# Figuring Wattage



## Auggie56 (Oct 4, 2008)

I have three 175 w Metal Halide fixtures on the outside of my garage. I want to use a single photocell to control them. What kind of wattage will I need in a photocell ? The system is 120 volt.


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## Bkessler (Feb 14, 2007)

Is this a trick question?


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## 480sparky (Sep 20, 2007)

Bkessler said:


> Is this a trick question?


Looks more like a DIY question.


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## Bkessler (Feb 14, 2007)

480sparky said:


> Looks more like a DIY question.


Oh, yup I did not notice.

That answer to the question is......


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## threewire (Jan 28, 2008)

Your going to need like 6 or 8 of them wired together to produce the proper frequency for the metal halide's. If the fused induced voltage is over amp'd you will need a buck and boost transformer to correct the power factor.

Sounds good right?


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## Marco Electric (Sep 18, 2008)

P=E x I...I think? Or something like that.


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## Trimix-leccy (Dec 4, 2007)

threewire said:


> Your going to need like 6 or 8 of them wired together to produce the proper frequency for the metal halide's. If the fused induced voltage is over amp'd you will need a buck and boost transformer to correct the power factor.
> 
> Sounds good right?


Sounds good to me BUT [and bearing in mind I am a UK Electrical Engineer and our electricicity differs to yours] you would need to consider whether your supply is dextro or levo rotatory. Plus 3rd hamonicas and transitional evoluments could, but are unlikely, to be an issue


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## Speedy Petey (Jan 10, 2007)

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