Discussion: Moving Light Lamp Power

GoboMan

Active Member
Hello, all!

So I was having a discussion with one of my stagehands the other night and I was wondering if you had any opinions/input.

At the venue where I work, we have a rig consisting of 12 moving lights, which is made up of VL2500s and Studio Spots. When I get to work every day, I power up the rig, do my channel check, and then test all of the movers to make sure the CMY wheels work, gobos, etc. Once my power up process is complete, I then power off all the lamps via the light board. The time between my power up process and the start of the show can be up to 3 hours, as we do the power up process early in case any repairs need to be done. I feel that rather than burn the lamps for three hours while the moving lights do nothing is a waste of energy, and I'd rather save hours on the lamps since they are expensive.

My stagehand feels that powering the lamps off and then back on before the show is more damaging to them. They attributed it to a computer, saying it takes more energy and loss of usable life to power it up rather than if you just kept it running all the time. If there was only a half hour between power up and start of show, I would agree, as the lamps wouldn't even be cool yet before turning them back on. But a period of three hours? I feel that as long as the fans in the movers are running and keeping the lamp cool, powering them back on 15 minutes before house open is not hurtful.

I would love to hear your thoughts. Thanks!
 
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With arc lamps there is a point where leaving them lamped on makes more sense than lamping them off. That point is a matter of much discussion, however.

It uses a lot more theoretical lamp life to strike the lamp arc than it does to maintain it. This is the reason that people leave movers lamped on if going away for a few hours. Lamps are also much less likely to burn out once they have struck, so sometimes people leave them struck to avoid an issue when relamping them on. If I walk away for less than a two hour dinner break, I'll leave everything on. When do you relamp the fixtures on currently? Do you leave yourself enough time that if the lamp doesn't strike you can still replace it?
 
A good rule of thumb when talking about lamp life vs lamp strike is that a lamp strike = about 1 hour of lamp life. If you have more than an hour between shows (or check and show), then it is a better use of lamp life to turn them off and re-strike them. 3 hours? Turn them off. Besides the lamp life, I would be more concerned about an unmonitored system. There are any number of issues that can arise, control, power, sensitivity of the fixture, etc and having a fully powered fixture just sitting there... that being said, I don't know if you have someone at the console all the time, and there are many examples of leaving a rig on for an extended period of time. I'm sure everyone has their own preferences.
But for a strictly lamp hour reason, in your case, off they go I say.
 
There are other factors to look at as well, such as the amount of heat contained in the fixture while the lamp is on. Nothing ages electronics, and dries out mechanics like heat. Yea, an hour or more, I would shut them down.
 
My go to rule of thumb is if I'm walking away for more than an hour, douse lamps. The heat build up from those extra two hours of unnecessary lamp on time, over months or years, can shorten the life of some of the parts in the fixture. Lamping off can also help because it will stop temperature-controlled fans from running after a little while, which will bring less dust in to the fixture. I've also heard the 1 strike = 1 hour from multiple people before, which is why that's my general guideline.
 
My go to rule of thumb is if I'm walking away for more than an hour, douse lamps. The heat build up from those extra two hours of unnecessary lamp on time, over months or years, can shorten the life of some of the parts in the fixture. Lamping off can also help because it will stop temperature-controlled fans from running after a little while, which will bring less dust in to the fixture. I've also heard the 1 strike = 1 hour from multiple people before, which is why that's my general guideline.

That would be an interesting thing to quantify. I know that capacitors especially have lives dependent on operating temperature. Not to mention the implication of motors energized and absorbing heat. At some point it comes down to fixture wear vs lamp wear.
 

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