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X10 is particularly horrible for a couple of reasons. For one I'll quote from the Wikipedia entry: > In the 60 Hz AC current flow, a bit value of one is represented by a 1 millisecond burst of 120 kHz at the zero crossing point (nominally 0°, but within 200 microseconds of the zero crossing point), immediately followed by the absence of a pulse. A zero value is represented by the absence of 120 kHz at the zero crossing point (pulse), immediately followed by the presence of a pulse. Command sequences are only 2 bytes (16 bits) long, and for certain commands ("all lights on", "all lights off") four of those bits are even ignored. This means it's quite common for electrical noise to be mistaken for signals. The other problem is increasingly we have more noisy electrical gear on the line, and more equipment that absorbs/filters the actual signals (UPSes, and pretty much any switch-mode power supply in computers, TVs, etc). I unfortunately put in a bunch of X10 stuff at my parent's cottage many years ago, and it had this problem. Somewhere between every couple days and every few weeks, all the lights would turn on. Sometimes while no one was there, sometimes in the middle of night when you were sleeping :) We since replaced it with Insteon dual-band, which uses both wireless and powerline, and it's significantly more reliable (and all those problems have disappeared). In case anyone's interested, we used this stuff because the main floor is basically one big open concept space, and has entrances on all four sides (deck, sunroom, stairs and front door) and the 'smart' switches avoided having to install a stupid amount of 3- and 4-way switches that were originally planned. There's now a keypad by the front door and one in the middle (between kitchen area and sunroom) that can control everything, and a few individual switches by other doors. You can press 'all off' by the front door when leaving and all 6 or 7 circuits in the main area plus the sunroom, hallway, stairs, and foyer turn off. |