Theater

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mshields

mshields

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Just picked up a 45,000 sq ft theatre. Have never done a theater. So I've reviewed Article 520 and I see that one of the things I'll likely have to contend with is a Stage Switchboard.

Are these typically custom made pieces of equipment or is a typical group mounted switchboard ok. Sounds like you have to have more accesibility to it than a regular switchboard and I imagine there are numerous small loads on it.

Any input would be appreciated.

Thanks,

Mike
 
theater

theater

I did some work on a new 16 cinema theater. This was small additional add on work. The projector room was kind of neat. One camera man runs around and operates all 16 cameras at the same time!:confused: :-?
 
mshields said:
Are these typically custom made pieces of equipment or is a typical group mounted switchboard ok. Sounds like you have to have more accesibility to it than a regular switchboard and I imagine there are numerous small loads on it.
Click to expand...

Stage Switchboard generally equals "really old resistance/autotransformer dimmer system". In a new facility, you won't have one. The stage loads will be supplied from the building's switchboard.

Usually a stage will have:
permanently-installed stage light dimmer system
permanently-installed house light dimmer system
(multiple) multi-hundred amp disconnects for portable dimmers/etc (there may be a small switchboard on the stage if the load is high enough)
a few panels of branch circuits for utility outlets, work lights, controls, etc

IME, usually a theatrical consultant does the design work for most of that, but go over any plans with a very fine tooth comb. The errors can be both hilarious and frightening:D .

Also, pay close attention to the size of the service, you may want to increase it. Get any "load letters" early in the process.

Edit- Unless you have a seemingly-insane amount of power, stage lighting people will try to consume every amp. If a switch is marked "400a 3-phase", they'll load it to 48kw/phase.
 
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ItsHot said:
I did some work on a new 16 cinema theater. This was small additional add on work. The projector room was kind of neat. One camera man runs around and operates all 16 cameras at the same time!:confused: :-?
Click to expand...


Isn't that referred to as "downsizing"?:D
 
And make sure someone who is actually going to use the place who knows what he (or she) is doing goes over what you plan to do. Employment of a theatre architect or consultant almost guarantees trouble, from the end-users point of view...

And as to the multiplex cinemas - the art of the projectionist is more or less dead these days, with platter systems and full automation one concession stand operator can indeed keep a multiplex full of projectors running. Sure the image is out of focus, but the customers dont care so why should the concession stand operator?
 
Theaters are fun....

movie theaters are interesting...the projection room can be a scary place in the middle of the night...

regular theaters are just plain fun...we are in the midst of a renovation on a theater about that size...but this one is 82 yrs old...

we are switching it from a system of dimming boards to a lutron system...it's definitely not for the faint of heart, and it's definitely very detail oriented...plan to spend an inordinate amount of time dealing with the A/E on this...
 
emahler said:
Theaters are fun....

movie theaters are interesting...the projection room can be a scary place in the middle of the night...

regular theaters are just plain fun...we are in the midst of a renovation on a theater about that size...but this one is 82 yrs old...

we are switching it from a system of dimming boards to a lutron system...it's definitely not for the faint of heart, and it's definitely very detail oriented...plan to spend an inordinate amount of time dealing with the A/E on this...
Click to expand...
You've watched to many horror movies!:smile:
 
ItsHot said:
I did some work on a new 16 cinema theater. This was small additional add on work. The projector room was kind of neat. One camera man runs around and operates all 16 cameras at the same time!:confused: :-?
Click to expand...


Sorry to pick nits here, but it's Projectionist and projectors. :grin: (As someone who has made a career of cinema, this always bugs me, just like changeover cues being called "cigarette burns".)

Cameras are for taking pictures or movies. :grin:

The reason one man can operate so many projectors at the same time is due to the invention of the platter transport system. An excellent site for all topics cinema related is HERE.

On topic, an example of a really old theater's switchboards can be found HERE There are four threads total you can find from that link.

A legit theater (which has a stage for live performance) has some very unique demands for power usage, load factors and so forth. For a dimming system in a theater, a good, conservative design practice is to figure that the stage dimming board can and sometimes will be used at 100% of it's capability for at least two hours at a stretch. In other words, don't count on a lot of load diversity. :)

A movie theatre usually doesn't have the same issues, the only real loads of any major size that need to be factored as 100% and continuous are the xenon lamps in the projectors and the HVAC. :)

And as for the high concession prices, little (publically) known fact: The studios get up to 95% of the ticket price, sliding down to no less than 65% at the tail end of a very extended run of a movie. Literally the only way the cinema can cover the house nut (overhead) is through the concession sales. Most cinemas operate at a 3% or less profit margin, which is why I have never owned a cinema. :)
 
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To answer some of your questions

To answer some of your questions

It's a performance theater not a movie theater. As for how I could get a 45,000 sq ft job and not know what to bid; I'm not bidding anything, I'm the EE on the job. We do have a theater consultant on the project and while I'm in the process of trying to connect with him, we haven't spoken yet. No, I'm not attempting to do stage lighting from the seat of my pants, that will be done by the theater consultant who can probably answer most of my other questions as well. Just wanted your inputs on the peculiarities of such a facility.

Thanks for the input.

Mike
 
I'm sure the theater consultant will drive most of this but here are some thoughts:

Either one dimming system for house and stage lights or if needed, add second smaller rack to handle emergency lighting circuits. The latter is sometimes less costly by utilizing a single transfer switch rather than a multi pole contactor. Also remember that most dimming systems have cooling fans that make noise!!

Typically separate audio and video feeds both from their own isolated/shielded K rated transformers. Usually 200 amp 3 phase each but depending on use, the video could go higher if remote truck connections are involved or a TV studio. In both cases, get the transformers as close as possible to the company switch or system they would feed without creating an ambient noise issue near the stage. When road crews come in and have a "noise" issue with their system, the first thing they will do is measure the neutral to ground voltage and if there is any ----- try to blame the venue's "poor electrical design" on a situation (usually a ground loop) that their wiring created. The facility manager doesn't always know better and then the Engineers start getting a bad wrap!

Stage lighting consumption would probably be between 144 & 216K max. Yes, in some venues (usually the older ones) the services would be maxed out but not likely unless this venue does some really big stuff. We will also see demand decreasing as more and more L.E.D. applications come to market not to mention the increased energy costs to run a typical show now.

The trend is to provide more 2.4 dim circuits to Electrics and other lighting positions which would allow as much as 50% diversity. keep in mind the overall feed capacity though, it needs to be delivered regardless of any diversity applied to the branches.

Separate neutrals for all circuits.

The code allows for diversity with wireways but not conduit?????

If you add company switches for touring rigs, 400 amp only! If you need more power than that, add another. The cabling schemes used are not rated for more than 400 amps and if you provide a 600 amp switch, it will have 400 amp wiring connected to it. The majority of touring rigs are in 200 or 400 amp configs.

Everything 3 phase!

Hope this helps or at least sparks questions
 
I'm currently involved with a theater. Seems that the major design concern is using 200% neutrals in all switchboards, panels, and transformers used for lighting and for feeders to company switches as well. All lighting homeruns have a separate neutral and share one EGC per conduit. All 400 amp company switches are fed with 5-600 kcmil conductors with a #2 EGC.

Everything else is pretty much the same as commercial work. Dressing rooms, hallways and common areas are all wired with MC cable. All exposed wiring is in EMT.
 
200% neutrals

200% neutrals

Wow - I'll apply that - thank you.

I've actually now got the benefit of our theater consultants drawings and he requires 1200A @208V for dimming (stage and house), a 150A @208V feeder via iso transformer for Audio and Video and a 600A distribution panel for Misc. Theatrical Systems and Power (like pit lift, rigging related, etc)

It looks like all I need to do is add my HVAC loads.

Any idea what kind of diversity to hit these numbers with to determine a service size.

Mike
 
mshields said:
I've actually now got the benefit of our theater consultants drawings and he requires 1200A @208V for dimming (stage and house), a 150A @208V feeder via iso transformer for Audio and Video and a 600A distribution panel for Misc. Theatrical Systems and Power (like pit lift, rigging related, etc)

Any idea what kind of diversity to hit these numbers with to determine a service size.
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(I assume you mean 120/208v 3-ph 1200a...)

You should be able to calculate house lighting using it's actual load, but for stage lighting assume 100% usage of whatever's available. Most stage lighting people don't understand the concept of derating ("It says 20a, I should be able to -get- 20a. Continuously.").

Is the sound/video feed for a build-in system? Many traveling companies will want a 150a or 200a disconnect for their sound systems. If they expect to have video or sound production trucks outside, expect at least 100a 2p for each of them.
 
zbang said:
Most stage lighting people don't understand the concept of derating ("It says 20a, I should be able to -get- 20a. Continuously.").
Click to expand...

Many dont understand the concept of overloading. I've seen 4KW loads on 2KW dimmers many times, and at one venue I regularly work at, 3KW of house lights are on a 2KW dimmer, itrs worked for years...
 
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