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Single phase/3phase


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#1 Chris Pritzlaff

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Posted 16 August 2008 - 08:57 PM

We are doing a shoot where the location has a 3 phase power supply but the cable and distro that is being supplied to us is single phase. I would assume that we can get by only running the two hot legs, neutral, and ground right? Or am I completly wrong and we need to swap out our whole distro system.

Sorry for the stupid question - I thought this would be fine, but someone posed this question to me during the prep and I am not 100% sure anymore.
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#2 Christopher Santucci

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Posted 16 August 2008 - 09:07 PM

You don't need 3-phase mains power for any lighting that I'm aware of.

Two hot legs from mains is fine depending upon the service supplied and your cabling/distro and what your total load is.

If you had a plant, you might want to balance the load across all 3 phases and of course make sure each of the 2 hots from the mains will give you the current you need.

Edited by Christopher Santucci, 16 August 2008 - 09:11 PM.

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#3 timHealy

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Posted 16 August 2008 - 10:24 PM

I think you just have to ask yourself if the two legs will provide enough amps for what you are doing.

Then you have to ask yourself what kind of lights you are using. if everything is 110 or 220, you'll be fine. But if you are using Xenon or some other specialty light you may need three phase.

Other wise you'll be fine.

Best

Tim
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#4 Chris Pritzlaff

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Posted 17 August 2008 - 03:20 AM

I think you just have to ask yourself if the two legs will provide enough amps for what you are doing.

Then you have to ask yourself what kind of lights you are using. if everything is 110 or 220, you'll be fine. But if you are using Xenon or some other specialty light you may need three phase.

Other wise you'll be fine.

Best

Tim



Cool - I think that answers my question - the only drawback that I was aware of is we could not use the full potential of the supplied power but I don't think we even have enough sources to make that an issue.

And all our units are 110volts so I think we are in good shape - thanks
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#5 Chris Pritzlaff

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Posted 17 August 2008 - 03:57 AM

But now on second thought I am again reconsidering this - shouldn't all the legs be relatively balanced? Or is that only a concern with generators? The power is supplied in the studio space directly so maybe this is not as much of an issue. Since we are running single phase distro and only 2 legs will therefore be in use, will that be a problem with the remaining leg having nothing on it?

I would imagine we will put around 100 amps on each of the two legs and the remining leg will have zero since we have only single phase distro. Should we switch out to three phase from another vendor at this point?

Edited by Chris Pritzlaff, 17 August 2008 - 03:59 AM.

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#6 JD Hartman

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Posted 18 August 2008 - 05:41 PM

The concern is not how much current you draw from each hot leg as much as how much current the neutral carries. In an ideal system (balanced loads on all legs), single or three phase, if you metered the neutral, your reading would be zero. Not a worry in your case, single phase tie-ins are okay, but try and balance your loads equally.
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