little sparkie
Member
- Location
- Mt. Airy, MD
I'm having ongoing issues with premature electronic ballast failure in HID fixtures. The fixtures are pendant-style, 120VAC, 150W MH, with the ballast in a cylindrical housing directly above the lamp. These fixtures are suspended from a 22' ceiling in a retail store, the bottom of the fixture about 14' off the floor and the ballasts about 18' off the floor. The ballasts last approximately a year and then burn out.
We have determined that there is no incompatibility between the ballasts and the lamps. The ballast manufacturer ran lab tests on the last batch of failed ballasts and came back with failure due to shorting to ground. There is no issue with miswiring of the ballasts nor has there been, nor is there any evidence in the fixtures of arcing or shorted anything. No breakers tripped, nothing burned, discolored or smelling odd in the fixtures.
The fixture manufacturer and the ballast manufacturer are now trying to figure out if there is any incompatibility between the fixtures and ballasts. I am going to put these lamps on a regular replacement schedule so they are swapped out after approximately 80% of their estimated life, rather than waiting until they burn out, because I believe old lamps stress the ballasts and can contribute to their early failure.
Heat may be a contributing factor as well. The ceiling is high, the area where the lamps hang is small, the ceiling and fixtures are painted flat black, there are numerous obstacles to free circulation of air at ballast level (e.g. HVAC ducting, none of which blows cool air on the ballasts, it is well below their level), the heat from the lamps goes directly up into the ballasts, and the ballasts tend to fail in hotter weather. I took temperature readings on the ballast housings in early morning on an overcast day, and it was about 5 degrees F warmer on the housings than it was at chest level from the floor.
What I need to ask is, has anyone out there encountered a similar situation, and what did they find as some possible causes for the problem? Any ideas would be welcome. Thanks.
We have determined that there is no incompatibility between the ballasts and the lamps. The ballast manufacturer ran lab tests on the last batch of failed ballasts and came back with failure due to shorting to ground. There is no issue with miswiring of the ballasts nor has there been, nor is there any evidence in the fixtures of arcing or shorted anything. No breakers tripped, nothing burned, discolored or smelling odd in the fixtures.
The fixture manufacturer and the ballast manufacturer are now trying to figure out if there is any incompatibility between the fixtures and ballasts. I am going to put these lamps on a regular replacement schedule so they are swapped out after approximately 80% of their estimated life, rather than waiting until they burn out, because I believe old lamps stress the ballasts and can contribute to their early failure.
Heat may be a contributing factor as well. The ceiling is high, the area where the lamps hang is small, the ceiling and fixtures are painted flat black, there are numerous obstacles to free circulation of air at ballast level (e.g. HVAC ducting, none of which blows cool air on the ballasts, it is well below their level), the heat from the lamps goes directly up into the ballasts, and the ballasts tend to fail in hotter weather. I took temperature readings on the ballast housings in early morning on an overcast day, and it was about 5 degrees F warmer on the housings than it was at chest level from the floor.
What I need to ask is, has anyone out there encountered a similar situation, and what did they find as some possible causes for the problem? Any ideas would be welcome. Thanks.
