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Arri 2K power advice


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#1 ed henderson

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Posted 17 September 2012 - 10:06 AM

Hi,

I am thinking about buying a second hand lighting kit from someone. Included in the kit is a Arri 2K Fresnel, my question is whether I'd be able to run this off a standard UK household mains supply?

I just want to make sure I'll end up using this light much as most of the productions I work on tend to run on a low budget and therefor no funds for a generator!

Many thanks,

Ed
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#2 Phil Connolly

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Posted 17 September 2012 - 10:30 AM

Hi Ed

It would be fine. To work out what size lamp in watts you can use you multiply Voltage x Amps

Since in the UK we are running around 230v and the average mains socket is 13Amps, you can connect:

230 x 13 = 2990 Watts - so plenty to run a 2Kw light.
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#3 ed henderson

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Posted 19 September 2012 - 05:02 AM

Hi Phil,

Thanks for that! I've searched everywhere for a simple answer like that, great little tip too.

Cheers,

Ed
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#4 ed henderson

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Posted 03 October 2012 - 10:30 AM

Just one more question!

The set I'm buying is made up of a 2k, 1k, x2 300's and x2 800's, would I be right in thinking that it would be possible to use all these on the same mains circuit? Obviously they wouldn't be running into the same 4 way but could I at least run them from one room?

Thanks again,

Ed
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#5 Chris Pritzlaff

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Posted 22 October 2012 - 03:30 PM

Hi Ed

It would be fine. To work out what size lamp in watts you can use you multiply Voltage x Amps

Since in the UK we are running around 230v and the average mains socket is 13Amps, you can connect:

230 x 13 = 2990 Watts - so plenty to run a 2Kw light.



I wish we had that kind of house power in the states! So frustrating to be on house power and find that your 1.2k s are plugged in with some other appliance and the circuit blows
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#6 Gregg MacPherson

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Posted 22 October 2012 - 06:41 PM

The set I'm buying is made up of a 2k, 1k, x2 300's and x2 800's, would I be right in thinking that it would be possible to use all these on the same mains circuit? Obviously they wouldn't be running into the same 4 way but could I at least run them from one room?

Thanks again,
Ed


We have the same voltage and similar wiring in New Zealand. We used to check which circut (back to the fuse board) that each wall socket belonged to, then spread the load over those. I never put more than a 2K on one circut. Kitchen ovens are useful. These are rough ideas. Some more precise ideas from an electrician or gaffer who knows how to safely load up the house circuts would be a good idea.

Cheers,
Gregg.
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#7 Stuart Brereton

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Posted 22 October 2012 - 09:12 PM

The set I'm buying is made up of a 2k, 1k, x2 300's and x2 800's, would I be right in thinking that it would be possible to use all these on the same mains circuit? Obviously they wouldn't be running into the same 4 way but could I at least run them from one room?


That's 5200w total. Although each circuit on a ring main in the UK is 13amps, that is the total for all outlets on that circuit. Some rooms may be fed by more than one circuit, but you'll have no way of telling this, so it's safer to split the load over different rooms, remembering to leave a little headroom on each outlet.
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#8 Gregg MacPherson

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Posted 22 October 2012 - 11:30 PM

...... each circuit on a ring main in the UK is 13amps, that is the total for all outlets on that circuit. no way of telling this........


You can identify the circut (circut breaker or fuse) that each socket belongs to with a test. For example switch off all but one breaker and a test light will show the active circut. If you know which sockets are on which circut then you can spread loads safely. Unless houses in the UK in fact have a separate breaker foir each room.

Cheers, Gregg.
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#9 ed henderson

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Posted 15 November 2012 - 05:55 AM

Wow, cheers all for the advice!
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#10 Guy Holt

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Posted 18 November 2012 - 03:47 PM

I wish we had that kind of house power in the states!


Ditto. The great benefit, as I see it from this side of the Atlantic, is that you can operate up to 4kw HMIs off your wall receptacles. The biggest light we can plug directly into the wall is the new 1800W Arri M18; and, even then we are taking a chance of tripping a circuit breaker.

The problem we have here with the Arri M18 is that many of our wall outlets are on 15 Amp circuits, and those that are on 20 Amp circuits probably use receptacles only rated for 15 Amps. This is a problem because the Arri 1800W ballast has an Apparent Power of 2250VA which means that it will draw 19.5 amps at 115V so it will always trip our ubiquitous 15A/120V house circuit and will trip a 20 Amp circuit if there is something else, like a computer or light, on the same circuit. Where you can't always know what else is on the same circuit, or even if it is a 20 or 15 Amp circuit, it is risky to plug the M18 into the wall. Especially since the house odds are stacked against you.

With a draw of 19.5A at 115V, the load of the M18 is just too close to the threshold to operate reliably. Since the M18 uses a “Constant Power” ballast, if there is any line loss from a long cable run, or increased resistance from an overheated plug end, the draw of the ballast climbs over 20 Amps and trips the breaker. It has been my, and other Gaffer’s, experience with the M18 in this country that the stinger plug-ends overheat because they are only rated for 15 Amps. The increased resistance that results from the heat causes the voltage to the ballast to drop and so it has to draw more power to maintain the 1800W load. At 110V it will draw 20.5 Amps. The power drawn by the M18 is just too near the operating threshold of a 20A circuit for it to operate reliably plugged into our U-Ground Edison wall outlet. The same is true of Arri 1200W HMIs since most Arri 1200W HMI ballasts in this country are non-Power Factor Corrected and will draw 18.5A at 120V.

The same is true of operating them on the 20A circuits of portable generators. Even though the generator’s Edison receptacles are rated for 20Amps, it has been my experience that you cannot run a M18 or non-PFC 1200 reliably on the 20A receptacles on the generator’s power panel. To the problem of line loss and overheating plug ends, you have the added problem with generators that as you add load the voltage drops on them. It is not uncommon for a generator to drop 10-15 volts under full load. The 1800W ballast that drew 19.5 Amps at 115 Volts off the wall will draw 21.4 Amps at 105 Volts off a generator.

For these reasons, I am convinced that the 1800W power class was designed primarily for the EU market where its’ Apparent Power of 2250VA fits comfortably in your 13A/230V circuit. Here they work best on a real film distribution system where every circuit is 20 Amps, you know what is on the circuit because you are loading it yourself, and you are bringing the receptacle to the light because you are distributing the power yourself from a tie in or generator. When you can run a 100A whip and drop a Lunch Box next to the light you won’t have a problem. But, if your style of shooting requires that you run multiple stingers to plug into a wall or generator outlet, you will likely have problems with the plug ends or receptacle overheating and causing the breaker to overheat and trip.

I have found that the only reliable way to power a M18 on wall out-lets or on portable gas generators in this country is from a 240V circuit through a 240v-to-120v step down transformer. A transformer will convert the 240V output into a single large 120V circuit that is more than capable of powering the 19.5A load of a M18. And, if the transformer is outfitted with a Bates receptacle, it will enable you to use a distro system that will allow you to move the generator off set (where it won’t be heard), compensate for line loss over a long cable run, and provide plug-in pockets conveniently close to the ballasts.

Posted ImageLeft: Honda EB10000 operating out of grip truck (note set atdistance (bright spot on right side.)) Center: 84A Full Power Transformer/Distro compensates for Voltage Drop over 350ft cable run. Right: Beach Set with 120v full line level 500ft from power source.


To record sync sound without picking up the noise of even open frame portable generators like Honda’s new 10kw EB10000, all you need to do is add 300' of heavy gauge 250V twist-lock extension cable between the generator and the transformer. This is usually enough cable to place the generator around the corner of a building, or to run it out of a van or truck - which is usually all the additional blimping you need with the Honda generators. By using a single heavy-gauge feeder cable, you eliminate multiple long cable runs to the generator and the appreciable voltage drop you would have using standard electrical cords. Unlike 15 Amp U-Ground Edison plugs, a 250V Twist-Lock plug end won’t overheat and so won’t add resistance and won’t cause additional voltage drop that will cause the ballast to draw more power.

Posted Image
Left: Beach Set lit by two 1800W Arrimaxes. Center: Secondary side power distributed with standard 100 Bates Gang Boxes. Right: Set viewed from generator (note: distance and extent of set power distribution.)


Using a 240V-to-120V step-down transformer is generally the only way we can plug 4kw HMIs into wall receptacles and portable generators in this country also. Where as, you can plug them directly into your Honda Generators and your larger ring circuits with the Euro style 16A/230V receptacles. If I were lighting an indie film, I’d rather be in shoes than my own.

Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rentals and Sales in Boston
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#11 Cory Lonas

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Posted 21 November 2012 - 10:39 AM

if you are worrie about finding the circuit breakers in a room you can buy this tool
http://www.bing.com/...inder&FORM=HURE
plug one end in the socket and run the other over the breakers at the box and it will beep when you hover over the corresponding breaker. in conjunction with flipping breakers and labeling the box this should paint a very good picture of your power limitations in any given space.

I also vouch for Guys converted generators. My company has 2 that have served us incredibly well. Being able to run a 6k par off its own dedicated generator far off in the distance without burying 500 feet of line is a real time saver.

Guy I have some production photos of your gennies in action if you would like them.
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#12 Guy Holt

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Posted 26 November 2012 - 10:40 PM

Guy I have some production photos of your gennies in action if you would like them.


Yes, I would be interested in any production stills you have of the gennies in action. If you send them to me with a description of the production I will feature them on our website or our new Facebook page. Please send them to my attention at rentals@screenlightandgrip.com.

Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston
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