Bath fan/light/heat 20 amp circuit

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jaylectricity

jaylectricity

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Location
Massachusetts
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licensed journeyman electrician
Quick version:
I installed a Broan/Nutone bath/fan/heat that in the instructions says to use a dedicated 20A circuit. Because I'd have to run a 12-3nm and a 12-2nm to have 3 switches I like to just give the heater a dedicated 15A using the 2- wire for that and put the fan/light on a 14-3 using the lighting circuit.

Are there any official documents out there by the manufacturer that state it is ok to do it this way?

More info:
Instead of 7 #12 conductors in the tiny junction box with one neutral unnecessary I have 7 #14 conductors.
I have a 12A fan fed by a dedicated 15A circuit
I have the fan/light, a wafer LED and a vanity light supplied by a dedicated 15A circuit

In my opinion the manufacturer's instructions are for people who need the instructions. My wiring method is safe and effective.

The inspector saw the wiring on rough, but claims he didn't know there was a heater involved. Not sure how you don't see the heating element as it is prominent.

But understandably he doesn't want to put his or the town's name on it for liability reasons.

To fix it we'll have to open up the tiled floor for the home run, the wall for the switches and the ceiling for the unit.

I understand the letter of the law, but there will not be a problem. Most inspectors understand this. Yes, I should have found out if he'd be ok with it beforehand.
 
For a 3-function unit, two runs of 12-2 will work; you don't need two neutrals. Re-color one of the whites.
 
So essentially the instructions call for a dedicated 20A circuit, and you ran a dedicated 15A circuit and part of another 15A circuit? Unfortunately if that is what the destructions say, I'm not sure of a way around it, other than arguing the wording of 110.3(B) and saying those instructions are not part of the "listing or labeling". Can you Photoshop the instructions or has he already seen them?
 
infinity said:
How do you run one cable with no neutral in it, grab the neutral from the other cable? We just run 12/4.
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Yes. Four conductors is four conductors. I have never seen nor used 4-conductor NM cable.

No different than two 14-2s between two 3-way switches for hot, neutral, and two travelers.
 
jaylectricity said:
Quick version:
I installed a Broan/Nutone bath/fan/heat that in the instructions says to use a dedicated 20A circuit..
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If heater nameplate load < 12A continuous, get Broan product support to clarify by email that product Nameplate overrides generic instructions not specific to all models.

If that fails, take product sheet to the planning department, and get permission to wire it per your multiple-circuit diagram. Inspector can't argue with the plans.
 
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Just make sure if the NM cables are going through a metal opening that both cables enter the same opening. i.e. Neutral and all hots have to go through same hole in metal box (like fan enclosure) to avoid induction heating. Plastic box, don't care, use any holes.

Same here, 12-4 not found usually, so never used it.

For the original question, I would have no issue using two different circuits to feed a combo unit. Heater on it's own circuit, and lights on general lighting circuit, unless the unit is over a water fixture that requires GFCI protection, then one circuit, one GFCI.
 
Dennis Alwon said:
They make 12/4 and 12/2/2 which has 2 sets of circuits. Black, white, Red and white with a red stripe.
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I'm well aware of them, just never been exposed to them.

I especially don't see the advantage of the latter, except for one less EGC.
 
LarryFine said:
I'm well aware of them, just never been exposed to them.

I especially don't see the advantage of the latter, except for one less EGC.
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Lower labor costs due to running one cable instead of two identical cables and having to keep track of which is which.
 
ramsy said:
If heater nameplate load < 12A continuous, get Broan product support to clarify by email that product Nameplate overrides generic instructions not specific to all models.

If that fails, take product sheet to the planning department, and get permission to wire it per your multiple-circuit diagram. Inspector can't argue with the plans.
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He did say if I can show him in writing that the manufacturer allows what I did that he would pass it.
 
480sparky said:
Lower labor costs due to running one cable instead of two identical cables and having to keep track of which is which.
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I'm thinking of the extra work and materials involved in making up the joints in the box where the one cable becomes two, whether in the first box on either circuit, or in a separate J-box.

Two single cables can be run directly to their respective first boxes with minimal box volume required like we've always done. I can imagine using it in some cases, but not enough to stock it..

Added: I've never priced it. How does 12/2/2, or 12/4 compare to 12/2?
 
augie47 said:
Todays price at local big box $1.00/ft vs /0.40/ft
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First, I have never, ever seen either 4-C NM cable in our local orange and blue stores.

Second, I'd consider it for one long home run if it was only twice the per-foot price.
 
LarryFine said:
I'm thinking of the extra work and materials involved in making up the joints in the box where the one cable becomes two, whether in the first box on either circuit, or in a separate J-box.

Two single cables can be run directly to their respective first boxes with minimal box volume required like we've always done. I can imagine using it in some cases, but not enough to stock it..

Added: I've never priced it. How does 12/2/2, or 12/4 compare to 12/2?
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I wired a fitness center in NM. Every receptacle got a separate circuit.

I ran 12/2/2 to one, dropped the red/white as a hot, carried the red + black to the next via 12/2, dropped the red, carried the black to the next.

3 circuits in a cable with one neutral 👍👍
Yay, labor saver

BTW, one roll of 12/2/2 costs 30% more than 2 rolls of 12/2
 
James L said:
... dropped the red/white as a hot ...
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Is that permissible? Why not 12/4 instead?

, carried the red + black to the next via 12/2,
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12/3, you mean?

3 circuits in a cable with one neutral 👍👍
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I get it for 3-phase. There, it makes perfect sense; "3-phase Romex". Again, why not 12/4?

We've been discussing using 12/4 or 12/2/2 vs 2x 12/2 for a single device in a residence.

BTW, one roll of 12/2/2 costs 30% more than 2 rolls of 12/2
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To me, that's why it would need to out-benefit using two runs of 12/2 in order to be worth it.

For the occasional multi-function bath fan, it doesn't make sense to buy more-expensive cable.

Now, having said that, if I already had a roll of either, and was wiring such a fan, I would use it.
 
LarryFine said:
To me, that's why it would need to out-benefit using two runs of 12/2 in order to be worth it.

For the occasional multi-function bath fan, it doesn't make sense to buy more-expensive cable.

Now, having said that, if I already had a roll of either, and was wiring such a fan, I would use it.
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I had a typo in my last reply, with the red + black in a 12/2. Yes it was 12/3

As for 12/4, I've never seen it. That's why I used 12/2/2

If I ever installed a heat/fan/light I would buy a roll of 12/2/2 and have the rest of the roll for future use.

I already do that with 12/3 because occasionally I'll wire a garbage disposal with the home run at the switch. Or I'll wire a bathroom in 12-wire and have a fan/light combo to wire. But those are rare. Mostly that wire collects dust
 
James L said:
I already do that with 12/3 because occasionally I'll wire a garbage disposal with the home run at the switch
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Now, we're talking. I'm a big fan (no pun intended) of using MWBCs.

We're still on the '14 NEC, and I hope we stay on it for a long time.


I still wonder whether it's compliant to use the white wire with the red tracer as a hot.
 
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