Regular incasdescent in a HPS ballast?

?
I know that HPS ballast can accept incasdescent...but in a lower voltage (I tested my NEMA head ballast with the incandescent...and the voltage was 100 volts to be exact.....
but will this work for every HPS ballast? I mean maybe some ignitor works differently from others....also some HPS ballast have capitiors...which running an incasdescent could be bad for it?

I do not know at all......can anyone help?

Thanks!!!!
-Jace-