1) You want this to be easy to reset.
2) You don't want this to be so easy to reset that children playing with it will do it by accident.
I feel that a good compromise between the two would be a rule of "flick the switch on and off three times in two minutes, with the on state being longer than 3 sec".
This makes it easy to reset, just flick it on and off three times slowly, but hard to reset accidentally, since children don't tend to flick light bulbs on and off that slowly. For added safety, you can make the "on" time 5 seconds instead of 3.
I don't think "flick it on and off slowly three times, with each flick lasting at least five seconds" is hard to follow.