How much power for generator

S

Shacke

Active member
Hi, i'll be doing some night shots with a 2000W and a 650W light. How powerful should the generator be, should it simply be minimum 2,650W or is there some other way of calculating the power requirement, i.e. not just adding up the wattage? Thanks.
 
You need a total of about 22 amps for those 2 fixtures, or yes, about 2,650 watts of power.

I doubt a 3,000 watt generator would work. You could get 2 putt-putt generators, one being 2,000 watts and the other being 1,000 watts, or a single 4,000 watt generator with at least one 20 amp circuit.
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I'm no electrician, but I'm sure you need more than the minimum due to the higher start-up current needed to turn lights on. Plus remember the numbers on the generators are maximum outputs for short start-up bursts and are not rated for constant use. Your needs will vary depending on the type of light and generator. Are they 110v or 220v lights? What's the circuit on the generator?
Remember this equation: Watts = Volts x Amps

Let's assume you are using 110V lights. If the generator has one 15A circuit running at 110V you could forget about the 2k light. Since the generator is only producing a maximum allowable of 1,650W.
Now if the generator has a 20A circuit running at 110V producing 2,200W you could only use the 2k light.

This is as far as I'm sure of. Hopefully some one will come by and add to this or correct me if I'm wrong. Just be careful where you plug in that 2k!
 
Johnnyfive said:
I'm no electrician, but I'm sure you need more than the minimum due to the higher start-up current needed to turn lights on.
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A 2K tungsten fixture can be powered by a 20 amp circuit of a generator.

A 1K tungsten fixture can be powered by a 15 amp circuit of a generator.

2 - 650 watt fixtures could be powered by a single 15 amp circuit of a generator.

Johnnyfive said:
Plus remember the numbers on the generators are maximum outputs for short start-up bursts and are not rated for constant use.
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Generators are generally rated as to what they can supply continuously. I would ignore the rating for intermittent loads beyond the continuous rating and just over estimate for the current draw. Keep power cables as short as possible and as high a gauge as you can use and you should be fine.

Johnnyfive said:
Your needs will vary depending on the type of light and generator. Are they 110v or 220v lights? What's the circuit on the generator?
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I'm not aware of any 2K or 650 watt HMI fixtures, and unless the OP is not in the U.S., his (more than likely) tungsten lighting as mentioned would be 120 volts.

Johnnyfive said:
This is as far as I'm sure of. Hopefully some one will come by and add to this or correct me if I'm wrong. Just be careful where you plug in that 2k!
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The worse thing that could happen if a 2K was plugged into a proper circuit that was providing less than the fixture drew in current is the breaker would trip.

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Thanks a lot for your replies.

Chris, I am in the UK and our voltage is 230V the lights i'm referring to a 2K blonde and a 650W Arri light.
 
Chris Santucci said:
Generators are generally rated as to what they can supply continuously. I would ignore the rating for intermittent loads beyond the continuous rating and just over estimate for the current draw. Keep power cables as short as possible and as high a gauge as you can use and you should be fine

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True for the rating. I meant one shouldn't follow the misleading numbers on the model of generator. These are usually the maximum outputs for short periods of time. Always look at the specs for the RATING. For example, a Honda EU3000iSA is NOT rated at 3000 watts but 2800 watts.
 
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