What is X10? Smart Home Automation Systems with X10 controllers

Home Automation can be as simple as to group controls (think of when opening the garage door, the lights in the house switch on), and can get as complex as remote control over all appliances in your house (think of turning on the heater on the way home, or even better the coffee machine).

What all the systems will have in common is a language to communicate between each appliance in the system. A language originally coined by a Scottish company called Pico Electronics in 1975 is X10. Even nowadays X10 is still the most commonly used “system” for Home Automation.


The communication is done over ordinary electrical wiring. But there is also a radio protocol defined (this, however, needs some additional hardware). The X10 signal consists of little bursts of radio waves representing a digital signal.
The protocol consists of 3 segments: a house code, a unit code, a command code.
The 4-bit house code (A to P) can divide your house into 16 areas (the kitchen, the office or all lights, all heaters).
The 4-bit unit code (1 to 16) can address 16 different appliances within a house code.
This makes a total amount of 256 (16 house codes x 16 unit codes) possible addresses (read appliances).
The command codes are handling the message sent to the address.

So for example:
The garden has house code B.
The lights in the garden have unit code 3.
The sprinklers in the garden have unit code 5.

Sending the code: B3-off followed by B5-on will turn off the lights in the garden, before turning on the sprinklers. All from within the comfort of your house. It gets even better when programming the system with a routine. At 7 pm / B3-on, at 9 pm / B3-off and B5-on, at 9:30 pm / B5-off and B3-on, creates an automatic garden watering program without exposing the turned on lights to water.

Phase Couplers

The X10 system operates seamlessly on most devices but runs into issues with high voltage appliances like a washer, a dryer, and an electric stove. This can, however, be solved by introducing additional phase couplers to distribute the X10 signal between the different phases.


Like any other signal, the X10 signal incurs loss over a distance greater than 240 feet of electrical wiring and that includes the junction boxes. For houses larger than 2000 square feet, this is not an uncommon situation. In this case, a repeater system that boosts the X10 signal is needed.

Further Recommendation

With this brief introduction into X10 for Home Automation, we have provided you with a starting point in getting your Smart Home smarter. For further reading why not check out our Breakdown of the Pros and Cons of X10.

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