For residential you can use twin breakers, they take one space and give you 2 circuits, GE makes brekers that fit in a federal panel.I can't imagine I'd need to upgrade as this is a small house (1400 sq ft), I just want to pull another dedicated to the fish room and split up some existing circuits. Right how the whole front of the house (built in 1906) is on 1 circuit. In the back the swamp cooler, window air conditioner, kitchen, and bathroom are all on one circuit, if you try to run the microwave while the air conditioner is on or if the wife fires up her hair dryer we pop that one. The fish room is currently on one 20A circuit and in order to expand, I'd need another circuit. It's just when they wired this place they just kept stringing stuff together. We have never popped a fuse anywhere else in the house so I assume that many of the others are only hooked up to a few overhead lights with very little draw. This house is old, added onto 3 times (assuming last time in the 70's or 80's) and there are wires running all over, some live, some not. I did have an electrician pull the wire to the fish room from an existing circuit that didn't have any draw on it but the box won't accommodate any more breakers. I appreciate everything!