Fixed some nasty wiring. Do I need additional circuits?

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Old 02-02-09, 08:04 PM
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Fixed some nasty wiring. Do I need additional circuits?

I recently moved into a new home and discovered some interesting wiring to say the least.

I had all of the following hooked up to a single 15A circuit breaker:
Kitchen recessed lights (5)
Over sink fluorescent light
Kitchen range hood
Three exterior lights
Dining room and entryway ceiling lights
Living room and dining room outlets (maybe 8 of them, lightly used)
Garbage disposal
Dishwasher

The sub-panel in my garage physically had 2, connected 20A breakers labeled Dishwasher and Disposal. I manage to trace a 12/3 wire from those breakers, through the attic, down to a junction box behind my fridge, which also contains an outlet hooked up to a 20A small appliance circuit. The 15A circuit described above also came into this J-box (definitely a safety hazard, almost zapped myself pretty good. Didn't realize the 15A circuit entered the box at the time). Then from this box, there were 2 12/2 wires going down, under the house to a junction box underneath my island where the d/w and disposal are located. One was hooked up to the incoming 12/3 circuit, and then terminated in the box under the island. The other was hooked up the 15A circuit and of course came up through the floor to power my d/w and disposal.
Realizing most of the wires were already in place, I rewired the outgoing 12/2 wires in that box to the 12/3 wire coming in. I also had to get under the house so that I could run two independent 12/2 wires for the d/w and disposal. I'm happy to say they're now both on their own 20A circuits. And we can run the disposal without fear of nearly every light in the house turning off!

I still have a couple of concerns.
Should I worry about the box that has two different live circuits entering now? I did cut the 15A circuit that had been feeding into that box. I'm using the outlet that lives there to plug in my fridge.

Do I need additional circuits to supply everything that's still connected to that 15A circuit? I think it would be fairly straightforward to run a new circuit to power all the kitchen lights and the range hood.

Thanks.
 
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Old 02-03-09, 08:48 AM
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You're on the right track and doing the right things. You have a good "instinct" as to the way things should be, so do the things you suggested above and the circuits will be less prone to overload and will be safer.

There should be at least two separate 20 amp dedicated GFCI counter top outlet circuits because things in a kitchen can be power hogs. I like the microwave to be on its own circuit. If you have other counter top power hogs like a deep fryer, good idea to run additional dedicated circuits for these as well. Then on Thanksgiving when you have all this stuff on at the same time, the breakers will not trip!

As to having multiple circuits in the same electrical box in a home, this is not a good idea due to safety issues. If this is necessary (like with a 4/5 gang switch box), I like to use tie-bar breakers for all the circuits going into the same box and post a note explaining that the breakers are tie-barred for safety.

As to 3 wire circuits, these may be what is called a Multi-Wire Branch Circuit (MWBC). They share the same neutral. New National Electrical Code requires that the breakers for these circuits be tie-barred so all breakers for the circuit must be turned off at the same time for safety.

I like the idea of lighting being on separate breakers. Then if a breaker trips, you still have lights.

As for doing electrical work, it is always a good idea to turn off the main power as you learned above.
 
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Old 02-04-09, 02:00 PM
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Thanks for the reply.

I don't really have 2 dedicated 20A GFCI counter top outlet circuits. It seems I have a 12/3 MWBC coming into the kitchen. One circuit feeds a single counter top outlet, and then makes its way into my family room to power my TV, stereo, etc (kitchen and family room form one large room). The other circuit feeds all the other kitchen outlets. It ends up powering the fridge, microwave, toaster oven, coffee maker. We've tripped this breaker by running the microwave and toaster oven at the same time. These 2 circuits used to be on independent 20A breakers but I have tied them together.
I don't think it will be very easy to rewire these circuits since most of the access would be behind my tile back splash. It might be easier to run a new circuit for the microwave, fridge, or both. I'm trying to avoid cutting into walls too much, but I would have to do so to run new circuits. I guess I'm not sure how deep I want to get into this. We might do some kitchen remodeling in a couple years at which point I would have to get this all fixed up anyway.
 
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Old 02-04-09, 02:23 PM
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Originally Posted by veeoo View Post
It might be easier to run a new circuit for the microwave, fridge, or both.
That's usually the best course of action. I prefer to let sleeping dogs lie with the existing wiring and just add new where it will be most beneficial. That allows you to meet your present needs in the kitchen while still maintaining the old grandfathered circuits.

and then makes its way into my family room to power my TV, stereo, etc (kitchen and family room form one large room).
This could be borderline depending on how the segments of the large room are defined. The small-appliance branch circuits are allowed to serve kitchen, pantry, breakfast room, dining room, or "other similar area". That would be a good one for the inspector, "I eat all my meals at the TV, therefore it's a dining room!"

We might do some kitchen remodeling in a couple years at which point I would have to get this all fixed up anyway.
That's true. If you did a kitchen remodel, the two 20A circuits would be mandatory at that point. You would also need a dedicated 20A for the range hood (new code).
 
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Old 02-04-09, 05:35 PM
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If I add circuits for both the fridge and microwave, should they both be 20A circuits? Would it be easiest to use another multi wire circuit and run 12/3 wire from my panel to the usage point? Both the fridge and microwave use the outlet behind the fridge. I also think I have an unused pair of tied, 20A breakers in my panel.
 
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Old 02-05-09, 09:41 AM
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Yes you could do that. I tend to shy away from multiwire circuits in most residences simply because of the potential complications with GFCI / AFCI protection and the added requirements on the neutral splices. You also may not really get much or any of a price break on the 12/3 over 2x 12/2 based on pre-packaged rates at the big box stores. You can still re-use the double-pole 20A breaker with two separate circuits, however you might not want to given that a microwave trip could cause a lot of money wasted on spoiled food.

I would probably run two separate 12/2. It's more straightforward and gives you more flexibility for re-use in the future kitchen remodel.
 
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Old 02-05-09, 09:49 AM
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My personal preference in my home is all 120V circuits 20 amps. Things are "happier" with 20 amp circuits!

Then in a home I prefer no MWBC's. Regular wiring easier to understand and safer (for the next DIY owner of house).

For large industrial businesses where only electricians would be working on the wiring, MWBC's are a different story.
 
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Old 02-05-09, 02:26 PM
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Thanks for all the advice. Looks like I will run two separate 12/2 wires on 20A breakers.

I have more questions. I noticed that the ground bar inside my sub-panel is full. The neutral bar still has several open slots. I've searched around and read a lot of conflicting information...Double them up? Don't double them up? Only double up on the ground bar, not the neutral? Add a new ground bar and tie it to the existing ground bar with a large gauge wire?

What's the best method? My panel is a Bryant and it says to use only GB series grounding bars. The existing ground bar is tied to the bare ground of the main line coming into the sub-panel from the main panel.
 
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Old 02-05-09, 02:46 PM
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The neutral wires must be one-per-screw on the neutral bar (NEC 408.41). Grounds of equal AWG may be doubled up on the ground bar according to manufacturer instructions (some even allow triples of #14). You can also buy an add-on ground bar kit for about $10 which will make more room for grounds.
 
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