How high can the difficulty go before people mining in their house can no longer add any more machines because of physical space restrictions and overloaded electrical systems stop your ability to keep up with difficulty increases ?
Most new homes have 150-200amps from the street. Of course this can be serviced by an electrical and the amperage increased though addition of new panels and the gauge of copper running from the street to the house. 150 amps at 120 volts will get you 18,000 watts. Most circuit breakers are 15 amps. To be safe each circuit breaker should support 1,800 watts at 15amps. You can buy higher amperage circuit breakers. But it doesn't seem very safe to run more than 1,800 watts on 1 circuit. Distribute your rigs if you can. Most rooms are usually on one circuit. With older homes there can be severe electrical limitations. It'd best to consult an electrician if you're having electrical problems.
That's 150-200amps at 230 volts from the street for 36,000 watts @ 150amps
20 amp breakers are more normal for branch circuits and plugs
newer homes will have at least a two circuits per room and one or 2 outlets on each wall
two circuits are so if one breaker pops you still can have an active lamp
20 amp breakers will trip at 20amps thats a max number not for a constant load
continuous load rating is considered 80% (16amps for a 20amp breaker)
By all means consult an electician any existing wiring may or may not handle larger breakers