Heat/Vent/Light/NightLight connection


Old 10-04-01, 07:04 PM
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How would you wire a Heat/Vent/Light/Night Light? It would be a 20 amp circuit with 12 gauge wire, but can I use Romex one 12/2 and one 12/3. If I do all the conductors in the circuit would not be together in the same cable. The 12/3 would have 3 hot and one equip ground the 12/2 would have one hot, one equip ground and the neutral.I think this would be a code violation. Any help would be appreciated.
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Old 10-05-01, 03:39 AM
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When I wired a similar situation I used 2 sets of 12-3 w ground just to keep future repair / replacement confusion at a minimum, because the whites can remain as neutrals and black and reds can be power. As far a code vioilation...I don't see why, but I don't know the book like some of the guys on this site...just my opinion
Old 10-05-01, 04:03 AM
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I assume that you already have power to the switch box.

You need one hot (non-white, non-bare wire) for every switch. If there are two switches to control this fixture, then you can get by with one 12/3 cable. If you have three switches, use two 12/2 cables. If you have four switches, use one 12/3 cable and one 12/2 cable. All the hots do not need to be in the same cable. Don't use the white as a hot -- the white in every cable should be a neutral.
Old 10-05-01, 03:29 PM
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Is there a instruction book? this is the first source, I assume you do not have it, that is why you are asking for help.

Absolutely use two 12-3 cables.
The light and vent are supplied by the first cable.
the night light and heat are supplied by the second.
(this is the setup that Broan uses, they own NuTone)
The white in the light/vent cable is only to be connected to the whites on those two components, they may share a white coming into the wiring box on the side of the unit.
Same procedure for the ntlt. and heat.
At the switches, the incoming and outgoing whites all connect together, the incoming black must be pigtailed to the switches.
Check the wiring diagram on the unit, it may clue you in on exactly how to wire this. My above described scenario may be slightly different than what is needed.

Old 10-05-01, 03:46 PM
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The NEC rule you are talking of is copied below from the 99 NEC.

300-3. Conductors
(b) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, trench, cable, or cord, unless otherwise permitted in accordance with (1) through (4).

If we stopped right there then John would be wrong. The above rule says all conductors of the same circuit must be in the same cable, etc. However read on concerning that 1 through 4 part of the rule. This backs up what John is saying, maybe. Would like some opinions on this and a wiring style at the end of this reply;

Article 300-3-B-3

(3) Nonferrous Wiring Methods. Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath shall, where run in different raceways, auxiliary gutters, cable trays, trenches, cables, or cords, comply with the provisions of Section 300-20(b). Conductors in single-conductor Type MI cable with a nonmagnetic sheath shall comply with the provisions of Section 330-16.

After reading the above part of the 1 through 4 metioned in 300-3-B, I tend to lean on the belief that John is right that the two cables may be separate going to the same appliance if each cable contains a grounded and grounding conductor serving that same appliance.

I am curious how others read the above rule and section 3 of that rule part. Then consider the following wiring design that I was asked an opinion on. Just for giggles I will tell you that I agreed with the neighboring electrical inspector that ruled the person below could not wire in the manner discribed. This did not make the electrician happy. He has been wiring this way for 20 years as a trade mark of his company. I was his competitor for years in business. It sure drove my electricians crazy trying to figure out what he did when we followed his wiring style.

This competitor wires his three way and four way switch systems using two 12/2 cables instead of one 12/3 cable. The nieghboring inspector rejected his wiring style ruling that all the conductors of the same circuit must be in the same cable.

The question in my mind is does 300-3-B-3 make it to be allowed for him to wire this way. He is using the white wire of one cable as a hot to serve only between two switches and not to the light fixture as a white hot conductor.

Like some opinions on this for my own safe thoughts. Can he or can't he?

Old 10-06-01, 11:53 AM
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It's hard for me to believe that the "all conductors of the same circuit must be in the same cable" rule is this restrictive. If it were, then every junction box in which one cable came in and fed two cables coming out would be illegal. Can't be so.
Old 10-06-01, 01:18 PM
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John this rule only applies to when you are paralleling two wires to the same device, appliance, motor and the like. The thing they are trying to protect from is harmonics problems causing a heating without the neutral being ran with one of the hot conductor concerning serving a certain appliance, switch system, motor and the like. This paralleling to the same piece of equipment is the only place thas this rule applies. Just wanted other thoughts on the subject of forbidding two 12/2 cables taking the place of one 12/3 cable serving the same switch system. Kind of runs along the same subject we had in this post.

Still curious


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