Hey guys. I just went to troubleshoot a large grow room. Breakers are tripping for the 36 - 1000w HPS lighting. The building is 208v, the lighting is 240v.
I unplugged all the ballasts and fired up the breakers and contactors. Everything held and no tripping breaker. I tested voltage at contactors and receptacles, everything is 'OK'. I told the guy looks like hes got some bad ballasts.
I started plugging in 1 ballast at a time to try and find the bad ballast. Well come to find out every ballast is bad. Most are just not working, a few others pop'd, sparked and smoked. After the 2nd pop, spark and smoke I stopped.
Scratched my head for a few minutes.
Went back to test the contactors. I killed power to the coil and tested the contactors in the normally off position. There was voltage on the load side while the contactor was off!
I'm thinking the contactor failed and when it shut off it didn't shut off fully and must of sent 208v down a leg and fried the ballasts. Quite odd it happened to all 4 contactors.
Hes running these same contactors and same load in another room and its been fine for 6 months.
The stats on the contactor are: FL=40a, RES=50a. The load was 9000w of HPS lighting powered by an electronic ballast.
I told him his contactors are overloaded and basically welded together, creating 208v down 1 leg and destroying his 36 ballasts. $10,000 in damages. He had a hard time believing it, saying the contactors are rated for 50a and they shouldn't do that. I told him they should be rated atleast 20% higher... I was talking outta my ass at this point cause I really don't know.
Can you guys give your opinion on this and tell me the proper sizing for the contactors. Or maybe he needs a different type of contactor, idk. My contactor experience is little.