Wiring houses is a lot of work, although we don’t really think about it because it’s simply what we do. Trading off electrification is simply not an option. And it’s not so bad when you’re building a house from scratch or doing a major remodel where the walls come down (or, at the very least, are stripped). But if you’re simply trying to change around how your lighting works, for example, replacing and moving switches around – perhaps with multiple switches at two ends of a room, things get difficult.
To wire a switch, you have to reroute power that will eventually get to the light. And the switch is probably nowhere near the light (especially if it’s a ceiling-mounted light). So the power for the light has to detour through the switch. If you have two switches – by definition far apart – then the wiring gets even worse. You will be patching drywall.
A modern alternative solution could be to put the switch in the light itself, using the “wall switch” not as a switch, but rather as a way of communicating your switching intentions from this wall spot to the switch in the light. We can do this via RF, using the switch as an RF transmitter to communicate wirelessly with the light switch. In that way, the light power can be delivered directly to the light, without going to the switch first.
That said, we would still need to run power to the switch – to run the RF. (We wouldn’t need to run it beyond the switch, which is still an improvement.) At CES, Maxim was demonstrating an RF light switch that solved even this problem: by harvesting the energy we deliver when actuating the switch. By definition, this will make the switch slightly harder to move, but the key word is slightly. By using this to power the RF, no wiring is needed at all for the switch. Power goes to the light directly, and the wall switch can be placed anywhere with no disruption to the wall.
Of course, we could also put a battery in it. But then, if the battery weren’t to outlast the switch, we’d need to change batteries occasionally in our light switches. Given our poor record of smoke detector battery maintenance – plus a century or so of expecting maintenance-free switches – it’s not clear that would work. The harvesting approach certainly solves that, along with battery waste concerns.
As a side note, multi-switch operation is somewhat less obvious – there has to be logic somewhere that manages state if traditional functionality is preserved. Either that, or we depart from switch up/down operation (which combines a command – turn on/off – with a state – up/down, whose meaning depends on the state of the other switch) and simply go to push-button switches, which are command-only (e.g., push one button for on, the other for off, regardless of what any other switch has commanded recently).
If you’re concerned about the continued proliferation of RF content in our environments (convincing data supporting this as a threat being either very sparse or very well suppressed), this probably won’t come as good news, although the duty cycle will be far too short to allow a headache to develop.