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Author Topic: 3 phase light tower questions  (Read 4545 times)

Blake Ross

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3 phase light tower questions
« on: June 23, 2011, 01:39:13 pm »

Hi, I need some help with my first outdoor concert using light towers for stage power.

 I apologize in advance that I have limited knowledge using 3 phase power, and that my question will probably be simplistic for the pro's here in the forum.

The promoter is providing 2 Allamand 20KW (model ML EX V 15/20) light towers for stage power. One unit is single phase, the other appears to be 3 phase (the visible labels on the pictures I had taken of the unit to be rented show the 125/250 twist locks are labeled 208 volt, the 60 amp hubble is a 4p5w which Hubble lists as a 3 phase receptacle (the rental company assures me the light towers are both single phase units and they have no other 20kW units available that day...

There will not be enough power to run sound and lights from a  single generator with the bands lights and tower lights running, so I'm hoping they can use the 3 phase tower for stage lights only, but I need more information on 3 phase power usage.

My question:

    Can they use the 3 phase lighting plant for powering the 240 volt band lights, or will the 208 volts at the 60 amp plug  cause issues for the lights and controller ?

(the band lights have 25 feet of cable terminated in a NEMA 14-50 style plug, the rental company does not have a 4p5w plug and cable to fit their own rental unit).

The manufacturer does not publish the voltage expected at the 60 amp receptacle.

Both of the light tower have  4 x 30 amp 125/250 4 prong twist jacks and  2x 15 amp GFI's, but only the 3 phase has the 60 amp jack.


Thanks in advance for any help you can provide, be it suggested reading, calling an electrician, running the other way fast...
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Charlie Zureki

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Re: 3 phase light tower questions
« Reply #1 on: June 23, 2011, 04:12:12 pm »

Hi, I need some help with my first outdoor concert using light towers for stage power.

 I apologize in advance that I have limited knowledge using 3 phase power, and that my question will probably be simplistic for the pro's here in the forum.

The promoter is providing 2 Allamand 20KW (model ML EX V 15/20) light towers for stage power. One unit is single phase, the other appears to be 3 phase (the visible labels on the pictures I had taken of the unit to be rented show the 125/250 twist locks are labeled 208 volt, the 60 amp hubble is a 4p5w which Hubble lists as a 3 phase receptacle (the rental company assures me the light towers are both single phase units and they have no other 20kW units available that day...

There will not be enough power to run sound and lights from a  single generator with the bands lights and tower lights running, so I'm hoping they can use the 3 phase tower for stage lights only, but I need more information on 3 phase power usage.

My question:

    Can they use the 3 phase lighting plant for powering the 240 volt band lights, or will the 208 volts at the 60 amp plug  cause issues for the lights and controller ?

(the band lights have 25 feet of cable terminated in a NEMA 14-50 style plug, the rental company does not have a 4p5w plug and cable to fit their own rental unit).

The manufacturer does not publish the voltage expected at the 60 amp receptacle.

Both of the light tower have  4 x 30 amp 125/250 4 prong twist jacks and  2x 15 amp GFI's, but only the 3 phase has the 60 amp jack.


Thanks in advance for any help you can provide, be it suggested reading, calling an electrician, running the other way fast...

    Hello, tell them you'll pass.  While these generators may be fine for lighting....they suck for audio....they will impart a nasty hum in your audio system...and they're freakin' loud.

  Hammer
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Blake Ross

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Re: 3 phase light tower questions
« Reply #2 on: June 23, 2011, 07:04:23 pm »

Thanks Charlie, I was concerned about the audio noise issue as well but I thought my post was getting a little long. I'm running 4 U15's over 4 UCS1's with 2 XTI 4000's stereo for tops and 2 1850 HD's bridged for the subs and a single XTI 2000 running monitors. On paper I should need about 6000 watts for (classic rock band, not too loud), but I'm not too happy sharing power with a bunch of lights.
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Chris Carpenter

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Re: 3 phase light tower questions
« Reply #3 on: June 24, 2011, 04:40:05 am »

It sounds like those generators are just going to give you trouble; just ask the promoter if you can have your own generator.
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Blake Ross

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Re: 3 phase light tower questions
« Reply #4 on: June 24, 2011, 12:17:12 pm »

I talked to the band as they have the agreement with the promoter. After mentioning 'audio hum' they were eager to contact the promoter to try a negotiate a stand alone genset for audio.

Are the lights on the tower the source of the audio noise problem, and if so,  will keeping the lights shut off on the tower eliminate the hum issue?

I contacted the light tower manufacturer (they don't publish any sound levels for their light towers) and suggested 68-70 dB under load. A Kubota genset web page suggested 63-65 dB for their 20 kW size, the Honda small inverters are under 60dB.

Is a 70 dB sound source 50 feet from the stage going to be difficult to live with? (of course assuming after years of rentals the unit still operates at the manufacturers estimated sound level)?

Thanks again for helping out!


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Rob Spence

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Re: 3 phase light tower questions
« Reply #5 on: June 25, 2011, 10:27:30 am »

I talked to the band as they have the agreement with the promoter. After mentioning 'audio hum' they were eager to contact the promoter to try a negotiate a stand alone genset for audio.

Are the lights on the tower the source of the audio noise problem, and if so,  will keeping the lights shut off on the tower eliminate the hum issue?

I contacted the light tower manufacturer (they don't publish any sound levels for their light towers) and suggested 68-70 dB under load. A Kubota genset web page suggested 63-65 dB for their 20 kW size, the Honda small inverters are under 60dB.

Is a 70 dB sound source 50 feet from the stage going to be difficult to live with? (of course assuming after years of rentals the unit still operates at the manufacturers estimated sound level)?

Thanks again for helping out!

The problem with "Light Towers" is that the Lights are not bothered by the poor voltage or frequency regulation that these generators have. Your entertainment gear (audio and perhaps lights) are sensitive to these issues.

Just get a 25kw quiet genset from a local rental company. Often they supply 100' of feeder and a spider box for distribution.
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Charlie Zureki

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Re: 3 phase light tower questions
« Reply #6 on: June 25, 2011, 11:19:18 am »


The problem with "Light Towers" is that the Lights are not bothered by the poor voltage or frequency regulation that these generators have. Your entertainment gear (audio and perhaps lights) are sensitive to these issues.

Just get a 25kw quiet genset from a local rental company. Often they supply 100' of feeder and a spider box for distribution.

   +1   The lighting installed (which is what this model is designed for) doesn't care as much about freq or voltage regulation.  And...when this generator revs up during peak demand....you hear how loud the generator can get.

    As Mr. Spence wrote...get an appropriate generator (quieter, more stable) and power distro.

    Good Luck.....the guy in charge probably got these gennies at a very cheap rental price.

    Hammer
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Blake Ross

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Re: 3 phase light tower questions
« Reply #7 on: June 26, 2011, 01:20:06 am »

Thank you gentleman, they're trying to swap one of the light towers for a 20kW genset, so I'm hopeful they'll come up with some 'clean' power for the show.
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ProSoundWeb Community

Re: 3 phase light tower questions
« Reply #7 on: June 26, 2011, 01:20:06 am »


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