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Two hots sharing the same neutral in the kitchen (+ GFCI breaker)

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ctviggen

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I have discovered in my early 2000s house that they wired two circuits in the kitchen using 12/3 wiring with two INDEPENDENT 20 amp breakers for each hot leg. In other words, you can turn off one leg via one breaker while the other one is on.

According to this:


They appear to be correctly wired in the sense that each leg goes to a different phase. However, it seems as if I should replace the two independent breakers with a (single) two pole circuit breaker.

Does this seem like a wise thing to do?

How I found this was I was going to add a GFCI breaker and remove the GFCI outlet in the circuit. The GFCI outlet protects three other outlets on this circuit, and for various reasons, I wanted to use a GFCI breaker instead to protect the whole circuit and remove the GFCI outlet. So, I ordered the proper 20 amp, single pole breaker for my breaker box and installed it...only to realize the above issue.

I assume that having a single pole GFCI breaker on one leg of a shared circuit (aka multi-wired branch circuit) is not a good thing to do? (I immediately went back to the "old" circuit once I saw this issue.)

Can I install a two pole GFCI circuit breaker in this situation?
 

ctviggen

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Hmmm...the two legs are (1) dishwasher; and (2) 4 outlets (including the 1 GFCI outlet that protects the other three). The dishwasher is hardwired and the wiring is not accessible without removal of the dishwasher.

So, if a two pole GFCI does work, it might not be a bad thing to do.
 

bud16415

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Do you have a tie strap between the handles of the two breakers so if one trips it trips the other or if you work on it you have to shut them both off?



I like the GFCI at the location as they have half a chance of being tested from time to time. They should be tripped once a month to make sure they are working properly. Almost no one does that though.



Sounds like you have a proper MWBC.

The pros should be along shortly.
 

ctviggen

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No tie strap. So, I have to shut them both off independently. In fact, I'm about to expand a box in the kitchen from one gang to two, and will have to turn both off (the second leg runs through this box). This box is really the only one of the four we use, and we need 4 outlets to run phone (yes, a hardwired phone), Alexa/Amazon Echo, and the one kitchen appliance we sometimes plug in.

After a ton of research, I can get a replacement for my particular breaker box (Siemens, hard to find locally):


And this supposedly self-tests monthly.

So, I'll order this from Amazon, wait the week it takes to get here, and install it. This should provide GFCI protection to both legs.

I do have one of those testers you plug into the outlet and then push a button to test GFCI functionality. I do it sometimes (just tested the GFCI outlet for instance), but not near monthly.
 

bud16415

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Just doing it that way if it does trip even a false trip as they sometimes do, you will have to go to the panel to reset it. My panel is in the far end of the basement and it would be a pain.



Some of them the in wall ones seem to trip a lot as plugging something in I bump the test button. Things like USB chargers etc.

Mine are in the wall and seem fine but if I had two breakers on a MWBC (I have none) I would want the tie bar just for safety.
 

JoeD

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Have you looked at the price of a two pole GFCI. When you do I think you will go with a two pole normal and leave the GFCI receptacle.
 

ctviggen

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They are a bit pricey.

What I did was put the GFCI outlet in and then wire the load part of it to the outlet next to it (see pic, which shows the Amazon Echo on there), then from there to the other three outlets. I checked that the GFCI works for the other outlets using a GFCI tester (you plug it in, it has LEDs to show proper wiring, then you hit the button and the GFCI goes off).

Everything works well.

I was wrong about the dishwasher: it is hardwired but goes to a switch on the wall. Sorry, I always forget about this switch, since I never use it.

So, if I don't replace with a GFCI two pole, should I replace with a normal two pole? That would be easier, and since everything works, I guess there's no reason to use a GFCI (though I would do the normal two pole).

I'm posting my first picture. I'm going to insert a thumbnail to see what it looks like.

20200706_151039[1].jpg
 

ctviggen

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Sorry. On my "vacation", I've been doing projects that have built up over time. One of which was to install some "Insteon" switches (these are programmable and can be controlled by Alexa/Echo). I've had these switches for a long time.

So, for that project, I installed switches for kitchen and outdoor lights....and the wiring was the same on these circuits as in the kitchen. That is, the neutrals were basically tied together, the hots were adjacent in the breaker box, and there was no bar across the two breakers.

My house was built in the late 1990s, I think 1998. Was this allowed by code back then?

I realize now that I believe the lights in my main bathroom are similarly wired.

Is there a way to determine which circuits are like this without pulling out switches and diagnosing the circuits? Or do I have to figure these out as I go, mark them as such, and install the proper breaker?
 

bud16415

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If you get behind the panel in your breaker box it should be apparent. Likely the wires leading to different locations in your home on MWBC will be black, white, red and the bare copper. Where you see them going to two breakers side by side it will be a MWBC.



There is nothing wrong with this method and it is to code.



I would just get the connectors for the breaker handles or replace them as you are suggesting if you feel you need to.



I have seen where they are also wired together thru the hole in the handle so the mechanically stay together. Do a google search on (circuit breaker handle tie) you will see the little pins that lock some together and the clips for others.

 

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