X10 is home automation technology that works by sending and receiving digital signals using the power lines of your home. Because of this, X10 performance and reliability is directly affected by the condition of the power lines, by range issues, digital signal strength and by electrical "noise" generated by appliances in your home. Any of these issues can prevent successful control of devices and can also cause devices to turn on and off unpredictably. If you're experiencing problems with your X10 devices, here are some suggestions that may help.
Install an X10 phase coupler / amplifier
A typical US electrical breaker panel is fed by two 120-volt power lines, or "phases". These phases are connected to the individual circuit breakers, alternating between breakers (top to bottom). Your X10 interface (TI103, CM11, CM15) is always installed on just one phase and may have difficulty communicating to X10 devices that are installed on the opposite phase. If you experience communication problems, consider installing a "phase coupler" to provide the necessary bridge for digital signals to flow from one phase to the other.
Install X10 noise filters
Powerline "noise" is generated by a variety of appliances including heating/cooling systems, water pumps, fans, refrigerators, freezers, microwave ovens, hair dryers and many other appliances. This noise can interfere with X10 signals and prevent reliable device control. To reduce powerline noise, consider intalling X10 noise filters on appliances that may be generating these problems. A bit of trial and error may be required here.
Analyze X10 Communications
X10 signal meters are the ultimate troubleshooting tool for any X10 problems. to analyze X10 communications in your home. These meters are somewhat expensive but can provide valuable assistance in identifying noise generating appliances in your home. In addition, they can measure the signal strength of your X10 communications to help determine if phase couplers, amplifiers or filters are required. If your X10 system is extensive, that alone may justify the cost.
X10 is an old technology, originally developed in the mid 1970's. New X10 products are no longer being developed and many newer home automation controllers do not support it. Legacy products such as the CM15a interface continue to be manufactured but the future of X10 and its "shelf life" appears to be pretty limited. Consider updating your system by introducing newer technologies like Z-Wave when adding or replacing devices in your home.