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Electrical supply for a new studio

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Michael Huffine
Electrical supply for a new studio
on Jan 19, 2010 at 11:12:31 pm

Hi! We are building a new facility with a 40x30 studio. I have been asked by the engineer about the electrical load in the studio area and how to distribute power. He has thrown out a number that I am having a difficult time interpreting. 277 volts for the entire facility??? I am assuming this will need to be converted to 120 for our use.
Perhaps I should also say this, the facility will have 4 edit suites, a couple of kitchens, bathrooms, conference room, green room, dressing room, etc. Approximately 4000 sq ft in total.

As a simpleton in the studio area, we are thinking to provide 10x 20 amp breakers and maybe a couple of 30 amp breakers. But I don't know if this will answer his questions.

I guess my question is how much power should be dedicated to the studio area?
As lighting pros, what would be an ideal set up for you?
How many watts would be ideal to work with? and how would you break it up?
How does 277 volts convert to amps for the building? and then into available wattage?

Help please, before I pop a breaker in my head. Thank you!

Michael



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Rick Wise
Re: Electrical supply for a new studio
on Jan 20, 2010 at 12:32:49 am

You are taking on a pretty large project. My recommendation: hire an electrical engineer who knows studio needs.

A simple answer to your volts-amps-watts question is: "West Virginia." That's the mnemonic for the formula: Watts = volts x amps.

From that it's easy to get to:
-- amps = watts divided by volts, etc.

One of the decisions you will need to make is what is the largest lighting unit you will be using? A 10K? 5K? 2K? etc. Are you sure this need will not change later? If in doubt, go for a larger service.

Edit bays must have dedicated, clean juice. Each computer should be on a dedicated line. Keep coffee machines, fridges etc. on their own circuits.

Hire a real pro. Or else, spend the rest of your life chasing down and resetting tripped circuit breakers. Clients don't enjoy that gladiator sport.

Rick Wise
director of photography
San Francisco Bay Area
and part-time instructor lighting and camera
grad school, SF Academy of Art University/Film and Video
http://www.RickWiseDP.com
http://www.linkedin.com/in/rwise
email: Rick@RickWiseDP.com


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john sharaf
Re: Electrical supply for a new studio
on Jan 20, 2010 at 12:38:18 am

Michael,

A 30x40' studio is a respectable sized facility, but in determining electrical capacity you must really consider the type of shooting that will go on in there, and the type of lighting equipment you will supply.

Obviously tungsten units draw more power (and create heat which is a air conditioning concern) than the very popular fluorescents like Kino Flo, so you should allow current for that type of lighting. A typical manifest would be 2 @ 5K's, 4 @ 2K's, 8 @ 1K's and maybe a set of 4K, 2K and 1K Softlights. That's about 330 Amps @ 120v. We usually budget power at 80% capacity so a 400 amp/120v service would be nominal, and because there are many units in this compliment larger than 20 amps, I'd recommend a motion picture distro service with 20A and 60A Bates connectors, and 100A pass through 10-hole Lunch Boxes starting with a 400 three-phase Camlock panel on the wall.

You'll also want to consider bringing power distro to the permanent rigging on the ceiling, at least half the available service.

I think this means that the service for the whole facility would be closer to 800 amps total, allowing for the edit rooms, kitchen(s) and air conditioning.

To be sure, you must spec out everything you could possibly use/need as a "power budget" and leave a 20% overhead. Your architect should be asking these same questions. Believe me it will be a lot cheaper in the long run to provide an adequate power supply when you build out, rather than adding it later.

JS





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Michael Huffine
Re: Electrical supply for a new studio
on Jan 20, 2010 at 4:47:34 pm

Thanks guys! All of that is a huge help. Firstly, you are right, I need to speak with the general about the electrical engineer he plans to hire.
Most of our own productions will be lit with kino, accompanied by a few 1ks, 650s, etc. But our thinking is to plan for what others may want. Perhaps being able to accommodate up to a 5k is is good, larger than that and I think I'd like to send work to an outside generator. Besides he would appreciate the business.

Hey thanks again - any other suggestions would be appreciated as well. I want to do this right.


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Richard Crowley
Re: Electrical supply for a new studio
on Jan 20, 2010 at 6:36:58 pm

Power for buildings is typically budgeted in "watts per square foot".
For example,
Basic Electrical Mechanical (1,500 to 2,000 Watts/Ton)
BldgType Watts/SF SF/Ton
Data Center 50, As Needed
Detention Facility 6, 300
Educational 6, 350
Hospital 20, 200
Hotel 6, 350
Medical Building 7, 300
Office Building 7, 300
Public Building 6, 300
High Rise Residential 4, 400
Retail 4, 300
Warehouse 2, 500

I have no first-hand experience specifying studio power. But if I had to, I would guess that a TV/film studio would be at least equivalent to the 50W/ft2 specification for a "data center" (comptuer room). That is probably on the low side for a big broadcast facility, but maybe more in line with the kind of productions you anticipate?

Your studio is 1200 ft2 * 50W = 60,000 watts = 500 Amps (@120V)
That would translate (roughly) into 25 circuits of 20A each.

Power for studios is typically rigged with long power ducts running
across the ceiling every 3-4 feet with "pigtails" hanging down to the height of the grid pipes. One pigtail per breaker. Big numbers on the power strip with the breaker number so you know what is what.

Remember that you will need an equal amount of air-conditioning to remove all that heat unless you are planning a studio in the arctic.

It would be good to have a regular (warehouse-style) lighting system at least as "work lights", independent from the production lighting system.

You didn't mention dimmers? Plan enough extra wall/floor space by the breaker panel and studio circuit distribution point to be able to install dimmers. If you anticipate using rented dimmers, then the drops into the studio need to plug in at the breaker panel so that you can re-plug them into the dimmer packs, etc.

277V is a typical scheme used for lighting warehouses and office buildings where they have big banks of fluorescent fixtures built in as part of the building. They are more efficient at 277V. But of course no production lighting runs on 277V, so be sure your electrical people understand that you need 120V!


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cowcowcowcowcow
Bill Davis
Re: Electrical supply for a new studio
on Jan 22, 2010 at 11:23:59 pm

So it's been about 10 years since I started building my studio - about 8 since I "finished" it. (Like much in life, it's an on-going journey!)

In the years since I've been VERY pleased. The essential decisions were as follows.

As in hospitals, run at least two separate feeds. One to standard white Edisons for "dirty" power - which will be used to drive any cycling or inductive loads including lighting, motors, office machines, etc.
Each box might also have one or more "clean power" (orange Edison) circuits that are kept separate. This will be used for all computers, computer monitors, and other data sensitive circuits.

One piece of good news is that power consumption has come WAY down since I did my calculations. Most solid state gear (amplifiers excepted) draw very little actual current. Likewise most of my studio lights are now fluorescent or LED, so I'm NOT drawing anywhere near the load of traditional tungsten.

On the wall behind where my edit bay sits - I specified 8 quad boxes. That's 32 separate outlets. In the second week I started having to mount power strips on the wall next to them. YOU WILL NEVER HAVE ENOUGH OUTLETS near your edit desk - NEVER.

To keep things simple, I had the electrician ceiling mount 4 quad boxes spaced along the edge of the grid rails. Each of the circuits is ganged and switched such that when I power wall switch A - the A outlet of ALL four of the boxes goes on. Same with B, C, and D. This alone is quite a bit of flexibility for simple light setups. I can set all the background lights on A, Pair a Key and fill on B for the first talent, And a Key and fill on C for a second talent. I was going to buy a dimmer package and re-set for more complex lighting, but I've never needed to. If I need a dimmer I just use an in-line rig for the individual light.

One final note. Pay a LOT of attention to your Air handling system. I spent a LOT on a Mitsubishi Split system that keeps the air handler separate from the compressor and mounted the inside unit in a small closet with our studio refrigerator so it can be closed off for noise. That plus making bends in the ductwork and using flexhose for the end of runs to decouple mechanical rattling achieved decent noise suppression such that I can run the AC full out with open mics in the studio.

That's a blessing here in Arizona!

Finally, sound control is the most difficult aspect to achieve in a video studio space. Efficiency in construction means parallel walls and right angles are good. These same features create standing waves and echo that cause recording hassles on an open stage. And soundproofing is it's only issue. Damping high frequencies are easy. But nothing stops bass frequencies but mass. That's why I had the entire studio shell clad in sheetrock, insulation, more sheetrock, and then 3/4" MDF sheets - which took six to eight guys to hold in place and nail up. But the mass keeps low freq airplane and traffic noise out and other than direct rain on the flat roof, I can record 24/7.

One more oddity - again for sound reasons, I specified that my control room have NO parallel walls to reduce the creation of standing waves. To achieve this we had to import a retired carpenter to do the control room framing because he was the only cat who wasn't intimidated by calculating all the weird cut angles necessary to build all the non-parallel and non-right angle walls.

Building a custom studio is fun. But it's not easy. Read and research a lot. Particularly about sound. I LOVE my studio. But it's something you have to either hire outside expertise or devote a LOT of research hours if you want it to turn out well.

Good luck.





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Greg Barringer
Re: Electrical supply for a new studio
on Feb 14, 2010 at 12:52:47 am

277 volts is the single phase voltage of a 277/480 volt, 3 phase system. In other words a single 20 amp breaker will give you 277 volts. A double pole or 3 pole breaker will give you 480 volts. Someone mentioned that 277 volt lighting is more efficient than 120 volt lighting, this is not true. The advantage to a higher voltage is that more fixtures can be placed on one circuit. Another advantage is higher voltage can be run a longer distance without a voltage drop. In a long run like 200 ft., smaller wire can be used. To get 120/240 volt, single phase or 3 phase from 277/480 you'll need a transformer. This would be purchased by you.

Since you know of no equipment that uses 277 volts, go with a 120/240 volt 3 phase system, if 3 phase is available. If 3 phase is not available, you're stuck with single phase. One advantage to 3 phase is in motors. A 3 phase motor will last longer than a single phase one. That means your AC Units would be better off using 3 phase.

Some of the calculations in earlier posts are flawed. An electrical engineer or a good electrician can calculate your total load but they need some of your lighting requirements. This can be found on each light or piece of equipment. It's on the required UL label. Write down the voltage, amperage or wattage of each unit. Tell them you want a dedicated 20 amp circuit for each computer and each could have a total load as high as 1500 watts each. They can then calculate the remaining load of AC, kitchens, and other requirements.

FYI, the correct formula for calculating a 20 amp circuit is;
120 volts x 20 amps = 2,400 watts.
A safety factor of 80% is required by the National Electric Code, so the true wattage of a 20 amp circuit is;
2,400 watts x .8 = 1,920 watts

Let say your total load is 60,000 watts.
In single phase the formula for the main service entrance would be;
60,000 watts / 240 volts = 250 amps
Using that same safety factor required by the NEC, you would multiply by 1.25
250 amp x 1.25 = 312.5 amps
The NEC also requires 30% for growth.
312.5 x 1.3 = 406.25 amps
Put in a 400 amp 120/240 volt single phase entrance.

In 3 phase you use the same formulas, then divide by the square root of 3
400 amp / 1.732 = 230 amps
Put in a 225 amp 120/240 volt 3 phase entrance.

You really don't need to know all this, all you need is an Engineer or Electrician you can trust. Sometimes they want to put in an 800 entrance because it's a money maker. Sometime they put in an entrance that's too small and that will cause major problems.

I'm an electrical contractor with 27 yrs experience. If you want further advice, email me: barringer4@comcast.net


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Greg Barringer
Re: Electrical supply for a new studio
on Feb 14, 2010 at 12:47:53 pm

Let me add that you've gotten good advice in the posts above. I have never wire a studio and other members will know much more about those details.

One other point is a 3 phase service will probably be 120/208 volts, not 120/240. 120/208 is a standard voltage in the U.S. just make sure to check the specs. when ordering 240 or 208 volt equipment. Msny UL labels will say 208-240 volts meaning it accepts both.


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