2 circuits on a 3 wire

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vdotmatrix

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BACKGROUND:

* (2) new 20 amp 12/2 circuits (each with own breaker of course), coming from the panel to the switch box in the bathroom.
* New Bathroom exhaust ceiling unit with HEAT, LIGHT, NIGHT LIGHT, and FAN. ( Panasonic FV-11VHL2 )
* (2) 12/3 wire coming from the ceiling unit to the switch box.

* FAN, LIGHT and NIGHT light will share neutral wire from circuit (a) pigtailed in the ceiling unit and in the switch box.
* 4-20A single pole switches in the box will each get their respective BLACK wires from the ceiling unit.

QUESTION:

1. (1) 3-wire cable from ceiling unit back to the box, will control the light (black wire) and night lite(red wire) on circuit (a).
2. the 2nd 3-wire from the ceiling unit will control the FAN (black wire and nuetral from circuit A) and Heat (red wire and neutral from circuit B).

So, if you can follow this narrative, my concern is:

Can I have 2 different circuits within the same 3-wire cable (#2)?

This is OK right?
 
Can I have 2 different circuits within the same 3-wire cable (#2)? YES

This is OK right? YES
 
If you would like you could scrap one of the twelve threes, and put in a twelve two. The whole unit will run on one circuit. You could have three switch legs for light on the twelve three if you color the white wire black with a sharpie marker. Then the twelve two could be black heater and white neutral. Just a thought, unless its too late......Good luck
 
I may be missing something but the way I read it you have no neutral for the lights.

Why worry about combining circuits? just have power (A) feed switch 1 &2 for the light (black) & night-light (red) and splice the whites. do same on 2nd pair of switches with power(B) for fan and heater
 
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The white wire spoke of in my reply is the neutral for all four switch legs. One power to all four switches and one neutral to fan/heat/lite/night lite.
 
triple D said:
If you would like you could scrap one of the twelve threes, and put in a twelve two. The whole unit will run on one circuit. You could have three switch legs for light on the twelve three if you color the white wire black with a sharpie marker. Then the twelve two could be black heater and white neutral. Just a thought, unless its too late......Good luck
Click to expand...

Thanks for the reply.
This is a bathroom exhaust with heat. Current NEC codes require dedicated 20A circuit for the heat portion. I ran 2 3-wires. Diagram to follow:)
 
KEITH said:
I may be missing something but the way I read it you have no neutral for the lights.

Why worry about combining circuits? just have power (A) feed switch 1 &2 for the light (black) & night-light (red) and splice the whites. do same on 2nd pair of switches with power(B) for fan and heater
Click to expand...

Can't combine circuits. That is the exercise here and my question. diagram to follow thanks:)
 
triple D said:
The white wire spoke of in my reply is the neutral for all four switch legs. One power to all four switches and one neutral to fan/heat/lite/night lite.
Click to expand...

The NEC requires an isolated dedicated 20A for the heat, I wanted to completely isolate the heat circuit all the way back to the panel ...I am not sure if this also means the neutral wire.:)
 
KEITH said:
I may be missing something but the way I read it you have no neutral for the lights.

Why worry about combining circuits? just have power (A) feed switch 1 &2 for the light (black) & night-light (red) and splice the whites. do same on 2nd pair of switches with power(B) for fan and heater
Click to expand...
View attachment 3_wirePS.bmp

Can't combine circuits. That is the exercise here and my question; neutral wires are pigtailed in the switch box and in the ceiling for the fan,light and night light and are not shown for either circuit in this diagram as well as the ground wire(s).

The HEAT's 12/3 shares nothing with the other circuit except the yellow covering on the cable; the heat 's red and the neutral belong to that 'heat" circuit.

So....I am sorry I didn't return to this forum earlier. I went to city hall and nailed down one of the electrical code enforcement folk and they said I was spot on with my wiring reasoning...I am no pro...

So if were to have pigtailed ALL the neutrals, for all four devices in the switchbox and in the ceiling, would this have been KOSHER?

I know the word neutral means neutral but wouldn't that be mixing stuff across circuits?
ALL devices will have their separate switches.

thanks
 
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Ok, here's a technique that is not commonly utilized in residential applications but, is still kosher.
You can share a neutral conductor between two individual circuits as long as they are from opposite phases in the load center (i.e.-slots 1&3 are on the same phase whereas, slots 1&2 are on opposite phases). Therefore, being that these are dedicated circuits, it would be safe to use just one neutral out of your 2 12/3 runs, for the entire bathroom.
So depending where you put those (2) 20A breakers in the load center, will depend on whether or not all those neutrals bundled together will be OK or not.
 
kok328 said:
Ok, here's a technique that is not commonly utilized in residential applications but, is still kosher.
You can share a neutral conductor between two individual circuits as long as they are from opposite phases in the load center (i.e.-slots 1&3 are on the same phase whereas, slots 1&2 are on opposite phases). Therefore, being that these are dedicated circuits, it would be safe to use just one neutral out of your 2 12/3 runs, for the entire bathroom.
So depending where you put those (2) 20A breakers in the load center, will depend on whether or not all those neutrals bundled together will be OK or not.
Click to expand...

WOW! That is where being an electrician can save one a lot of time and cost down the road. Yeah, I put them both on the other side, bottom right in the panel... The heat circuit are the red and white to the right side..not neutrally pigtailed as you can see the others are! IMG_6263ps.jpg I ran the 2 12/3 to keep the number of wires in to either boxes down to a minimum since after all, the switch box is only 34cu blue box and i may be approaching the limit of number of wires going into it...

OMG, I hope I haven't exceed the limit of wires going into this switch box:eek:
 

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not even sure what I'm looking at in the second pic but, don't like what I'm looking at if I'm seeing it correctly. And the first pic isn't close enough to read anything, it's just an exposed load center.
For all practical purposes, you could have pulled one 12/3 wire from load center to switch box. Share the neutral (white), heater on the black from phase A (breaker #1) and light and fan on the red from phase B (breaker#2).
 
kok328 said:
not even sure what I'm looking at in the second pic but, don't like what I'm looking at if I'm seeing it correctly. And the first pic isn't close enough to read anything, it's just an exposed load center.
For all practical purposes, you could have pulled one 12/3 wire from load center to switch box. Share the neutral (white), heater on the black from phase A (breaker #1) and light and fan on the red from phase B (breaker#2).
Click to expand...

Don't know what you mean about what you don't like in the picture, but the diagram clearly shows what I have done in the previous post. ...the other stuff about different phases and such may be beyond the scope of the average home owner doin his own work....I have kept things simple as far as I can.....Thanks for your response:)!
 
No worry, it's just a personal preference thing w/me. I don't like to see wirenuts in a load center and I've never seen any diagram in any of your posts. I'm always hesitant to redirect someone unless they are doing something wrong. There are multiple ways to accomplish what you are doing and being that you understood your approach, I just went with it but, then later advised you of alternative approaches (of course my method would leave the average homeowner scratching their head). You'll be just fine with either setup.
 
KOK Man thanks for looking. I appreciate a place like this where people can come in and get help doing some of this stuff...Now I have learned a different aspect of wiring which I will read up about which is phasing in regard to wiring!!!! We save a lot of money doing a lot of this work ourselves..

I do like to caution people who do it yourselves with regard to plumbing and electrical work; HAVE THE WORK INSPECTED BY YOUR LOCAL CODE ENFORCEMENT PEOPLE and pull a permit.40 or 50 dollars is a small price to pay for expert advise on the work you do on your own home. After all, you don't want to endanger your family with work done that is not up to the latest code. The other reason to have stuff inspected , especially electrical , is that if you do have a fire, the Marshall will check at city hall to see if your work was approved, if not your insurance might not pay for damages......

Cheers and thanks to everyone!
 
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kok328 said:
No worry, it's just a personal preference thing w/me. I don't like to see wirenuts in a load center and I've never seen any diagram in any of your posts. I'm always hesitant to redirect someone unless they are doing something wrong. There are multiple ways to accomplish what you are doing and being that you understood your approach, I just went with it but, then later advised you of alternative approaches (of course my method would leave the average homeowner scratching their head). You'll be just fine with either setup.
Click to expand...

MAn I was making Waffles for breakfast this morning and i was thinking about "wirenuts in the load center" and was trying to figure what your were talking about. LOAD Center, load center....OH, he means the electrical panel!!!!!!!!!!!!!!

Of course!!!!!!

Okay...I don't like it either but you have to have some background. The contractor that put in our new addition 5-6 years ago ended up with a few circuits that went NOWHERE at all. But they were attached to a breaker....

I needed a slot on that side of the , a-hemmm, LOAD CENTER, for a welding circuit for the garage and saw that one....I pulled out the wire and secured everything out of the way and capped everything with wire nuts until I can go in and trace this perfectly good 12/2 20A circuit to nowhere through the basement ceiling and so on....

That is why yuo see the blue wire nut!!! GOOD EYE DUDE!!!!!!!!!!!!


:)
 
Correction to my previous post where I stated:
"You can share a neutral conductor between two individual circuits as long as they are from opposite phases in the load center (i.e.-slots 1&3 are on the same phase whereas, slots 1&2 are on opposite phases). "

Slots 1&2 are on the same phase & slots 1&3 are on opposite phase.
 
kok328 said:
Correction to my previous post where I stated:
"You can share a neutral conductor between two individual circuits as long as they are from opposite phases in the load center (i.e.-slots 1&3 are on the same phase whereas, slots 1&2 are on opposite phases). "

Slots 1&2 are on the same phase & slots 1&3 are on opposite phase.
Click to expand...

Well there ya go! I would have failed the inspection ( not because of you), if I would have located the breakers on the wrong side of the LOAD CENTER.

This is a way advanced electrical concept/technique, which would have made the Inspector otherwise, not have to examine the load center for this premise; but this could have saved wire if you didn't have enough room in the box due to wire volume calculation limit and would have been clever!

Wow what a mess, to have to have gone back in and rewire the load center for opposite phases for these 2 circuits....uggg.

Alright Poindexter, now I have to know...from the picture of my 40 slot load center, the 2 "new" breakers for this project are located on the right hand, "even" side, #36 and #38.

Are these circuits phased equally or opposed? :D
 
36 & 38 are on opposite/adjacent phases.

However, if they were not, you don't have to rewire anything, just move the circuit breakers.
 
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My project passed both electrical and mechanical final inspections this morning!!!

Thanks to everyone for their interest!!!


cheers:D
 
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