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Author Topic: Power Ratings  (Read 5062 times)

Lyle Williams

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Re: Power Ratings
« Reply #10 on: May 17, 2014, 01:12:38 am »

It is worthwhile having a current meter (power meter) inline with a similar system for at least one show.  That will give you an idea of how much current you really need.

If you tell the electrician you need 20kW they are right to check that there hasn't been a mistake in your calculations.

Electrical theory might lead you to think your required amps is:

   AmpClaimedWattsOutput divided by AmpEfficiency divided by SupplyVoltage divided by PowerFactor

but that theoretical number may be out by a factor of ten due to not considering the dynamic range of the material.
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TJ (Tom) Cornish

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Re: Power Ratings
« Reply #11 on: May 17, 2014, 08:18:58 am »

This is exactly what I am looking for.  Aside from my specific application mentioned above, I am looking for basic info, not job site talk that makes sense in industry speak.  I want to be able to talk to an electrician and not get funny looks.  I find it very frustrating to work in an industry with standards and then talk to an electrician who doesn't get anything about those standards that our gear is using.  I come rolling in with a sensor rack and say I need 100amps at 208V and they look at me like I'm crazy and tell me there is no way that equipment needs to run that way.  My only answer is, well they all do it this way.  As it is with my stated example my electrician thinks I'm crazy, because back on the job site in the day 240V was enough for them.  The meeting of worlds!

Thanks for the terminology info, I will think in those terms instead from now on.  It does make more sense that way.
Being an "electrician" doesn't guarantee theoretical understanding or specific knowledge of any area. I suspect that only a tiny fraction of electricians has ever seen a camlok connector.

Knowledge is power and the whole point of this forum section is to try to bridge the gaps in knowledge and communication, because we have some unusual needs for what we do. Kudos to you for seeking understanding.
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Stephen Swaffer

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Re: Power Ratings
« Reply #12 on: May 17, 2014, 10:20:19 am »

Being an "electrician" doesn't guarantee theoretical understanding or specific knowledge of any area. I suspect that only a tiny fraction of electricians has ever seen a camlok connector.

Very true!  I have met (and worked with!) electricians who could make conduit bending look like an art form, but had no idea how (or even that it should be done) derate  a conductor or even wire a 3-way switch.  Especially with a large contractor, once they finish apprenticeship they might wind up running pipe and rarely terminating a wire, and even more rarely actually having to determine wire size.  I hold a license that allows me to design/build virtually any wiring project in my state-but if I were to do a healthcare facility or even a service station I would be in over my head and have to spend some time in the Code to get it done right.  The A/V industry has some considerations that are not necessarily addressed by code.  Personally, I will do my best to meet a customers needs, but I can tell in just a few minutes how well they understand what they need-the better they understand, the more serious I will take their special requests.  I suspect that that would be a common reaction.  And, by the way, the better you understand what you need, the better you can judge whether the electrician is capable of understanding what you need.

Saying someone is an electrician is a lot like saying someone is an engineer.  An engineer can build a road, and an engineer can design an automated control system-but probably not the same engineer.
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Steve Swaffer

Tim McCulloch

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Re: Power Ratings
« Reply #13 on: May 17, 2014, 11:11:04 am »

Very true!  I have met (and worked with!) electricians who could make conduit bending look like an art form, but had no idea how (or even that it should be done) derate  a conductor or even wire a 3-way switch.  Especially with a large contractor, once they finish apprenticeship they might wind up running pipe and rarely terminating a wire, and even more rarely actually having to determine wire size.  I hold a license that allows me to design/build virtually any wiring project in my state-but if I were to do a healthcare facility or even a service station I would be in over my head and have to spend some time in the Code to get it done right.  The A/V industry has some considerations that are not necessarily addressed by code.  Personally, I will do my best to meet a customers needs, but I can tell in just a few minutes how well they understand what they need-the better they understand, the more serious I will take their special requests.  I suspect that that would be a common reaction.  And, by the way, the better you understand what you need, the better you can judge whether the electrician is capable of understanding what you need.

Saying someone is an electrician is a lot like saying someone is an engineer.  An engineer can build a road, and an engineer can design an automated control system-but probably not the same engineer.

Exactly.

And TJ is right, most electricians that don't do temporary, portable power distribution have never seen a camlok.  Most electricians are not familiar with NEC 520/525, either.

When our county opened its new downtown arena, I was "head electrician" for the first 3 events - 2 concerts and a WWE live TV show.  The electrical contractor sent 2 guys to be on site in case there were issues.  They really had little idea of how we distributed and used the services they had installed and how much power was used by various types of events.  I walked them through, from company switch to lighting truss, to give them an idea of the scope of temporary service.  They were equally informative and took me around the facility to show how it was wired and introduced me to several things I'd never considered, as I don't get involved in the interactions of HVAC and other high-load services.  It was a great day at the office. :)
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Ivan Beaver

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Re: Power Ratings
« Reply #14 on: May 17, 2014, 12:24:23 pm »

Exactly.

And TJ is right, most electricians that don't do temporary, portable power distribution have never seen a camlok.  Most electricians are not familiar with NEC 520/525, either.

When our county opened its new downtown arena, I was "head electrician" for the first 3 events - 2 concerts and a WWE live TV show.  The electrical contractor sent 2 guys to be on site in case there were issues.  They really had little idea of how we distributed and used the services they had installed and how much power was used by various types of events.  I walked them through, from company switch to lighting truss, to give them an idea of the scope of temporary service.  They were equally informative and took me around the facility to show how it was wired and introduced me to several things I'd never considered, as I don't get involved in the interactions of HVAC and other high-load services.  It was a great day at the office. :)
We all learn from each other.  Sometimes our little world seems really small and there are often other more important things to consider-that can affect us.

The more we know about the "whole picture" the better off we will be in times of trouble.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

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Chris Jensen

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Re: Power Ratings
« Reply #15 on: May 19, 2014, 03:55:28 pm »

We all learn from each other.  Sometimes our little world seems really small and there are often other more important things to consider-that can affect us.

The more we know about the "whole picture" the better off we will be in times of trouble.

I agree with this Ivan.  The hardest time I ever have is when you are in a non performance venue.  Usually like a museum doing some sort of a full fledged summer concert or dance show.  They hire out production but then you have to face the building engineer who thinks your crazy because he has never seen lights use that kind of power.  This is one of the reason I want to start observing from their end a bit more.
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Jonathan Johnson

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Re: Power Ratings
« Reply #16 on: May 19, 2014, 04:27:52 pm »

We all learn from each other.  Sometimes our little world seems really small and there are often other more important things to consider-that can affect us.

The more we know about the "whole picture" the better off we will be in times of trouble.

In my day job as a contract network/server technician, I like to spend a little time to learn about how my customers do their jobs and what their company does or makes. This does two things: by understanding their workflow, I am better able to make their systems work for them, and by showing an interest in what they do, and it gives them a sense that I'm there as much or more to help their business as I am to help myself.
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Re: Power Ratings
« Reply #16 on: May 19, 2014, 04:27:52 pm »


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