Blowing HID ballasts

Status
Not open for further replies.

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
sceepe's post reminded me of something that happened to me a couple of years ago that i didn't understand. A convenience store owner called me and said he wanted to change the switching on his 125W HID lighting on the outside of store. there were about 14 of these lights controlled by a 20A 120v breaker. he wanted to separate the two over the entrance so he could turn only those on. i separated those two fixtures and put them on another 20A 120v circuit. after turning them on, i walked outside to make sure they were burning, and as i came within sight, i saw the lenses blowing off the fixtures from what i assume was pressure off the exploding ballast. i robbed two ballasts from lights in the rear of the store and replaced the bad ones. i turned the lights on and quickly checked the voltage. all was normal so i quickly turned them back off. i had someone else turn them on while i was standing outside, and they made an awful buzz; the same one you hear when you have an extreme ground fault. i checked all of continuity in the wiring and everything else i could think of. everything seemed to be perfectly normal. the problem wouldn't cease, so i had to reconnect them as they were and replace two ballasts. anyone have a clue? btw, they were multi-tap ballasts.
 
The only thing that springs to mind is the possibility your added circuit was not 120v, but on a bastard 277v leg. A lot of convenience stores around here are in quasi residential/light commercial districts and this is the typical service they have.
 
well, at first i thought, "oh you idiot, you put it on the high leg!" But that's why i checked the voltage. it was a 120/208 3 phase and i was definitely on the 120.
 
we had a similar issue years ago while renovating an office building. is it possible that the 2 circuits are on the same leg and sharing a common neutral. The ones we had were 277v flourescent still HID. When we flipped the breaker lts on 1 ckt cycled off and on while the ones on the other made this god awfull buzzing. Craziest thing I had seen in a while.
 
Last edited:
Status
Not open for further replies.
Top