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Guy Holt

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About Guy Holt

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  • Occupation
    Gaffer
  • Location
    Boston
  • Specialties
    Custom Honda generator systems for motion picture production including paralleling systems with 100A output.

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  • Website URL
    http://www.screenlightandgrip.com

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  1. You can use the 1kW Iris lights without flicker. The reason that you get flicker from small filament bulbs (<5kW) is that at high speeds the camera will capture the changing intensity of the light output of the bulb as it rises and falls as the voltage waveform rises and falls. If you use three 1kW Iris where you would normally use one, and put each fixture on a separate phase of the power service, the light output between the three fixtures will be constant as each compensates for the drop in intensity of the other. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rentals &
  2. No. It depends on the ballast. I have only been able to do limited testing of HMIs but for example an Arri 4k power factor corrected ballast dumps 16.22mA of current into the EGC while a Power Gems 4k non-power factor corrected ballast dumps only 2.47mA. In order to reduce the amount of RF emitted, UL permits but does not require manufacturers of electronic devices to capacitively couple high frequency harmonic currents to ground (UL1244, UL1950, UL3101.) To accomplish this, some but not all ballast manufacturers include a mains input filter to stop electrical noise from being passed i
  3. Not really supposed to market products on these boards. Contact me off list through message or at rentals@screenlightandgrip.com for details. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston
  4. Let's try this again. Use this link to Shock Stop's marketing material and training guide. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental and Sales in Boston.
  5. Use this link to Shock Stop’s marketing literature and training guide. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental and Sales in Boston.
  6. The GFCI outlets on portable generators are not portable. They are hardwired into the generator. UL943 requires open neutral protection of portable GFCIs because they are likely to be used on wiring of questionable integrity that could have an open neutral, such as the temporary power systems of construction sites or the portable power systems of motion picture sets. Where open neutrals with GFCIs can create hazardous conditions UL943 requires portable GFCIs to interrupt power to the load if there is a break in the line side neutral conductor. It is nearly impossible for the neutral conductor
  7. Don’t try to power an ARRI 1200 HMI Par with non-pfc electronic ballast with the Voltec. To reduce the amount of RFI emitted into the atmosphere, the ARRI 575/1200 non-pfc electronic ballast shunts the high frequency harmonic currents drawn by the ballast to the EGC. The end result is 16.4mA of leakage current on the EGC that trips unfiltered GFCIs like the Voltec every time. I’m not sure the Guardian LG20 has harmonic filtration (I haven’t found an inline GFCI dongle that does.) I don’t know for certain, but I suspect the Guardian LG20 is a rebranded Southwire Model 25230. They look id
  8. Yes, but this is the same company that calls a product (the LG400) that does not meet the NEC definition of a GFCI by that name and promotes the use of it in a manner that does not satisfy the NEC requirement for GFCI protection where prescribed by the Code. It would be great if you could send me that picture. My email address is rentals@screenlightandgrip.com Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental and Sales in Boston.
  9. They also state their LG400 is a GFCI when it clearly is not. Shock Block prevaricates whether their LB100 (also made by AC Power Distribution) conforms to UL943 or UL1640. As I said before, I could be wrong and there is a wall box style GFCI receptacle with open neutral protection. There is only one way to settle this debate definitively. That is for Kyle to take the cover off his Guardian boxes to get the manufacturer and model number of the wall box style GFCI receptacles on the box. A Google search of the part number will tell us if it provides open neutral protection as required by U
  10. This is a complicated topic because there are three standards that can apply to the ground fault protection equipment we use: UL943, UL943C, and UL1053. As well as a standard for portable power distribution equipment: UL1640. There exists a lot of confusion and misinformation about “GFCIs” because too often manufacturer’s and their representatives conflate these standards, gloss over the differences, and use a single brush to paint everything as a “GFCI” when it is not. The NEC is very precise in its definition of what constitutes a GFCI. The NEC Article 100 definition for a GFCI is:
  11. This is a good case in point why electrical distribution should be left to qualified persons. As you may recall from my post above, NEC Article 530 requires that an individual using portable lighting and power distribution equipment know how to comply with NEC safety rules when performing installations. The NEC Section 100 definition of a GFCI is a “Class A device” as specified by UL943. Among UL943’s many requirements is that portable GFCIs trip if there is a break in the line side neutral conductor of a circuit. It does not require the same of GFCIs meant to be permanently installed in a wal
  12. The problem with this type of industrial GFCI is that they are prone to nuisance tripping with HMIs, Kinos, & LEDs. To improve the generally poor reliability of early GFCIs, in 2013 UL revised the standard for GFCIs to allow them to trip on an “inverse time” curve. An inverse time curve introduces a delay that decreases as the magnitude of the current increases. The advantage to an inverse time trip curve is that it permits a transient imbalance that is sufficiently short in duration so as not to pose a danger to pass while keeping current through the body to safe levels. To assure the lat
  13. Without meters you are tethered to the camera and the camera can be a real bottleneck when it comes to each department of a production (Electric, Grip, Camera, Wardrobe, Make Up, Set Dec, etc.) having to accomplish what they have to accomplish before the camera can role again. The value of meters, and knowing how to use them, is that they provide you the information you need to light a scene in your mind's eye and then translate that to reality. Rob Draper, when he was teaching at the Maine Film Workshops, used to call it the Zen of Cinematography and tell this story about how he works.
  14. American Grip makes a 4x4 frame on which you can mount 16 1x1 mirrors on their mirror holders. This rig will allow you to redirect the output of the M18 in 16 different directions, so that you can aim light to each opening in the curtains. Another approach I have used in situations like this is to use a convex mirror like those used to see around corners. The convex of the surface spreads the light while maintaining its hard quality. Guy Holt, Gaffer, ScreenLight & Grip, Lighting rentals and sales in Boston
  15. That about sums it up, and I haven’t even got into half of it. For example, Massachusetts now requires GFCIs on outdoor set lighting of 150 V or less, and 50 A or less (Section 210.8 (B)(4)). Whereas the City of Los Angeles, where much production takes place, exempts outdoor sets from the requirement for ground-fault protection with GFCIs. How two AHJs, on opposite sides of the country, can come to opposing positions says a lot about the nature of the Code. Let’s explore how it came to this, its ramifications for the distribution of power on set, and what we can do about it. The benefit o
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