you might want to consider a split-receptacle
along with a waterproof cover
if your mounting your transformer outside in the elements. I'm not really sure about the code requirements for wall receptacles that have solid state electronics inside (x10)--can you mount these outdoors under all-weather receptacle covers??? I would assume you could since gfci's have solid state circuitry too, and they're allowed under weather-proof covers but it may also depend on the approved temperature operating specs of the individual units. (depending on if you live in montana or phoenix) larry could answer this question better than me.
I have 2 malibu 300w transformers in my garage out of the weather and they work fine with appliance modules. they are also downstream of a single gfci and I haven't had any problems with signal strength. there are also several mail order retailers who sell appliance mod relay decora x10 switches in both (10 and 15 amp)so you could control a regular outlet (or wire direct to the transformer thru emt--doesn't the hadco transformer have half-inch knock outs?) from the switch. 
and there's also a dimming switch that can control up to a 500w magnetic transformer load if I remember correctly.(again as larry said this is a specialty dimmer switch and not a regular x10 dimmer switch or dimmer lamp module)(I'm also guessing if you're using x10 for a timer you're not going to be using the timer that comes with the hadco transformer??)
This message was edited by jrx10 on 04/13/04 16:41.
