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Tech Forum

February 2017

LED Compatibility?

I replaced some outside 60W bulbs with CREE dimmable LED replacements. The lamps are  controlled and dimmed using X10 switches. When switched off, the lamps still glow at about 20% and will not shut off completely unless I use the disable feature of the switch. However, this prevents the timer from automatically controlling the lights. What causes this and is there a fix, or are LED replacements not compatible with X10?

Christoffer Mortensen
Piscataway, NJ


Conventional x10 switches require a small current to run through the load (i.e. an incandescent light) in order to work correctly. For non incandescent loads such as CFL or LED lights you need a x10 switch specifically made for them. I currently use a WS13A x10 wall switch and also an XPFM x10 fixture module to switch LED lights (and CFLs). These x10 switches are not dimmable though. In general, LED lights need a dimmer specifically made for LED lights. I have had a good success with Lutron CL digital dimmer (e.g. MACL-153MH) as a manual dimmer but I do not know of an x10 compatible dimmer designed for LED lights. Perhaps someone else knows of one that will work.

Dan Koellen
Roseville, CA

I go through this problem whenever I use x10 in a small project. x10 appliance modules need some kind of load resistor, but due to the 110VAC appearing when it turns on, I do not advise it. Instead, a batter way to solve it is to connect a 110VAC relay parallel to the LED bulb. If you want to use a resistor 33K 1W will be OK (I tested up to 42K that works), BUT be very careful about insulating the wire leads. I tested both methods (resistor turn on only a second in on state), they work perfectly.

Ankur M Bhakta
Tulsa, OK