Theater Lighting Load Demand
- Thread starter Artemis
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zbang
Senior Member
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- Roughly 5346 miles from Earls Court
I've never seen one. There's a lot of "it depends"... is this a dimmer-per-circuit installation, large dimmers with patching, or simple disconnects for portable dimmers? Also, some theatrical electricians will assume that they can stack 72kw on a 200a 3p breaker and use it all at once. (I also have to say that some theatrical electricians do understand demand factors, derating, and even proper N-G bonding for generators, but unfortunately they're in the minority.)
There is already a thread on here discussing this topic. LINK. (My input starts with post #12) but past experience shows that you need to assume that ALL dimmers can and will be loaded to full rated capacity, especially on an ambitious production. And the NEC's definition of a continuous load being over three hours is not a good guideline in this case, there will be considerable heat buildup in conductors used for lighting loads that will be on for more than say an hour (which I think would make a more realistic definition of what is a continuous load.)
Be generous in feeder and load conductor sizes to avoid future problems aand callbacks, the extra up front cost will save your reputation.
Be generous in feeder and load conductor sizes to avoid future problems aand callbacks, the extra up front cost will save your reputation.
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zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Oh, and you may need oversized neutrals for the dimmers (for the harmonics). Depends on the actual dimmers.
dbuckley
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- Canterbury, New Zealand
It mostly an artistic question - how much lighting can a lighting designer put in there and have on at once? On a big show a couple of hundred fixtures (at 1K each) is very possible but 500 fixtures much less so. Bear in mind that as the fixture count goes up, it is to give more choices, rather than more brilliance. So the big question is just how magnificent a venue this is? Radio City is a bit diffferent to a small community theatre.
Another big question is how much heat removal is there?
I would suggest that theatre lighting has more or less reached its peak in power consumption; a couple of decades ago moving lights with discharge sources didn't exist, but they are now commonplace. One mover can replace several conventional lamps. We're within a few years of LEDs being common: There are LED lamps today, but as "spotlights" they are dim, and cant complete with conventionals. But LED screens are commonplace, as are LED bars.
What this leads to is that a couple of decades back pretty much all lighting power went through the dimmers. Today only the conventionals do; the movers, LEDs, screens etc all want non-dim "hard" power. And some of this stuff (stuff with discharge lamps, so especially movers) uses full power from startup (and hour before the doors open maybe) until shutdown, which is likely well more than three hours.
From memory the NEC requires that all panelboards running dimmers and the like need 200% rated neutrals.
Another big question is how much heat removal is there?
I would suggest that theatre lighting has more or less reached its peak in power consumption; a couple of decades ago moving lights with discharge sources didn't exist, but they are now commonplace. One mover can replace several conventional lamps. We're within a few years of LEDs being common: There are LED lamps today, but as "spotlights" they are dim, and cant complete with conventionals. But LED screens are commonplace, as are LED bars.
What this leads to is that a couple of decades back pretty much all lighting power went through the dimmers. Today only the conventionals do; the movers, LEDs, screens etc all want non-dim "hard" power. And some of this stuff (stuff with discharge lamps, so especially movers) uses full power from startup (and hour before the doors open maybe) until shutdown, which is likely well more than three hours.
From memory the NEC requires that all panelboards running dimmers and the like need 200% rated neutrals.
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First, thanks for the great responses and the link to the previous thread. It is a full production theater that seats approx 600. The info I have currently from the theatrical designer is 5-600 amp dimming panels and misc lighting loads from spots to rotating lights (an additional 1,000 amps) . I got the same answer from the designer as in this thread that the dimmer feeds need to be 100% rated. In sizing my switchgear 4,000 amps @ 208v 3 phase of lighting seems exceedingly high.....what am I missing?
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
For what its worth, that sounds -way- too big for a 600 seat theater. Doing a back-of-the-envelope calculation, a normal hang in a place that size would be 200-250 instruments. Even if they are 1kw each (highly unlikely*), that's under 700a 3ph. Ask the theatrical designer if they understand how much heat they're talking about...
*The popular Source4 lights are generally 575w incandescent.
I'd expect 2 or 3 400a 3p switches for portable dimmers, a 200a 3p switch for portable sound systems, and maybe 1200a 3p for fixed dimmers. Add house lights and other loads to that.
Or, in another way, good luck getting a 4000a service from the POCO for building that size (or is it part of a larger building?).
*The popular Source4 lights are generally 575w incandescent.
I'd expect 2 or 3 400a 3p switches for portable dimmers, a 200a 3p switch for portable sound systems, and maybe 1200a 3p for fixed dimmers. Add house lights and other loads to that.
Or, in another way, good luck getting a 4000a service from the POCO for building that size (or is it part of a larger building?).
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