Amps Required for Lighting System

[GoboMan]

Hello,

Let's say there's a new lighting rig going into a new building. The lighting plot consists of Source Fours, VL2500s, SolaSpots, and various LED wash lights and practicals. If the entire rig (all instruments) would be powered up at 100%, it would draw 236 kilowatts of power. The conventionals are going into a 96-channel LMI dimmer rack with 20A modules.

How many amps would be required to be fed into the building to power this system safely?

 

[TJCornish]

What quantity of fixtures? How did you arrive at 236KW of power?

Is this the only use of this building forever or are you allowing for the inevitable changes that will happen in the future?

 

[GoboMan]

The estimated breakdown is this...
96 Source Four 750w
8 VL2500 Spot
2 Studio Spots
2 SolaSpot Pro
45 Practicals (~75w each, type A bulbs)
15 LED TriPAR fixtures

25 of the Source Four fixtures will have Coloram II scrollers. The practicals will be plugged into Leprocon dimmer packs that are plugged into the convenience switches on the 96-channel dimmer rack.

I got my total wattage by adding the capacity of all 96 dimmers in the rack plus the extra movers and practicals powered on and running at 100%.

Also, this would be a temporary site used just for this show.

 

[icewolf08]

Hello,

Let's say there's a new lighting rig going into a new building. The lighting plot consists of Source Fours, VL2500s, SolaSpots, and various LED wash lights and practicals. If the entire rig (all instruments) would be powered up at 100%, it would draw 236 kilowatts of power. The conventionals are going into a 96-channel LMI dimmer rack with 20A modules.

How many amps would be required to be fed into the building to power this system safely?

Typically in the US, 96-channel racks are connected to 400A or 600A service. Given that you also have a bunch of other non-dim equipment, you likely will want one or two additional 400A disconnects that you can conned PDs to as needed.

The thing is, this only accounts for the theatrical lighting equipment, you also have to factor in the needs of the rest of the building, including offices, HVAC, audio, video, non-theatre lighting, etc. etc. With that said, it is probably best to work with your contractor and whatever theatre supplier you are using to get your equipment and installation as they will be able to work out the electrical needs of entire building.

In other words, take any numbers thrown out here with a grain of salt as none of us know all the circumstances of your facility.

 

[GoboMan]

Yes, my question is strictly for the theatrical lighting aspect only. Every other electrical element of the building itself will be handled by other departments. I'm just looking for lighting system requirements.

 

[RonHebbard]

Hello,

Let's say there's a new lighting rig going into a new building.

Let's ask if this new building will be supplied by a three phase or single phase service.
You've got questions.
We've got questions.
Teasing you only a little. Basically we'll need to know far more about your space and your needs to come anywhere near giving you more useful answers.
Toodleoo!
Ron Hebbard.

 

[GoboMan]

Let's ask if this new building will be supplied by a three phase or single phase service.
You've got questions.
We've got questions.
Teasing you only a little. Basically we'll need to know far more about your space and your needs to come anywhere near giving you more useful answers.
Toodleoo!
Ron Hebbard.

Hahaha! I don't blame you one bit! From what I understand, it will be a 3-phase system.

 

[BillConnerFASTC]

For the quartz lighting, use the connected load, not dimmer capacity. For instance, the 96 - 750 w units require 200 amps 3 phase. That would allow you to bring all to full, which is usually unlikely. I don't have the data for the other units but just add it up. The LEDs will have some inrush but as long as the power is shared and you have not run all up to full, you'll be fine. Don't trust this but without all the data it seems a 250 SMP feed or 300 at most would be satisfactory.

Or ask your theatre consultant.

 

[JD]

Using the number from your original post:
Your full inventory on at the same time would be 236Kw. Therefore 236000/120v = 1967 amps, if balanced on 3Ph /3 = 656 amps per leg.
So, you start with the raw number, but to get to the finished number, you need to hire in a qualified theater electrical consultant. There are two factors that will modify this number:
First, your OCPD needs to be loaded only to 80%, so that drives the number much higher.
Second, a Diversity study to determine how much of that load will really be used at any given time. That drives the number lower.
Sounds like you would end up with a 600 amp OCPD, but "sounds" is not good enough

 

[BillConnerFASTC]

I've worked on over 100 theatres and have never used the 80% derate except for work and house lights. Theatre lighting is highly unlikely to be continous per NEC and no need to plan for it.

PS Pretty sure the 80% only applies to branch circuits, not feeders anyways. Steve Terry will correct me if I'm wrong. And it may have to do with breaker and wire because 100% is allowed with the correct breakers and wire.

 

[JD]

I've worked on over 100 theatres and have never used the 80% derate except for work and house lights. Theatre lighting is highly unlikely to be continous per NEC and no need to plan for it.

Thus statement number two, Diversity!
I remember running a 36k club show off a 50X2 one night. I was counting in seconds! (... 3 second full back wash, followed by a 12 second 2k blue cross stage for cool down...) Bit nerve wracking, but we made it through the night! (Rock Show)

 

[RickR]

I've worked on over 100 theatres and have never used the 80% derate except for work and house lights. Theatre lighting is highly unlikely to be continous per NEC and no need to plan for it.

This is more true the further up the supply chain you go. Any single circuit could be at full maybe even for 3 hours. (Movers struck before house opens and stay on through photos on stage.) The feed to the whole building, never!

Something I've not studied in detail is the cooling rate of components. NEC says 3 hours = continuous, based on heating of wires and connections. So a 2.5 hour matinee followed by a 2 hour break (partial load) followed by another show, leaves us where? This certainly isn't covered in the code but might lead to issues down the road.

Then lets consider future growth in program and equipment.

 

[BillConnerFASTC]

In my work, I don't include diversity. I add the planned load and size the feeder for it at 100%. I show this in a schedule to be code compliant. Typically I use 2 * 575 per 2400 watt dimmed circuit, or actual load for house, work, and utility to size feeder.

 

[JD]

In my work, I don't include diversity. I add the planned load and size the feeder for it at 100%. I show this in a schedule to be code compliant. Typically I use 2 * 575 per 2400 watt dimmed circuit, or actual load for house, work, and utility to size feeder.

Ah! But, "Planned Load" is the core of Diversity! Of course, dimmer values have far less relevance, which is why the inventory of a house is far more important. If you had a show with 300k of dimmers and 100k of lights, you would plan your electrical based on the 100k of lights and the fact that your full inventory would most likely never be left on for 3 hours straight.
The new wildcard is that once you move away from conventional lights then you have to plan differently. Most noticeably with discharge-type movers. Suddenly you are dealing with lights that not only will remain lit for the full show, but also demand more than their rated wattage due to PF's that are less than 1, and strike currents that far exceed run currents.

 

[Jay Ashworth]

And, just so we're all speaking the same language: when you guys talk about a "200A service" or "600A service" at three-phase; you mean *amps per leg*, right?

So I can take 1800A of 120V off a 208/3@600 service?

 

[DavidJones]

Good topic. This comes up a lot. This depends on they type of shows and the planned use of the building. I have never had an issue with a 400a service for a 96 dimmer rack, and often see a 600a feeding 2x 96 dimmer racks. It is often assumed(planned) that while there are a lot of circuits, they are mostly distributed for convenience, and will not all be utilized at the same time. A rock show with a ton of blinders can certainly change your calculations for how much power is used, but that can be considered on a sow-to-show basis especially if that would be less than typical.

I think 2x 400a services would be sufficient. If you have outside tours bringing in lighting packages, I would probably do all of the house on one service and have a separate for guests, or possibly keep just dimmers on one, and everything else on the other. It really depends on your needs. The good news is that new LED fixtures are really bringing down power requirements, so if you have "just enough" power now, in a couple of years with more efficient fixtures you will have plenty of capacity to spare.


@Jay Ashworth, That is what I am used to. A 400 amp service, unless otherwise specified, is a 400a 120/208 wye. So indeed 400a per leg, or 1200 amps single phase 120 total..

 

[RonHebbard]

I've worked on over 100 theatres and have never used the 80% derate except for work and house lights. Theatre lighting is highly unlikely to be continous per NEC and no need to plan for it.

PS Pretty sure the 80% only applies to branch circuits, not feeders anyways. @steve Terry will correct me if I'm wrong. And it may have to do with breaker and wire because 100% is allowed with the correct breakers and wire.

@BillConnerFASTC
I'm not disputing what you're typing, not at all, but I can site two retrofits within two venues within one building (In Hamilton, Ontario, Canada) where the two new racks were inspected by two different AHJ's with one enforcing the 80% rating / derating and the other not. The inspector decreeing the 80% was primarily used to approving feeders for large industrial motors, several hundreds of HP and up, whereas the second AHJ, several years later, was more used to inspecting demands for multi-story apartments and condo's. Each had their backgrounds and differing interpretations. I was playing an IA assistant head LX and IBEW 5th year apprentice at the time and thus hung well back with my ears open, mouth closed and showing proper reverence. There's always something to be learned though occasionally it can be how to incorrectly interpret various sections of the code.
Old blind geezer back in his hole.
Rant off and lectern relinquished.
Toodleoo!
Ron Hebbard.

 

[EdSavoie]

I'm no expert, but the box next to our 70 dimmer CD-80 exclaims "three phase 300A", so I'm going to guess that's total, not per leg.
Especially since running everything we own on the dimmer (including 2x 2KW super alt spots, 9KW of foots, 10 KW for zones, 6KW scoops, and a 5KW cyc...) comes up to 283.3 Amps (excluding the odd 500W fresnel and such)

 

[DavidJones]

@BillConnerFASTC
I'm not disputing what you're typing, not at all, but I can site two retrofits within two venues within one building (In Hamilton, Ontario, Canada) where the two new racks were inspected by two different AHJ's with one enforcing the 80% rating / derating and the other not. The inspector decreeing the 80% was primarily used to approving feeders for large industrial motors, several hundreds of HP and up, whereas the second AHJ, several years later, was more used to inspecting demands for multi-story apartments and condo's. Each had their backgrounds and differing interpretations. I was playing an IA assistant head LX and IBEW 5th year apprentice at the time and thus hung well back with my ears open, mouth closed and showing proper reverence. There's always something to be learned though occasionally it can be how to incorrectly interpret various sections of the code.
Old blind geezer back in his hole.
Rant off and lectern relinquished.
Toodleoo!
Ron Hebbard.

I tend to agree with bills approach here, but I think the real issue is the inspectors not understanding that the requirement is a combination of 80% and/or diversity, as well as probably not understanding the way that dimming systems are utilized, and often most of the dimmers will not be on, most of the time. I think it comes down to knowing the individuals on your AHJ, and if they actually know what they are doing. Let's face it this is often very small state and local governments; they sometimes have very unqualified people in various jobs. That's the reality of our system. Your mileage may vary.

That is not to say that most, or even many inspectors are unqualified, but you might run into some, and maybe they are qualified but just overworked. Usually, its best to be polite and say something like, "Hmm, I though I was reading the NEC and XXX would apply in this case? Can you look into that?"

 

[RonHebbard]

I'm no expert, but the box next to our 70 dimmer CD-80 exclaims "three phase 300A", so I'm going to guess that's total, not per leg.

@EdSavoie I could guide you to a similarly populated CD80AE rack in a Cathedral Basilica in Hamilton, Ontario, Canada where a similarly labelled and rated 3P common trip 300 Amp breaker is providing 300 Amps per phase leg. If the same rack were fully populated with 48 dual 2.4 Kw modules I would normally anticipate it being supplied by a 3P common trip 400 Amp breaker. 3 phase 5 wire WYE as I believe a previous poster suggested.
Tag! You're it @EdSavoie
Toodleoo!
Ron Hebbard.