... -pressure sodium (HPS) lights. More than 10 years later, all but three of the original 36 induction ... Additional systems were installed in 2002 and succeeding years, both indoors and outside, with excellent resultsHaving said ... Some other manufacturers only rate their ballasts for 60,000 hours, even though the bulb may last ... they may last 100,000 hours, after 60,000 to 100,000 hours of operation the ...