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Author Topic: Permanent Install  (Read 7438 times)

Jonathan Johnson

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Re: Permanent Install
« Reply #10 on: October 15, 2013, 01:54:52 am »

Electrical codes require there be only a single service entrance -- the point where the utility lines enter the building -- for each structure. In a typical strip mall, you'll see a bank of meters and switches/breakers serving the individual suites with a single, common utility connection. (If you see multiple service entrances, there may be double firewalls between sections of the structure, which in code terms means they are considered separate buildings.) In your case, you're repurposing the entire structure, removing the "suites" and creating a large, single-occupancy space. That means you're probably planning to completely redo the electrical infrastructure.

You'll probably want to place the electrical service entrance closest to the greatest load. If you have kitchen facilities, it may be near the kitchen. Otherwise, it will probably be the stage. Either way, you'll probably end up with one or more subpanels throughout the building. In a large commercial installation, the main panel will be a bank of large (100A or greater) breakers feeding multiple subpanels.

I would recommend installing a subpanel at the stage. That's where most of the load in the sanctuary/auditorium will likely be, since you'll probably be placing the amps and dimmers near the stage. It's also where visiting acts will expect to find power to connect their distros.

For FOH, you can either do home run to the stage panel, or install a subpanel there. If you install a subpanel, feed it from the stage panel to reduce ground currents and other interference.

In order to get the best value for your money, involve these professionals, in this order, prior to putting a job out for bid or beginning construction:
  • A reputable acoustics engineer and audio system designer (since sound is the most important part of worship) before you even sketch a design
  • A licensed architect with experience in church design
  • A reputable lighting designer
  • A licensed structural engineer (to ensure the structure will support the hanging loads)
  • A licensed electrical engineer (to ensure adequate and safe power for all loads in the building)

Note that the subsequent engineering may require revising earlier engineering. The entire team needs to work together.
« Last Edit: October 15, 2013, 05:30:40 pm by Jonathan Johnson »
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Gary Creely

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Re: Permanent Install
« Reply #11 on: October 15, 2013, 08:47:52 am »

Electrical codes require there be only a single service entrance -- the point where the utility lines enter the building -- for each structure. In a typical strip mall, you'll see a bank of meters and switches/breakers serving the individual suites with a single, common utility connection. (If you see multiple service entrances, there may be double firewalls between sections of the structure, which in code terms means they are considered separate buildings.) In your case, you're repurposing the entire structure, removing the "suites" and creating a large, single-occupancy space. That means you're probably planning to completely redo the electrical infrastructure.

You'll probably want to place the electrical service entrance closest to the greatest load. If you have kitchen facilities, it may be near the kitchen. Otherwise, it will probably be the stage. Either way, you'll probably end up with one or more subpanels throughout the building. In a large commercial installation, the main panel will be a bank of large (100A or greater) breakers feeding multiple subpanels.

I would recommend installing a subpanel at the stage. That's where most of the load in the sanctuary/auditorium will likely be, since you'll probably be placing the amps and dimmers near the stage. It's also where visiting acts will expect to find power to connect their distros.

For FOH, you can either do home run to the stage panel, or install a subpanel there. If you install a subpanel, feed it from the stage panel to reduce ground loops and other interference.

In order to get the best value for your money, involve these professionals, in this order, prior to putting a job out for bid or beginning construction:
  • A reputable acoustics engineer and audio system designer (since sound is the most important part of worship) before you even sketch a design
  • A licensed architect with experience in church design
  • A reputable lighting designer
  • A licensed structural engineer (to ensure the structure will support the hanging loads)
  • A licensed electrical engineer (to ensure adequate and safe power for all loads in the building)

Note that the subsequent engineering may require revising earlier engineering. The entire team needs to work together.

I agree this is certainly the best way to go, however we are talking about a guy who has maybe 10k in gear and the aforementioned team would be well into the 6 figure range.

Luke,

It sounds to me like the budget for AVL is really low- too low. The entire system will likely need to be revisited down the road, but in the mean time I have a few suggestions that will be very helpful.

1. Get a good conduit plan and have it installed. Often in these projects you can slide that under the electrical budget rather than the AVL one.

2. Get an architectural dimmer! Do not put a ridiculous bank of rheostats on the wall.

Here is a suggestions (one of my favorites)  http://www.lightronics.com/architectural_wallmount_dimmers_ar602.html
About $2000

This is 6 20amp channels of dimming, made in the USA, rock solid, and I have used many of them. There are various remotes available, and this will control your house lighting. Besides architectural remotes you would then have control of the house lights via your DMX lighting board.


Jonathan's suggestion is the right way to go, and realize even my suggestions fall pretty short of being adequate, but they will help to have some of the infrastructure that is difficult to do after the fact.
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Jonathan Johnson

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Re: Permanent Install
« Reply #12 on: October 15, 2013, 11:41:43 am »

I agree this is certainly the best way to go, however we are talking about a guy who has maybe 10k in gear and the aforementioned team would be well into the 6 figure range.

You're right, of course. Sometimes budgets mean you can't afford a highly qualified team of experts. Nevertheless, the same principles still apply: the architecture needs to be driven by the physics of sound propagation throughout a space; proper lighting is important and can't be determined until the design is roughed out; you need to know what loads you'll be suspending in order to design an adequate structure; and proper infrastructure to power everything can't be determined until you know what you're powering.
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Scott Wagner

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Re: Permanent Install
« Reply #13 on: October 15, 2013, 11:57:33 am »

You're right, of course. Sometimes budgets mean you can't afford a highly qualified team of experts. Nevertheless, the same principles still apply: the architecture needs to be driven by the physics of sound propagation throughout a space; proper lighting is important and can't be determined until the design is roughed out; you need to know what loads you'll be suspending in order to design an adequate structure; and proper infrastructure to power everything can't be determined until you know what you're powering.
The other side to this coin is that hiring the proper team is usually cheaper than trying to fix whatever mess you've made by not hiring them.  "Fixes" after the fact are always more expensive (if they're even possible).  All of these areas of study are complicated.  Add them together, and they get exponentially more so.  The chances of unexperienced people getting all of this correct is almost zero.
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Tom Bourke

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Re: Permanent Install
« Reply #14 on: October 15, 2013, 12:00:16 pm »

For example: 200A service >> conditioner / limiter (at FOH?) >> PA mains, or service directly to PA?
I think you may be misunderstanding the relationships between AV equipment and power distribution.  That is OK because you really should not have to worry about it.  You need to come up with what equipment your using and where.  What potential upgrades and alternate uses may happen.  This is pie in the sky time.  No one ever regrets having too many outlets and circuits!

When I did the theater system described above I did not design the actual system.  I had a meeting with the electrical contractor and described my needs with a walk threw.  Granted I could talk on their level because I do have an electrical back ground but it was not necessary.  The basic meeting was describing our problems and goals. "We needed more power and for it to all be on the same transformer/sub-panel.  We need 3 phase available for chain motors."  We also went into some detail on  proper grounding for audio systems but they were already on the ball and that was more of side conversation.  Then we did a walk threw and I pointed out where I wanted outlets and circuits.  We discussed potential loads for each location.  I let them decide how big of transformer and panel to put in. I did request we have plenty of empty breaker positions for future expansion.  Together we decided on a location for the panel and transformer based on cost and convenience.  Keep the transformer out of the main space, they buzz or hum!  I think total cost was around $25k.  This included a transformer and a tie in to a very funky 600V building distribution system in a tunnel 3 stories down.

In your case I really hope the electrical is being done by a competent and licensed commercial electrical firm.  This kind of system design is nothing like a house or even an apartment building.
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David J. Thomas

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Re: Permanent Install
« Reply #15 on: October 16, 2013, 10:58:38 am »

As electronics developed, the common return paths of various circuits were also referred to as
“ground,” regardless of whether or not they were eventually connected to earth. In addition, a
single ground circuit most often serves, either intentionally or accidentally, more than one
purpose. Thus, the very meaning of the term ground has become vague, ambiguous, and often
quite fanciful. Some engineers have a strong urge to reduce these unwanted voltage differences
by “shorting them out” with massive conductors — the results are most often disappointing. [8]
Other engineers think that system noise can be improved experimentally by simply finding a
“better” or “quieter” ground. Many indulge in wishful thinking that noise currents can somehow be
skillfully directed to an earth ground, where they will disappear forever! [9] Here are some
common myths about grounding:
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Kevin Graf

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Re: Permanent Install
« Reply #16 on: October 16, 2013, 11:29:28 am »

David, your link to the 'grounding myths' didn't stick,  but here are some from Henry W. Ott's new book:

3.1.7  Grounding  Myths

More myths exist relating to the field of grounding than any other area of electrical engineering.  The more common of these are as follows:

1.   The earth is a low-impedance path for ground current.  False,  the impedance of the earth is orders of magnitude greater than the impedance of a copper conductor.
2.   The earth is an equipotential.  False,  this is clearly not true by the result of (1 above).
3.   The impedance of a conductor is determined by its resistance.  False,  what happened to the concept of inductive reactance?
4.   To operate with low noise,  a circuit or system must be connected to an earth ground.  False,  because airplanes, satellites, cars and battery powered laptop computers all operate fine without a ground connection.  As a mater of fact,  an earth ground is more likely to be the cause of noise problem.  More electronic system noise problems are resolved by removing (or isolating) a circuit from earth ground that by connecting it to earth ground.
5.   To reduce noise,  an electronic system should be connected to a separate “quiet ground” by using a separate, isolated ground rod.  False,  in addition to being untrue,  this approach is dangerous and violates the requirements of the NEC (electrical code/rules).
6.   An earth ground is unidirectional,  with current only flowing into the ground.  False,  because current must flow in loops,  any current that flows into  the ground must also flow out of the ground somewhere else.
7.   An isolated AC power receptacle is not grounded.  False,  the term “isolated” refers only to the method by which a receptacle is grounded,  not if it is grounded.
8.   A system designer can name ground conductors by the type of the current that they should carry (i.e., signal, power, lightning, digital, analog, quiet, noisy, etc.),  and the electrons will comply and only flow in the appropriately designated conductors.  Obviously false.

Henry W. Ott
« Last Edit: October 16, 2013, 11:32:02 am by Kevin Graf »
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Jonathan Johnson

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Re: Permanent Install
« Reply #17 on: October 16, 2013, 02:49:46 pm »

The earth is a low-impedance path for ground current.  False,  the impedance of the earth is orders of magnitude greater than the impedance of a copper conductor.

How I learned this:

First, some background. I grew up on a farm. An electric fence charger has one lead connected to the fence wire which is supported on insulators, and the other lead is connected to a ground rod. The fence charger provides a high voltage (typically 3kV-7kV), high impedance pulsed direct current energy energy source to the fence wire. An animal coming in contact with the electric wire completes the circuit between the wire and earth ground, and receives a nasty shock. Because of the high impedance of the charger, the amperage is too low to cause harm.

Anyway, one day during a rather dry spell, I happened to touch the ground rod and received a shock. Because the soil was dry, the connection between the rod and the soil was high resistance. My body provided an alternate, complementary current path between earth ground and the "ground" terminal of the charger.

If the earth were a low-impedance current path, there might be a lot less lightning and nearby lightning strikes could be less deadly due to lower "step potential."

(By the way, when an electric fence has a short circuit, the arc generates an RF signal. I've used a de-tuned AM radio to detect and find faults in electric fences. As you approach the fault, the pulse becomes louder in the radio.)
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