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Lamps => Modern => Topic started by: lightman64 on July 25, 2009, 11:05:00 AM

Title: Mercury Vapor lamps and cold weather
Post by: lightman64 on July 25, 2009, 11:05:00 AM
Why do MV lamps have trouble starting in cold weather? And when they do start, they don't get as bright as normal.
Title: Re: Mercury Vapor lamps and cold weather
Post by: icefoglights on July 26, 2009, 12:43:49 AM
I'm not sure.  I know from first hand experience that it can vary from manufacturer to manufacturer.  I have an older GE and GTE Sylvania at home that would start like champs even at -40° but a Philips Lifeguard, Regent and Caster bulbs that refuse to start at -15°F.  However, once lit they all seemed to reach full brightness with no problems.
Title: Re: Mercury Vapor lamps and cold weather
Post by: bluelights on July 26, 2009, 08:05:19 AM
I thought the light output of high-pressure lamps is not dependent on ambient temperature (within "normal" limits) because the arctube burns so hot that it's not influenced by (in comparison) little fluctuations of ambient temperature...

Title: Re: Mercury Vapor lamps and cold weather
Post by: Medved on July 26, 2009, 01:08:38 PM
@bluelight: The light output does not, but the required starting voltage does depend and a lot. And if the temperature drop so, the starting voltage is higher then the ballast deliver (the mains voltage in 230V areas), it does not ignite.