Installing X10

Posted by Steve on Wed, 08/23/2006 - 8:49pm


The previous article was an introduction to X10 home automation. Now I'll talk about how it works and how to install it.

X10 isn't a product but a communications protocol for sending data over your existing household wiring. As you'll see, that's both really convenient and a bit of a headache at times. X10-compatible devices are marketed by a few companies, including Leviton, Radio Shack and SwitchLinc.

Every X10 device is assigned one of 256 available codes. These codes are broken out into 16 alphabetic house codes (A-P), each of which has 16 numeric unit codes, assigned to it: 1-16. In other words, an X10 address looks like B8 or A15. This lets you build an extensible coding system where the A house codes control your living room devices, the B house codes control your dining room, and so forth.

So I just replace my living room ceiling light switch with an X10 switch, address it as A1 and, presto, I've got an X10 controlled living room ceiling, right?

Basically, yes. But all you've bought yourself is an expensive light switch if you have nothing to control that switch.

Aha, so I'll install another X10 switch in the hallway and address it as A1 and now it will control that first switch, correct?

Not so fast, grasshopper. Here's where we need to discuss the difference between X10 receivers and X10 transmitters. It's the first "gotcha" in X10. Actually, two "gotchas".


An X10 receiver switch functions like a normal light switch but also responds to ON/OFF (and often DIM) codes from an external controller. It doesn't actually generate an X10 code on the household wiring itself. It's best to think of a receiver as a slave.


An X10 transmitter (usually) only transmits X10 codes. Normally, it doesn't actually control a household device like a lighting fixture. It sends a code to an X10 receiver to do that job for it. An X10 transmitter is what you need for your second switch in the above scenario though.


There are X10 transceivers which both transmit X10 and control a household device but let's not muddy the water yet.

The second "gotcha" is more serious.

X10 transmitters and X10 receivers have different wiring requirements.


An X10 receiver can simply replace a standard wall switch. A standard wall switch is wired across the "hot" (black) wire to the lighting fixture, breaking power to the lamp, outlet, whatever.

This kind of switch replacement is well within the skills and available tools of the average person. Just remember to turn off the breaker first!



An X10 transmitter -- and this includes transceivers -- has to be wired like a household outlet, requiring both a "hot" (the black wire) and a "neutral" (the white wire) to work. This isn't how a typical wall switch is wired so installing a transmitter switch will sometimes involve minor household electrical work. Four of the six upgraded wall switches in my house did.

Unless you're competent with household wiring and wall repair, that means an electrician and probably a plasterer/painter. Sometimes you'll get lucky and find that your existing switch box has that white wire in it. Just don't count on it.

If you don't want to hack your existing household electrical, all is not lost. There are other transmitter options, notably tabletop controllers. You just plug these into a wall outlet and you're good to go.

But let's assume that your Uncle Jack is a handy electrician and that he's wired up that transmitter wall switch for you. The receiver switch is set to A1, the transmitter switch is set to A1, Now you've entered the world of X10 home automation.

That X10 transmitter switch could be located anywhere in your house. Let's say you wanted to be able to control the downstairs entry ceiling light from the top of the stairs but your old house didn't come with a three-way switch to do it. X10 to the rescue!

In fact, you could have two, three, four or more such transmitter switches all controlling the same household device without a major household rewiring job. For instance, you could control the outside lights from the kitchen, the patio, the garage and the main entry. X10 doesn't care. It's just four transmitters all addressing the same X10 receiver to control that light.

There's more. Let's say you have your porch light and the driveway spotlight on separate switches, one in the entry way and one in the garage itself. Wouldn't it be nice to have them both controlled from one switch? Easy: install two receiver switches on the same X10 address and use an X10 transmitter switch to control them both.