I was looking at adding an extra breaker or two to my panel as I have two open slots. I opened the front of my panel to see what I was dealing with inside and was perplexed by what I found, I'm going to obviously need a professional for this but for my own education I'd like to find out what's going on in these two slots, it doesn't look like a 2-pole breaker would go there but I could be wrong? Can someone clue me in, thanks!

Picture of open panel with open slot

Panel door

Edit: My house was built in 1960.

Based on Harper’s answer I’d like for the time being until I have the funds to go with the Easy Option. I do have a few follow up questions in regards to it. This is being done with the intention of adding some extra lighting and outlets to my attached garage. I have a single 40 watt and 15 amp plug in my ceiling not great for a workshop.

I would like to run two independent 120v circuits, one for the outlets, one for the lighting. If I wish to each independent circuit to be 20 amps, would that be a 20 amp 2-pole breaker or a 40 amp 2-pole breaker?

When wiring it this way I’d use the proper gauge wire (12 or 8 depending on amp breaker). But would I just be running #/2 one to each hot terminal for the independent loads?

I would never ask electrical advice at a big box store, my question was more so could I go to one and purchase the supplies? So I can go to a big box store and get the proper Square D “QO” breaker?

Update questions Part 2

@Harper Thank you for updating your answer with more info. If I were to keep the lighting on it's current circuit that looks like it's going on breaker 10 which is the current light and opener, microwave, half bath lights, basement stair lights and the side door light, that's only a 15 amp and I have some old 2 bulb fluorescent units I was going to install in the garage (4 or 5 of them), would this circuit be able to handle that additional load?

Spot 5/7 for the range is a 40 amp double pole that is not in use, we piped in gas because well I hate electric stoves. Could I remove that breaker, put in another 20 amp double pole and do the same thing and run my lighting off of that one? Is there a requirement that you provide a 240v for a stove?

Finally, when wiring up a double pole as two separate 120v services, would you wire up each pole like you would a single pole? As in Hot to one leg, neutral to neutral bus, ground to the ground bus.

  • Well, it would help if you'd also take a picture of the sticker on the door. I can see just the edge of it... Mar 13, 2019 at 15:35
  • I meant the sticker on the left. Mar 13, 2019 at 17:38
  • @Harper I will get a picture of that when I get home and post them.
    – JacobRyan
    Mar 13, 2019 at 18:01

4 Answers 4


Got it.

This is a "Rule of Six" aka Split Bus panel

Early on, most homes got 60A of AC electric service. Later on, houses wanted more - but 100-125A main breakers were much more expensive. So they just had multiple main breakers, all in the cheaper <60A range. Regulators didn't want homeowners having to switch off 20 breakers, so they wrote the Rule of Six that there can be no more than 6 main breakers to turn off the whole house. That forced them into a split bus design, where one of the six breakers powers additional spaces in the panel, an internal "subpanel" if you will.

You have a "mini". Which means you have four dual spaces, intended for four 2-pole breakers. Water heater, A/C unit, range, dryer, electric car charger, large table saw, etc.

The one in the upper right carries power to the "rest of the panel", the area with all the single breakers and double-stuff's. That lower area is, effectively, a subpanel in the same box. Shutting off that breaker shuts off power to the "subpanel's" buses. It is impossible for you to shut off power to the upper area.

You must use particular breakers, and it appears this panel is compatible with simple breakers in the Square D "QO" family. That is great; this is a top tier panel that is commonly used in industry. One would not be out of place in the Boeing factory. And the family is still made, so if you go with a subpanel, you can continue with QO, and I recommend you do.

There are 3 such 2-pole breakers currently installed, including breaker for the "subpanel" area. It appears you have the option to install one more. I wish I had a better view of the panel labeling, however it appears to say ONLY a 2-pole breaker is allowed there, or alternately a "dual 2-pole" which serves dual 240V circuits. You are not allowed to put single breakers there end of subject. (however that is not a barrier).

So several options from here.

Best option: Subpanel.

In this case you stick a 2-pole, say 50-60A breaker ($10) in that location. You then feed a subpanel, where you have liberty to add a number of circuits.

Now on this forum we recommend very large panels (i.e. 40-space, $190) even if a small 12-space ($80) would suffice for now -- because the cost differential is tiny, compared to overall project cost of installing a panel. And you'll never need to upgrade your panel again, ever, and even more importantly, your ambitions are never limited by panel spaces.

(QO is also a more expensive panel than some; you don't have to remain loyal to QO, it simply allows you to exchange breakers.)

I'll take it one step further still. Choose your subpanel, and its position, with an eye toward making it the main panel in the future. That is, locate it where it'll have easy access to the conduit from the meter. At some future point, you reverse the deal, and make the old Rule-of-Six panel the subpanel.

Once your new subpanel is in, you add new circuits to it. There's no reason to fuss with the old panel; it can cheerfully serve forever as a subpanel, and is actually legal for new installation today as a subpanel.

Easy option: Plain 2-pole breaker in that location

The simplest way is to stick a plain 20A 2-pole breaker in that empty slot, exactly like the labeling tells you to. How do you put a plain 20A 120V circuit on a 2-pole breaker? Easily - land the neutral on the neutral bar, and the hot on one of the hot terminals. And you're done!

You're getting 20A off that one side/leg of the service, so use 12/2 cable.

There's another 20A side/leg unused. Could you attach another, independent 20A/120V circuit there also with 12/2 cable? You bet. They will be independent, except they will have common-trip, and common maintenance shutoff.

Could you do a multi-wire branch circuit with 12/3 cable? Yeah, the 2-pole breaker would be correct for it, but you really need to know what you're doing with MWBCs, and they have issues with GFCI and AFCI, so they have largely gone out of style. I can do them because I have a lot of experience with MWBC, but nonetheless, usually I don't.

Now, from your edit, you say you want to upgrade both lighting and receptacles in the garage. Use the old existing circuit for all the new lighting. Use these two new circuits for receptacles only. That way, when you find out a table saw + a dust collector will trip the breaker, you won't be in the pitch black with your fingers inches away from a spinning blade! You always want lighting on a different circuit when possible.

Maybe option: Install a quadplex 2-pole x 2 breaker

You see where there are other double-stuff breakers in this panel already. There is a type of double-stuff called a quadplex, or two 2-pole breakers in the space normally occupied by one 2-pole breaker. The labeling on this panel appears to support that.

This would give you dual 2-pole breakers, allowing you to do the above trick twice, giving 4 circuits.

However, it's quite an old panel, and it plainly intended to support certain series of QO breakers which may no longer be made. You would need to closely study the labeling and the specs of the currently available QO quadplex breakers, and any Siemens "QD" quadplex which may exist -- to see whether the new breakers are listed for that panel.

Normally, you must not use brand X breaker in brand Y panel, as they won't fit properly. Siemens QD was specifically engineered to fit in QO panels (won't fit Siemens), and UL tested and classified them as a safe match.

The labeling clearly shows it's not intended to support the "open quadplex" breakers where you have a 1-pole, a 2-pole in the middle, and a 1-pole.

Followups from your update 2:

All that lighting and the opener will fit on the circuit fine especially if it's LED, but the microwave is a bridge too far. The fluorescents, if they're old, figure about 100W (0.83A) per 2-lamp fixture. If they're reasonably modern T8 fluorescents then 65-75W (0.54-0.63A). I upgrade old fluorescents to T8 since the cost is very low (buy "pull" ballasts on ebay).

Yes, you can change that range breaker to a 20A. Cap off the old wires in case the next guy wants an electric range.

Yes, when hanging 2 circuits on a 2-pole, you just pretend they are 2 separate breakers without a handle tie, hot to the breaker, neutral to the neutral bar etc.

  • Wow Harper, thank you for such a detailed reply. Is there a way I can message you to get a few more details so it’s not done in the comments?
    – JacobRyan
    Mar 13, 2019 at 17:35
  • @JacobRyan This isn't a discussion forum and I'm not a consultant, the way we do that kind of thing is either comments, or editing your question to add detail. Mar 13, 2019 at 17:37
  • @Harper I totally understand, I’ve updated my original question with some sub questions regarding your easy option. Thank you.
    – JacobRyan
    Mar 13, 2019 at 17:56
  • @Harper Updated with just a couple more questions, thank you for your continued education.
    – JacobRyan
    Mar 14, 2019 at 14:26
  • @Harper Thanks for all the info, I really appreciate the education. After further looking I am now debating on a subpanel since I effectively have two 2-pole slots open since the range has never been used, though my thought might be to put it directly in the garage with quick access to it.
    – JacobRyan
    Mar 14, 2019 at 17:00

You need a Square D QO style breaker, a 20 amp single breaker would be QO120, a QO115 would be a 15 amp, for 120v circuits. For 240v circuits you would need a double pole would be QO220 & QO215 for 15 and 20 amp circuits.


I defer to the superior answer by Harper that has the correct description of this older panel that I didn't know the history of.

This is an older style "Square D" breaker panel with some two-pole breakers (that take up two slots) and some old-style tandem breakers (one slot, two switches).

You probably can't find that style tandem breaker anymore unless you find some NOS (new, old stock) ones on eBay or similar. You have two open slots so you could use two single pole breakers for 120v loads or you could use one two pole breaker for a 240v load.

Also, I don't see a main breaker in this panel, so it's probably in a box by itself. Make sure you know how to cut off the power (I'll just assume you did before taking off the front panel).

I guess it may look odd because of the metal contacts that connect to the breakers. There are two silver metal bars (left and right) and each bar has a "finger" that extends out on every other slot. With this arrangement, each row in the breaker panel is on a different "leg" of service, and two pole breakers that take up two slots can pick up both legs. The breaker has a connector near the center of the panel, so it doesn't touch the larger part of the finger that you see on the second free slot.

  • I can tell you that the newer Square D QO breakers (Square D now has QO and HOM (Homeline) breakers) use the same style contact as your box (the wide metal fingers), but I do not know if a new breaker will fit in a box that old. I feel like it would and I'd try it, but if you're not familiar with installing breakers you might not know if it feels right or not. If you knew how old the panel was, you might be able to find a chart somewhere that says if it will work.
    – JPhi1618
    Mar 13, 2019 at 14:45
  • I added a picture of my panel door with some info, does that tell you anything?
    – JacobRyan
    Mar 13, 2019 at 15:35
  • @JacobRyan I added the picture to your question. It doesn't tell me for sure one way or another, but maybe someone else will know.
    – JPhi1618
    Mar 13, 2019 at 15:44
  • I’ll try to get a few more pics when I get home of the stickers in the panel to see if they sell me anything.
    – JacobRyan
    Mar 13, 2019 at 15:49
  • Update the question with the year your house was built as well. You edited my answer last time, be sure to edit your question.
    – JPhi1618
    Mar 13, 2019 at 15:51

I think it's better to split receptacle and lighting circuits if possible. Two single pole circuits. I'd run 12 ga for the receptacle, 20 amp breaker. Get 20 amp receptacle too, they are much better.

If you are using a heater or heavy drill etc and trip the breaker for the receptacles then the lights wont also go out.

  • Lights and receptacles on separate circuits make sense. But if you put them on a double breaker then a trip of one will trip the other. As far as 20A receptacle, you can use duplex 15A receptacle on a 20A circuit - rated for 20A pass-through and no substantive difference for most uses. The bigger thing is to go a step up in quality ($3 vs. $1). May 2, 2021 at 20:37

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