Lighting – Smartify 50s low-voltage lighting system

Without home aut, one controllable lamp requires a switch, which interrupts the 110V/230V wire between the power source and the lamp. When you need another lamp, you have to find the point, where you can join to the 110V/230V, a switch and a lamp.

In a centralized system, you have to lead 2 wire from the button to the center, and another 2 between the lamp and the center. Switching to home aut. requires complete re-wiring. When you need another lamp, you have to another 2+2 wire for lamp and for button, you have to provide a relay for the lamp, a free slot on the controller for the lamp (sometimes built together with the relay), a free input slot. If your controller device has no free slot, you have to buy another one. Sometimes adding new devices is not a simple task, e.g. if the controller is connected to the computer with RS232 or other point-to-point cabling, you have to expand the computer. So, when the hardware is OK, you have to configure it in your software.

So that's why this part of the home automation is less advertised: you have to completelly re-organize the electrical stuff in your house. It can be quite expensive.

There are other kind of home automation systems, where there're no central panel, but each actuator/sensor is intelligent. These manufacturers say that it's more reliable than centralized systems, but you will forget it as soon as you will see the price of that sysems.

There're solutions avoid cabling: the smart guys say X10 is not the best choice, it's unreliable etc., the future is ZigBee and EnOcean. (I just have to write EnOcean driver for our system.)

So, when you choose system, take care of expandability, ask these questions: what if I double my lamps? How can I add +1 dimmer switch?

X10 (and other power line communications) signals can travel back up to the transformer, and they can interfere with other systems which are connected to that same transformer. You can purchase a "signal blocker" to prevent the signal from making it back up the line, but these will typically need to be installed in the breaker panel (which may or may not be DIY for you).

In general, most new home automation products use wireless transmission protocols. There are several standards out there, but the main players are Insteon, Z-Wave, and Zigbee. More or less, these options are very similar. They are low power RF protocols, centered around a "mesh network" scheme. All nodes can transmit and receive commands, and signals can be re-broadcast to other nodes which may be out of range of the original signal.

Insteon - This is a proprietary protocol, designed to address the shortcomings of X-10 Basically a hybrid between X-10 and a full wireless solution. Signals are broadcast wirelessly, and also over the power line. There is support in the protocol for data encryption, but in general it is not supported by the hardware. Without the encryption, commands can be intercepted and spoofed by an attacker. You also have the same powerline problems that are present in X-10.

Z-Wave - This is also a proprietary protocol, but is completely wireless. There is no encryption of the transmitted data.

Zigbee - This is a standards based (IEEE 802.15.4-2003) wireless protocol. It uses an encrypted communications channel to communicate between nodes (AES 128 bit). Generally speaking, this is the most secure of the 3.

All of these protocols are relatively widespread, with several companies producing controllers and modules which support one (or more) of them.

Given that you seem to be concerned about the security of your automation system, I would likely choose either a Zigbee system or an X-10 system with a signal blocker installed. The X-10 system will likely be cheaper, but depending on the hardware you purchase and your specific electrical setup, the system may or may not be completely reliable.