X-10 weakness

9/2/2010 7:23 PM EDT

X-10 home automation products have been around for a very long time. I know that I have been using them since at least the early 1980s, and at that time, X-10 had the only economical DIY home automation products on the market.

X-10 supplies a wide range of home automation devices: replacements for wall switches, units that plug in and control table lamps, line isolated switches for low voltage loads, and wireless and wired controllers to make the switches turn on/off/dim, when you push a button or on a preprogrammed schedule. They also have computer programs that interact with and configure the devices.

One note: They also have all this stuff and more on the world’s most pushy web site, which is designed to SELL SELL SELL. (x-10.com)

On the technical side, X-10 uses a mostly one-way signaling scheme over the power line and using RF over the air. Since communications is one-way it is not very robust. Sometimes signals just don’t get through, and things don’t turn on/off as commanded.

There are better products on the market now, and with utility backing and the smart grid initiative, perhaps Zigbee, or Z-wave or something else will finally replace X-10.

However, even now, there are no product families available for DIY home automation that can provide the wide variety of RF and power-line controllers and actuators that are available from X-10. And none of the alternatives can provide anywhere near as low a cost per node as X-10 can.

I am still a moderate DIY user of home automation and I have not yet converted to another product. I still have about a dozen actuators and controllers in my home, controlling scene lighting, security lighting, an exhaust fan and a hot tub. With careful initial installation and programming of the controllers, the lack of communications robustness can be mitigated.

However X-10 parts have always had one significant design weakness. The electronics in the switches last well, but the physical switch contacts that turn the units on/off are significantly under-designed, and are always the first thing to fail.

When I decided to write this piece, I looked in my junk box to find a broken switch, and I took one out of service to have an example of a working switch. As it turns out, the one I took out of service was about to fail as you will see below.

I remembered that some DIY’ers actually replace the broken switch with a physical push button and have documented that on web sites. I found one such site to use as an example for this piece, and reading the site found out that the author thought that X-10 had finally fixed the product weakness. So, I dismantled a brand new switch and found that X-10 now ships product from the factory with a physical push button. Pictures of that are near the end of this piece.

So, to start off, here is what a wall switch unit looks like.


WS467 Wall Switch

Here is what it looks like disassembled.


Switch Disassembled

The on/off push button switch is implemented as a spring contact that pushes against the PCB. It is barely visible below the red and black disks. It will be clearer in the close-up to follow.

The thin spring leaves on this contact are the weak point in the product and fail in two common ways.

Either the metal fatigues and breaks or it comes loose from its plastic mount.

The following pictures show a contact that has come loose and the burns on the mating PCB lands. I discovered this when I removed and dismantled a switch that was in use, intending to demonstrate a good unit. I think this unit was close to failure. I won’t put it back in the wall.


Switch Broken Loose

Burned Contacts

Here is an example from my junk box of a switch with both leaves broken off.


Switch leaves Broken

This failure mode of X-10 switches is so well known that DIY’ers have replaced the contacts with a real pushbutton, and posted the repair online.

Here is one URL of such a repair:

http://smithsrus.com/HomeAuto/WallSwitch/index.html?seenIEPage=1

As I mentioned at the start of this piece, when I read this web page I noticed that it says that the newest switches come from X-10 with a real pushbutton switch. Out of curiosity, I took apart a newer switch and found that to be correct. This switch has a new “soft start” capability as well as a real pushbutton, so perhaps the pushbutton was added as part of that functional redesign. Here is what the switch looks like in present production.


New Switch with Pushbutton

Not bad, it only took X-10 20+ years to fix this design weakness.