Probably another simple switch question

[COamateur]

I've got 4 different sets of fixtures between our dining room and kitchen: 1 set of can lights + 1 set of pendants in EACH room. I'd like each fixture group to have it's own dimmer switch, all in the same switch box.

The source power comes in directly between the rooms with 12/3 nm cable (the dining room is branched from the red to create a separate circuit).

I'm trying to figure out the easiest way to switch all of these devices. Especially if there's a way where I don't need to run 4 separate 12/3 cables from the switch box to each group of fixtures. Wasn't sure if there's a way around that.

Thanks for any advice!

 

[westward10]

If they are all on the same breaker you would only need two cables to the switch bank, one 12/3 and one 12/2. Using a joint box at the power source you only need take one hot to the switches and four hot returns that is five wires. The neutrals stay at the joint box and not to the switches.

 

[COamateur]

If they are all on the same breaker you would only need two cables to the switch bank, one 12/3 and one 12/2. Using a joint box at the power source you only need take one hot to the switches and four hot returns that is five wires. The neutrals stay at the joint box and not to the switches.

They're actually on 2 different breakers, which are ganged together at the panel. I believe it's considered a multiwire branch circuit (not as common, for good reason).

Does that change any of the above info?

 

[westward10]

Unfortunately I am not US based to answer that without giving correct advice however @Megawatt may know.

 

[Megawatt]

They're actually on 2 different breakers, which are ganged together at the panel. I believe it's considered a multiwire branch circuit (not as common, for good reason).

Does that change any of the above info?

What do you mean breakers ganged together. You cannot share neutrals and with at least 2 separate hots in one switch is a accident waiting to happen. As @ Westward mentioned all you need is 1 live to power on all the switches. Dimmers are larger than regular switches and I’m not sure they will fit but as stated above you will need a neutral. Please don’t get the 2 neutrals crossed. The cable with one of your live wires and that neutral with needs to be used.

 

[COamateur]

What do you mean breakers ganged together. You cannot share neutrals and with at least 2 separate hots in one switch is a accident waiting to happen. As @ Westward mentioned all you need is 1 live to power on all the switches. Dimmers are larger than regular switches and I’m not sure they will fit but as stated above you will need a neutral. Please don’t get the 2 neutrals crossed. The cable with one of your live wires and that neutral with needs to be used.

Sorry for the confusion @Megawatt It is a 20amp double pole breaker.

 

[COamateur]

Sorry for the confusion @Megawatt It is a 20amp double pole breaker.

What do you mean breakers ganged together. You cannot share neutrals and with at least 2 separate hots in one switch is a accident waiting to happen. As @ Westward mentioned all you need is 1 live to power on all the switches. Dimmers are larger than regular switches and I’m not sure they will fit but as stated above you will need a neutral. Please don’t get the 2 neutrals crossed. The cable with one of your live wires and that neutral with needs to be used.

Here is a diagram showing what was previously going on:

• The source power 12/3 came into the kitchen pendant
• An additional 12/3 cable connected the kitchen and dining pendants (red to red; black to black; white to white...all at the kitchen pendant)
• The switch leg for the kitchen lights tied into the kitchen pendant (switch black to fixture black; switch white to source black)

At the dining room chandelier:

• The 12/3 black connects to 12/2 black (leading to living room outlets)
• The 12/3 white connects to 12/2 white (leading to living room outlets) + Light Fixture Wire
• Black from 12/2 switch let connects to Light Fixture Wire
• White from 12/2 switch leg connects to red from 12/3

 

[westward10]

I'm non too au fait with US wiring so @Megawatt why would you have a 12/3 source cable and not a 12/2?

 

[Megawatt]

I'm non too au fait with US wiring so @Megawatt why would you have a 12/3 source cable and not a 12/2?

I'm non too au fait with US wiring so @Megawatt why would you have a 12/3 source cable and not a 12/2?

@Westward the only reason that I can think of is 3 way switching which is maybe one of the reasons that he has 12/3. What he needs is 12/2 to do the whole installation. The power needs to be took off the double pole breaker and make it 2 single breakers

I'm non too au fait with US wiring so @Megawatt why would you have a 12/3 source cable and not a 12/2?

@Westward For the installation he has requires

I'm non too au fait with US wiring so @Megawatt why would you have a 12/3 source cable and not a 12/2?

12/2, where and for what purpose that he has 12/3 is beyond me unless he has one set of lights on 3 way light switches or the red is on 1 breaker and the black is on the other breaker which he says is a double pole. It’s dangerous to have two circuits on different phases in the same box just for lighting

 

[Megawatt]

They're actually on 2 different breakers, which are ganged together at the panel. I believe it's considered a multiwire branch circuit (not as common, for good reason).

Does that change any of the above info?

COamateur my advice to you is hire a qualified electrician

 

[COamateur]

Thank you @Megawatt . I received more clarity around what I have. I called a local electrical inspector and walked him through it. Apparently it's a common practice — multi-circuit branch system with a shared neutral. Basically it's 2 circuits, on a double breaker, sharing a neutral. And it's legal It took me a little while to get my brain wrapped around it. But I figured it out!

Thanks all for the help! Certainly appreciate it!