Ampacity

[wwhitney]

Nobody has any thoughts on my alternative options to comply with 312.5(C)? Versus just putting 1-6 NM cables through individual knockouts with properly rated NM clamps? Not suggesting it's a good idea, more of a thought exercise.

Cheers, Wayne

 

[infinity]

This thing needs to ripped out and started over. Either comply with all of 312.5(C) or use individual NM connectors for the cables based on the quantity and size of the cables permitted in the listed connectors.

 

[Dennis Alwon]

Hope this helps. Touches on most everything everybody mentioned.

That is for raceways. This is not a raceway but a sleeve.

 

[Greentagger]

Appears there was no reason not to use listed NM clamps to enter top of panel? If so this discussion would be for naught?

 

[infinity]

Appears there was no reason not to use listed NM clamps to enter top of panel? If so this discussion would be for naught?

Apparently the single 2" PVC is a faster short cut used instead of installing multiple individual NM connectors. I'm surprised that they didn't just use a 2" SE cable connector which I have seen done often.

 

[paulengr]

Look at the rules for gutters. It’s so short it’s not a conduit.

 

[infinity]

Look at the rules for gutters. It’s so short it’s not a conduit.

Are you saying that the 2" PVC qualifies as a gutter?

 

[Dennis Alwon]

Look at the rules for gutters. It’s so short it’s not a conduit.

It is a piece of conduit but it is not a raceway. From Chapter 9 notes

(2) Table 1 applies only to complete conduit or tubing
systems and is not intended to apply to sections of
conduit or tubing used to protect exposed wiring from
physical damage.

(4)Where conduit or tubing nipples having a maximum
length not to exceed 600 mm (24 in.) are installed
between boxes, cabinets, and similar enclosures, the
nipples shall be permitted to be filled to 60 percent of
their total cross-sectional area, and 310.15(B)(3)(a)
adjustment factors need not apply to this condition.

 

[kwired]

That is for raceways. This is not a raceway but a sleeve.

I almost said that earlier on, but the word "raceway" is in the exception. The word "sleeve" is not. I don't believe those that wrote this intend it to be considered a sleeve as much as they intended it to be considered a raceway. That said I think there is still some holes in the logic. As others mentioned a flush mount panel would be where one would have more desire to do this, but the CMP clearly doesn't want to see that

 

[Dennis Alwon]

We mention 312.5(C) Here it is

(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:
(1) Each cable is fastened within 300 mm (12 in.), measured along
the sheath, of the outer end of the raceway.
(2) The raceway extends directly above the enclosure and does not
penetrate a structural ceiling.
(3) A fitting is provided on each end of the raceway to protect the
cable(s) from abrasion and the fittings remain accessible after
installation.
(4) The raceway is sealed or plugged at the outer end using approved
means so as to prevent access to the enclosure through the raceway.
(5) The cable sheath is continuous through the raceway and extends
into the enclosure beyond the fitting not less than 6 mm (1∕4 in.).
(6) The raceway is fastened at its outer end and at other points in
accordance with the applicable article.
(7) Where installed as conduit or tubing, the cable fill does not exceed
the amount that would be permitted for complete conduit or
tubing systems by Table 1 of Chapter 9 of this Code and all applicable
notes thereto. Note 2 to the tables in Chapter 9 does not
apply to this condition.

 

[Dennis Alwon]

I watched the video of Paul Ryan, posted above, and I don't think I agree with the premise. IMO, a sleeve does not need to be filled to a max 60% if it is less than 24". I also thought the pipes in the panel were 2"-- maybe I missed it that they were 2 1/2" but Paul used 2 1/2" raceway in his explanation. I have never seen anyone use 2 1/2" Pvc that way

 

[kwired]

I watched the video of Paul Ryan, posted above, and I don't think I agree with the premise. IMO, a sleeve does not need to be filled to a max 60% if it is less than 24". I also thought the pipes in the panel were 2"-- maybe I missed it that they were 2 1/2" but Paul used 2 1/2" raceway in his explanation. I have never seen anyone use 2 1/2" Pvc that way

Again per the wording in the exception they seem to to be considering this to be a raceway more so than a sleeve.

More then that it is a specific situation and not a general application that they have here. You can't use this allowance for other than non metallic cables entering the top of a cabinet. Allowance to enter a box via a sleeve is in a different code section with different details.

 

[Dennis Alwon]

Again per the wording in the exception they seem to to be considering this to be a raceway more so than a sleeve.

More then that it is a specific situation and not a general application that they have here. You can't use this allowance for other than non metallic cables entering the top of a cabinet. Allowance to enter a box via a sleeve is in a different code section with different details.

It is note 7 that is the clincher-- It states Note 2 does not apply to this situation in 314.5(C). Mea Cupa

 

[david]

312.5(c) exception starts out raceways not less than 18 in. (F) states race ways conduit or tubing. so I went to definitions a" an enclosed channel"
so any enclosed channel recognized by the NEC is subject to the code section. Limited by the section.

so all conduit or tubing raceways are subject to chapter nine table one by specific referance in 312.5