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Author Topic: Power Dist Question  (Read 2711 times)

Michael Montag

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Power Dist Question
« on: February 19, 2018, 03:00:31 pm »

Pretty new to the world of Power Distribution.  Recently purchased a line array that comes with an amp rack that has power distribution on board via a 30amp twist lock plug.  My question is what to do when I'm at a smaller venue or park where this is not possible.  What if I only have access to standard 20AMP standard plug circuits?  Is there a safe way to convert this?
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Mac Kerr

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« Reply #1 on: February 19, 2018, 03:02:48 pm »

Pretty new

Please go to your profile and change the "Name" field to your real first and last name as required by the posting rules displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section, and on the registration page when you registered.

Mac
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Scott Helmke

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Re: Power Dist Question
« Reply #2 on: February 22, 2018, 12:43:51 pm »

Pretty new to the world of Power Distribution.  Recently purchased a line array that comes with an amp rack that has power distribution on board via a 30amp twist lock plug.  My question is what to do when I'm at a smaller venue or park where this is not possible.  What if I only have access to standard 20AMP standard plug circuits?  Is there a safe way to convert this?

There's not a reliably safe way to connect one twist lock to two or more wall outlets.
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Nathan Riddle

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Re: Power Dist Question
« Reply #3 on: February 22, 2018, 02:30:05 pm »

There's not a reliably safe way to connect one twist lock to two or more wall outlets.

Doesn't have to be two wall outlets though. Depends how this 'twist lock' is wired.
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Don T. Williams

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Re: Power Dist Question
« Reply #4 on: February 22, 2018, 05:19:58 pm »

You can wire a 30A TL connector to a 15A "Edison" cord set, BUT if your system draws more that 15A (or 20A if a 20A plug/circuit) the circuit breaker will function - IT WILL KILL YOUR POWER!  In the middle of a show, it is more than just inconvenient.  I have Crest Pro 9200 amps that came factory wired with 30A TL's.  I used the 30A TL with my distro, but have rented the amps to customers with 15A Edison adapters with no problems, but these customers are never connecting more than a stereo 4 ohm load to the amps. To the best of my knowledge, they have never had any problems.  Even a mid sized line array is another story.

My most recent event with a well know and respected "Red Dirt" act in a 2500 seat arena gave me a chance to measure the current draw during the performance.  I was using 12 DB Tech T12's, 4 T8's, and 6 S30N subs for audio, and 32 LED 100 watt hex wash lights, 8 ADJ PARZ1003K's for spots, 3- 360 watt LED blinders, and a dozen 300 watt LED movers.  The typical draw was just under 20A per leg 120/208 three phase.  This included stage power for the band, but no foggers or haze machines, as per the band's request.  This wasn't a really loud band but typical of country acts.  I was surprised!!!  Much lower that expected!
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Mac Kerr

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Re: Power Dist Question
« Reply #5 on: February 22, 2018, 05:36:47 pm »

My most recent event with a well know and respected "Red Dirt" act in a 2500 seat arena gave me a chance to measure the current draw during the performance.  I was using 12 DB Tech T12's, 4 T8's, and 6 S30N subs for audio, and 32 LED 100 watt hex wash lights, 8 ADJ PARZ1003K's for spots, 3- 360 watt LED blinders, and a dozen 300 watt LED movers.  The typical draw was just under 20A per leg 120/208 three phase.  This included stage power for the band, but no foggers or haze machines, as per the band's request.  This wasn't a really loud band but typical of country acts.  I was surprised!!!  Much lower that expected!

I have measured a 3 400A service that was powering a good sized V-DOSC rig with 40 Crown MA5000VZ amps, with a pretty loud band at full tilt boogie. An amp clamp on the separate feeder legs read about 40-50 amps/leg. This included all sound power.

Mac
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Stephen Swaffer

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Re: Power Dist Question
« Reply #6 on: February 22, 2018, 09:50:56 pm »

So 40 X 5000 = 200,000

200,000/8=25,000 watts

Measured was 50 X 208 x 1.73 = 17,992

Hence the 1/8 power rule of thumb?
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Steve Swaffer

Mac Kerr

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Re: Power Dist Question
« Reply #7 on: February 22, 2018, 10:28:49 pm »

So 40 X 5000 = 200,000

200,000/8=25,000 watts

Measured was 50 X 208 x 1.73 = 17,992

Hence the 1/8 power rule of thumb?

Could be. All I know is it was LOUD. 40 V-DOSC, 24 SB218 subs, 12 dv-DOSC down fills, plus, at the artist's insistence, 12 S4 subs, and a loud Clair monitor rig. All this pre IEMs. The FOH mixer thought it sounded great, better than their regular tour rig, but wouldn't admit that to the production mgr. Did I say it was loud? Blow the doors open in a 10,000 seat arena.

Mac
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Keith Broughton

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Re: Power Dist Question
« Reply #8 on: February 23, 2018, 09:04:00 am »

I have measured a 3 400A service that was powering a good sized V-DOSC rig with 40 Crown MA5000VZ amps, with a pretty loud band at full tilt boogie. An amp clamp on the separate feeder legs read about 40-50 amps/leg. This included all sound power.

Mac
Was this average or peak?
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Mac Kerr

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Re: Power Dist Question
« Reply #9 on: February 23, 2018, 11:29:40 am »

Was this average or peak?

This was with a Fluke 8020a. AFAIK it's average,  but it was with all those amps pretty much full out.

Mac
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Keith Broughton

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Re: Power Dist Question
« Reply #10 on: February 23, 2018, 11:43:34 am »

This was with a Fluke 8020a. AFAIK it's average,  but it was with all those amps pretty much full out.

Mac
I did some peak current measurements (long time back) and it's surprising how high the reading was for a fairly conservative system.
That said, average is probably more in line with how cct breakers see the load.
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Stephen Swaffer

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Re: Power Dist Question
« Reply #11 on: February 23, 2018, 01:18:17 pm »

Most circuit breakers have both a thermal and a magnetic trip mechanism.  Thermal works off the average and has a setpoint corresponding to the breaker rating-it is intended to prevent wire from overheating.

The magnetic or "instanteous" mechanism has a much higher threshold intended to protect against short circuits where milliseconds can make a significant difference in the amount of collateral damage casued by a fault.
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Steve Swaffer

ProSoundWeb Community

Re: Power Dist Question
« Reply #11 on: February 23, 2018, 01:18:17 pm »


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