I installed some 400 watt 120volt hi bay metal halide fixtures in a gymnasium in 1996. In the past two months two ballasts have needed replacement. Both shorted out and tripped the breaker, each at different times. My questions are (1) what is the general life span of this type of ballast, (2) Do they normally short out when they die or is this abnormal. I don't do much with this type of fixture so I am not too familiar with them. Thanks in advance for any help.
Scott
