# touching arc source lamps



## ship (Feb 23, 2007)

Ok, say on a sports lighter lamp or just about any parking lot light arc source lamp, it's ok to touch the bulb/glass. 

On a inner capsule stage and studio lamp that also has an outer globe and as similar to the above, also a inner burn arc capsule, such as on a MSR 575/2, it's not ok to touch the outer globe. 

What's the difference and why in why one could say touch a 1.5Kw arc source bulb but not even a 250w arc lamp's outer globe?


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## koncept (Feb 24, 2007)

I am guessing here, but I think it has to do with the temperature the lamp operates at. It has been my experience that stage/studio lamps get much hotter than most other lamps. A cool lamp should not react to the oils (aka not burn...?) like a high temp lamp


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## Radman (Feb 25, 2007)

I think that the stage ones are much more compact too. The glass is closer to the arc. But that's a guess.


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## fosstech (Feb 25, 2007)

That's what I was thinking. We had the arc lamp in one of our spots die because somebody had touched it. Shortly after striking it for the show, the spot op comes on clearcom and says that her spot is smoking. We tell her to destrike. We come up and have a look at it. A portion of the outer envelope was nice and black. Down the toilet went a $150 lamp; luckily we had a spare on hand.


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## socali (Feb 25, 2007)

ship said:


> Ok, say on a sports lighter lamp or just about any parking lot light arc source lamp, it's ok to touch the bulb/glass.
> 
> On a inner capsule stage and studio lamp that also has an outer globe and as similar to the above, also a inner burn arc capsule, such as on a MSR 575/2, it's not ok to touch the outer globe.
> 
> What's the difference and why in why one could say touch a 1.5Kw arc source bulb but not even a 250w arc lamp's outer globe?


The globe on the Utility Merc Vapor or Hi Pressure Sodiums are much thicker, and much further away than the stage/studio types. The envelope pressures are also much lower. However, it is never advisable to touch any globe. The oil from your fingers penetrates the microscopic pores of the glass, and when heated hot enough, turn to vapor, bulf=ging and burning the glass.


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## Schniapereli (Feb 26, 2007)

Cool. Welcome to CB.

I second what he said...


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