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sixspeed 06-03-2012 12:37 AM

Converting a 30 Amp 120/240V circuit into two 20 Amp 120V circuits
 
I presently have a 30 Amp 120/240V dedicated circuit that powers a mini kitchenette appliance with two electric stove burners and a small refrigerator. I would like to remove this all-in-one appliance, and in its place, install an undercounter refrigerator and cabinet/wall mounted microwave.

Can I take the 30 Amp 120/240 circuit and split it into two separate 20 Amp 120V circuits?

The 30 Amp 120/240 circuit is wired with 10/3 from the panel to a surface mounted receptacle behind the kitchenette appliance. I'm thinking of replacing that receptacle with a junction box. From there, run a 12/2 to a standard receptacle for the microwave, and another 12/2 to another receptacle for the refrigerator.

#10 hot (black) ---------------> #12 hot (black - microwave circuit)
#10 neutral (white) <====== #12 neutrals (whites from microwave & refrigerator)
#10 hot (red) ------------------> #12 hot (black - refrigerator circuit)

Then at the panel swap out the 30 Amp double-pole breaker, and replace with 20 amp breaker.

If this plan is acceptable:
1. Do I replace the 30 Amp double-pole breaker with two 20 amp single-pole breakers or a 20 amp double-pole breaker?
2. There is not a problem sharing the #10 neutral return, whether the microwave or refrigerator condenser is operating separately or concurrently?

k_buz 06-03-2012 12:48 AM

I find nothing wrong with any of your ideas. It all looks good. As of the 2008 NEC you would need to install a 2P breaker or two single pole breakers with a handle tie for a multi-wire branch circuit.

frenchelectrican 06-03-2012 12:57 AM

I know you say Red , Black , White but where is green or bare ground conductor ? if so you are good to go.

( Let us know if you do ran this in the EMT conduit that will useally a big plus )

Merci,
Marc

sixspeed 06-03-2012 01:08 AM

What is the NEC reasoning for requiring 2P/tied breakers when the circuits are serving two physically separated 120v appliances?


The 10/3 cable is actually an armored metal cable with no separate bare ground. I would attach it to a metal junction box, then bond a pigtail to the box and tie all the bare grounds from the new cables to the pigtail.
Thanks for the clarifying the details.

Techy 06-03-2012 02:58 AM

because if you only turn one hot of a mwbc off, the neutral is still carrying current, and can shock you.


If this is actually an armored cable, and there is no 'bond strip' (usually folded back at the end of the cable), then you do not have a functional ground per the NEC.

Jim Port 06-03-2012 07:10 AM

Sound like this is in a kitchen so it would require GFI protection also.

You could just add the junction box and add a 2 gang cover plate.

rrolleston 06-03-2012 07:28 AM

If you don't have a proper ground then you could use a 30 amp single pole breaker and use 30 amp 120v circuit. Either way since 10 gauge is such a pain to work with I would install a small outdoor panel and use smaller wire with GFCI breakers for everything except the fridge.

stickboy1375 06-03-2012 08:09 AM

Quote:

Originally Posted by rrolleston (Post 935084)
If you don't have a proper ground then you could use a 30 amp single pole breaker and use 30 amp 120v circuit.

What would this accomplish?


Quote:

Originally Posted by rrolleston (Post 935084)
Either way since 10 gauge is such a pain to work with I would install a small outdoor panel and use smaller wire with GFCI breakers for everything except the fridge.

That is just crazy, why install a panel when he can just install a jbox and accomplish the same exact thing?

stickboy1375 06-03-2012 08:13 AM

Quote:

Originally Posted by sixspeed (Post 935014)
I presently have a 30 Amp 120/240V dedicated circuit that powers a mini kitchenette appliance with two electric stove burners and a small refrigerator. I would like to remove this all-in-one appliance, and in its place, install an undercounter refrigerator and cabinet/wall mounted microwave.

Can I take the 30 Amp 120/240 circuit and split it into two separate 20 Amp 120V circuits?

The 30 Amp 120/240 circuit is wired with 10/3 from the panel to a surface mounted receptacle behind the kitchenette appliance. I'm thinking of replacing that receptacle with a junction box. From there, run a 12/2 to a standard receptacle for the microwave, and another 12/2 to another receptacle for the refrigerator.

#10 hot (black) ---------------> #12 hot (black - microwave circuit)
#10 neutral (white) <====== #12 neutrals (whites from microwave & refrigerator)
#10 hot (red) ------------------> #12 hot (black - refrigerator circuit)

Then at the panel swap out the 30 Amp double-pole breaker, and replace with 20 amp breaker.

If this plan is acceptable:
1. Do I replace the 30 Amp double-pole breaker with two 20 amp single-pole breakers or a 20 amp double-pole breaker?
2. There is not a problem sharing the #10 neutral return, whether the microwave or refrigerator condenser is operating separately or concurrently?

This is all acceptable, just change out the breaker to a double pole 20 and you're good to go. :) I would just verify that the existing 10-3 cable does in fact contain a bonding strip inside...

rrolleston 06-03-2012 10:03 AM

That is just crazy, why install a panel when he can just install a jbox and accomplish the same exact thing?[/QUOTE]

Disregard what I said.

I was thinking outdoor kitchen. I have many people thinking about those and had that on my mind at the time.

stickboy1375 06-03-2012 10:04 AM

Quote:

Originally Posted by rrolleston (Post 935196)
That is just crazy, why install a panel when he can just install a jbox and accomplish the same exact thing?

Disregard what I said.

I was thinking outdoor kitchen. I have many people thinking about those and had that on my mind at the time.[/QUOTE]


HEHE, i was hoping your mind was somewhere else. :)


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