Added a 100 watt mercury vapor light with junction from a old outdoor outlet on a screen porch that was enclosed as a sun room.
Started going thru fixtures when a heater was used in room. I think the voltage drop was causing problem. Replaced fixture to try one more time and still have a problem.
Is there much difference if I change to a 70 watt fixture or am I forced to try different location since there is no good way to run another circut to light.
Thanks

ahh mercury vapour lights are kinda voltage senstive but what you mention heater .. but should check the voltage drop when the heater actived and alot of hids are pretty voltage senstive it can stand from 5 % to 50% volt drop for a monteary but really should check the wiring for any loose connetion if any doubts just get the professeal electrican to help you to make sure the voltage is corret

merci marc

rayh78,
What sort of wattage rating does the fitting have?.
Sounds to me like the voltage drop caused by the heater running is, in turn causing the lamp to draw more current to maintain it's arc.
This sound right?(or even plausible?).