Originally Posted by JRigby
8 of those 8' lamps is 480W plus you will have some loss at the ballasts, your sensor is rated at 500W. What is the VA rating of the ballasts? First check to see if the ballasts are magnetic or electronic, then check the VA rating and make sure you are not overloading the motion sensor.
I am pretty sure the inrush current will knock the motion sensor out pretty fast due the mangatic ballast inrush current can be up 2 to 4 X of running amps.
By the way I never read the bulb wattage if you are going to size the circuit or switch rating I have to go by ballast rating so you will have to look it up but IIRC 8 foot slimline they will take about 1.5 to 2.5 amp depending age of ballast itself.
Note: with bad slimline ballast they will draw more current than a good one will draw.