Bundled conductors

[Ken Amelin]

Is it OK to bundle all these conductors through the joists as shown in photo?
If not, What code article(s) would this be breaking?

Thanks

[John Kogel]

Bump.
Good luck, Ken. I seem to recall that bundling for 4 feet was not a terrible thing, but will bow to the consensus here.

[Jerry Peck]

NEC 310.15.(B)(3)(a)

Each two-conductor NM cable has two current-carrying conductors.

4-6 current-carrying conductors is derated to 80 percent
7-9 ... derated to 70 percent
10-20 ... derated to 50 percent
21-30 ... derated to 45 percent
31-40 ... derated to 40 percent
41 and above ... derated to 335 percent

The derating is taken after any ambient derating (basement likely has no ambient derating, attic ambient derating is a killer).

The derating is from the 90 degree C column, which means that derating is taken from:
14 AWG NM-B ... 25 amps (copper)
12 AWG NM-B ... 30 amps (copper)
10 AWG NM-B ... 40 amps (copper)

Looks to be 10-12 or more two-conductor NM cables in each bundle, for 20-24 current-carrying conductors, which would require derating to 45 percent:
14 AWG NM-B ... 25 amps (copper) derated to 11.25 amps
12 AWG NM-B ... 30 amps (copper) derated to 13.5 amps
10 AWG NM-B ... 40 amps (copper) derated to 18 amps

The derating takes place when spacing is not maintained for more than 24 inches.

The solution there, if the NM cables have enough slack to pull back to there, would be to nail is 3 2x4 nailers (to give one going across the open space) and staple the NM cables out side-by-side-by-side at the middle of each bundle. That would be about the only way (at this point) to come close to meeting the code requirements.

Someone may have though they were doing a real 'neat' job keeping all those NM cables together. :(

[Chris Roth]

I'm going to say what Raymond's father says "HOLY CRAP!!!!" It also appears that the joist or beam is over notched at the top but not repaired. Can't tell whether that is a joist or a beam??



NEC 310.15.(B)(3)(a)

Each two-conductor NM cable has two current-carrying conductors.

4-6 current-carrying conductors is derated to 80 percent
7-9 ... derated to 70 percent
10-20 ... derated to 50 percent
21-30 ... derated to 45 percent
31-40 ... derated to 40 percent
41 and above ... derated to 335 percent

The derating is taken after any ambient derating (basement likely has no ambient derating, attic ambient derating is a killer).

The derating is from the 90 degree C column, which means that derating is taken from:
14 AWG NM-B ... 25 amps (copper)
12 AWG NM-B ... 30 amps (copper)
10 AWG NM-B ... 40 amps (copper)

Looks to be 10-12 or more two-conductor NM cables in each bundle, for 20-24 current-carrying conductors, which would require derating to 45 percent:
14 AWG NM-B ... 25 amps (copper) derated to 11.25 amps
12 AWG NM-B ... 30 amps (copper) derated to 13.5 amps
10 AWG NM-B ... 40 amps (copper) derated to 18 amps

The derating takes place when spacing is not maintained for more than 24 inches.

The solution there, if the NM cables have enough slack to pull back to there, would be to nail is 3 2x4 nailers (to give one going across the open space) and staple the NM cables out side-by-side-by-side at the middle of each bundle. That would be about the only way (at this point) to come close to meeting the code requirements.

Someone may have though they were doing a real 'neat' job keeping all those NM cables together. :(

[Jim Port]

I would be more concerned about the two holes drilled too close together and the location of the holes.

[Jerry Peck]

I would be more concerned about the two holes drilled too close together and the location of the holes.

I would be equally concerned with both.

They have placed a 'heater' in those holes. :biggrin:

[Jim Port]

Gravity works all the time. Current only flows part of the time to generate heat and only some cables will have any current at all.

[Jerry Peck]

Gravity works all the time. Current only flows part of the time to generate heat and only some cables will have any current at all.

And that has been, apparently, resisting gravity for some time as those do not look like 'new wood'.

Thus, while 'not permitted', there may be sufficient support there to resist gravity.

Live loads, like the current you refer to, are like the current you referred to - not there all the time.

I restate that BOTH are a concern.

[Ben Jacks]

Is it OK to bundle all these conductors through the joists as shown in photo?
If not, What code article(s) would this be breaking?

Thanks
Ken,
Depending on the local codes, if NEC 2014 ART. 210.12 is required for AFCI runs, length distances are limited to 50 ft max for 14 awg, and 70 ft max for 12 awg branch runs and 24" maximum parallel bundling distance in tight trunk runs or in conduit for temperature adjustments per ART. 310.15(b)(3)(a). Can't tell from photo but check out if AFCI's are in excess of 50 and 70 ft per awg noted.
Also note the raceway terminology for parallel conductor quantity applies to conduit and bundled tight trunk lines noted in Art. 310.15 that also include 10 awg and larger current carrying conductors. As a side note, those large drilled holes must not notch or drill out over 40% of the beam, joist, or stud of sawn cross-sections structure. (I.e. see IRC R502.8.1 and R602.6) The holes are within 24" of the supporting bearing wall to be compliant from span load tear line values.

[Scott Turner]

NEC 310.15.(B)(3)(a)

Each two-conductor NM cable has two current-carrying conductors.

4-6 current-carrying conductors is derated to 80 percent
7-9 ... derated to 70 percent
10-20 ... derated to 50 percent
21-30 ... derated to 45 percent
31-40 ... derated to 40 percent
41 and above ... derated to 335 percent

The derating is taken after any ambient derating (basement likely has no ambient derating, attic ambient derating is a killer).

The derating is from the 90 degree C column, which means that derating is taken from:
14 AWG NM-B ... 25 amps (copper)
12 AWG NM-B ... 30 amps (copper)
10 AWG NM-B ... 40 amps (copper)

Looks to be 10-12 or more two-conductor NM cables in each bundle, for 20-24 current-carrying conductors, which would require derating to 45 percent:
14 AWG NM-B ... 25 amps (copper) derated to 11.25 amps
12 AWG NM-B ... 30 amps (copper) derated to 13.5 amps
10 AWG NM-B ... 40 amps (copper) derated to 18 amps

The derating takes place when spacing is not maintained for more than 24 inches.

The solution there, if the NM cables have enough slack to pull back to there, would be to nail is 3 2x4 nailers (to give one going across the open space) and staple the NM cables out side-by-side-by-side at the middle of each bundle. That would be about the only way (at this point) to come close to meeting the code requirements.

Someone may have though they were doing a real 'neat' job keeping all those NM cables together. :(
In this case you only count the hots, not the neutrals. IE: 12/3 with a ground. That's 2 hots.

[Ben Jacks]

In this case you only count the hots, not the neutrals. IE: 12/3 with a ground. That's 2 hots.
12/3 is a 3 current carrying conductor cable having 2 ungrounded and one unbalanced grounded conductor. Neutrals are counted as current carrying regardless of being a balanced grounded conductor. A 12-2 can be a hot and neutral or two hots in a circuit without a neutral and still be 2 current carrying conductors.

[Jerry Peck]

In this case you only count the hots, not the neutrals. IE: 12/3 with a ground. That's 2 hots.

Incorrect - you count "current carrying conductors", but not "neutrals" (a "neutral" only carries the unbalanced current of the two 'hot' conductors, so it is not 'carrying its own current').

It is a common mistake to 'count only the hots'.

That said, yes, with 14-3 or 12-3, there are typically only two "current carrying conductors".

[Ben Jacks]

In this case you only count the hots, not the neutrals. IE: 12/3 with a ground. That's 2 hots.

NEC Definition: A "neutral conductor" is defined in ART.100 as the conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

A NM 12-2 w/g= 2 current carrying conductors with an equipment grounding conductor and a 12-3 w/g cable = three current carrying conductors with a single bare equipment grounding conductor.

[Jerry Peck]

NEC Definition: A "neutral conductor" is defined in ART.100 as the conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

A NM 12-2 w/g= 2 current carrying conductors with an equipment grounding conductor and a 12-3 w/g cable = three current carrying conductors with a single bare equipment grounding conductor.

Ben,

Look at 310.15 (B)(5)(a) - A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15 (B)(3)(a) ... which is "More than Three Current-Carrying Conductors.

[Ben Jacks]

Ben,

Look at 310.15 (B)(5)(a) - A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15 (B)(3)(a) ... which is "More than Three Current-Carrying Conductors.
Hi Jerry,
The NEC adjustment factoring considerations include same circuit and paralleled bundling together. Under most unusual dwelling circumstances would running NM cabling of 12-3 with a neutral be applied to factoring in 310.15(B)(3)(a) unless there is bundling separation and certainly not in more than a length of 24" of conduit. Note that 310.15(B)(3)(a) would be more relevant to commercial lighting using a common neutral having 20 same circuit wiring. Of course that condition might happen in Chicago. :) rbj

[Jerry Peck]

Ben,

It's applicable to all wiring of such configuration - which includes multiwire branch circuits (DW/DP, and other multiwire branch circuits).

The reasoning is that, for heating of the conductors, it is no difference if there is 20 amps is on each hot leg or if there 20 amps on one and 10 amps on the other with 10 amps on the neutral ... same heating of the conductors which needs to be addressed.

I don't see a lot of MWBC in newer homes, but it was common in the 60s, 70s, and 80s (at least in South Florida where I used to inspect).