To expand on the circuit breaker item above: Because most of the outlets in your home are split between two phases of AC, it meant that the X10 transmitter woul

To expand on the circuit breaker item above: Because most of the outlets in your home are split between two phases of AC, it meant that the X10 transmitter would only be able to talk to half your power outlets (and you didn't know which half ahead of time), unless a phase coupler was wired into your breaker box that would repeat the signal on the outlets connected to the other phase.