Installed a 100 watt mercury vapor outdoor light. It was fine until winter now its going thru bulbs. Problem started when customer is using a small electric space 1500watt heater on inside on same circut.
Is it a defective fixture or to much on circut.
Thanks

What voltage do you have at the light with both the heater and light drawing current??

GJ

did not check, assumed if it was drawing to much would trip breaker

The 100 watt light draws about.9 amp (100W/110V=.9091A)
The 1500 watt space heater draws (1500w/110v=13.6364A)
total draw is 14.5455A
A 20 Amp breaker will carry this all day.
A 15 amp breaker will propally carry this if the heater does not run all the time.
If 14AWG wire was used and the heater and light are over50-75' away you propably have a voltage drop causing the light to pull more than normal. If so the bulb will heat up more than normal and burn out much to soon.
You need to do a voltage check at the circuit breaker feeding this circuit and at the heater and at the light. Be careful and use a good quality meter. Avoltage drop of greater than 5% is a problem.
You may need to seperate the heater and light. Also check if anything else is on the circuit.
Good luck

Ray,
One thing I do know, is that any type of Gas
Discharge lighting, does not particularly like Voltage drop, it can damage the control gear as well as the lamps.
If possible, I would put the MV Lighting on a dedicated circuit.
Hope this helps.