Thank you! I’ve been googling and googling and get no answers.... Now to figure out if my box can handle another 240 v outlet...

If you have the space, the box should be able to handle it, so adding a breaker should not be an issue. What is your breaker box rated for, what loads does it already have on it, and what is the total maximum load likely to be running when the air conditioner is on?

I have a 200 amp box and it has at least 400 amps worth of single and double breakers as well as a 125 amp double breaker for a sub-panel, and the electrical inspector had no issues with it. Just because you have a lot of breakers means nothing as long as you aren't trying to draw lots of power through all of them simultaneously, like running your air conditioner, your hot tub, your furnace, your table saw, your freezer, your stove, your tanning bed, and charging your Tesla all at the same time. Of course, if you have a 60 or 100 amp panel, you could trip the main breaker if you have a lot of things going on, but I suspect this won't be an issue as long as the cable to the air conditioner outlet is properly sized.

It is a 100 amp breaker box. I went and looked at it personally and there is no more space. Does that mean I’m going to need to upgrade my box? Or is there a cheaper loop hole?

There is something called a tandem breaker, which allows you to fit two breakers in the space that one normally takes. Whether your particular panel is compatible with this type of breaker is something you’ll have to determine; not all are. If this is an option for you, then you would replace a number of your existing breakers with tandem breakers to free up the space you need. Here is a little more information to explain: https://m.startribune.com/how-to-know-when-tandem-circuit-breakers-can-be-used-aka-cheater-breakers/140688183/

It's not often a big deal, and moving one breaker isn't likely to cause a major imbalance, but when you reconfigure your panel you should try to keep the load as closely balanced across the two sides of the line as you can. Other than that, swap away.

Also, I resemble that remark, "cheater breakers." :)

It's usually possible. You may have to make a small pigtail if the wire going to the breaker isn't long enough, but that's allowed. I'll make a small correction to the statement: MOST breaker slots are the same. There are a few things you would have to look for like split panels or tandem breakers which can only go into certain slots.

If you only have a 100 amp box, you need to do a load calculation and estimate your actual needs. The total breaker amperage (add them up) will often be twice as much as the main breaker, but you have to consider what will be running at the same time.

For example, you might need a 30 amp breaker for the A/C and that could be fine if you have a gas water heater and gas stove. But if you need 30 amps for the A/C, 30 amps for an electric water heater, and 40 amps for an electric stove, it could be a problem if everything comes on at once and your spouse is also using a 1500 watt hair dryer in the bathroom. It may work fine most of the time, but you would be frequently right on the edge of exceeding your capacity.

Bruce

"you would be frequently right on the edge of exceeding your capacity."

I wouldn't say "frequently." Even with an electric water heater and stove, you seldom have everything running at one time. And the breakers for these items are larger than the actual load, sometimes much larger.

A 3-ton 16 SEER air conditioner will use only around 10-12 amps (for 12 SEER, more like 15 amps). And only in the very hottest weather will it run all the time; normally it will cycle on and off.

A range might use 45 amps with all the elements and the oven on 100%, but how often do you have them all on at full power at the same time? Even for Thanksgiving dinner, once the turkey's roasting, the oven is cycling on and off. Once you've brought the water for the potatoes to a boil, you lower the heat to simmer.

A typical water heater will use less than 20 amps, and again, only until the water is hot.

In most cases, if your service's original load calculation was done properly and you haven't added too much since, and if your 120 volt loads are reasonably well balanced across both side of the line, you're very unlikely to have problems.

In more than 6 decades of life, I've lived with 60 amp and 100 amp mains, never 200 or more. With varying combinations of gas and electric appliances, I've never had a main breaker in my house trip.

As an aside, it's a different story in Europe. There you can request a lower limited capacity from the utility, and your electricity cost will be lower. So, homeowners tend to undersize their services. Although 12 kilowatt (60 amp main) service is becoming common in France, there are still plenty of people on 6 kilowatt and 9 kilowatt services. Three kilowatts isn't too unusual in Spain.

Now that electric vehicles are becoming common there, this has become more of a nuisance. So some of the EVSEs for them (called wallboxes there) have built in load management devices that monitor total household load, and throttle the EV's charger to prevent overloading the service.

I’m still so confused. And the Menard’s person wasn’t helping me with crap... so my step dad is telling me to get a one breaker box, the size breaker I’d need (which again I have no idea!), wire to run the outlet, and then the 240 volt outlet for the a/c. It is a new a/c unit for it would be ran on energy efficiency and would only go on if needed! I have a 100 amp breaker box in my home... gas stove, electric washer and dryer, electric water heater and I have stem heat for furnace. Honestly if I had the room in the breaker box I don’t think it would be a problem bc I don’t run everything all the time... just the fact the lack of room, that is the issue!

All we know is that he wants to add A/C. We have no way of knowing what existing devices and circuits are in the house, which is why I recommended a load calculation, or a least a roll-up list of what devices you might run concurrently.

Bruce