Calculating Studio Power Needs

12th July 2004

Hey Folks --

We're building a small studio here in Northern California, and I'm trying to calculate our power needs. Since I'm not an electrician, I'm wondering if you guys can help me.

We shoot mainly simple industrial/corporate stuff. We do a lot of one person and two person chroma key stuff and some small set shoots. We have a small grid. Budget IS a limitation. I'm not looking for a dream set-up, I'm looking for basic requirements.

About the most power intensive set-up I can ever imagine us doing would be something like below. These lights may not all be burning at once, but for the sake of planning let's imagine they are :

* 4-6 KinoFlo 4x4's (used to light blue/green screen and as subject lights)
* 3 or 4 300k-600k fresnels
* 3 Lowell Tota fixture -- (750k each) 2250k
* maybe a 1k fresnel or two
* camera and monitor
* two or three laptop computers
class="style9 style10">* two or three more standard outlets for misc. audio, practicals, etc.

This doesn't include house lights, those will be on a separate circuit.

How would our power needs change if we ever wanted to punch a big daylight source like a 5k or something through window of a set? This would be a nice to have.

Finally, can anyone recommend a console to run some or most of these lights, with individual dimmable switches. Is that a nice way to go? How much?

Thanks in advance ...

Daniel Cowles


So with that said - Best to hire an electrician to sort out your needs. It is very difficult to respond adequately and safely to your request.

I mean I could recommend that you get six 20A circuits without addressing the 5K or dimmer. The 5K and dimmer changes everything. Perhaps you need a breakout box off a 200A disconnect but do you have single phase or 3 phase?

Will you want the chance to use a 2.5K or larger HMI (real daylight sources)?

You're best bet is to hire a real film electrician to address your specific needs.

Always hire professionals to do a professional job. Especially when it comes to electricity.

Jim Sofranko

Thanks Jim --

Good feedback. We are indeed hiring professionals ... I'm not doing this myself, just trying to make some estimates. I'll pursue this further with an electrician.

Daniel Cowles
Producer, Macromedia Inc.
San Francisco, CA

A good rule of thumb that allows extra margin for safety and capacity is to divide the wattage of the instruments to be used by 100. Thus 1800 watts of light needs at least 18 amps or a 20 amp circuit. The true calculation results in a different number, but as I said, this way builds in a safety factor, and is good for rough estimates.

Steven Bradford
Collins College
Phoenix AZ

Dan Cowles writes :

>I'll pursue this further with an electrician.

Also pursue it with the electric company. They may have some experience with studios.

BTW, your rates etc. may vary greatly depending on the actual amount (kilowatt hours) of electricity you use at peak times.

It is as Jim Sofranko says not a simple matter, but don't just leave it to an electrician when you may be paying the bill for a long time.

Brian Heller
IA 600 DP

>Good feedback. We are indeed hiring professionals...I'm not doing this >myself, just trying to make some estimates. I'll pursue this further with >an electrician.

I'm glad you understand as it would be too easy to mislead you. There are simply too many things to take into consideration.

Generally, a rule of thumb for estimating is 1,000 watts equals 10A (amps). So a 20 amp circuit will take 2,000 watts maximum.

That's as far as I'll take it as it gets too easy to give inappropriate advice in terms of layout and design.

Best Regards,

Jim Sofranko

A 120 amp box will do more than you need. I have built six insert stages and that is where I start my power minimums at. Sounds like you are in the same place.

We don't look at what light you use but what potential you might need. Usually without a stage my clients are like, you, "here is what we are doing". But a stage is going to introduce you to new ideas and eventually someone in your group is going to say "we ought to get some more permanent lights for the studio" or "let's do more now that we can".

Walter Graff
BlueSky Media, Inc.
Offices in NYC and Amherst Mass.


You don't say how big the studio is other than "small". I suspect studio designers have some guidelines based on floor space that they apply when figuring out how much total amperage to build into a studio space. If you are building a 20'x20' stage the possible extravagance of your power needs and lighting set-ups will be much lower than if you have a 30'x50' or 70'x70' space.

That said, the lights you describe only total less than 10,000 watts (83 amps) if used simultaneously. I would always want to have the option of also bringing in a few 5K's, 6K Space lights or even 10K's for extreme use of the studio you might not contemplate now i.e. high speed, table top, deep focus, big source through window, translight backlighting, etc. Unless the studio is really so small that it precludes all of the above I'd allow for a generous amount of power so that you always have options. Of course one possibility is bringing a generator to the studio on those rare occasions that you exceed the power design. But that should be allowed for now in the design and building of the studio so you can bring in your feeder cables without leaving a door open somewhere. Here in LA stages have special cable pass-throughs just for that purpose.

While your budget may not allow you to dream, I would anyway, at least enough so you have options when you finally use your new space.

My 2 centavos worth.

Randy "give me all the power you got, Scotty" Miller, DP in LA

>At least 600 amps, 3 phase... At least. Why? Cause you just never know >when you are going to need it.

This is why I didn't want to get into this too specifically...

A 200 amp, 3 phase service has a total capacity of 600 amps. In electrical terminology it is called a 200A (amp) 3 phase service.

There is no such thing as a 600 amp service but, as you suggested, a total of 600 amps may be a good start for a studio. It is very often considered the minimum. But it truly depends on the needs of the situation, the existing service, budget, and local electrical codes.

Sorry to be such a stickler for details but I was a gaffer for too long and know how easily this terminology gets confused and misunderstood.

Jim Sofranko

>At least 600 amps, 3 phase... At least. Why? Cause you just never know >when you are going to need it.

I believe you said this is a 25x25 studio? If so 600 amps is about 480 too many.

Walter Graff
BlueSky Media, Inc.

>There is no such thing as a 600 amp service

That is not true. There is such a thing as any number of service panels from 100 amp up a 2000 amp service. Requirements, supply voltage and feeder cabling size determines the limit. It usually goes 100, 200, 300, and 400 for a residential scenario with 300 usually being the upper norm and 100, 200, 400, 600, 800, 1000, and 2000 for a commercial service panel. Of course 2000 is not the limit either, just one of the more standard larger size service panels that are normally installed. For an insert stage of about 25x25, 200 amp service is the bottom line. With that you can easily light 16-25 fixtures of the size mentioned in the original post.

The odds of you needing a 5k HMI in this scenario are pretty slim. You could get the same quality of light in a studio of the size I mentioned with a 400 watt HMI.

Walter Graff
BlueSky Media, Inc.

Maurice Jordan wrote :

>I agree with Miller... The more power the better...

Something to consider is the cost of usage, or Non Usage.

The Studio manager of a production company I worked for, told me that they paid a huge electric bill every month whether or not they used the power, because the power company (Con ed) said that if they were wired for that much power and Con Ed had to be able to supply it, then they would charge for it.

It was two medium sized stages, which sounds bigger than what the original poster asked about, but it is something to check on.

Steven Gladstone
Cinematographer - Gladstone Films
Cinematography Mailing List - East Coast List Administrator
Better off Broadcast (B.O.B.)
New York, U.S.A.

Steven Gladstone wrote :

>told me that they paid a huge electric bill every month whether or not >they used the power,

I was told its not the size of service but the peak draw during the month.

This is what happened at Cinema World Studio in NYC. Last few times I shot there, we worked off a 2000amp genny in the yard! I was told that if they have a heavy draw one day of the month but no draw the rest of the days they still pay a monthly rate based on that peak draw (as if they used that amount everyday). Seems like they got hit for a 10,000 or such bill even though they used little during a months time except for that one or two day usage.

John Roche,


John Roche writes :

>I was told its not the size of service but the peak draw during the month. >This is what happened at Cinema World Studio in NYC. Last few times I >shot there, we worked off a 2000amp genny in the yard!

Actually, it's both, and it depends on the size of the service and the amount of electricity consumed. And it is negotiable.

You may have to agree to a minimum usage in order to get a large service, or you may have to pay for the entire installation. If you go over the agreed amount then you will have to pay the higher rate for the entire billing period. It costs the electric company to have excess capacity available, and they are in business to make money. However, if you are a large enough user, they may pay you not to use a certain amount of power during peak periods.

Many large users have installed generators to use in this "peak shaving" process.

Brian Heller
IA 600 DP

>There is no such thing as a 600 amp service

>That is not true. There is such a thing as any number of service panels >from 100 amp up a 2000 amp service.

You're absolutely right about that Walter.

I stand corrected. I was thinking of the service entrance designation and the difference of the total amps. Oopps.

Thanks for pointing that out.

Jim Sofranko

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