I have 3 slots left in circuit box. Can I add a 220 or 240 volt and two 110 volt to my circuit box?

I have 3 circuit breaker slots or poles available in my main circuit box.  I see generally the 220 volt takes two slots.  Does 220 or 240 volt have to take two slots?  I want to have a 220 volt added for a mini split, then add two dedicated 110 volt lines and hoping that it can be done with those 3 circuit breaker slots that I have available.

I guess another way to ask this question is, does 220 or 240 volt circuit breaker have to have two poles when used by an appliance like a mini split?  I do see there are single pole 240 circuit breakers, but I'm not sure if they are for special use or are less safe.

9 Answers

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  • 2 weeks ago

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  • 1 month ago

    Normally you want both poles to shut off during a short or overload. This means the circuit breaker should be the ganged (tandem) type where one pole can trip both at the same time. I don't think a "single pole 240 breaker" exists because a single pole can only install into a single pole slot or the 120 volt A or B rail. 

  • 1 month ago

    Unless your home is very old and has never had its electrical service updated, it has 240-volt service from the street and into the main electrical panel as well.

    Nearly every main electrical panel has two 120-volt wires and one neutral wire running to it from the utility company. Each wire powers one “bus” (copper vertical leg) inside the main service panel. That’s why you usually see two columns of breakers (or fuses) when you open your service panel door. The common 120-volt circuits that power everything from your lava lamp to your vacuum cleaner are powered from one of those two buses. The standard 15- or 20-amp circuit breakers work by clipping onto one of the buses. Then the circuit’s hot (red or black) feed wire is clamped to the circuit breaker, while the neutral (white) wire and bare copper ground wire are clamped to the common neutral bar.

  • 1 month ago

    240 volt circuit will take 2 slots. That leaves you with one slot. Purchase a tandem breaker and you will be able to connect two 120 volt circuits on that dual breaker. However you must remember that you have 2 circuits running off one leg and you can easily overload this leg. This may be an option if both circuits on the tandem breaker are not pulling over 2400 watts when wired with 12/2 wire. 

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  • 1 month ago

    Physically, yes.

    You HAVE NEVER seen a single pole 220v breaker in the US, because a single pole only connects to ONE 110 volt leg. The handle may not be full size, but the actual breaker MUST be.

  • y
    Lv 7
    1 month ago

    The 220/240 takes two slots, they use the two different legs, each 110/120, to get your 220/240.  That leave on open, depend-in on city and state. You may not be able to use the splitting type. They are not allowed in my town for instance. To be honest, the way your question reads, leads me to believe that you should not be messing around in a box.

  • 1 month ago

    yes, 220v [240v is the same] takes two adjacent slots.  however, you can get a double breaker that will fit into the 3rd slot and allow two separate circuits to be separately protected [it has two handles] -- ask the salesman at your local store.  better yet, take one of your existing breakers in with you to make sure you get one that will fit in your box [there are, i'm told, five different kinds used in North America].  -- grampa  PS;  DO this safely -- wear rubber sole shoes and long pants.  and use insulated pliers to grab the breaker -- or turn off all power at the main breakers when you do this.

  • Droopy
    Lv 5
    1 month ago

     No you'll need a double pole breaker for 220.  The ones you see that are 1 slot with 2 poles are piggy bsck breakers there both 120 each as they only connect to one bus bar.

      What Amperage do you have comeing to your main breaker for the box.  If your box is that full an you have a lower amperage service like 100 amp.  Your box might not have room even though theres empty spaces.  

  • Joe
    Lv 7
    1 month ago

    In U.S. residential main panelboards, the "double wide" breaker is needed to connect to both "hot" buss bars.

    But first, and more to the point: if your panelboard is *that* full, you may not have enough electrical capacity (Amperes) for the additional loads you want to serve.

    If that's not a problem, you have a couple of options.  Some manufacturers produce paired breakers in a single slot width.  If you can get those for your panelboard, you could replace two existing breakers with one of these mini-pairs, and free up a slot.

    The second option would be to install a sub-panel, right next to the main panelboard, and move some branch circuits over.

    I hope that helps.

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