We thought my objectives for this project would be quite easy to meet but, it turned out not to be the case.
The objectives are:
- To learn about X10 and its capabilities by testing its ability in a few scenarios in our existing home.
- To enable automation and control of the light in the hallway of our existing home.
- To be able to control the light via our Home Control System (HCS).
- To be able to replace the existing single switch in the hallway with one that switches the hall light on and off.
- For the Home Control System (HCS) to be able to see hall light switch events and log the fact that the hall light switch has been operated.
- It is also desirable to be able to control the brightness (dim) the hall light if possible.
On the face of it, nothing particularly challenging in the requirements. The problems arise because the hall light is actually a low-voltage (12V ac) cluster of ten 20W halogen bulbs, chosen for its style and look. To save energy, some of the 20W halogen bulbs have been replaced by LED equivalents, reducing the light output a little. The fact that it uses a step-down transformer means that the load is inductive and many X10 wall switches are not capable of controlling inductive loads.
The issue is further complicated by the fact that there is no neutral wire in the wall box and only a switched live passes through the wall switch. This rules out all of the wall switches that I can currently find, that are capable of driving inductive loads.
Our research basically involved reading the X10 protocol document (MS Word doc).
For now we are ruling out X10 as a viable technology for serious home automation on the grounds that it is not flexible or stylish enough for our needs. That combined with its relatively poor reliability means that we can't find a situation where its use is justified over a better and more appropriate technology.
Still continuing to research the Internet and various forums but have not come up with a solution to the above problem yet.
Update 17th Oct 2009
Decided to give X10 one more chance. Planning another project using this technology for non-critical lighting and appliance control. Started another X10 project for appliance control.
We decided that X10 was simply not a reliable technology for home automation and replaced it with Z-Wave technology. X10 is a 'one way' technology only, so it is not possible to query the status of X10 devices. It is also prone to interference on the main power network and this makes it unreliable. Because it is uses one-way communications, there are no acknowledgements to confirm that devices have been turned on or off.