Hi, I'm about to shoot a low budget music video. I will be SCUBA diving with a 5D mrk iii, at the bottom of an 8-9 foot pool. Talent will only be a couple feet underwater.
However you decide to shoot the pool scene be sure to use GFCIs on all the cables supplying your lights – whatever size they happen to be. After that NYU student was electrocuted I am surprised safety is not at the forefront of this thread. GFCIs are a must when working within 25’ of water in order to avoid someone taking a potentially lethal shock. If you stick with smaller quartz lights, you will be fine with the hardware store variety of GFCI cords. But, if you use HMIs, or even Kinos, you will need film style GFCIs, like Shock Blocks, that are specifically designed for motion picture lights. To prevent the nuisance tripping that electronic Kino & HMI ballasts can cause with standard GFCIs, film style GFCIs sense on an "Inverse Time Curve." And, to deal with the harmonics that non-PFC Kino & HMI ballasts kick back into the power stream (that will cause other GFCIs to trip), film style GFCIs include a harmonic filter with a frequency response up to 120 hz. 3rd harmonics are attenuated by 50%, and by 500 Hz are down to 20%. Attenuated by the filter, the harmonics generated by dirty loads such as non-PFC Kino & HMI ballasts, pose less of a problem.
A single 100A GFCI "Shock Block" can provide ground fault protection on wet
locations for the entire distro system of a Honda 6500 portable generator
when used in-line with a Step-Down Transformer/Distro.
One problem with Shock Blocks is that they don’t come smaller than 100Amps. If you can’t rent a tow generator with a distro box with 100A pockets, the next best thing is a step-down transformer like the 60A Full Power Transformer/Distro we make for our modified 7500W Honda EU6500is generator. A transformer will step down the 240V output of a portable gas generator to a single 60A 120V circuit that you can put a Shock Block on.
A 100A GFCI used inline with a transformer can provide safe and secure ground fault protection for an entire distribution system consisting of Bates Extensions, Splitters, and Break-Outs to Edisons – eliminating the need for hardware store 20A GFCIs that are not designed to be used with harmonic generating loads like non-PFC HMI & Kino Ballast, & LED Power Supplies. Used in-line with transformer/, a 100A Shock Block will provide a larger GFCI protected circuit than is commonly available in homes. In fact, it enables the operation of even 4k HMIs on portable generators with GFCI protection.
For more detailed information on using Shock Blocks to provide Ground Fault protection with portable Honda generators, I would suggest you read a curriculum I developed for IATSE Local 481 on GFCIs and grounding. You can find it online at http://www.screenlig...I_Workshop.html
Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston