X10 Home Automation Q and A - Part # 4

by DoItYourself Staff

How do I control fluorescent and halogen lights with X10?

Lamp modules and standard X10 wall switch (e.g. X10:WS467) generally do not work well anything other than incandescent lights. There are several reasons why this is so. Both lamp modules and wall switches cut out part of the power sine wave to dim the lights that are connected to them; the waveform available at the load is no longer a simple sine wave, but a sharply-truncated version of a sine wave. Even at full brightness, there is some power cut. This is not too critical for a simple incandescent light. For a compact fluorescent lamp that has some electronic circuitry in the base to drive it, however, this is not a good idea since the circuitry is designed around the expectation of a stable waveform at standard voltage. Trying to dim a compact fluorescent by modifying the input power supply is like trying to turn down the volume on your radio by putting it on a dimmer circuit. It may sort of work with unpredictable results, but cause damage to the load being dimmed.

Standard lamp modules and appliance modules have full access to house current since they are plugged directly into a power outlet. Standard X10 wall switch modules, however, rely on getting their power from current leaking through the filament of the incandescent bulb(s) in the circuit they control even when the bulb is off. If the load they control is not a standard incandescent bulb, there may be no (or not enough) current to the switch and it may not operate as designed. This may be especially true for fluorescent bulbs, or special power saving bulbs that have diodes built into the base. As noted above, the voltage output from lamp modules and standard X10 wall switches is not a pure sine wave. Transformers are generally designed for a certain frequency or range of frequencies (e.g. 50-60 Hz). They may not be able to handle the higher frequency harmonics present in the sharply truncated sine wave output from a lamp module or wall switch. As a result, they may heat up and/or burn out. This is true of halogen or fluorescent lamps that have an integrated transformer. It's true of any device with a transformer (e.g. some radios and computers) or with a motor (e.g. garage door opener or electric fan).

A standard APPLIANCE MODULE (X10:AM486) may work for loads that are other than incandescent lights. Note that when used with a compact fluorescent bulb, the local control mode in the appliance module often senses a small current flow and keeps turning on. Using an appliance module on a halogen light should work in most applications, but will not permit remote dimming. If the light has a built-in dimming control, this can still be used.

There has been some success reported in using the standard X10 incandescent wall switch for controlling halogen lights that do not have a transformer in the light fixture. There are many types of halogen bulbs; mileage may vary. Use at own risk.

How do I control an X10 device from a standard light switch?

The simplest situation is where you have a standard wall switch that controls a standard wall outlet (sometimes only half of a split outlet). This is common in newer homes where a switch by the bedroom door controls an outlet for a light at the bed, or a switch at the living room entrance controls an outlet for a floor or table lamp.

For the simplest case, you'll need an AC adaptor that puts out a DC or AC voltage in the range 6-18 VDC, and an POWERFLASH INTERFACE (X10:PF284, RS:61-2687). Plug AC adaptor into controlled wall outlet. Plug the POWERFLASH INTERFACE into an adjacent wall outlet that is continuously on (may be the other half of the split outlet). Connect the output of the AC adapter to the input of the POWERFLASH INTERFACE, select input mode 3 and select which unit you wish to control with the dial on the POWERFLASH INTERFACE.

When you turn on the wall switch, a voltage will be produced by the AC adapter and trigger the POWERFLASH INTERFACE to send the X10 ON command to the selected unit. When you turn off the wall switch, this will cut current to the AC adapter and the POWERFLASH INTERFACE will send the OFF command to the selected unit.

The not-so-simple situation is where your wall switch controls a light fixture. In this case, you would have to hard wire the above components into place, or install a split power outlet half controlled by the switch and plug them in.

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