you can put a 100 amp breaker in a 200 amp box but not the other way around. A 20 amp circuit will not run 3 window air units. you would need to add a circuit for each A/C unit. If you upgrade box I would go with the 200 amp. but you would need to replace wire & conduit from whre the power comes in from the power co. Meter base and conduit up to the connection point. I was an electrican for 45 years. an changed out a lot of fuse boxed.OK when we bough this place in NC it had fuse boxes, and still does, 100 amp
I want to install a breaker box so that I can, solve a few problems insurance wise and blown fuse wise
now I can fond 100 amp breaker boxes all day, and 200 amp breaker boxes, the dominion power line to my house is 100 amp ( I assume and we all know what assume does)
anyway, I keep blowing the 20 amp that basically runs 3 ac's and several outlets, IF I install a breaker box I can eliminate half the problem by installing breakers for each room easy enough
My question is two fold
(1) if I install a 200 amp breaker box can I use 100 amp breakers in it?
(2) since a 100 amp breaker box comes in a 20 bay size, will 200 amp breakers fit, I know that if I have 100 amp installing a 200 will not give me 200 amps, I just want to know that question for availability issues