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# Diagram of junction box

#1
06-03-19, 12:42 AM
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Join Date: Feb 2012
Location: USA
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Diagram of junction box

I'm trying to learn about what's going on inside this light switch box inside my bathroom. There's 2 switches. One controls the ceiling heater and the other switch controls some lights on the wall above the vanity.
So it looks like the conduit to the light switch is the bottom left out. And the conduit that runs to the bathroom heater is the upper right. I'm curious if there's a way you can tell (besides trying to follow where they run in the attic) which conduit comes from the breaker box versus which one runs to more lights and what not in the circuit?
Also why are there 2 neutrals running out the upper right conduit? I'm guessing that one is for the ceiling heater and the other is for the light that's inside the heater box maybe?
And why are there (apparently) 2 hots that run to the bottom left out?

#2
06-03-19, 05:38 AM
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Location: welland ontario
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I'm curious if there's a way you can tell (besides trying to follow where they run in the attic) which conduit comes from the breaker box versus which one runs to more lights and what not in the circuit?
It's probably one of the brown/white conduits. Disconnect the brown from one of them. If everything goes out that was the feed from the panel. If only some stuff goes out that is the out going feed.

Also why are there 2 neutrals running out the upper right conduit? I'm guessing that one is for the ceiling heater and the other is for the light that's inside the heater box maybe?
And why are there (apparently) 2 hots that run to the bottom left out?
Two neutrals is odd. Also using yellow for neutral is not correct. I wonder if yellow was for a light part of heater/light.
Two hots on the bottom left is because one is switched and the other is constant hot for something that is not switched.

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#3
06-03-19, 06:24 AM
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Join Date: Apr 2019
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I'm in agreement with all of Joe's comments.
The neutral conductor must be colored white or gray according to 200.6 of the NEC.
It could be that the yellow wire goes to the light and this separate wire is there so that the light can be switched independently of the heater. There's a good possibility that the wiring at the light has the neutral and hot reversed. If the light has a bulb with a screw-in base you should measure the AC voltage on the outer ring inside the lamp socket relative to the grounded metal housing, after turning on the switch. There should be close to zero volts. If not the hot and neutral connections are reversed.

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#4
06-03-19, 04:56 PM
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Ooops! Disregard my first diagram. There was one mistake on there. The yellow wire that goes into the upper right conduit (to heater/light) actually comes from the other daisy chain. I've made the change with a BOLD line. I'm trying to learn about about the upper right wires because I'm looking to upgrade the heater/light to a heater/fan/light. It looks like maybe it was set up to turn on both the vanity lights AND the light inside the NuTone box. Would you agree? There is no light bulb connector in the NuTone right now, but I may have removed it a few years back. Can't remember.
Could I re purpose the yellow wire as a ground wire (for my new NuTone installation which calls for ground wires)? And if so, do they sell green paint for re color coding electrical wire? Or is the proper way to just pull the yellow cable out and then pull a correctly colored cable in?

Last edited by AndyRooney; 06-03-19 at 07:54 PM.
#5
06-03-19, 08:37 PM
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Join Date: Sep 2002
Location: welland ontario
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The yellow is controlled by the light switch. If there was a light in the heater then then it would come on with the other lights.
You can not use the yellow as a ground. You could use the yellow as a pull to pull in a green wire.
If the conduit is metal then the conduit is your ground.

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#6
06-04-19, 12:16 AM
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Join Date: Feb 2012
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If the conduit is metal then the conduit is your ground.
Conduit is indeed metal.

The instructions for this NuTone that I just bought call for a ground wire running to the unit. Also calls for a (red) hot wire to control the heater. I guess I would pull a red wire through using the yellow wire. I'm going to run some Romex and was going to use that ground.
The heater switch is grounded to the metal box (but I didn't draw that in).
Page 3 (Step 5 has the wiring instructions...
https://images.homedepot-static.com/...1bf4a9c5a9.pdf

#7
06-04-19, 05:20 AM
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Join Date: Sep 2002
Location: welland ontario
Posts: 6,293
Just use the yellow for the hot. Yellow is a legal hot wire.
They show a red wire because most people use NM cable which has a black and red wires.

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#8
06-05-19, 10:44 AM
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Join Date: Feb 2012
Location: USA
Posts: 250
Nobody in the insulation forum has answers. I know this is an electrical forum but maybe someone has some insight.

Must the exhaust duct be insulated or can I just use a standard dryer vent with the foil? I am having to travel about 10 or 12 feet to the louver that vents outside.
I know the concern is moisture condensation turning to mold. I live along the coast of Los Angeles where generally in the Winter time the coldest it gets is into the 40's.

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