Running two 10-2 NM-B for electric dryer

[pkelectrical]

On the rough, the GC told me in the last minute that the dryer is electric.
I only had 10-2 on the truck so I ran two 10-2. The run was only about 15'

Inspector failed me for running two 10-2, and told me it has to be 10-3.

The two 10-2 were terminated in a 2 gang box, with neutrals tailed together, same with grounds.
In the breaker panel, I used cable ties to keep the two hots together. I did same thing with neutrals before terminating them into neutral bar.

Is there a code that prevents me running two 10-2 NM-B for 240V appliance like the dryer? With two 10-2 you have extra neutral and ground conductor, which in theory is better than having just one. I always use 10-3 because obviously it is cheaper and faster, just never expected to fail for something like this.

 

[augie47]

Sounds like a violation of 300.3(B) "all conductors of a circuit must be in the same raceway or cable" and 310.10(H) conductors smaller than 1/0 can't be paralleled and possibly 110.14(A) if both wires terminated on the device or breaker..

 

[peter d]

The neutral has to be insulated, and the EGC can't be a current carrying conductor. It was never correct to run 10/2 NM cable do a dryer.

 

[Little Bill]

The neutral has to be insulated, and the EGC can't be a current carrying conductor. It was never correct to run 10/2 NM cable do a dryer.

You are correct but not what the OP asked.

Is there a code that prevents me running two 10-2 NM-B for 240V appliance like the dryer? With two 10-2 you have extra neutral and ground conductor, which in theory is better than having just one. I always use 10-3 because obviously it is cheaper and faster, just never expected to fail for something like this.

Technically the OP has an insulated neutral. It's just that he didn't do the install correct to get that insulated neutral!:happyyes:

 

[wwhitney]

Sounds like a violation of 300.3(B) "all conductors of a circuit must be in the same raceway or cable"

I don't see that, I would think it would be allowed under 300.3(B)(3) "nonferrous wiring methods".

and 310.10(H) conductors smaller than 1/0 can't be paralleled and possibly 110.14(A) if both wires terminated on the device or breaker..

Indeed, but that could be solved easily by using only three out of four of the insulated conductors present in two runs of 10/2. Just leave one white wire disconnected at both ends, it's a spare.

Cheers, Wayne

 

[peter d]

You are correct but not what the OP asked.



Technically the OP has an insulated neutral. It's just that he didn't do the install correct to get that insulated neutral!:happyyes:

I missed that. :slaphead:

 

[ptonsparky]

The inspector was correct although he should have given you the sections that pertained. Sometimes those shortcuts don't save you any time or money.

 

[JFletcher]

Im not seeing the code violation so long as no wires are paralleled*. 2 10/2 is 4 insulated wires with 2 bare grounds. So long as the 2 blacks were the ungrounded conductors, ONE white neutral and ONE bare ground were used (the others cut or capped off), how is this any different that running 2 12/3 to a 4 function fart fan with heater, light and nightlight? Run both cables thru the same KO in the box and in the panel.

300.20

*You cannot parallel the neutrals as mentioned above

 

[GoldDigger]

Im not seeing the code violation so long as no wires are paralleled*. 2 10/2 is 4 insulated wires with 2 bare grounds. So long as the 2 blacks were the ungrounded conductors, ONE white neutral and ONE bare ground were used (the others cut or capped off), how is this any different that running 2 12/3 to a 4 function fart fan with heater, light and nightlight? Run both cables thru the same KO in the box and in the panel.

300.20

*You cannot parallel the neutrals as mentioned above

The violation is that not all of the conductors are in the same cable.
An exception for running separate conductors in two or more non-ferrous raceways does not directly apply to cable wiring methods.

Even if it were allowed, it would require the inspector to be able to verify that the two NMs were bundled tightly all the way from one end to the other.

One can make good argument that multiple runs to a fan combo are allowed because they are actually multiple circuits (not separate branch circuits, but separate circuits, just as a switch leg does not have to be in the same cable or raceway with the power feed to the device.

 

[ptonsparky]

Im not seeing the code violation so long as no wires are paralleled*. 2 10/2 is 4 insulated wires with 2 bare grounds. So long as the 2 blacks were the ungrounded conductors, ONE white neutral and ONE bare ground were used (the others cut or capped off), how is this any different that running 2 12/3 to a 4 function fart fan with heater, light and nightlight? Run both cables thru the same KO in the box and in the panel.

300.20

*You cannot parallel the neutrals as mentioned above

We run 1/2" flex to those fans or talk them out of the dang night lite.

 

[JFletcher]

The violation is that not all of the conductors are in the same cable.
An exception for running separate conductors in two or more non-ferrous raceways does not directly apply to cable wiring methods.

Even if it were allowed, it would require the inspector to be able to verify that the two NMs were bundled tightly all the way from one end to the other.

300.3(B)(3) leads to 300.20(B). 2008 NEC. If this has been changed in the 11+ NEC, ok, but running 2 NM is not a violation.

Last year I posted about one of those 4 fucntion fans and had numerous members say to run 2 12/x to make it work since 12/5 NM doesnt exist.

 

[GoldDigger]

300.3(B)(3) leads to 300.20(B). 2008 NEC. If this has been changed in the 11+ NEC, ok, but running 2 NM is not a violation.

Last year I posted about one of those 4 fucntion fans and had numerous members say to run 2 12/x to make it work since 12/5 NM doesnt exist.

Take a look at the CMP ruling in this old thread: http://forums.mikeholt.com/showthread.php?t=112177

And, once again, the fan case is significantly different.
To avoid having the neutral in a different run of NM from a switched or unswitched hot wire and also not parallel two neutrals, you might have to wire power to the fan and then run 2 or 3 switch legs in 12-2 to be compliant. But that can be done!

 

[wwhitney]

The violation is that not all of the conductors are in the same cable.
An exception for running separate conductors in two or more non-ferrous raceways does not directly apply to cable wiring methods.

The plain language of (2011) 300.3(B) would permit using (2) 10/2 NMs equivalently to a 10/4 NM. Here's the operative language for cable installations, with the extraneous language removed:

300.3(B) Conductors of the Same Circuit. All conductors of the same circuit . . . shall be contained within the same . . . cable . . . unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4).
. . .
300.3(B)(3) Nonferrous Wiring Methods. Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath, where run in different . . . cables . . . shall comply with the provisions of 300.20(B).

So if you use a wiring method with a nonmetallic or other nonmagnetic sheath, and you comply with 300.20(B), then 300.3(B)(3) exempts the installation from complying with the general rule of 300.3(B). This would apply to NM cable or even MC cable with an aluminum (nonmagnetic) sheath.

Is the above text commonly interpreted as having a different meaning?

Cheers, Wayne

 

[GoldDigger]

The plain language of (2011) 300.3(B) would permit using (2) 10/2 NMs equivalently to a 10/4 NM. Here's the operative language for cable installations, with the extraneous language removed:



So if you use a wiring method with a nonmetallic or other nonmagnetic sheath, and you comply with 300.20(B), then 300.3(B)(3) exempts the installation from complying with the general rule of 300.3(B). This would apply to NM cable or even MC cable with an aluminum (nonmagnetic) sheath.

Is the above text commonly interpreted as having a different meaning?

Cheers, Wayne

Apparently, did you look at the thread I referenced? By CMP 3:

Recommendation:


Delete the following:

Exception: Conductors installed in nonmetallic raceways run underground
shall be permitted to be arranged as isolated phase installations. The raceways
shall be installed in close proximity, and the conductors shall comply with the
provisions of 300.20(B).
Substantiation:


The exception is not required. Such installations are permitted

by 300.3(B)(3) in all locations, not just underground locations.
Panel Meeting Action: Reject
Panel Statement: This exception is necessary to permit installations where
nonmetallic raceways are installed in close proximity with all of Phase A in one
raceway, all of Phase B in another raceway, all of Phase C in another, and all
the grounded conductors in another raceway. Where this is useful is between
underground manholes so the phase conductors can exit the raceways and be
easily racked within the manhole, taking up less space, and making it easier to
do testing and maintenance on the installation. This would not be permissible
without this exception.
Number Eligible to Vote: 13

 

[jaylectricity]

how is this any different that running 2 12/3 to a 4 function fart fan with heater, light and nightlight? Run both cables thru the same KO in the box and in the panel.

#1 "Fart fan" is so uncouth and unprofessional. Never mind that it's not for farts it's for something a little deeper than a fart as well as moisture.

#2 You're not running separate cables to feed the same equipment. One of your 12/3's is feeding a light and a night light, the other 12/3 is feeding a fan and a heater. In OP's situation there is only one piece of equipment being fed, not four.

 

[wwhitney]

Apparently, did you look at the thread I referenced? By CMP 3:

Yes, I saw that. I guess I have two comments:

1) NEC is primary, Panel Statements are useful as a secondary source when the NEC as written is ambiguous. I see nothing ambiguous in 300.3(B)(3), and if the Panel Statement contradicts the text of the NEC, then the text as adopted controls until a TIA or revision.

2) Even if the Panel Statement has enough weight to change 300.3(B)(3), the statement only refers to nonmetallic conduit. The portion of 300.3(B)(3) dealing with nonmetallic cables is unchanged.

Cheers, Wayne

 

[JFletcher]

#1 "Fart fan" is so uncouth and unprofessional. Never mind that it's not for farts it's for something a little deeper than a fart as well as moisture.

#2 You're not running separate cables to feed the same equipment. One of your 12/3's is feeding a light and a night light, the other 12/3 is feeding a fan and a heater. In OP's situation there is only one piece of equipment being fed, not four.

#1: Fine, "Bathroom exhaust fan". Happy? But I thank you for the PC term, as if I didn't know it. If I'm unprofessional and uncouth because I call a spade a spade, or a fart fan a fart fan, so be it.

#2: A combination exhaust fan, heater, light, and night light is UL listed as a single piece of equipment, as is a dryer, despite it having several functions as well (heated drying, air fluff, door light).

I suppose "dryer" is a pejorative now too; must be "timed cyclic humidity removal appliance".

Just so I have this correct: 2 10/2 following the exact same path (same bored holes, etc.) to a dryer, going thru the same KOs on the box and panel ISN'T kosher, but 2 12/3 following the exact same path (same bored holes, etc.) to a bathroom exhaust fan going thru the same KOs on the box and panel IS kosher?

 

[GoldDigger]

The code does not, AFAIK, say anything about feeding the same equipment. It uses the term "the same circuit" or similar.
I feel that it is possible to have more than one circuit feeding separate loads within one piece of equipment.
One example is a resistance heating furnace.
A typical one might have one 60A circuit feeding the fan and one heating element and another 40A circuit feeding the second heating element.
In that case you clearly also have two different branch circuits.
But I still feel that separate switched circuits off the same branch count as separate circuits even if they are inside the same single piece of equipment.
In any case, there is still a perfectly good way to avoid that whole issue with the combo bathroom fan by running power to the fan junction box and as many switch legs as necessary back to the group of switches.
That would not work for a dryer, since it has only one set of terminals inside the cabinet to which to attach power.

 

[iwire]

I don't see that, I would think it would be allowed under 300.3(B)(3) "nonferrous wiring methods".

You are right, it could be if you jump through all the needed hoops to do so.

And then the inspector looks at it when you are not there, makes a mistake, fails the job and things are delayed

Run the numbers on that and see if it makes sense to do so vs a 10/3.

 

[iwire]

#2 You're not running separate cables to feed the same equipment. One of your 12/3's is feeding a light and a night light, the other 12/3 is feeding a fan and a heater. In OP's situation there is only one piece of equipment being fed, not four.

One UL listing = one piece of equipment.