Do Raceways create heat.

[David C. Macy]

Does the PVC raceway at the top of the panel change or could change the temperature of the wires?

Looks like a nice neat install and had no temperature differencial when testing with a laser thermometer.

Just curious.

[David P. Valley]

David,

What sort of insulation jacket is that?. I've never seen it before.

Anyways, branch wiring should not be bundled, period. It creates heat build-up. Wiring can be doubled under one staple but bundling of branch wires is not allowed.

[David C. Macy]

Originally Posted by dvalley

David,

What sort of insulation jacket is that?. I've never seen it before.

Anyways, branch wiring should not be bundled, period. It creates heat build-up. Wiring can be doubled under one staple but bundling of branch wires is not allowed.

I have seen the raceways they use in parralel & between the floor joists but this was a first for me. Thats why I posted.

There is some formula the electicians use for the temperature ratings.

[jtedesco1]

See NEC Section 312.5(C)

This installation would be acceptable only when all of the conditions in the Exception (a) through (g) can be verified.

also:

FPN: See Table 1 in Chapter 9, including Note 9, for allowable cable fill in circular raceways. See 310.15(B)(2)(a) for required ampacity reductions for multiple cables installed

in a common raceway.

[Speedy Petey]

That is not a receway. It is a sleeve for protection, although PVC Sch40 is no more protection than the NM itself. In this installation no protection is actually reaquired.

Originally Posted by dvalley

Anyways, branch wiring should not be bundled, period. It creates heat build-up. Wiring can be doubled under one staple but bundling of branch wires is not allowed.

Do you have any code reference to back this up, or is it just opinion?

[Speedy Petey]

To answer the original question, no, a raceway does not "create" heat. The conductors inside do.

[Speedy Petey]

This installation actually fits 312.5(C) to a tee. All except for the fastened within 12" requirement.

[Paul W. Abernathy]

I would not worry about the heat issue. If it is atleast 18 inches and not over 24 inches then i would make sure it is sealed, the cables are secured within 12 inches of the conduit and a fitting on the end.....oh and not filled beyond 60 percent of conduits cross section area.

[David P. Valley]

Originally Posted by Speedy Petey

Do you have any code reference to back this up, or is it just opinion?

Nope, I don't do code. JMO.

While we are on this topic. Can a licensed sparky tell me how many #12 or #14 AWG branches can be tie wrapped together for a distance of 50 to 60 feet (Not including protective conduit).

Example: An addition has just been built. Instead of installing a simple 50 or 60 Amp LSE at the addition, the Electricians' installed every branch wire at the Main SE, stapled them to within twelve inches of the SE panel, then tie wrapped them in a bundle all the way over to the addition, then distributed them from there.

What amount of wire can be bundled?

[Speedy Petey]

Originally Posted by dvalley

Nope, I don't do code. JMO.

Then how can you make a statement that something is "not allowed".



Up to nine CCCs (current carrying conductors) (#14-#10) can be "bundled" together or put in a raceway.
Now...Bundling is an obscure term. In your example I don't think anyone can deny that they are bundled. IMO just running through bored holes is NOT bundled.

For reference, here is the code section:

(a) More Than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

I say nine conductors above due to several factors. NEC 310.15(B)(2)(a) is the main one along with 240.4(D) and T310.16. There are also exceptions for nipples less than 24" and for the neutral of a multi-wire circuit cable (3-wire homerun).

You can theoretically have four 12/3NM cables tie wrapped together for 500' (or more) and the derating will NOT affect it's ultimate ampacity of 20 amps.

I don't mean to be a jerk when asking for a code reference about these things, but making blanket statements that something is "not allowed" solely based on opinion can be very misleding to those who don't know all the facts.

[jtedesco1]

See 334.80 here

NEC Section 334.80

Article: Nonmetallic Sheathed Cable, Types NM, NMC and NMS
Section/Reference: Ampacity

Change: The following text was added to this section:

Where more than two NM cables containing two or more current carrying conductors are bundled together and pass through wood framing that is to be fire- or draft-stopped using thermal insulation or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a).

Rationale: Technical substantiation was provided to indicate that when multiple NM cable is installed as outlined above, a real potential exists for the cable to reach an operating temperature above 90C.

Impact: Where such conditions exist, the ampacity shall be de-rated in accordance with NEC 310.15(B)(2)(a) which could lead to increasing the size of the wire or drilling more holes.

Also, supporting and securing Type NM cables properly is also necessary to be considered as a proper installation.

See 334.30 in the NEC.

[Speedy Petey]

KEY words in this change:

Originally Posted by jtedesco1

Where more than two NM cables containing two or more current carrying conductors are bundled together and pass through wood framing that is to be fire- or draft-stopped using thermal insulation or sealing foam,

Also, this is a change for the 2005 NEC.
Unless the place is new and was built under the jurisdiction of the 2005 NEC this change does not even apply.

[jtedesco1]

More Information Here

[Marcel R. Cyr]

Dosen't anybody have an issue with the water pipe above the panel?
Just curious.

Marcel

[jtedesco1]

Yes, it may be a violation!