X10 SYSTEM

There are many parts to the X10 system, and there are many different companies that sell the same thing under different names (RCA, RadioShack, Westinghouse, Honeywell, IBM, etc) which makes this more complicated that it should be. There are many explanations describing the X10 systems, but I find they are either too simple and leave out important things, or too complicated and not worth the time reading.   Smarthome.com and X10retail.com are two good places for information.  I've bought the stuff at Lowes.

X10 is a system that lets you control lights and appliances in your house.  Using signals that travel either wirelessly or via the existing wiring in your home, you can control lights and appliances remotely or automatically.
 

SWITCHES/OUTLETS/MODULES (also know as UNITS)

WALL SWITCHES AND OUTLETS to replace existing switches and outlets

X10 Dimmer Light Switches - Looks like a regular light switch that you install in your wall. Limited to 400W or 500W incandescent lights. Can't be used with fans or fluorescent lights. (price: $17-$20)

X10 Light Switch - can't find this type for any reasonable price yet. (price: $75-$95) X10

Outlets - 110V and 220V varieties. Can be used for ANYTHING that a regular outlet can handle. Simply remove the old wall outlet and replace with the X10 controlled outlet. (price: $15-$50)

PLUG IN MODULES to plug into existing outlets

X10 Light Dimmer Modules - Small box that plugs into ordinary outlet. Limited to incadenscent lights up to about 300W. (price: $15-$20)

X10 Appliance Modules - 3 pronged version of above, except it's just on/off without dimming so it can be used for more than lights. Limited to 400W and 1/3HP motors. (price: $15-$20)

X10 Lamp socket adapter - Screw this into lightbulb socket and then screw lightbulb into this. ($20)
 

WIRED SWITCHES to wire into appliance or light fixture

X10 in-line module - a small box that you wire into the appliance or light fixture when it's not convinient to use wall outlet/switch or plug-in module (price:$25-$50)
 

WIRED CONTROLLERS
Small boxes that plug into ordinary electrical outlet to control the X10 switches, outlets and modules around the house. Some control 2, 4, 8 or up to 16 different switches/outlets/module units in your house. Some look light a small clock radio and can be used to time the on/off cycles of the lights, etc. Most have buttons to:
* Turn on one light/appliance
* Turn off one light/appliance
* Dim one light
* Brighten one light
* Turn on all lights (light dimmer switches and light plug in modules)
* Turn off all units (lights AND appliances and outlets)

WIRELESS CONTROLLERS
The first thing you have is a transceiver which that looks like a light dimmer plug-in module, except it has a small antenna. It plugs into an ordinary outlet and sends signals to the light switches, wall outlets and plug-in modules around the house. Then you have some sort of wireless thing that talks to the transceiver. Either a small key fob, or various type of small remotes, some look like a wall switch and can be glued to a wall where a switch doesn't exist. The wireless controller sends a wireless signal to the transceiver telling it to send a command to the light switches/outlets/modules.

COMPUTER CONTROLLERS
Oops, there are three types of controllers. You can get a controller that connects to your PC so your PC can control everything.
 

MISCELLANEOUS NOTES
The X10 system can be simple or complicated, depending on what you try to do with it.  Here are some notes I've made about the system.

* I installed an X10 outlet in the wall to control an lamp in the living room.   I used an outlet rather than a plug in module, because I wanted it to look neater.  I discover that when I press the "All lights on" button on my controller, that my lamp doesn't turn on.  That's because only lamp modules and light switches respond to the "all lights on" command.

* Wireless controllers force you to use unit numbers. If your keyfob wireless controller can control two units, it will be unit #1 and unit#2.  If you are controlling 4 lights in your house with a timer controller you can still use a wireless keyfob for two of them but you number number them #1 and #2.

* I've heard people have problems when they try to use X10 system to control devices like large dust collectors in their workshops.  Plug in modules have limitations, either the number of watts or the highest horsepower motor it can handle. They are usually 300W-500W and 1/3 HP.  Outlets on the other hand are rated just like any ordinary outlet.  My 1.5HP dust collector worked fine on an ordinary 110V-15A outlet in the workshop. It works just as well with a X10 110V-15A outlet.

* Wireless limtis: I'm not sure what thee wireless distance limit is, but with one keyfob remote and one transceiver, I can use the keyfob anywhere in my house.

* Wire limits, although the wireless remotes doesnt seem to have any distance limits, I've found (and heard from others) that sometimes you can't control all your units in your house from one controller.   A controller can control all units that are connected to the same branch ciricuit in your house.  It can also control units that are on other branch circuits in your house, but it seems to be based on the proximty of the circuit in the circuit breaker box.