Don’t care. Refuse to solve puzzles about stupid people.
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Start messing about with one switch, flicking it off and on, etc.
Up the voltage in that line so the fan spins faster or catches fire.
Wait for someone to come down to the basement and complain, then ask them where they live.
Repeat for second switch.
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There are some more or less valid suggestions here, but I’m confused: if the wiring is good enough to support the various shenanigans people are advocating, why was the electrician called in?
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A bit annoying, since there are several things that aren’t clear. From the way it is written, it seems like pressing twice turns it off, whether it is on or not. Not sure how a button can work that way, but that’s what it says, and seems like the only way to answer the question of what state the fans are in at the beginning. The candle idea doesn’t work since you would have to go up twice to set the candles. I like the string idea, although it’s a stretch. It seems like the hour to climb the stairs is meant to avoid any claim that you can tell if a fan was recently on. Even claiming that the motor would still be hot is a bit of stretch…
Edit: Oh, and I will be very annoyed if the temperature of the room is involved in any way. Ceiling fans do not cool rooms, just make people feel cooler because air is blowing across their skin. They actually slightly raise the temperature since there is a motor involved.
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The important part of this is to remember that a fan will continue to spin for a while after being turned off. Turn on fan A and fan B. After a few minutes turn off fan B. Go upstairs quickly. Find the fan that is not moving, that is C. Find one of the spinning fans, if it slows down and stops it is fan B, if it keeps spinning it is A.
First of all, you would have to assume all 3 fans are off.
I think the key to this problem is that you need to push the button twice to turn off. Most switches are binary and the assumption is made that the fan is as well, either ON or OFF. I think in this situation of having to push a button twice to turn OFF, leads me to believe the fan has a third state. HIGH,LOW, and OFF.
So the electrician would push button A one time to put the corresponding fan on HIGH.
He would then push button B two times to put the corresponding fan on LOW.
He could then push button C three times to go from HIGH to LOW and back to OFF, but since he is a lazy electrician, there is no need to push button C at all.
He then goes upstairs and identifies which fans, 1,2,3 are HIGH, LOW and OFF.
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The puzzle says it takes him an hour to get upstairs, I think specifically to thwart that solution.
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Damn I missed that part.
Switch one fan on.
Leave the second fan off.
For the third, isolate the switch and connect a tone tracer (https://www.amazon.com/dp/B00APD16D2) to the cable.
When she gets to the top of the building, one fan will be running, and two will be off, she can tell the difference because the tone tracer receiver will beep for the third fan.
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He could likely just throw a meter across the buttons to find their current state.
If he happened to have a tone generator on hand, that could probably simplify the identification process as well…
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I actually have a circuit tracer set - similar to this but with more gadgets, probably about twice as expensive.
I got it for free; a company needed to have some heavy stuff traced, and they were willing to foot the bill for the gadget set, and then they said “we don’t want that thing, the job we needed it for will never occur again” so I threw it in the trunk. I’ve only used it a couple of times but it comes in handy when you do need it.
Using that kind of tech for this puzzle is cheating! 
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Wire each of A, B, and C with switches that can be controlled via a phone app.
Go up to the third floor and trigger each switch until a fan starts up.
Repeat with the second and first floor.
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Similar to iooiiioiio - Notice the wire colors on the switches. In amerka, black tends to be hot, and white tends to be neutral. Turn one fan on, turn another off, and make sure the third switch is wired so the hot wire is white and the black wire is neutral. turn that fan on. trudge upstairs and check which running fan is wired with the wrong colors
1 Like
Actual electrician with an actual solution that will work with little effort.
Turn one switch on.
Open a different switch. Disconnect the switch leg wire from the switch. Now remove the wire nut for the neutrals. Now wire nut together both the switch leg and the neutral for the fan together.
Now go upstairs and identify which fan is the one you turned on.
Then go to one of the fans not on and open up the wiring. Disconnect both the neutral and switchleg from the fan. Use the ohm reading on your multimeter to test for continuity between the two wires (known as ringing out for the sound of the meter).
If the wires have continuity then it belongs to the switch you took apart.
If not, then it belongs to the third switch you did not touch.
Problem solved
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Hey, that’s pretty good! Absolutely would work if the fans were wired to spec!
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I was thinking Kleenex, which appears to be similar to the string ideas. Drape a tissue on each fan, cycle one, leave another running, and Bob’s your uncle.
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Use a multimeter to ensure all switches are in off position.
Install a 5 k-Ohm resistor in series with fan B; turn on A and B. Leave C off.
Go upstairs; one that turns is connected to A; one that does not turn and has no power to it is C; one that does not turn (or barely turns), but has power coming, is B.
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Wouldn’t work exactly like that in my house, the hots are switched, the neutrals run separately, there’s no neutral in the switchboxes. But you could pin one of the outgoing switch legs to safety ground to get the same effect.
I’m a former electrician myself. But that was long ago. I have a Wiggy somewhere.
I’ve just gone and looked at the original problem statement and realized that I (and several others) have violated the conditions - we are assuming the electrician starts from the top! But he doesn’t, so setting anything up in the rooms and then checking it afterwards means climbing the stairs twice.
Your solution does not make that mistake - well done! One on, one off, and one with the feed hot pinned to neutral or ground, that’ll do it.
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Also, since it’s a lazy electrician, breaking out tools seems to indicate a less than optimal solution.
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Like the old saying:
A good engineer will use any amount of effort to avoid extra effort.
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