
using approved means so as to prevent access to the enclosure
through the raceway.
(e) The cable sheath is continuous through the raceway
and extends into the enclosure beyond the fitting not
less than 6 mm (

1⁄4 in.).
(f) The raceway is fastened at its outer end and at
other points in accordance with the applicable article.
(g) Where installed as conduit or tubing, the allowable
cable fill does not exceed that permitted for complete conduit
or tubing systems by Table 1 of Chapter 9 of this Code

and all applicable notes thereto.

Jerry,

That is an every day report write up for me and I'm sure all of the other HI's on board here in this area.

Sparky's in this area seem to have a total disregard for code and the AHJ's overlook it as it is the way it has "always been done".

Rick

.....

Originally Posted by Rick Hurst

Jerry,

That is an every day report write up for me and I'm sure all of the other HI's on board here in this area.

Sparky's in this area seem to have a total disregard for code and the AHJ's overlook it as it is the way it has "always been done".

Rick

Yeah, I had this yesterday and was trying to decide what to say in my write up. What do you say?

Rick H.
Bumping this thread on behalf of JB.

Originally Posted by Nolan Kienitz

Rich H.

Bumping this thread on behalf of JB.

I've never understood. What is "bumping"?

Originally Posted by JB Thompson

I've never understood. What is "bumping"?

Just insert some verbiage to bring the topic/thread back to the top for visibility and a reminder (in this case to Rick H) to see if he can get a chance to reply to your question.

Originally Posted by fritzkelly

Here is what we usually see:
Attachment 19128
I don't see how we can report that as a code violation, or am I missing something?

This has puzzled me:

Article 312.5, (C) Cables, (b) The raceway extends directly above the enclosure

and does not penetrate a structural ceiling.

But if installed in a garage that has the HVAC equipment, a vent to the attic is allowed to the attic to replenish combustion air. If the intent is to maintain a fire block between the attic and the garage it appears to be a conflict. A properly installed raceway to the attic would make it easier to install and maintain the service panel, and you wouldn't have the plate above the service panel drilled to death.

The other question is I have seen 2 non-metallic cables entering a service panel through one connector and passed. How many cables can be used in a connector (based upon size)?

Originally Posted by fritzkelly

Here is what we usually see:
Attachment 19128
I don't see how we can report that as a code violation, or am I missing something?

First you need to understand that the exception posted by James is text addressing 'surface- mounted' enclosures. The pictures shown are 'flush mounted enclosures' so the exception doesn't apply.

The enclosures shown are not allowed to use chase nipples or knockouts to route all the cables into the enclosure. The panels shown including the op's must have the cables ran thru a clamp or approved non-metallic connector.... they are not 'surface mounted'.

You cannot put more than one cable thru a clamp unless the clamp is listed for more than one non-metallic cable. The listing specifications for the clamp is not always obvious. Sometimes if you purchase a bag and not individually the manufactures listing will be on the bag instructions. For clamps already installed I don't believe there would be anyway to tell the listing. Some clamps allow 2 cables. You would have to visit the manufactures web-site (if known) to see if the clamp used is listed for more than one
cable. The ul white book also has some information on this.

Please refer to this link for clarification when a surface mounted panel comes into play.

Termination requirements where NM cables enter a panel

I should add that even with a 'surface mounted' enclosure you cannot choke the nipple or conduit if over 24" in length. You must abide by the conduit fill for non-metallic cables (it's different than individual wires) and also have to derate the ampacity of the nm cables. If the panels shown were surface mounted and those cables were adjusted for amapcity, having been routed thru a conduit or nipple 24" or longer or bundled, they would not have a useful ampacity in the end.

A couple of electricial installs recently obversed

Pictures....the thing I like the most about this site. Many thanks.

OK, so where do we find how many NM cables can fit into X" diameter conduit?

Originally Posted by Ken Amelin

OK, so where do we find how many NM cables can fit into X" diameter conduit?

Chapter 9 note 9 of the NEC then if I remember correctly the conduit can be filled to 60% under the exception. I can check if you want. Wait .. I believe the link I posted says 60%.

I don't think that we got,in the original picture posted,118 #14 THHN wires becouse this is a limit for 2" PVC based on table C.9 of chapter 9 of NEC unless some one take time to count then!

Originally Posted by Ken Amelin

OK, so where do we find how many NM cables can fit into X" diameter conduit?

Wrong question.

The question should be: How many cables can fit into the REQUIRED clamp at the enclosure?

That has already been answered above, but here it is again: ONE ... unless the clamp is listed for TWO ... but that is the limit ... and if the cable is a 'round' 3-conductor cable - then a clamp listed for two conductors is still only listed for one.

Thus, not matter how you look at it, EACH cable is required to be in its own clamp to the enclosure (but at the most TWO flat 2-conductor cables per clamp).

It is not 'conduit fill' you should be looking up, it is 'number of clamps required' which you should be looking at. I.e., if you see 20 NM cables then you should see 20 clamps, or at the very least 10 clamps.

Originally Posted by Alexei Chaviano

I don't think that we got,in the original picture posted,118 #14 THHN wires becouse this is a limit for 2" PVC based on table C.9 of chapter 9 of NEC unless some one take time to count then!

Wrong table but like previously said your chasing the wrong tail.