Where are you located ?

 

New York City

 

I was wondering. I am remodeling my kitchen and I would like to use 12/3 wire with ground to bring power to my fridge and 2 outlets at the counter top. The outlets would have its dedicated line 1 Hot(red) and the Fridge would have the other hot (black) dedicated for the fridge only. My questions is since they're 2 hot lines coming from the panel could one neutral handle it. The 2nd question is the phase. I have 2 phase coming to the house. Should I place both of the Hot line on the same Phase or If I put them on different phases would that be dangerous.

Local codes aside, what you are proposing is a multi-wire branch circuit (MWBC). You can share a common neutral as long as the two hot wires are connected to opposite legs with the appropriate breaker. You do have be careful in wiring a MWBC, though, as there is potential to pass 240V through a single leg of the circuit if the neutral fails. This means that all neutral connections *must* be pigtailed (you cannot pass the neutral through a receptacle from one side of the circuit to the other; if one of the receptacles fails, then whatever is plugged into the other one will probably go "boom"). Also, you need to use a double-pole 20a breaker with a tie-bar, so that if one circuit trips the breaker, both legs are cut off.

Personally, I wouldn't use a MWBC to power a fridge, since there's potential for the fridge circuit to trip off because of another appliance on the other side of the MWBC, but that's my personal preference.

 

when you mean legs do you mean phase. I was thinking to get a twin breaker that is on the same phase. Should I put it on regular single breaker on separate phase.

 

Residential service is 240V single phase. You have two hot legs coming into your service panel (the voltage between either leg and the neutral is 120V, while the voltage between the two hot legs is 240V). While these two incoming hot lines are sometimes referred to as "phases," it is incorrect.

In a multi-wire branch circuit, you *must* use a double-pole breaker with tie bar. This will tie each of the hot wires in your MWBC to opposite legs in the panel. You cannot use "skinny" or tandem breakers to power a MWBC, as these draw from a single leg. The neutral wire in 12/3 is not sized appropriately to support 40 amps of return current, which is the potential if both hot wires are connected to the same leg.

Additionally, you cannot use two single breakers to power a MWBC. If one leg of the MWBC overloads and trips, the other leg is required to trip simultaneously. This is because of the shared neutral; if only one leg trips, and the other remains hot, the neutral could still be live on both sides of the MWBC if a load exists on the untripped side of the MWBC. Using single breakers also allows for the possibility of the breakers being installed incorrectly to a single hot leg in the panel. A double-pole breaker with tie bar eliminates all of these possibilities.

MWBCs are a bit more complicated than standard 20a circuits. You must use a double-pole breaker with tie bar that will trip both legs of the circuit if either leg overloads; the double-pole breaker must draw from opposite hot legs in your service panel, and you must pigtail all neutral connections in all junction boxes (you cannot pass the neutral through receptacles),

 

NEC states that you need (2) 20 amp GFCI protected circuits dedicated to serve your counter tops!

 

I don't believe the specification dictates what sort of GFCI protection is required (breaker vs. receptacle), only that the protection must be provided. For an SABC, I would prefer point-of-use protection for easier access to resets.

I believe that a MWBC would technically be permitted if point-of-use GFCI protection is provided on the SABC, although I personally wouldn't connect a refrigerator to a double-pole breaker on an MWBC (I would prefer to isolate the fridge to its own circuit to reduce the likelihood of that circuit being tripped).

 

Maybe we should ask why you want to use 12/3. It seems like a poor design decision.

NEC does require two Small Appliance Branch Circuits (SABC)to serve kitchen countertops and that they be GFI protected.

Putting an appliance and general purpose plugs on a MWBC is asking for troublesome wiring.

 

Not all Kitchens are going to need two GCFI protected circuits. I can get away with only needing one, because it is such a small Kitchen (8x10), and just went with a GCFI breaker, since it is a older home, and did not want to tear all of the Rock-lathe down for a retrofit job.

 

Again According to the NEC 2008 the kitchen countertops need 2 dedicated 20amp gfci protected circuits. NEC does not state only kitchens over a certain size.

If you were to have done a complete rewire you would have had to bring it up to that standard. You however have not done so and are not required to do such!

 

For separate outlets I would use two separate circuits, and not a MWBC. Where I would use a MWBC is if you have an outlet you want to make a "spit" where the top outlet is a dedicated 15 or 20 amp circuit, and the bottom is another dedicated circuit. Then you use 12/3 and a double pole breaker.

You could probably make your two outlets split if you want. Though personally for the fridge I'd run a dedicated circuit and I think that may even be code in some areas. Kitchens have very perticular codes so it's something to look into before doing any changes. Some of the codes imo don't really make sense from a safety point of view and can make things harder, but still have to follow them.

 

My Kitchen has 3. Not all kitchens are going to have two counter cicuits, especially if they are small kitchens. I would only have one outlet if I had left it as is, but in my case, three outlets was the magic number. I know what the NEC states, but pointing out the obvious, not all Kitchens warrant two GFCI protected circuits. That does nothing to state how many outlets, it is circuits (ie more than one breaker).

 

Well if it is being done to code as it should be. It must have 2 circuits serving the kitchen counter tops. We are here to encourage DIY's to do things in a professional and legal way, Thus we should only make recommendations as the code reads.

 

My kitchen is 8x12 & I have 3 SABC & a dedicated fridge circuit
It originally had only one circuit
Toaster = 850w, Microwave over 1100w, Toaster oven 1500w
Try running that on one 2400w circuit
Add in blender, a few crock pots, electric hot plate for breakfast & its impossible
You are not required to retrofit an older kitchen
But once you renovate yes you need 2 SABC
Its not about what you need or can get by with, its about what the next owner may need & whats required by code

 

Not anyone is going to run all of those small appliances at the same time Dave. Show me someone that wants to do that, and I will show you how to start a fire with all of that load when the breaker fails. A 15 amp circuit will trip if you try to run a toaster and a microwave at the same time. A 20 amp circuit will trip if you try running a toaster, blender and Microwave, maybe lucky to run a toaster oven, or portable Dish Washer at the same time for maybe five minutes before the breaker fails with all of that load.

If it ever comes down when we go to sell the house, and the buyer is so wanting ACFI's and another GCFI to protect the circuit on the opposite side of the Kitchen, I may make that change, but for now, the one by the sink and the one on the opposite side of the Kitchen are sufficient, because the only one that would get used for a Toaster or Blender is to the Right of the sink. The one by the stove is there for convenience, same with the one behind the microwave for the portable Dishwasher & Microwave to plug in.

In the lines of what the OP is wanting to do, MWBC are great if wired correctly, and needing multiple circuits for GCFI protected it would work in this case. Running two separate circuits such as what they are wanting to do (GCFI & dedicated for a fridge) is not going to work, because as mentioned ,the GCFI does not like sharing the Neutral, same with ACFI's. If trying to do it with a ACFI protected circuit, it will not work, without tripping the ACFI when ever a load is placed on the line heavy enough. As mentioned before, you could plug in a small radio, the circuit may not trip, but plug in a heavy enough load on a ACFI circuit, it will fail.

 

Code states one thing, but feasibility is another when you do it in the real world. There is no way a 80 square foot Kitchen may warrant any more than one Small Appliance circuit, lucky to have one outlet only, but a larger Kitchen 100 sq foot or larger can warrant two or more Small Appliance circuits and more than one outlet per circuit. It comes down to semantics when you put it in a real world situation.

 

Code is a minimal standard. We should not instructed DIYers to do anything less than that.

 

That may be in your case, but in ours, we are lucky to run the toaster, which at the same time, would have the coffee pot on at the same time. Everyone's needs are different, and yes, the code is correct, but from feasibility, sometimes it makes no sense, especially in this case, where only one outlet is used all the time, and that is to the right side of my sink. I did make sure that if I ever decide to split the outlet to the left from the one on the right, all I have to do, is change it out in the junction box to add the second SABC if decided. The second outlet was only a addition to allow for power for the portable dish washer to not have to be pulled into the room.

It may change when we do the cabinets this Spring, since the wife wanted the electric done now, and not have only one outlet. In the case of the OP, I thought of using a MWBC in my case, which I could do, but from the headache point, it is not worth it, especially if the next person comes in, and starts messing with the junction box downstairs on the ceiling, and decides to feed 240 to the normally 120v circuit.

 

Its not a matter of what YOU use
Its a matter of what is required by CODE

 

He is gonna keep arguing this. I just hope whatever field he is in, he makes sure his customer get a code complainant job!

 

Refrigerators are allowed on a SABC. If you were to install the fridge and one c.t recep on one leg of a 12-3 circuit and then supply one other c.t recep with the other leg you would have a code compliant installation.

 

I myself would never do anything but give the fridge it's own dedicated circuit. ( again not required) I would not want something else on that circuit to trip breaker while on vacation or away from the house for a good period of time!

I have a total of 7 circuits just for my kitchen!

 

Mine is only four circuits. Dining & baseboard outlets on one circuit, this includes the fridge, lighting for the Kitchen and Dining, 3 Countertop outlets, Disposal is the fourth.

 

What field do you work in? Do you give the customers a code job or just whatever they think is cheapest?

 

Who says I work in the field. I am only giving an example since we all are comparing apples to oranges. In no way, is everyone going to have the same circumstances that they may have the same number of circuits as the next guy, or have it wired in the same way. That is why it irks me, when everyone spouts the NEC as the bible in a way, that everyone's circuit design in the number of circuits needed or outlets needed is going to be the same.

One person's house may have less circuits, than the next guy's, so that is why I myself look at these forums as a guideline, not as this is how you are going to do it, you can not do it any other way. If everyone took the information on the Internet as law, and did not consult with local code authorities and follow what the NEC states in what you can and can't do, we would not see problems in the houses we buy, that some joker thought that zipcord is the proper way.

Again, the circuits that I pointed out with my instance is an example, and I do not expect the OP or someone else to do the same. As for the answer to your question, there is no more need for more circuits in my kitchen, because it is overkill for the small size of it. If it was 125 square feet or larger, yes there would be more circuits wired in it, but in my case as shown as comparison to yours, it only needs four.

 

It's not about what YOU use
It's about what is required in every kitchen
So that the next person does not have to rewire because someone only needed one circuit
Case closed