This is for a central vacuum unit. I would like to be able to tell my home automation when the central vacuum unit is running. A relay or an optic isolator or some item/device that can change states when the vacuum unit is powered on. The simplest way I think is to use the low voltage wires...
I need Help measuring central Vac low voltage circuit. I would like to put a relay in line if possible to trigger when the unit powers on. I measured 17.78 DC volts when off and then 0 when vacuum powers on. Seems like an odd voltage for the contacts that start the unit when you insert a hose.