I recently moved into a home where the light switches are all wrong. I was able to fix one problem, and the rest is a daily reminder that usability doesn’t just happen—it takes planning.
On one wall, a pair of light switches was poorly mapped. The left switch operated a lamp to the right, and the right switch operated a lamp to the left. The previous resident’s solution to this confusing mapping was to put a red dot on one of the switches, presumably as a reminder. I put up with that for about three days.
After three days, it was time to rearrange the switches.
Now, the left switch is for the lamp on the left, and the right switch is for the lamp on the right. That’s natural mapping.
If you want to read more about natural mapping, check out this blog about interaction design and usability. It presents a classic natural-mapping problem: on a kitchen stove, which dial controls which burner?
Meanwhile, at my home there are other problems with light switches, but they aren’t about mapping. In one case, the light switch is far from the door, so at night I must cross a dark room to reach the switch. In another case, the light over the stairs is controlled by two switches that are improperly wired, so both switches must be in the “on” position. If you guessed that one switch is upstairs and the other downstairs, you’re correct. To light the stairs, often I must run up or down the dark staircase to flip the switch.
All this is both amusing and irritating and, as I already said, a daily reminder that usability doesn’t just happen. To get it right, usability takes planning and attention during implementation.
Hmmm..sorry Rand..dimmers do NOT work by resistance. It uses PWM (pulse width Modulation) for DC dimming or fo AC dimming dimmers use a Triac or SCR to chop pulses of varying voltage out of the sinusoidal waveform which is not very wasteful at all. The dimmer just picks out the volage it needs to produce dimmer or brighter light.
Having worked in building trades, I would posit that the vast majority of electricians (and apprentices) are competent enough to install a pair of three-way switches.
What happens far more frequently is the owner-occupier making changes later without a reasonable understanding of the standards, materials, tools and dependencies related to the work. I’ve seen it in electrical, plumbing, painting, roofing, flooring and landscaping.
We can all certainly see the analogy as applied to software.
I strongly disagee with the suggestion about dimmer switches – they work by varying the amount of electrical resistance, and where there is high resistance (low current and thus lighting) the result is heat produced as a byproduct. Wasteful at best, potentially dangerous at worst, and does not actually address the problem. I suspect one or both of the three-ways have been inadvertently replaced with standard two-ways; will take an electrician about six minutes to correct.
Having light switches that do the “both need to be on to be on” thing isn’t a usability problem, it means your house has been wired by bad electricians.
Rather than call in more bad electricians, simply replace both switches with dimmer switches and never ever turn the light fully off again.
Another usability problem solved!
p.s And make sure your house insurance is up to date