Dear Rabbi Simon
We just moved to a new apartment building and live on the 4th floor. The light is always on in the building, but on some floors when you go up the stairs the light becomes stronger as it detects your movement. So it’s not that the light was off and turns on, but it just gets stronger as you walk by. My question is that on Shabbat, we obviously don’t take the elevator, and walk the stairs. But what shall we do about activating the light in the stairwell? Is this acceptable or do we have to find another apartment, considering its very complicated where we live?
Thank you for your very practical question.
If it is realistic to have/wait for another person to ascend/descend the stairs ahead of you, thereby activating the lights, as you describe, that would be a halakhically preferable solution. However, in light (excuse the pun) of the fact that there is some illumination in the stairwell continuously, you can rely on those authorities (such as Cheshev ha-Efod 3:83) who permit inadvertently (even if inevitably) activating a motion-detector light when the benefit is minimal.
Best wishes and I wish you every happiness in your new home.
Rabbi Rashi Simon