number of dimmers and channel capacity of high schools

[BillESC]

Dimmer per circuit vs. patch panels. Old argument with currently no new answers.

Just as every venue is different and every venues budget is different either method has its' place.

Example:

In a 60 seat dinner theatre I was asked to help in I found six Lightronics 4 - 1.2kW circuit dimmer packs in various locations across the ceiling. Some circuits had instruments plugged directly into the packs, some circuits had orange cords of up to 50' running to a fixture that happened to near a different pack. The place was a mess.

We stripped the ceiling and mounted all six packs next to the breaker panel back stage. We then created circuit cables to the first, second, third and FOH pipes, 48 in all. The 48 circuit tails hang next to the dimmer packs. In essence this is a patch panel system.

One town over is the middle school auditorium which has 196 - 2.4kW circuits and is dimmer per circuit. I design for both and both have their merits.

 

[STEVETERRY]

Anyone know what a "modern" patch panel in the US looks like? I'm guessing 200 male 10' 12/3 SO cables with 2P&G plugs hanging out of boxes and 96 flushmount receptacles mounted in adjacent boxes? STEVETERRY, would the circuits need individual breakers per the NEC? (Like the Telephone Operator and Slider Patch panels used to have?) And would it be possible to mix 1.2Kw and 2.4Kw dimmers in such a system? How about some 6.0Kw dimmers, I'm sure those would require branch circuit breakers. Or if the males and females both were 60A-2P&G would that not require BCBs?
The cost of the above could exceed the cost of another 96x2.4Kw rack, including labor and materials, hence my opinion of patch panels not being economical or viable. Maybe BillESC could comment also.

Any male pigtails or flush mount connectors that feed permanent building wiring must have a circuit breaker, per NEC section 520.50 Road Show Connection Panel. This is the case even if they are going to plug into a female outlet (presumably on a portable dimmer system or on the patch panel itself) that is already protected by a circuit breaker of the right ampacity.

One you figure in the cost of this breaker, additional dimmers are often cheaper than a patch panel.


ST

 

[SteveB]

Any male pigtails or flush mount connectors that feed permanent building wiring must have a circuit breaker, per NEC section 520.50 Road Show Connection Panel. This is the case even if they are going to plug into a female outlet (presumably on a portable dimmer system or on the patch panel itself) that is already protected by a circuit breaker of the right ampacity.
One you figure in the cost of this breaker, additional dimmers are often cheaper than a patch panel.
ST

Agreed.

I believe it was Sonny Sonnenfeld who wrote a Theater Crafts or Lighting Dimensions article way back in the early 80's, detailing exactly what Steve is indicating, that at that time, it was now more cost effective to so Dimmer-Per-Circuit as opposed to a patch panel. Sonny worked for Strand at the time and was mostly comparing the custom lighting manufacturer built patch panels (Of which the Kliegl Safe-T-Patch as an expensive version).

I cannot imagine what with the cost of copper these days, as well as the labor for a licensed electrician paid by the hour, that any type of SOOW/multiple circuit breaker/with lots of 2P&G connectors, etc... patch panel is going to be cheaper then all hardwired dimmers. Building one is moving in the wrong direction, IMO.

Steve B.

 

[cutlunch]

I agree that if you have to have a circuit breaker on patch circuit it would get expensive.
Here in New Zealand this doesn't seem to apply. Which I think is logical because a patch circuit never has power on it until you connect a power source such as a dimmer. Where is the circuit breaker right, at the patch panel end or down near the stage end? If its right at the patch panel I think this is over kill as you have two protection devices right next to each other. Provided the wire you used for the patch lead is rated for a higher current then is supplied by the dimmer this should increase the safety factor.
If I was getting a new installation done with dimmer per channel but I knew I might add more dimmers later I would get the wiring done for the possible extra dimmers at the start. I am not sure if this would be legal in the states. But If I thought I might double the number of dimmers later I would have double the circuits wired to the bars now. It will be cheaper on a electricians time to make twice the circuit outlets on a bar now then have to come back and haul extra wire into the lighting bar later. These circuits would be marked as not working and the wire ends would be secured with enough spare length to be wired to the extra dimmers later and put in some space out of the way ie the roof space above the dimmers. If you didn't upgrade for a few years you would have saved some money by having it done when things are cheaper. Also you could add one pack at a time as you get the money. This is instead of waiting until you had enough new dimmer circuits to justify the cost of having to rewire all the bars.
With you having to have all those circuit breakers on a patch panel I can see the cost problem. This has been an interesting discussion and thanks for putting me straight on how you have to do things in the States.

 

[SteveB]

I agree that if you have to have a circuit breaker on patch circuit it would get expensive.
Here in New Zealand this doesn't seem to apply. Which I think is logical because a patch circuit never has power on it until you connect a power source such as a dimmer. Where is the circuit breaker right, at the patch panel end or down near the stage end? If its right at the patch panel I think this is over kill as you have two protection devices right next to each other. Provided the wire you used for the patch lead is rated for a higher current then is supplied by the dimmer this should increase the safety factor."

US systems in olden tymes might typically have dimmers rated at 1.2kw, 2.4kw, 3.6kw, 4.0kw, 7.2kw and/or 12.0kw. The dimmers would have over current protection sized to the capacity of the dimmer.

As per US Nat'l Electrical Code, if you connected branch circuits via a patch panel and the branch circuits were typically at a 2.4kw rating, you needed branch circuit protection sized for the branch circuit capacity.

"If I was getting a new installation done with dimmer per channel but I knew I might add more dimmers later I would get the wiring done for the possible extra dimmers at the start. I am not sure if this would be legal in the states."

Perfectly legal here to have branch circuit wiring installed but not connected. FWIW, we call it "Dimmer-Per-Circuit" not "Dimmer-Per-Channel" as the Channel refers to the console control access.

"But If I thought I might double the number of dimmers later I would have double the circuits wired to the bars now. It will be cheaper on a electricians time to make twice the circuit outlets on a bar now then have to come back and haul extra wire into the lighting bar later. These circuits would be marked as not working and the wire ends would be secured with enough spare length to be wired to the extra dimmers later and put in some space out of the way ie the roof space above the dimmers. If you didn't upgrade for a few years you would have saved some money by having it done when things are cheaper. Also you could add one pack at a time as you get the money. This is instead of waiting until you had enough new dimmer circuits to justify the cost of having to rewire all the bars."

I have exactly what you describe. When we renovated in '04, we installed 48 dimmer circuits in 4 wall mounted boxes on the stage level. The renovation ran out of money and we never had the existing wood stage floor replaced (now scheduled for summer '09), thus we never had the new floor pockets installed. Ea. floor pocket circuit (48 total in 8 boxes) was a repeating circuit from the wall boxes. The wiring for the floor pockets ran out of the wall boxes down into the basement, where they were wire nut capped in junction boxes awaiting a future floor and floor pocket installation.

"With you having to have all those circuit breakers on a patch panel I can see the cost problem. This has been an interesting discussion and thanks for putting me straight on how you have to do things in the States.

I think there can certainly be scenarios where a locally built patch panel can be the only cost effective solution. I always recommend (not that anybody asks) that monies be found to do DPC.

SB

 

[STEVETERRY]

I agree that if you have to have a circuit breaker on patch circuit it would get expensive.
Here in New Zealand this doesn't seem to apply. Which I think is logical because a patch circuit never has power on it until you connect a power source such as a dimmer. Where is the circuit breaker right, at the patch panel end or down near the stage end? If its right at the patch panel I think this is over kill as you have two protection devices right next to each other. Provided the wire you used for the patch lead is rated for a higher current then is supplied by the dimmer this should increase the safety factor.
If I was getting a new installation done with dimmer per channel but I knew I might add more dimmers later I would get the wiring done for the possible extra dimmers at the start. I am not sure if this would be legal in the states. But If I thought I might double the number of dimmers later I would have double the circuits wired to the bars now. It will be cheaper on a electricians time to make twice the circuit outlets on a bar now then have to come back and haul extra wire into the lighting bar later. These circuits would be marked as not working and the wire ends would be secured with enough spare length to be wired to the extra dimmers later and put in some space out of the way ie the roof space above the dimmers. If you didn't upgrade for a few years you would have saved some money by having it done when things are cheaper. Also you could add one pack at a time as you get the money. This is instead of waiting until you had enough new dimmer circuits to justify the cost of having to rewire all the bars.
With you having to have all those circuit breakers on a patch panel I can see the cost problem. This has been an interesting discussion and thanks for putting me straight on how you have to do things in the States.

Let's be clear as to the reason the NEC requires that "extra" circuit breaker.

Let's say a TV shoot was occurring in your theatre. The crew brought in a rack of 6kW dimmers. They plugged that male patch cable right into one of the 6kW's, using an "illegal" 20A to 50A adaptor. Then they decided to load it with 4000W of Audeince light PARS, even though it is a 2400W circuit, "because they'll only be on for a few minutes".

Without that breaker, there is a possibility of overloading the building wiring and causing a fire hazard. The building wire is hidden in the walls , so we want to make absolutely sure that doesn't happen.

ST

 

[cutlunch]

Let's be clear as to the reason the NEC requires that "extra" circuit breaker.
Let's say a TV shoot was occurring in your theatre. The crew brought in a rack of 6kW dimmers. They plugged that male patch cable right into one of the 6kW's, using an "illegal" 20A to 50A adaptor. Then they decided to load it with 4000W of Audeince light PARS, even though it is a 2400W circuit, "because they'll only be on for a few minutes".
Without that breaker, there is a possibility of overloading the building wiring and causing a fire hazard. The building wire is hidden in the walls , so we want to make absolutely sure that doesn't happen.
ST

I see your point but I think this is over the top. For one thing if it is your theatre you tell them no. You could have them split the load over multiple patch leads. Does this happen a lot in the States, that people throw out commonsense, when it comes to electrical safety?

I am not getting at you guys. I know our electrical regulations on tap-on plugs got tighter when a few Australians electrocuted themselves by miss wiring extension leads.

 

[gafftapegreenia]

Took a look at the studio theatre today:

There are a total of 5 electrics evenly spaced. Each electric has 12 circuits. In total, the space has 60 circuits.

Dimming is via two Klieglpac9's. There is no seperate patch panel. In the booth there is simply a break-out of the 60 circuits, and the two klieglpac9's stacked on eachother on a rack. Each dimmer of the klieglpac has the ability to patch in 3 circuits. So, with three circuits running off each dimmer, 54 circuits would be in use.

The board is a kliegl 2 scene board. Each scene has 18 faders.

Heres the link to klieglbros.com, we have 2 pacs, and thus, we have the larger board, with a second bank of faders(not pictured):
http://www.klieglbros.com/catalogs/SpecSheets/KP9/kp9c81brochure.htm

 

[STEVETERRY]

I see your point but I think this is over the top. For one thing if it is your theatre you tell them no. You could have them split the load over multiple patch leads. Does this happen a lot in the States, that people throw out commonsense, when it comes to electrical safety?
I am not getting at you guys. I know our electrical regulations on tap-on plugs got tighter when a few Australians electrocuted themselves by miss wiring extension leads.

The problem is that the "Honor Code of Overcurrent Protection" does not fly with the NEC.


ST

 

[ElectroCarp]

When I was in HS our proscenium we had two Strand CD80 Supervisors with 96 dimmers a piece with an ETC express (forget which model) and in our Studio Theater we had the 24 module ETC Sensor + SineWave rack for a total of 48 dimmers.

 

[chausman]

Well, this thread and the [thread=8386]Your Lighting Inventory[/thread] thread seem to go hand in hand, so, my high school has 2 CD80 racks (96 each) and 125 channels.

 

[LXPlot]

We have 2 sensor racks and a strand c21 racks. I don't know how big each one is, but I know it adds up to 285 dimmers. A little ridiculous, yes, but works for me.

 

[techno89]

My school has an SR48 with probably only 40 dimmers installed max. kinda sucks. Express 24/48 control.

8x S4 36 deg
4x S4 19 deg
10x 3cr 8ft altman r-40 strips
8x PAR64

 

[tyler.martin]

The first high school i went to had a Strand CD80 96Channel rack with an Strand 300 Clamshell console.

The Second Highschool I went to had a Strand CD80 Rack, with 24 Dimmer modules that were our property, but then another 24 that were district floaters, that were shared among 4 highschools in the district. Unfortunatly we had a Colortran Innovator for control.

The theatre that I was TD at (attached to a high school but operated separately) had 3 Sensor 48 Racks fully loaded for 288 Dimmers, with both an Ion and an Express 48/96 for control.

I just finished 2 Install projects in high schools in Western Canada,the biggest One had 4 Sensor racks 384 Dimmers, an Ion for control, 6 VLX's 6 VL3's, 12 Mac 350 Entours and 50 Selador's...

 

[chausman]

I just finished 2 Install projects in high schools in Western Canada,the biggest One had 4 Sensor racks 384 Dimmers, an Ion for control, 6 VLX's 6 VL3's, 12 Mac 350 Entours and 50 Selador's...

Can I come to Canada?

 

[BTHSSWSam]

I'm the sound board op at Brooklyn Technical High School right now.
We have one of the three largest non-arena seating arrangements in NYC (the first being Radio City). We have 136 circuits and only 48 dimmers. We just got a new ETC ION console, and we'll be doing electrical work over the summer, installing 200 new circuits. I believe we'll be upgrading to 96 dimmers at that point.

 

[Sony]

142 in the large theatre and 48 in the small theatre. Large theatre has 137 Stage Dimmers and 5 Dimmers for House Lights.

 

[sdauditorium]

We are a mid-sized high school/community auditorium house (600 seats). We a CD-80 Supervisor rack with 96 dimmers..original install/construction in 1991. Control is a Express 24/48, but with all of the color scrollers and movers we have are looking into an Element or Ion in the future.

 

[JWilsonLX]

~700 seats. When I left, we had a 144 channels of Sensor dimming(a whole 24 dimmers for houselights). Main control was an ETC Express 125, moving light control varied between an ETC Insight 1 with no video output or an NSI/Leviton 7524. There was also an NFG Express 24/48.

 

[Tex]

Our main stage (804 seats) has four ETC Sensor+ racks with a total of 378 D20 dimmers and 6 R20AF relays. The black box has 1 1/2 racks with 144 dimmers and 2 relays.