I want to put a 220 outlet in do i need to add another sub pannel?
Question:my main is 2 100 breakers do i just jup off them and if so how
Answers:
One leg of the 220 line supports 100 amps. the other leg supports 100 amps. The question is how many amps are you using now ? Will the new appliance exceed the 100 amps on each leg ? When installing gas piping you have to figure the total load, then you have to figure the expected load. It is known as "Possible versus Probable". I have kitchen circuit that is 15 amps, I can run the electric griddle, deep fat fryer and coffee maker, no problem but something has to go if I use the microwave, then I kick the breaker. As a rule the 220 will use 1/2 the amperage as 110 Volts. But if you have an all electric house and the furnace and water heater run at the same time as this new appliance you could be over running the amperage.
If your panel box has extra spaces (blank covers). You just run your wiring into the box and install a new breaker.
You have 220 in your panel now. You have to connect both sides of the power to get that at an outlet. I would not recommend working inside your panel if you don't know what you are doing. Dead people don't use a lot of electricity.
If you have room for a 220 breaker in the panel buy one and run the wire to where you need it. Turn the breaker off before you put it in and connect the ground to the buss bar. put in your outlet and when you are all done, plug in the breaker. The breaker can be turned on at this point. If there are no spots left call an electrician to put in another box.
If you have room in your breaker panel to install a 220v breaker then you are good to go.
It sounds like you haven't done a lot of wiring and should probably call an electrician as you can get hurt and you can do somethign that might someday cause a fire or hurt someone else.
But, to answer your question. There are two issues already partially covered by other posters.
One is space in the box - you may have spare slots for the new breaker in whihc case you are good to go. Find out what brand box you have and what size breaker you need and head for the hardware store (where they have good books on basic wiring...) If there are no spaces left it's likely that you still do not need a sub panel. You can now get special breakers ("1/2 width", "tandem", other names) that fit two single pole breakers in one space. By changing out four of your existing full width breakers for a pair of tandems you can make room for the new doubl epole that you need. Sometimes you can get double pole tandems and just change out an existing 220V breaker for one that takes the same space but provide two circuits.
The other issue is the size of the service to your house. It sounds like a 100 amp service which is small by today's building standards. Still, unless you have a big air conditioner, electric range, and electric dryer and try to run them all at once you may get by. If your service is too small then you need a new meter a new drop from the pole (lord help you if your service is underground) and a whole new distribution panel - could be a $1000 to $5000 job. Some of the books have a section on service sizing that would help you do the calculations. Your hardware store book section may have a 'book' called 'Code Check Electrical' that shows examples of how the calculations are done.
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