On Fri, 29 Jun 2018 06:00:52 -0700 (PDT), TimR wrote:

I don't know what kind of circuit that would be a problem for, if any.

Power factor of the load is not relevant. The original problem was that
many models of motion-activated light switches use the load as a virtual
ground for the sensor circuit. Thus there is always a small current flow
through the load while the sensor is checking for motion.

Full current is applied when motion is detected, and the small continuous
flow while it is 'waiting' is not enough to light an incandescant bulb.

But it *is* enough to light the much more efficient LEDs. Thus they end up
being slightly 'on' while no motion is detected. Because of the design of
the AC power supply in the base of the LED that convert & filters the
current for the LED, often they will blink very fast instead of lighting up
very dimly.