I am putting in a bathroom fan/light/heater on its own 20 amp circuit. I'll be using a switch with a timer plus 2 rockers.

So I'll need 3 hot, 1 neutral, and 1 ground from the switch box to the unit.

I could use 12/4. But would it be ok to use 2 12/2 cables instead?

 

Didn't know they made 12/4?. So, 3- 12/2's would be the ticket.

Or 1-12/2 and 1-12/3.

 

Yes they do make 12/4 (black, red, blue, white, ground) but it's probably a special order item. There's also 12/2/2 (black, white, red, red stripe, ground) which you could re-identify red stripe as a hot wire using a Sharpie pen.

If the fan/light/heat fixture has separate neutrals for each function, you could use a 12/2 and a 12/3; or three 12/2. Just be sure to keep the correct switched hot with its matching neutral.

Or you could install some ENT "smurf tube" flexible PVC conduit and pull individual THHN conductors through in appropriate colors. I would probably go this route.

 

For this set up there are two thing you will useally need to do this.,

Get two gang switch box ( minuim size ) { trust me on this one you will have issue with the numbers of conductors }
otherwise 3 gang switch box will have more leeway and room to work around.

you can use 12-2-2 { pretty common item in AFCI required states } or use the 12-4 { you can get it but some place may have specal order for this }

Or

Run with smurf tube { nonmetalic fexiable conduit } and run proper sized THHN/THWN conductors

Myself I rather run the latter if there is no issue bring it in.

Merci,Marc

 

Just checked the catalog. Southwire seems to be the only manufacturer who makes true 12/4 NM-B, but only in 250' rolls and 1000' spools.

Southwire and Cerrowire both make 12/2/2, but again only in 250' and 1000' lengths. The supply house may be willing to sell on a per foot price. Personally, the ENT route sounds easier to deal with.

 

Just a quick aside, ib ...

I see a lot of installed low-voltage systems that were labeled with Sharpie pens. After a few years the Sharpie ink dries out and disappears off of PVC-jacketed wiring.

As much as I hate electrical tape, this is one time I would use it instead of a Sharpie.

Just sayin' ...

 

Can someone explain why the posters idea of using 2 12/2 is not ok? Assuming common neutral for all (he said he needed 3 hots, 1 neutral and 1 ground). from first 12/2 use 1 hot, 1 neutral and 1 ground. from second 12/2 use black as hot, relabel white as hot. and I guess you would have to use the ground as well since you can't have conductors without ground, correct? Since it was said he need 3 12/2, I assume you can't relabel the white in this situation. Can someone explain please. thanks.

 

For any given circuit, the hot, neutral and ground conductors must be in the same raceway. Separate cables are separate raceways.

 

so the outer jacket counts as raceway? someone said could use (1) 12/2 and (1) 12/3 or (3) 12/2. if doing either of these, I guess you would have to connect all the neutrals together and all the grounds together. I guess that is why easier to use the conduit as you only need one neutral and one ground.

 

Yes, the outer jacket of a cable is a raceway (or at least is treated like one). He can use a 12/2 + 12/3 if the heat, light, and fan functions of the fixture have separate neutrals. He can then match them with the proper switched hot in each cable. In my opinion though, the conduit, 12/4 cable or remarked 12/2/2 cable is the proper way to go.

 

Thanks for the replies. No, there are not separate neutrals. I don't have the switch or unit yet, but I have the wiring diagrams. I guess I'll go the 12/4 or 12/2/2 route if I can get a short length of it, otherwise the conduit.

 

So I went to Home Depot to see if they had 12/4 or 12/2/2/. They didn't, although they had a 12/2/2 sign on their cut by the foot display.
Anyway, their electrical person advised me to use a 12/2 plus a 12/3. But unlike ibpooks says above, there are not separate neutrals, just one. The HD electrician said to tie the two neutrals together. Bad idea?

 

While a few HD employees are retired electricians some have at most just a couple of hours training watching a very basic computer based training program. Others may have been to a few manufactures training seminars.

 

Tieing the neutrals together serves no real purpose, and only adds some confusion and wiring time. NEC 300.3 (3) allows, using NM cable, cable grouping. Basically, run the two NM together for the run, and enter any metal box using the same hole/clamp. 300.20 (A) is referenced also.

 

After this thread popped up last time, one of the other moderators and I had a brief discussion about this topic and decided that you can use 12/2 + 12/3 for this purpose. The code article 300.3 applies as referenced by telecom guy.

 

It is allowed to do that in few situation it been done like that more than once.

But a nice gotcha as Telecom and Ipbooks and myself I will mention that if you have plastic switchbox then it is not legit at all unless you have NM clamp to keep the NM's bundled as above.

Merci,Marc

 

Just an FYI but, you can only re-identify a white to feed a switch, not use it as a switch leg.

 

Thanks, what is the reason for the metal box requirement? If the neutrals are not tied together, will I have one loose?

 

She wasn't old enough to be retired, but seemed pretty knowledgable. She had wired one of these units before, she said.

 

Once you see how small the junction box is on the fan you are going to wonder how to get all of them to fit in there when using multiple cables.

I feel the best approach is to run smurf tube (ENT) or a flex conduit with individual conductors.

 

This should be the best method. Only one ground wire on each end to deal with, and you can run a red, orange, black for the 3 hots. Only one white. How many total watts?

 

Ok, I am starting to warm up to the ENT approach. What diameter would I need for the 3 hot, 1 neutral, and ground? This will be a dedicated 20 amp circuit.

 

Half inch, 1/2" ENT is good for up to 7 #12 THHN conductors.

 

Just a suggestion use stranded wire if you go ENT. Easier to work with.

 

I believe up in northern US/southern Canada area, they sell Romex with a blue sheath. It includes 3 hots, 1 neutral, and 1 ground, as was stated as a requirement. If you can buy this, Then I believe that's the way to go. Beware, however; I believe it only comes in 10 AWG and 8 AWG sizes. You may just want to use the Romex I stated at 10AWG and put it on 20a breakers that are bolted together or tripped at the same time in the event of a short, etc. Tell the inspector that you used 10AWG to compensate for voltage drop. He'll probably take that in and pass it out.
Sparky

 

Hello. I'm sure the problem's been taken care of after 4 years.