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7K Honda Generator on a Boat


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Hi all,

Shooting on a docked boat, the HMCS Haida to be specific, and will be using a 7K Honda generator to power some lights and production. The boat itself is grounded and has it's own electrical system.

Wondering how I should go about grounding the generator/operating it on the boat/not getting in trouble with the electrical authority.

Thanks!

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On 8/14/2022 at 2:50 PM, Sam Holling said:

Shooting on a docked boat, the HMCS Haida to be specific, and will be using a 7K Honda generator to power some lights and production. ...Wondering how I should go about grounding the generator/operating it on the boat/not getting in trouble with the electrical authority.

Sam, when there is a potential difference in charges between two points expressed in volts, current will flow if they make contact with each other and form a circuit. Since it takes only milliamps to electrocute someone, you can receive a lethal shock if you are the one making the contact.  For this reason, the National  Electrical Code (2014 NEC Article  250, Subsection 20(D)) requires  that when two sources of power ("separately derived systems" in NEC parlance) are located within 20 feet of each other, or when one supplies equipment which might possibly come within 20 feet of equipment supplied by the other (unavoidable on a steel ship), the two sources of power must be bonded together so that they share a common ground point.  Connecting to a common ground, creates a zero reference or zero potential difference, and eliminates touch potential, thereby eliminating the shock hazard.

According to Code, the bonding conductor can be covered, insulated or bare and is not required to be installed with other circuit conductors or in a raceway.  It must be solidly connected (expect the inspector to kick the connector) and metal-to-metal (so you may need to scrape off some paint.). Use the rating of the ship's largest circuit  overcurrent device and 2014 NEC Table 250.122 to size the bonding conductor, keeping in mind that it cannot be smaller than 6 AWG.

ANSI E1.19, Section 6.4.2 stipulates that "Class A GFCI protection shall be used on all 15 to 100 ampere 120-240 Volts AC, single and three phase receptacles and circuits where water or moisture is present or is likely to be present" which is just about everywhere on a ship.  This may be the hardest requirement to comply with since, many HMI, Kino, and LED motion picture lights generate sufficient residual current to nuisance trip hardware store GFCIs and /or the GFCIs on the Honda.  The solution is to use a small step-down transformer to convert the unprotected 30A-240V output of the Honda to a 60A-120V circuit, and a film-style 60A GFCI (like the Shock Stop 60-60IL.)  The Shock Stop has a more forgiving trip curve and harmonic filtration to eliminate nuisance tripping from residual currents.  Hardware store GFCIs and the GFCIs on the Honda do not.

Another benefit to using a 60A step-down transformer/distro with the Honda is that it enables you to use standard film style distribution equipment (like 60A Bates Extensions, 60A Bates Siamesses (sp?), and 60A Bates-to-Edison breakout boxes) to distribute power around your set.  And since 2020 NEC 215.9 permits an upstream feeder to be GFCI protected in lieu of the requirement  for such interrupters on branch circuits (as specified in 2020 NEC210.8), a 60A Shock Stop just downstream of the transformer/distro will provide Code compliant GFCI protection of your entire distribution system. Another benefit to using a step-down transformer/distro is that it will enable you to run a 4k HMI on the Honda.

For more detailed information on using small step-down transformer/distros and film style GFCIs to provide ground fault protection with portable Honda generators, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. 

Of the article Harry Box exclaims:

"Great work!... this is the kind of thing I think very few technicians ever get to see, and as a result many people have absolutely no idea why things stop working."

"Following  the prescriptions contained in this article enable the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before."

The article is available online

The use of small step-down transformer/distros with portable Honda generators is also covered in the latest editions of Harry Box's Set Lighting TEchnician's Handbook and Blain Brown's Cinematography: Theory and Practice.

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

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