Crazy motion sensor and a three-way.
I have an electrical question. I recently intsalled a motion detector on an outside electrical box. The switch for that fixture is in a tree-gang box along with two other switches, both of which are three-way. If the motion sensor is energized, and I turn on the flourescent fixture in the kitchen, the motion sensor light will come on. Is something wired incorrectly, or is this a characteristic of three-way switches? I am a cabinetmaker and don’t know very much about electrical work, so I would appreciate hearing from someone who does. Thanks.
Replies
If the motion sensor light stays on permanently, then things are wired wrong. If it just comes on and goes off after a time-out period as if it had been triggered by something moving, then the problem is a transient from switching one light fooling the sensor for the other.
-- J.S.
Thank-you for your reply. By transient do you mean the traveller wire in the three-way wiring, or something else. Thanks again.
A transient is an event, not a physical object. It's electronic noise, a glitch in the voltage waveform caused by switching a load on or off, or by a noisy load. For instance, a pop noise on a radio when you flip a switch is a transient. Speckles on your TV picture when you run an electric motor are transients. It may be that the electronics in the motion sensor get fooled by a strong transient from switching another load nearby on the same circuit. In designing the motion detector, they had to make a tradeoff between cost and immunity to transients.
-- J.S.
Thank-you for a most informative reply. I now see what you mean by a transient.