Life span of Metal Halides

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hambone1216

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Rochester new york
Having problems with a group of six MH250/m58/u lamps burning out signifigently before the suggested 10000hr. life span. Average actual is 1000-1600hrs. Supply voltage at each head is 212-216 volts. Using 208v taps on the Advance Adapter ballasts and wiring in the following(Line1-208 tap:Line2-common tap: cap1-cap tap: cap2-lamp center: lamp shell-common: grnd-housing) the only cause that i see is the slightly higher voltage. Any ideas?
 
If I recall the hour rating works like this.

50% of the lamps will last at least the hours stated.

So how did you come up with your average, did you include the ones that have not burned out?
 
switching ? lights that are switched multiple times per day or on bad photocells/contactors or switch on and off during dawn and dusk hours because of indirect lighting can prematurely wear out bulbs . suggest you monitor what's actually occuring in a 24 hr period to see what the cause is. (of course, could also be bad batch of bulbs) also check spikes (is this in an area where lots of trees hit power lines during storms ?)
 
Check the voltage during the strike cycle, MH's will usually pull twice the rated load during the strike cycle, if sever enough it can prolong the strike cycle and can cause premature lamp and ballast failure That is why I try to mostly use the Pulse start MH fixtures now, and they have a much longer lasting end of life rating, as much as 5 years. at least that's what Rudd guaranties them for, they use half the rated current for start up and produce way more lumen's per watt than a regular MH fixtures.
 
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