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I would like run two 20-Amp circuits to a 2-gang box with two duplex outlets.

One duplex outlet on Phase A and the other on Phase B.

I know to keep the hots and neutral separate and that the grounds can be combined.

Is there anything special I need to do at the panel?

For example, should I use a tandem breaker with these two circuits.

Revised: 2020-June-04

More clarification to come.

All work will be inspected by the city that I live in. I want to make the inspector proud of me and my quality work. I am taking no short cuts. If the inspector makes me do it again, I'll do it again. This is how I will learn.

The work will on a 2-story unfinished 20x24 detached garage. The second floor will be a studio apartment style (for my personal use only - no renters). I plan to use the first floor for combo car-garage and workshop (car/wood/kids projects/etc.). I do not believe I will need any 240V circuit.

The idea is if I have a 120V air-compressor and 120V ShopVac running at the same time, I did not want to start tripping breakers. All the equipment would not be stationary. For example, I can move everything to one side if I need to work on a my car.

Trying to plan for a future requirement is driving me crazy. So I am trying to build in flexibility so I want have to bang my head on the floor too hard.

I had the panel upgraded to 200A Eaton Plug-on Neutral and I have currently installed plug-on neutral breaker (GFCI/AFCI combo).

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  • What sort of space are you doing this in, if I may ask?
    – ThreePhaseEel
    Commented Jun 2, 2020 at 2:40
  • This is a 24'x20' detached two story garage. The second floor is a versatile studio apartment type space with full bath and kitchenette used for teen hangout, dad get away space, home office, art studio, rock-band practice space, groupies maker space, and/or STEM lab.
    – Turtle Turtle
    Commented Jun 2, 2020 at 2:47
  • If possible, I would like this installation to be safer that the NEC would require. If it cannot be accomplished safely, I'll try to figure an alternative.
    – Turtle Turtle
    Commented Jun 2, 2020 at 2:50
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    I'm more asking because there are some applications where the ability to have both 120 and 240V available is valuable (such as in a shop space)
    – ThreePhaseEel
    Commented Jun 2, 2020 at 2:53
  • 2
    You may get better results by describing your current situation (including a pic of your current power panel), your location in the world, the destination space (as in your 1st comment), and your desired uses (120/240v, number and types of expected devices to be used, etc), then describe your planned solution. Ask for input on that solution and recommended changes/improvements. There are quite a number of electricians who frequent this board who will provide code compliant recommendations that will meet your needs instead of vague guesses based on very limited info.
    – FreeMan
    Commented Jun 2, 2020 at 11:43

4 Answers 4

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What you're proposing is totally fine.

Let's be clear about what a yoke is. A yoke (literally) is the metal frame that holds the recep and that the 2 mounting screws go through. As long as there is only 1 circuit on that yoke, you don't need to do anything special.

So your proposal is 2 circuits, 1 per yoke, all in a 2-gang box, and that is fine.

(If you were proposing to put 2 circuits on 1 yoke, they would need to be handle-tied for common maintenance disconnect.)

I believe you are correct to run 2 separate circuits with 2 separate neutrals. They do not need any special breakering, the breakers can be anywhere. While a 2-pole breaker would be fine (and unnecessary), I recommend against tandems. You will want full-size breakers. Because, when the inspector pinches you for the breaker not being AFCI, you'll need a full space for the AFCI.

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Heads up...

If you live in the USA, and in a state that adopts the most-recent NEC, just be aware that almost any space in a dwelling needs an AFCI breaker per changes in the 2020 code. Making changes to a circuit removes the grandfather provision that prevents us all from having to replace all our breakers if we're not doing other work.

"Who's going to inspect it, anyway?". Nobody, perhaps ... unless you have a fire. Then your insurance agency will have a reason not to pay your claim since your system did not meet code (I work for a utility in a county with no electrical inspectors, and we strongly caution our members against skimping on code compliance).

AFCI detects patterns in the voltage and/or current waveforms that signify an arc fault that could be too low for ground-fault or normal overcurrent breakers to detect and interrupt.

They're only expensive compared to the cost of other breakers. Compared to having a fire, they're priceless (I'd surmise every victim of a dwelling fire had said or thought, "It won't happen to me").

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  • However, how do you define "space in a dwelling?" For most habitable spaces, as well as their adjoining bathrooms, this is obvious, but what about accessory occupancies?
    – ThreePhaseEel
    Commented Jun 2, 2020 at 16:36
  • Yes, the code includes just about everywhere in a dwelling. It's easier to define where it's not needed. My understanding (I'm no expert nor consultant nor professional nor lawyer nor butcher nor baker nor candlestick maker): A single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation. And... kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas
    – pdtcaskey
    Commented Jun 2, 2020 at 17:05
  • Yeah -- I'm more referring to unfinished (workshop type) spaces, myself (note that garages aren't on that list, but it's not 100% clear what you'd do with unfinished spaces, especially outside of a basement)
    – ThreePhaseEel
    Commented Jun 2, 2020 at 17:13
  • Understand. But the real question is whether it's worth $40 to prevent a fire. Besides, would it be considered similar to a closet, hallway, or laundry area?
    – pdtcaskey
    Commented Jun 2, 2020 at 17:20
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Well, you can run two totally separate circuits to the box, from two toally separate single-pole breakers. That way if one trips, the other does not. Nothing wrong with that.

You can also run a "Multi Wire Branch Circuit" (MWBC) from a two-pole breaker (a fault on either will shut both down) with a single neutral and two hots. The savings is not particularly large so you can go either way. If doing this, you need to pigtail the neutrals so that removing one outlet would not interrupt the neutral on the other outlet.

My personal preference with this sort of setup is to use different receptacle colors, though choice is limited without having the price get absurd (many colors are made, but some cost 10X what the "common" colors do) so some other sort of indication on the faceplate (such as actual labels) to indicate that they are different circuits (and hey, state what breaker number they are, too) is another approach.

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  • no no, you mean a 2-pole breaker. An MWBC on a tandem would be the Bad Thing.
    – Harper - Reinstate Monica
    Commented Jun 2, 2020 at 14:31
  • Colors: You could get one in beige and the other in almond :-)
    – manassehkatz-Moving 2 Codidact
    Commented Jun 2, 2020 at 14:50
  • Right you are @harper. I don't even consider those double-breaker-in-one-slot deals, just messed up the terminology.
    – Ecnerwal
    Commented Jun 2, 2020 at 16:26
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Can you have 2 separate Fed 120v 20 amp receptacles in the same box? yes! there are many ways you can do this. I would recommend a double pole GFCI breaker since you are in a garage, they need to be GFCI protected, having a double pole breaker would be the safest way with both being in the same box , , if the kids are into electronics and will be using multiple circuits I would feed each line from the same leg (us residential is split phase and are referred to as L1 & L2). The reason I would do this is because having multiple projects powered by different sources can blow things up (I did this as a teenager trying to build a really big amplifier , once I had both circuits on the same leg it worked but was a dead short with both hots connected when they were L1/L2). Other things If using audio amps making sure the amps are on a separate leg from a fog maker or other electrically noisy devices so it depends what they will be doing, GFCI protection but breaker or receptacle is required and if L1/L2 I think the best and safest is for a handle tied breaker or double pole breaker as allowed for a multi wire branch circuit.

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