I have a similar situation with one 12/3 supply that feeds 8 receptacles in the living room, 5 receptacles in the mud room, and one receptacle in the garage. These are 2-prong 20amp receptacles. I am in the process of adding GFCI to the first receptacle of each branch in the house so that I can switch to 3-prong receptacles (per code). However, I believe having two circuits tied together with a common ground wire will cause the GFCI to trip continuously. I am thinking that I will have to replace the 12/3 with two 12/2 2 WG. I have plaster walls and trying not to have to tear them out to do this work. Do you have a (by code) workaround? Where would I find a reference to this in the NEC code book? I am reading the NFPA 70 book for 2023.
From the comments and the video title, I see you are calling this two circuits. Note that the NEC calls this a single circuit because that’s what it is. It is no different than the line feed or service entrance to your panel. It is a single, 240v circuit. Because of Ohms law and the increased resistance, 120v loads work, with the neutral carrying any imbalance. In fact, if the circuit had perfect balance, there would be no current on the neutral. One circuit. In short, we don’t consider the feed to a panel or a service drop on a house two circuits, and multi-wire branch circuits also aren’t two circuits. This is a most useful distinction when you want to run power to a detached building, and don’t want a sub panel. By being one circuit, you don’t need to drive additional ground rods, but you have twice the power in the out building.
Awesome. Thanks for the walk through! Definitely cheaper to run a single 12/3 wire since it is 2/3 the amount of copper than running two 12/2 wires. I guess it comes down to the price of the breakers: two single pole vs. one two pole. Great video!
Have a condo 1970's and using alumiconn connectors. But they have a 3 wire coming from box with black to fridge outlet, shared neutral and red going to GFI and Dishwasher switch. Source is one 20 amp breaker. Electrician ran a separate copper on separate breaker so should use that for gfi/dw and the 3 wire for fridge. But how do I alumiconn 3 wire aluminum to copper? Have the green screws and box with raised grounding hole.
I’m upgrading my old glass screw in fuse panel in garage to seimens panel. Currently 12/3 is the feed. 20a breaker from main panel, and 10 120v outlets in garage with lights. How can I wire the new seimans panel safely without too much rewiring
You should be able to replace it without any rewiring. The only issue will be if the existing wires are long enough. You may have to adjust the location of the box or use junction boxes if wires are to short.
Is it permitted to run this method in my wood shop to create a 3 gang box thats jas one 12/3 and has 2 duplex 120v outlets for my miter saw and table saw/sander or whatever else needs to be plugged in on seprate circuts to eachother then a single 220v plug for my planer at the end of the loop?
Maybe a better way to explain. Have the black go to a outlet then pass on, then have the red go to a outlet and pass on making them like the video on 2 circuts, then connect the black and red to a single 220v plug?
@@timpalmer-logstolumber1999 Thankyou! I searched forever for this very set up, and finally found your video, you explaned it it detail and easy to understand. Thanks Again!!
Wouldn't you be potentially overloading the neutral wire? Say if 10A is being used on both circuits then 20A will be going through the neutral etc. I was wondering cause I realized they did this on my house quite a bit on all the breakers. Furthermore the metal piece that ties the seaman breakers together doesn't work well to trip both at the same time. these are ones that are used on the single slot breakers that have the dual breakers.
I'm going to end up answering my question but I didn't think about it that since they are on the different phases the return current cancels out. But its good to note that you do need to make sure each hot wire is on a different phase.
This is confusing, it sounds like what you are saying is for example you could run the 12/3 to a 220v outlet and pull 36 amps from the two 20 amp breakers / toggles that are tied together. Is this correct? I have no idea just looking for the awnser, Thanks!
If you use two breakers tied together you have 120 volts with a shared neutral. Each half will pull max 20 amps. The neutral will balance them out. If you want 220 volts you would use a double breaker.
I just ran into that set up. The breakers are not tied together. Using a none touch sensor to test if they are hot it sounds and lights up that both are hot unless I turn both breakers off. Could this be a false alarm because the two hots are so close together?
Don't worry about running 2 separate circuits for your dishwasher and disposal. They can share the same circuit and breaker. Reason being that a disposal will run for 30 seconds or less even if you run it while the dishwasher is running. So don't waste the wire or extra breaker. Where the problem arises is now everything in a kitchen has to be on GFCI. Well for your countertop outlets that's easy . Just feed the first receptacle as a GFI and then it will protect anything downstream. For dishwasher and disposal they will both have to be GFCI. You can use a GFI outlet under the sink to feed both appliances or you can use a GFI circuit breaker in your panel or to have the best of both worlds you could use a dead front GFCI on the counter with other switches or stand alone. A dead front GFI doesn't have slots to plug in appliances. Just a test and reset button. On your dishwasher we use to hard wire to the #12 Romex and make the connection in the little junction box. But I think code requires a disconnect for the dishwasher. You can buy a ready made 6' pigtail that is rated for 15 amps for the dishwasher and you will also need a pigtail for the disposal. I would use 2 receptacles under the sink. That way you have each appliance plugged into it's own receptacle. The disposal receptacle will be fed by the switch on the counter. The dishwasher receptacle has a direct connection to power. But you must have a gfi protection for both appliances. For convenience use a dead front GFI. Line side will be power from electrical panel. Load side will feed both disposal and dishwasher. So on the Romex feeding disposal you will come from load side of gfi to a switch at a convenient location and then down to the receptacle designated for the disposal.
So watching your demo here it seems like I could safely run 2 12-3 wires from my main house panel to a tiny house I’m building that will need 4 20 amp circuits. If so, I have an existing 1” pvc conduit under my driveway- would that be adequate for the two 12-3 wires?
While it might "fit" you can't run more than 1 branch circuit to a detached building without adding a full subpanel and thus, you will also need grounding rods at the detached building. This is also known as a MWBC (Multi Wire Branch Circuit). So if you're pulling permit as mentioned below, that's a no go.
@@WhittyOne I don’t need a permit but I want to be safe. It would mean breaking up a lot concrete to do another conduit to the tiny house if needed but I think I need four circuits over there. 1 for the heat pump, 1 for small water heater and fridge, 1 for lights and 1 for outlets. Is there any way to do that safely in a 1” conduit that you know of? I’m fine with a sub panel and grounding rods at the tiny house.
Your theory is correct as far as using 12/3 to use two different circuits, however you demonstration isn’t. Demonstration is 2 20a single circuits with 240v in the panel.at the boxes You just used the 12-3 traveler to tie power through to the box jumper.nothing was done with the red traveler. Now, your explanation was correct, however you can no longer do this because you now have two 20a circuits sharing one neutral rated for one circuit back to power source.
@@timpalmer-logstolumber1999what if you drove 18-19amps on both circuits at the same time? Wouldn’t that push 36-38amps back through the neutral if they are on the same phase/pole? I just moved into a place with a home theatre wired up like this with 14/3 shared on 2 15amp breakers on a single phase. Worried about overloading the neutral before tripping either breaker. or does this scenario mean you can only collectively use 15amps total. So 8amps run off each circuit together would trip the 15amp breaker?
@@kamac1980 They are two separate circuits. Each can pull 20 amps but rarely does. The neutral takes the excess power back to the panel box. A circuit only pulls power when there is something on. So if each is pulling 18 amps that means something is using 18 amps and only a little stray amps goes back on the neutral. Hope this helps.
You can share the neutral as long as the Power conductors are not on the same phase. Look at your panel and bussing closely. You will see that circuits 1 and 2 are on phase A. 3 and 4 on phase B. 5 and 6 on A. 7and 8 on B. And so on down the panel. So to use a 3 wire cable. You have to use a 2 pole circuit breaker that has one pole that connects to the A phase in your panel and the other connects to B phase. So it follows, circuit 1 and 3 are on phase A and B and the breaker plugs into those fingers automatically. If you want you can use spaces 2 and 4 and you will connect to phases A and B.
I don't see the benefits of a shared neutral. You still have to shut off both circuits to work on one circuit. Cost savings can’t be that much when wiring a small house. I say this because the moron I bought my house from ran a shared neutral on two separate breakers with no tie bar. I found the hack job in the attack. He ran a 14 gauge neutral from a 20amp circuit to close a 15amp circuit.
I mapped out the two circuits (used a Klein tracer) and pulled out the 14-2 nonsense used to cross neutrals. Rewired with 12- 2 and no more shared neutral. It was total bs.
’m no pro electrician. Took a house wiring class in 10th grade in 1992 - common sense early. To add to the idiocy, whoever crossed the neutrals in my attic ran them on the same phase.
Yeah but with today's code this isn't legal. All circuits must have their own neutral in residential wiring and Arc Fault breakers won't work in this application.
Nicely done, to the point with no bs
This is 5th vid/page I saw trying to figure it out. You nailed it. Thanks!
Glad to be of service
Thank you sir. This video has cleared a few things up that I had been confused about.
thank you! Easy to understand.
clear and understandable
I have a similar situation with one 12/3 supply that feeds 8 receptacles in the living room, 5 receptacles in the mud room, and one receptacle in the garage. These are 2-prong 20amp receptacles. I am in the process of adding GFCI to the first receptacle of each branch in the house so that I can switch to 3-prong receptacles (per code). However, I believe having two circuits tied together with a common ground wire will cause the GFCI to trip continuously. I am thinking that I will have to replace the 12/3 with two 12/2 2 WG. I have plaster walls and trying not to have to tear them out to do this work. Do you have a (by code) workaround? Where would I find a reference to this in the NEC code book? I am reading the NFPA 70 book for 2023.
Thanks!
From the comments and the video title, I see you are calling this two circuits. Note that the NEC calls this a single circuit because that’s what it is. It is no different than the line feed or service entrance to your panel. It is a single, 240v circuit. Because of Ohms law and the increased resistance, 120v loads work, with the neutral carrying any imbalance. In fact, if the circuit had perfect balance, there would be no current on the neutral. One circuit. In short, we don’t consider the feed to a panel or a service drop on a house two circuits, and multi-wire branch circuits also aren’t two circuits.
This is a most useful distinction when you want to run power to a detached building, and don’t want a sub panel. By being one circuit, you don’t need to drive additional ground rods, but you have twice the power in the out building.
Awesome. Thanks for the walk through! Definitely cheaper to run a single 12/3 wire since it is 2/3 the amount of copper than running two 12/2 wires. I guess it comes down to the price of the breakers: two single pole vs. one two pole. Great video!
Have a condo 1970's and using alumiconn connectors. But they have a 3 wire coming from box with black to fridge outlet, shared neutral and red going to GFI and Dishwasher switch. Source is one 20 amp breaker. Electrician ran a separate copper on separate breaker so should use that for gfi/dw and the 3 wire for fridge. But how do I alumiconn 3 wire aluminum to copper? Have the green screws and box with raised grounding hole.
They make connectors for it.
I’m upgrading my old glass screw in fuse panel in garage to seimens panel. Currently 12/3 is the feed. 20a breaker from main panel, and 10 120v outlets in garage with lights. How can I wire the new seimans panel safely without too much rewiring
You should be able to replace it without any rewiring. The only issue will be if the existing wires are long enough. You may have to adjust the location of the box or use junction boxes if wires are to short.
Do the two breakers have to be the same amperage? or can I run a 15 amp for a lighting circuit and a 20 amp for a receptacle circuit?
Should not mix breakers
Can you use a two pole arc fault breaker to protect this circuit?
Arc fault breakers don't work with shared neutral
Is it permitted to run this method in my wood shop to create a 3 gang box thats jas one 12/3 and has 2 duplex 120v outlets for my miter saw and table saw/sander or whatever else needs to be plugged in on seprate circuts to eachother then a single 220v plug for my planer at the end of the loop?
Maybe a better way to explain. Have the black go to a outlet then pass on, then have the red go to a outlet and pass on making them like the video on 2 circuts, then connect the black and red to a single 220v plug?
No that will not work. It has to be either 120 volts or 220, it can't be both.
Can I connect more receptacles by continuing out of the second box with the 12-2 wire?
yes, you can run them like other plugs
@@timpalmer-logstolumber1999 Thankyou! I searched forever for this very set up, and finally found your video, you explaned it it detail and easy to understand.
Thanks Again!!
Wouldn't you be potentially overloading the neutral wire? Say if 10A is being used on both circuits then 20A will be going through the neutral etc. I was wondering cause I realized they did this on my house quite a bit on all the breakers. Furthermore the metal piece that ties the seaman breakers together doesn't work well to trip both at the same time. these are ones that are used on the single slot breakers that have the dual breakers.
I'm going to end up answering my question but I didn't think about it that since they are on the different phases the return current cancels out. But its good to note that you do need to make sure each hot wire is on a different phase.
@@firefox2026 that is correct, that is why they need to be tied together
This is confusing, it sounds like what you are saying is for example you could run the 12/3 to a 220v outlet and pull 36 amps from the two 20 amp breakers / toggles that are tied together. Is this correct? I have no idea just looking for the awnser, Thanks!
If you use two breakers tied together you have 120 volts with a shared neutral. Each half will pull max 20 amps. The neutral will balance them out. If you want 220 volts you would use a double breaker.
I just ran into that set up. The breakers are not tied together. Using a none touch sensor to test if they are hot it sounds and lights up that both are hot unless I turn both breakers off. Could this be a false alarm because the two hots are so close together?
You could check the first box on the circuit to see they go in different directions.
Back feeding thru the neutral wire. Youll get voltage from neutral to ground doing this.
I have an existing 10/3 wire. I want to use this principle to take the 10/3 wire and power two 20A receptacles. Is this problematic?
No
Can this be done for the disposer and the dishwasher?
yes
Don't worry about running 2 separate circuits for your dishwasher and disposal. They can share the same circuit and breaker. Reason being that a disposal will run for 30 seconds or less even if you run it while the dishwasher is running. So don't waste the wire or extra breaker. Where the problem arises is now everything in a kitchen has to be on GFCI. Well for your countertop outlets that's easy . Just feed the first receptacle as a GFI and then it will protect anything downstream. For dishwasher and disposal they will both have to be GFCI. You can use a GFI outlet under the sink to feed both appliances or you can use a GFI circuit breaker in your panel or to have the best of both worlds you could use a dead front GFCI on the counter with other switches or stand alone. A dead front GFI doesn't have slots to plug in appliances. Just a test and reset button. On your dishwasher we use to hard wire to the #12 Romex and make the connection in the little junction box. But I think code requires a disconnect for the dishwasher. You can buy a ready made 6' pigtail that is rated for 15 amps for the dishwasher and you will also need a pigtail for the disposal. I would use 2 receptacles under the sink. That way you have each appliance plugged into it's own receptacle. The disposal receptacle will be fed by the switch on the counter. The dishwasher receptacle has a direct connection to power. But you must have a gfi protection for both appliances. For convenience use a dead front GFI. Line side will be power from electrical panel. Load side will feed both disposal and dishwasher. So on the Romex feeding disposal you will come from load side of gfi to a switch at a convenient location and then down to the receptacle designated for the disposal.
So watching your demo here it seems like I could safely run 2 12-3 wires from my main house panel to a tiny house I’m building that will need 4 20 amp circuits. If so, I have an existing 1” pvc conduit under my driveway- would that be adequate for the two 12-3 wires?
I would think they would fit
Yes if you aren’t using a permit 😂
I’m not getting a permit but I still want to be safe. I’d be interested in your take.@@benjaminsmith4054
While it might "fit" you can't run more than 1 branch circuit to a detached building without adding a full subpanel and thus, you will also need grounding rods at the detached building. This is also known as a MWBC (Multi Wire Branch Circuit). So if you're pulling permit as mentioned below, that's a no go.
@@WhittyOne I don’t need a permit but I want to be safe. It would mean breaking up a lot concrete to do another conduit to the tiny house if needed but I think I need four circuits over there. 1 for the heat pump, 1 for small water heater and fridge, 1 for lights and 1 for outlets. Is there any way to do that safely in a 1” conduit that you know of? I’m fine with a sub panel and grounding rods at the tiny house.
If a short fault occurs on one leg/branch with the breakers mechanically bonded, how or does it trip both breakers?
You have to connect the two breakers, so one trips both.
@@timpalmer-logstolumber1999 hey, thanks for your reply.
@@sidwalker6902 Not a problem, glad I could help
@@timpalmer-logstolumber1999 So basically a 220 breaker, then?
@@billmonroe8826 yes
Your theory is correct as far as using 12/3 to use two different circuits, however you demonstration isn’t. Demonstration is 2 20a single circuits with 240v in the panel.at the boxes You just used the 12-3 traveler to tie power through to the box jumper.nothing was done with the red traveler. Now, your explanation was correct, however you can no longer do this because you now have two 20a circuits sharing one neutral rated for one circuit back to power source.
Why do you need two breakers if both circuits can hold up to 20 amps? College student just trying to learn.
By “hooked together” do you mean them being side my side and the wires being screwed in the breaker?
They are separate circuits. Each circuit carries 20 amps but they share the neutral. It is usually so you can run one three wire instead of two wires.
@@chrismac9315 The toggles on the breakers are tide together so that when you turn off one, they both are turned off.
@@timpalmer-logstolumber1999what if you drove 18-19amps on both circuits at the same time? Wouldn’t that push 36-38amps back through the neutral if they are on the same phase/pole? I just moved into a place with a home theatre wired up like this with 14/3 shared on 2 15amp breakers on a single phase. Worried about overloading the neutral before tripping either breaker. or does this scenario mean you can only collectively use 15amps total. So 8amps run off each circuit together would trip the 15amp breaker?
@@kamac1980 They are two separate circuits. Each can pull 20 amps but rarely does. The neutral takes the excess power back to the panel box. A circuit only pulls power when there is something on. So if each is pulling 18 amps that means something is using 18 amps and only a little stray amps goes back on the neutral. Hope this helps.
Thought sharing neutrals was not recomended
In this case they are shared. As long as both circuits are turned off at the same time so you don't get feedback through the neutral.
You can share the neutral as long as the
Power conductors are not on the same phase. Look at your panel and bussing closely. You will see that circuits 1 and 2 are on phase A. 3 and 4 on phase B. 5 and 6 on A. 7and 8 on B. And so on down the panel. So to use a 3 wire cable. You have to use a 2 pole circuit breaker that has one pole that connects to the A phase in your panel and the other connects to B phase. So it follows, circuit 1 and 3 are on phase A and B and the breaker plugs into those fingers automatically. If you want you can use spaces 2 and 4 and you will connect to phases A and B.
Best to run two Romex now that everything has to be onstc fault breakers.
I don't see the benefits of a shared neutral. You still have to shut off both circuits to work on one circuit. Cost savings can’t be that much when wiring a small house.
I say this because the moron I bought my house from ran a shared neutral on two separate breakers with no tie bar. I found the hack job in the attack. He ran a 14 gauge neutral from a 20amp circuit to close a 15amp circuit.
Different gauge wires should not be used on same circuit. If it can't be changed make sure it's breakered at smaller amps. Label for future reference.
I mapped out the two circuits (used a Klein tracer) and pulled out the 14-2 nonsense used to cross neutrals. Rewired with 12- 2 and no more shared neutral. It was total bs.
And therein lies the problem. Everyone thinks they are an electrician. Thank you Home Depot!
’m no pro electrician. Took a house wiring class in 10th grade in 1992 - common sense early.
To add to the idiocy, whoever crossed the neutrals in my attic ran them on the same phase.
Yeah but with today's code this isn't legal. All circuits must have their own neutral in residential wiring and Arc Fault breakers won't work in this application.
When you teach wiring you have to show the old stuff that you may run across when working on older houses.
This meets code and some arc fault breakers are listed to be tied together for multi wire applications. GE is one of them.