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Bildrb 12-21-2010 07:15 PM

Bath Fan Wiring Dilemma
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My old bath fan worked off two wall switches, one for the lights (heat lamps) & the other for the vent fan. Those two 12/2 lines met with the power line in a box on the fan/light enclosure. I have NO IDEA whatever possessed me to think I knew what the devil I was doing when I disconnected everything after deciding my memory was as good as any photographic image.

I unpacked the new unit that fit the hole in the ceiling. The new unit comes complete with lights/fan/ AND HEAT. Each of these three items has two lines coming out of the plug ins.

So now I have a total of six separate sets of wires. And grey hair. What's left of it after working most of yesterday trying to get the thing to work properly without burning down my house or frying the new unit.

My plan is to extend each set of wires from the bath unit to a junction box that holds the two sets of wires for the bathroom switches and the power wire because there is simply not enough room in the fan enclosure to hold all those wires and wire connectors. Once I have everything in the junction box I have no idea how to make all those connections.

As I only have two switches in the bathroom I am going to have to wire two of the three sets of fan unit wires to work off one switch. My wish is to wire the lights and the heat unit to one switch and the vent fan to the other switch. I have made a drawing as well as taken a photograph of a drawing. Don't know which will properly show here so am trying both.

gregzoll 12-21-2010 07:19 PM

Unless you can pull a third wire, you can go with the two NM's. Whites get tied together for the Fan & Light, and as for the heat, it would go to the other. Keep in mind, if the NM is 14/2, it may not be up to the spec's that the manufacturer uses for the heat, if they recommend 12/2.

Bildrb 12-21-2010 08:19 PM

What's an NM?
Thanks for the prompt reply. I understood a bit of this but no idea what an NM is. I'm thinking perhaps non-metallic?? All the wires are 12/2 except of course for the ones coming from the bath unit. Believe me, I wish I could pull a third wire, would make my life some much simpler I think. Will crawl back into that attic in the morning and give it another go seeing as how I don't have enough bruises already. Thank you Greg.

darren 12-21-2010 08:26 PM

Are the two switches in the same box or are they in two different spots.

Bildrb 12-22-2010 12:43 PM

Switch location
Thanks Darren. The switches are both in the same box. The issue I have with that box is that the whoever wired it left no, and I mean NO, extra wire to work with beyond what would be used to attach the switches. And the box is an older one with not much room in it. Were you thinking of some kind of jumper or something? No idea if that's even possible, practical or safe but if so it would not work due to the lack of room issue with the box.

Bildrb 12-22-2010 12:50 PM

Question for Gregzoll
In sitting and staring at your answer for an extended length of time to make certain I have it right in my head, a question arises. I noted where you have the heat on a switch by itself while the fan and light work off the other switch.

Does your answer imply that it would be unwise for some reason to make the hookups such that the light and heat would be on one switch and the fan by itself on the other switch?

Jackofall1 12-22-2010 01:16 PM

NM is the wire trade name.

What is the wattage of the heater?

Once this is know it can be determined if the 12/2 conductor is suitable in size to feed power to both the light and the heat lamps.

bob22 12-22-2010 02:31 PM

NM= nonmetallic (refers to jacket on cable)
typical brand name is Romex.

Bildrb 12-22-2010 02:41 PM

Heater Wattage
Thanks guys. I rather thought that NM meant non-metallic but wasn't positive. As for the wattage of the heater it's 1400 watts. The light is a recommended 60 watt bulb per the packaging.

clashley 12-22-2010 02:56 PM


Originally Posted by Bildrb (Post 555551)
Thanks guys. I rather thought that NM meant non-metallic but wasn't positive. As for the wattage of the heater it's 1400 watts. The light is a recommended 60 watt bulb per the packaging.

That's a total 1460 watts. The capacity of 120V 15A breaker with 14AWG is 1440 watts (rated at 80%). I'd put the light/fan unit on a dedicated 20A breaker wired with 12/2.

Jackofall1 12-22-2010 02:57 PM

Well the light and heater or the light and fan, could be put on the same 20 amp circuit, that if it is indeed a 20 amp circuit as they are both wired with 12/2.

1400 w heat x (125% of the largest load + the sum of all other loads) 1.25 = 1750 + 60 = 1810 Watts or 15 amps Safe to go on a 20 amp circuit.

The next question you have to ask yourself, do you want the heat on when the light is on or the fan on when the light is on?

Is this the only light in the bathroom?

Bildrb 12-22-2010 07:10 PM

20 amp circuits
Thanks to all of you who have helped me out with this issue. When I had the house rewired years ago I specifically made certain that every circuit was a 20 amp circuit and that 12/2 being the smallest wire used for the wiring. I have a huge 200 amp panel. I made sure there were extra lines on 20 amp circuits put in boxes in the attic as well as under the house so they'd be there in case of any future need. Turns out I was right. But this fan unit had me flustered.

So. Finally my daughter happened to stop by, heard me grunting and swearing in the attic, called her father in law who is a millwright and he came in and in about 10 minutes the light was finished. And the thing works. So now I owe him a beer but after that it should be a six pack of micro-brews.

I did as he instructed while he watched over my shoulder, (only room for one hanging over that rafter) and hooked all the wires up. STILL don't have it straight in my head but it's done and with so many other worries on board I think I can safely let this one go and just accept it.

So again gentlemen, thank you so much for all the offered assistance. it is greatly appreciated. I can only hope that as time goes on I'll be able to be of assistance to some other poor guy like me.

Jackofall1 12-22-2010 08:41 PM

So what did you end up doing light and heater or light and fan?

Bildrb 12-23-2010 12:32 PM

Switch choice settled
Good morning. I went with the light and heater on one switch and the exhaust fan on the other. Things are working well and I'm glad to get out of the attic! I can't thank you all enough for the help. I will hope that one day I can be of assistance to someone else. Just so long as it's not about wiring.. ;-)

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