Grounding Honda Generators & GFCIs

[Isabelle Landers]

I'm gaffing a small film that takes place in a boatyard, on docks, and on day fishing boats for the most part. On our first few days on location, we tried using HMIs to maintain continuity when the sun went behind a cloud, but couldn't get them to work on the dock power. We first tried using an Arri 1800W Baby Max on the 20A dock receptacles but breakers kept tripping on the circuits. We next tried a 1200 Par. The breaker didn't trip, but the GFCI kept tripping. Why do HMIs trip GFCIs? It doesn't matter, because while the 1200 was up, we found it just didn't have the output we needed. What we need is a 4k Par, but the docks and boats don't have the service for it and we don't have the budget or man power to run feeder back to a generator on shore. I could operate the 4k at 240V on a Honda EU6500, but how do I get the ground fault protection we need shooting on or around the water? And do I need to ground the generator? If I do, how can I do it without running ground cable to shore? Any help would be greatly appreciated as we are in the midst of production and are scheduled to go back out on the docks and boats soon.

Isabelle Landers, Gaffer, Nashua, NH

 

[Tim Duran]

Good question. I'm hoping you get an answer so I can learn too. You might want to send the same message to David Mullin's direct thread here. He's the answer man on stuff like this.

 

[Guy Bryan Holt]

I could operate the 4k at 240V on a Honda EU6500, but how do I get the ground fault protection we need shooting on or around the water? And do I need to ground the generator? If I do, how can I do it without running ground cable to shore?

In this case, grounding is as important as using GFCIs because the GFCIs will not operate reliably unless the generator is grounded. Even though GFCIs do not sense ground leaks on the equipment grounding wire (they sense discrepancies between the Hot & Neutral), studies have shown that in the case of Honda portable generators, grounding is required for them to operate reliably.

There has been a lot of debate of Isabelle’s question on the CML. To quickly summarize that debate: some Gaffers believe that Honda portable gas generators, like Crawford Studio units, do not require grounding, and that GFCIs will function regardless of the grounding arrangement. Others, myself included, believe Honda portable generators need to be grounded in order for GFCIs to operate reliably. What fuels this debate in regard to Honda portable generators is, I think, a general ignorance that there are two distinct types of portable Honda generators – those with Floating Neutrals and those with Bonded Neutrals. Which type of generator you are using determines whether it should be earth grounded with a ground electrode and what grounding arrangement is required to make GFCIs operational.

“Floating Neutral”, “Grounded Neutral”, “Bonded Neutral”, “Floating Ground”, “Earth Ground”, “Ground Fault”: if you are unfamiliar with the meaning of these terms I would suggest you first read an article I wrote for our company newsletter on the use of portable generators in motion picture lighting before proceeding further. Neutral Bonded generators have their Neutral bonded to the frame of the generator. Neutral Bonded generators offer a high degree of protection against Ground Faults (if there was a fault to the frame via the Equipment Grounding System, the generator’s circuit breaker would trip eliminating the fault), and so they can be operated without an Earth Ground in what is called a Floating Ground arrangement. Crawford Studio generators are Neutral bonded, but most Honda portable gas generators are not. In most Honda portable gas generators the neutral circuit is not bonded to the frame of the generator or to the earth ground lead. These generators are commonly called Floating Neutral generators. The floating neutral configuration is common for applications such as connection to a recreational vehicle and connection to home power where the transfer switch does not switch out the neutral to ground connection. When used as a stand-alone power source (a “Separately Derived System” in NEC parlance), OSHA requires that portable generators, like the Honda EU6500is, have a bonded Neutral and GFCI protection for reason we will explore (use this link for the complete guidelines.)

Tests conducted by The Construction Safety Association of Ontario (CSAO) uncovered significant problems in using GFCIs on ungrounded portable generators with Floating Neutrals. While the CSAO conducted their tests to determine the effectiveness of GFCIs used on portable generators in typical construction scenarios, their findings are equally applicable to motion picture production applications (use this link for the complete report.)
The GFCIs used in the CSAO tests were of both the extension cord and receptacle type. A rheostat was used to simulate the current leak to ground (ground fault). Generators connected to GFCIs were tested on wet ground, dry surfaces, and an isolated surface (the back of a pickup truck). In addition, tests covered variable grounding conditions: proper ground, ground with some resistance, no ground.

Based upon their tests, the CSAO report drew the following conclusions:

1) In the case of ungrounded Floating Neutral generators, where the neutral is not bonded or grounded but "floating", GFCIs failed to trip even when the current leak reached higher than acceptable levels. Without a Neutral bond, electricity did not leak to the equipment grounding conductor to trip the GFCI.

2) GFCI test buttons functioned regardless of the generator's grounding property. The buttons cannot be used to test the effectiveness of GFCIs or grounding. The test button should only be used to test GFCIs after grounding has been established.

4) Grounding can vary from one place to another, even when both are relatively close. In one test the GFCI tripped when the generator was grounded in wet earth but failed to trip when the generator was grounded 1OO feet away in soil that was drier and better drained.

Testing also proved that wet surfaces can ground generators operating in a Floating Ground arrangement – making the protection offered by Floating Ground operation of generators precarious at best.

A United States Department of the Interior study drew similar conclusions: simply using a GFCI on a Floating Neutral generator will not ensure a safe system. A GFCI will only operate reliably if one side of the generator winding is grounded to the generator frame because otherwise fault current has no path back to the winding to complete the circuit. Only when Neutral is bonded to ground, will current go to ground to complete the circuit when there is a current leak. In other words, a complete circuit is required to create an imbalance and cause the GFCI to trip. A combination of grounding the generator winding (bonding the Neutral) and adding a GFCI is necessary. For this reason OSHA requires both on all generators used on jobsites. When these requirements are satisfied OSHA permits the generator frame to serve as ground, and a ground rod does not have to be used, as long as the generator can be completely isolated from earth ground. However, absent a Neutral ground bond, a ground rod, even though it provides no protection for personnel and can even create a hazardous situation, should be used with Floating Neutral generators because it is the only means of establishing a ground fault circuit for electricity to travel back to its source – creating the imbalance required to trip a GFCI device.

So that they can provide an industrial generator that will pass OSHA job site inspections, manufacturers like Honda provide special industrial generator lines that meet these requirements. The EB generators are Honda’s “Industrial Generators.” The EB3800, EB5000, and EB6500 generators are neutral bonded and GFCI protected to meet OSHA jobsite regulations. Unfortunately the Honda EB generators are AVR type (prone to voltage waveform distortion from dirty loads) and quite load because of their open frame design. For example the Honda EB6500 is more than twice as load (72 dBA sound level) as the comparable Honda EU6500is (60 dBA) under full load. Since the Honda EU6500is is an Inverter type, it is less susceptible to voltage waveform distortion, and quite a bit quieter than the EB6500 under less than full load because its’ speed is load dependent (use this link for details about Inverter generators .)

While Honda’s EB generators meet OSHA requirements, they are too loud and too susceptible to voltage waveform distortion to be used in motion picture production. Unfortunately, Honda’s generator line that meets the noise and power quality requirements for motion picture production, the EU series of Inverter generators, are not Neutral Bonded and do not offer GFCI protection and so do not meet OSHA guidelines for use on job sites. Honda doesn’t even make an Inverter generator that meets OSHA guidelines (the EM5000is is not Neutral Bonded and does not offer GFCI protection.) So what is Isabelle to do.

One approach suggested that meets OSHA requirements would be to use a transformer to step-down the 240V output of the Honda EU6500is to a single 120V circuit large enough to operate her 4k. Since Transformers bond the Neutral to Ground on the secondary load side they provide a low resistance path for fault current back to the Transformer windings and so satisfy that requirement of OSHA. And, if the Transformer has a breaker wired into it (like our 60A Full Power Transformer/Distro) that will trip from an over-current situation, it offers more protection against faults than does the generator used alone. And, since the Neutral and Ground are bonded in the Transformer, GFCIs will operate reliably even when power is being generated by a Floating Neutral generator like the Honda EU6500is. To completely comply with the OSHA requirements for the use of a EU6500is on job-sites all Isabelle would need to do is put a GFCI inline after the transformer.

For more detailed information on using shock blocks 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.

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

 

[Guy Bryan Holt]

On our first few days on location, we tried using HMIs to maintain continuity when the sun went behind a cloud, but couldn't get them to work on the dock power. We first tried using an Arri 1800W Baby Max on the 20A dock receptacles but breakers kept tripping on the circuits. We next tried a 1200 Par. The breaker didn't trip, but the GFCI kept tripping. Why do HMIs trip GFCIs?

Since the 1800W Power Factor Corrected (PFC) HMI did not trip the dockside GFCIs, and the non-PFC 1200W HMI did, it was concluded that the harmonics that the non-PFC ballast dumped back into the power stream is what set off the GFCIs. It was recommended that she use a GFCI device, like those manufactured by Bender and Shock Block (pictured below), that is specifically designed for dirty loads like the non-PFC HMI, Kino, & LED power supplies that we use in our work.

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. ​

To prevent such nuisance tripping by non-PFC power supplies, 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), they 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 (use this link for details.)

Of the many benefits to using a Transformer/Distro with a Honda EU6500is Generator mentioned above, the ability to use GFCI protection designed for motion picture lighting applications has got to be one of the greatest. Most productions do not use GFCIs with portable generators because of the nuisance tripping caused by the harmonics that non-PFC HMI, Kino, & LED power supplies dump back into the power stream. Adapted with 60A Bates connectors, a 100A film GFCI is easy to install in-line after a Transformer/Distro and will provide safe and secure ground fault interruption for an entire distribution system – consisting of Bates Extensions, Siamese, and Edison Breakout Boxes - eliminating the need for finicky individual 20A Hardware Store type GFCIs. Used in-line with a Transformer/Distro, a 100A film GFCI will also provide a larger GFCI protected circuit than is available on any portable generator (by comparison the largest GFCI circuit available on a Honda “industrial generator” is only 30Amps.) It would, in fact, enable the operation of Isabelle’s 4k HMI with GFCI protection. Specifically tailored to the type and size loads used in motion picture production, 100A film GFCIs, like Shock Blocks or the Bender LifeGuards, will provide reliable ground fault protection for larger lights, or more smaller lights, than has ever been possible on a portable gas generator when used with a Transformer/Distro. If for no other reason, I think that is enough reason for Isabelle to tote a transformer out onto the docks she is shooting on.

For more detailed information on using shock blocks 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.

This article is cited in the just released 4th Edition of Harry Box's "Set Lighting Technician's Handbook" and featured on the companion website "Box Book Extras." Of the article Harry Box exclaims:

"Great work!... this is the kind of thing I think very few technician's 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 enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before."​

The article is available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html.

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston

 

[Tim Duran]

As usual, Guy, our electrical engineer cum laude, has come to the rescue with a highly technical, but very thorough analysis of how to solve this problem. My personal thanks to you, Guy.

What I'm not sure about is what are you grounding the distro to? I used to have a large boat with onboard generator. It was grounded to the keel. Why isn't there some way to ground to a line you drop to the bottom (sand, gravel or whatever)? How does all this play with electrocution around water?

Lastly, Isabelle doesn't want to run cables to the shore. Your picture shows the distro on land, but you say it can be taken out onto the pier. Can you touch on this please.

Again, thanks for all your insight. I'm a fan of your threads.

 

[Michael Hastings]

As usual, Guy, our electrical engineer cum laude, has come to the rescue with a highly technical, but very thorough analysis of how to solve this problem. My personal thanks to you, Guy.

What I'm not sure about is what are you grounding the distro to? I used to have a large boat with onboard generator. It was grounded to the keel. Why isn't there some way to ground to a line you drop to the bottom (sand, gravel or whatever)? How does all this play with electrocution around water?

Lastly, Isabelle doesn't want to run cables to the shore. Your picture shows the distro on land, but you say it can be taken out onto the pier. Can you touch on this please.

Again, thanks for all your insight. I'm a fan of your threads.

Guy, I am interested in this as well. I occasionally use surface supplied lights, either our 350 watt tungsten - usually through a variac transformer to step down the voltage to 36 volts (there are also 82volt bulbs as well) or Hydroflex 1200 HMIs. And it always scares the crap out of me because I can never get a clear answer on the grounding and GFCI situation. I put a GFCI on the AC in side of the Variac but have no idea if it does anything - and I'm never sure if we are supposed to run a three wire ground to the lamp head (we mostly use them with 36 or 24 volt dc battery operated so not a big issue there). The last time we used the HMI's the crew grounded the Generator to the boat- and nobody died - but again I'm not quite sure how safe we were. Even when I have rented the Hydroflex there doesn't seem to be much info available.

What are the real issues when working actually underwater?

Help!

 

[Guy Bryan Holt]

Guy, I am interested in this as well. I occasionally use surface supplied lights, … and it always scares the crap out of me because I can never get a clear answer on the grounding and GFCI situation.… Help!

Michael, bear in mind that OSHA permits the generator frame to serve as ground, and a ground rod does not have to be used, as long as the generator can be completely isolated from earth ground and the Neutral is bonded so that GFCIs will operate reliably. It is only absent
a Neutral/Ground bond that a ground rod is needed to provide a means of establishing a ground fault circuit for electricity to travel back to its source – creating the imbalance required to trip a GFCI device.

To ground or not to ground is a complicated issue. On the one hand, if you have a Bonded Neutral system, and you can effectively isolate it from ground, there is good reason not to ground it. It is a common misconception that circuit breakers and ground rods are there to protect you. A circuit breaker is there to prevent fire created by heat from an over-current or short-circuit and protect the equipment. The amount of current it takes to electrocute a person is much smaller than the amount needed to trip a circuit breaker. Add the fact that a ground round will never pass enough fault current to trip an over current device and you realize that they are not there for personal safety. Where this is so contrary to popular belief, allow me to explain.

As the Figure of a Utility Line-men above clearly demonstrates, even though there will be current traveling on the grounding electrode, because of the high impedance of the rod, not enough will travel on it to open a breaker. Using Ohm's law, if we calculate how much current a ground rod will fault to the source through the earth at 25 Ohm's (the prescribed impedance of a grounding device according to the NEC) at 120 volts, we find that a ground rod will only allow for 4.8 amps to flow through it. 4.8 amps will not open any breaker save a GFCI.

As illustrated above, an electrical shock current of one hundred milliamps (100mA or 0.1A) is a very serious shock capable of causing paralysis of the lungs and heart muscle. The smallest circuit breaker we use is 20A – that’s about two hundred times more current than is needed to kill you. So in the final analysis, a ground round will not pass enough fault current to trip an over current device, that is the job of the grounded circuit conductor (Bonded Neutral.) As Article 250.4 (5) of the NEC explains, bonding is to provide a path for fault current:

“Article 250.4 (5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be used as the sole equipment grounding conductor or effective ground-fault current path.”​

​

​

In short, ground rods and circuit breakers provide almost no increase in safety for people. They do not provide equal potential nor do they clear faults. Installing a rod for a generator with bonded Neutral will only provide a path for a person to get in between the source and return. In fact, a case can be made that the installation of a ground rod decreases safety. Without the rod, there is no potential to the earth, but as soon as you bond the system to the earth there is potential to earth. It is only absent a Neutral ground bond (as in a Floating Neutral generator like the Honda EU6500is) that a ground rod, even though it is not sufficient to activate over-current devices, offers personal safety because it is the only means of establishing a ground fault circuit for electricity to travel back to its source – creating the imbalance required to trip a GFCI device. Without the ground rod the GFCI will not operate on a Floating Neutral generator as clearly demonstrated by the CSAO study I cited earlier.

1) A fault in a metal fixture energizes the entire housing.
2) Since, electricity seeks the path of least resistance back to its’ source, the
bulk of the fault current will travel through the grounding wire, instead of the
individual making contact with the housing, because it is of a much lower resistance
than the individual.
3) Because the ground wire and the neutral wire are bonded on the secondary side of the
transformer, the current carried by the ground wire back to the transformer creates a dead
short (over-current situation), and the breaker trips.
4) If for some reason the breaker does not trip (the short is high resistance), enough current flows through the ground wire to create an imbalance between Hot and Neutral and the GFCI, as a fail safe system, trips in response – shutting off power to the distribution system.​

Our approach meets OSHA requirements for use of a Honda EU6500is because we use a grounded transformer that enables reliable operation of GFCIs with Floating Neutral generators like the Honda EU6500is. With Neutral and Ground bonded only in our Transformer/Distro and not in our modified Honda EU6500is, you have a complete circuit on the load side of the Transform/Distro that creates the low resistance path (illustrated above) for fault current back to the transformer windings, and a breaker that will trip from the over-current situation, required by OSHA. Where this is the case, to completely comply with the OSHA requirements for the use of a EU6500is on jobsites all you need to do is use GFCIs on the load side of our 60A Full Power Transformer/Distro. With the Neutral and Ground bonded in our 60A Transformer/Distro, in the event of a Fault, current will go to ground and GFCIs will operate reliably even when the power is being generated by a Floating Neutral generator like the EU6500is.

The use of our 60A Full Power Transformer/Distro with a 100A GFCI satisfies all the criterion of OSHA for the use of a Honda 6500is on job-sites. Does our Transformer/Distro require grounding with an electrode? Where I am out of space on this post, I will have to pick up that topic in a subsequent post.

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston

 

[Guy Bryan Holt]

Does our Transformer/Distro require grounding with an electrode? Where I am out of space on this post, I will have to pick up that topic in a subsequent post.

The use of our 60A Full Power Transformer/Distro with a 100A GFCI satisfies all the criterion of OSHA for the use of a Honda 6500is on job-sites. Does our Transformer/Distro require grounding with an electrode? In the case of Transformers, Section 250.20(D) of the NEC requires that the grounded conductor (Neutral) on the secondary load side, must be connected to a grounding electrode, when there is no direct electrical connection to the primary grounded conductor. In other words, because a Transformer, as illustrated below, is also a Separately Derived System, it must be connected to a grounding electrode.

Since as illustrated above, the Neutral on the secondary side of a Transformer is bonded to the equipment grounding conductor, what is the purpose of the Ground Rod? After all, if there was a fault to the equipment grounding system, the transformer’s circuit breaker would trip eliminating the fault. And, as we saw in the case of Bonded Neutral generators, ground rods serve no purpose in clearing line to line or line to case faults. And, in the case of a Bonded Neutral generator in a Floating Ground arrangement, we saw that an electrical system will operate adequately “ungrounded.” So then what is the purpose of earth grounding the Neutral on the secondary side of a Transformer?

The purpose of the Ground Rod, or more accurately Grounding Electrode System is given in NEC Section 250.4(A) (1) and (2):

“(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.
(2) Grounding of Electrical Equipment. Non–current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.”​

​

​

A historical perspective, offers some added insight why the NEC requires that transformers be earth grounded. Earth grounding transformers was the earliest grounding requirement in the National Electrical Code®, becoming mandatory in the 1913 edition. In that edition of the NEC, the main purpose of grounding (earthing) the system at the neutral of the transformer secondary was to prevent high (primary) voltages from being applied to premises wiring (homes) due to a breakdown of insulation between the transformer primary winding and secondary winding from lightning strikes. In such an event, a primary-to-secondary short would apply thousands of volts to a house, whereby causing an insulation failure in the wiring and a subsequent fire. In other words, the requirement in the Code to earth ground transformers was precipitated by the insurance companies and their concern about large scale fire loss to numerous home owners since the transformers at question serve large portions of the grid.

So, in the final analysis the purpose of the ground rod at a transformer is to limit the voltage from surges, lightning or unintentional contact with high voltage lines. That is, the only protection you get from grounding a Bonded Neutral system - actually sticking Mother Earth with a rod - is from lightening strikes or if by some chance a High Voltage line drops down on your generator or transformer. Given the chance of either one of these occurrences happening on set, and the subsequent consequences, you would probably die from the shock of surprise first. But, to adhere to the letter of the Code, you should earth ground the transformer.

To isolate a Honda EB6500 from earth requires insulation between all metal points and the ground. ​

Finally, I am of the personal opinion, that even though OSHA permits the use of the generator frame as ground, and so does not require a ground rod when the system can be effectively isolated from ground (a Floating Ground arrangement), I think that in the case of Honda portable generators, it is best to earth ground the generator regardless because it is nearly impossible to effectively isolate a Honda portable generator from earth ground (as the CSAO study demonstrated.) When you think about it, to effectively isolate a portable generator, like the Honda ES6500is, from earth requires insulating the entire system - generator, distribution equipment, and loads - from earth ground. You must therefore place a rubber mat or apple box, as illustrated above, under any metal parts of the generator that typically touch the ground. If the generator is on the back of a truck, any type of lift gate or tow chains on the truck must not touch ground. Distribution cable must be free of cuts or nicks that would expose copper to getting wet. Cable connections must be wrapped so that they are water-tight. Distribution equipment like snack boxes must be placed on apple or "Swamp" boxes. Finally, light stands must be placed on rubber mats. After all that, as the CSAO study illustrated, portable generators like Hondas can still be inadvertently grounded by moisture and even high humidity. Where that is the case the protection afforded by using a Floating Ground arrangement is precarious at best, and since the NEC Article 250.52 requires a grounding electrode system be installed if complete insulation is not possible, it makes sense to ground your system regardless.

1) Current goes out on the hot (black conductor) to the light housing fault.
2) Even though current travels on the ground wire (if it is in good condition), current also
travels through the worker's body into the earth back to the generator windings, because there
is no clear return path because of the un-bonded condition.
3) Current enters the generator frame and goes back to the generator winding through the second Fault
on the Neutral side. Because the impedance of the ground rod limits the Fault current it passes, the current
will not be high enough to open the breaker.
4) But, since the ground rod creates a circuit for the ground fault to return to the generator winding through the second fault, the Fault current goes to ground, creating the imbalance between Hot & Neutral requird to trip a GFCI if it is present. ​

Even though a ground rod will not pass enough current to activate an over-current device, (as illustrated above) grounding generators to earth offers some degree of protection from electrical shock in the event of a double ground fault – it is for this reason that it is mandated by OSHA in the event that the power system cannot be effectively isolated from earth. When the equipment grounding conductor is earth grounded with a grounding electrode, the equipment grounding conductor offers a path of lesser resistance then the individual/ground route for the current to travel back to its’ source through the second fault. As the figure of the Utility Line-men above illustrates, the individual making contact with the energized housing will receive a lesser shock, because some of the fault current will travel through the equipment grounding wire instead. That is, in the event of a double fault, the individual will receive less of a shock than if the system were not earth grounded. And, since the ground rod creates a circuit for the ground fault to return to the generator winding through the second fault, the Fault current will go to ground, creating the imbalance between Hot & Neutral requird to trip a GFCI if it is present. So in the final analysis, I think it is best to ground portable generators like Hondas in almost all situations even though OSHA permits you not to under some.

“Floating Neutral”, “Grounded Neutral”, “Bonded Neutral”, “Floating Ground”, “Earth Ground”, “Ground Fault”: without a doubt grounding is a complicated issue to completely understand. For more detailed information why to ground 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.

This article is cited in the just released 4th Edition of Harry Box's "Set Lighting Technician's Handbook" and featured on the companion website "Box Book Extras." Of the article Harry Box exclaims:

"Great work!... this is the kind of thing I think very few technician's 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 enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before."​

The article is available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html.

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston

 

[Guy Bryan Holt]

Lastly, Isabelle doesn't want to run cables to the shore. Your picture shows the distro on land, but you say it can be taken out onto the pier. Can you touch on this please.

In the end, it was recommended in the CML discussion that Isabelle not use a portable generator because of the grounding issue, but instead use a step-down transformer to power her 4k off the 50A/240V receptacles that Marinas provide. Because of the difficulty in grounding it, the consensus was that there is no point to introducing a portable generator in the equation, when Isabelle could use the same step-down transformer/distro that she would use with a portable generator to step down the 50A/240V circuit provided by the Marina to a single 120V circuit.

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.​

The advantage to this approach is that, as was the case of using a Honda 6500 described above, she could use a single 100A shock block (like the one pictured above) to provide ground fault protection for a distribution system consisting of 100A Bates Ext., 100A Siamese, and 100A lunch boxes. And, because the Secondary of a transformer is electrically isolated from its’ Primary, the GFCI on the Dockside 50A/240V receptacle that is prone to tripping from the harmonics dumped back into the power stream from non-PFC HMI ballsts, is removed from the equation (use this link for details.)

Master shot of an iRobot commercial lit with a 4kw HMI Par (outside) & 1.8kw HMI Par (inside) powered from a 30A/240V dryer outlet through a step-down transformer/distro. Note: Sunny feel created by 4k Par on an overcast day. ​

Used in-line with a step-down transformer, a 100A shock block would provide a large GFCI protected circuit for her 4k, as well as 20A branch circuits for smaller lights and other production equipment, that is designed for the type of loads she is powering.

I used a similar approach on a recent commercial for iRobot (use this link for details.) The spot contrasted the iRobot Scooba designed to clean kitchen floors to the old mop and bucket approach. For the mop and bucket approach we had a haggard looking Mom slopping water all over the kitchen floor as kids ran slipping and sliding across the floor.

Left: Transformer/Distro plugged into a 30A/240V dryer outlet. Right: 4K HMI Par under rain protection powered by Transformer/Distro​

Because we knew water would get everywhere we used one of our 60A Transformer Distros on a Dryer Plug to power a 4K HMI, a 1800W HMI, and some Kinos. We put a 100A Shock Block on the load side of the transformer/distro to provide Ground Fault protection inside around the wet kitchen floor. It was a good thing that we did, because it ended up pouring rain that day and so the Shock Block did double duty for the crew tweaking the 4k that was outside the kitchen window. More details on how we used the Shock Block to provide Ground Fault protection on a Dryer/Range plug is available online.

Left: Arri AS18 1800W Par powered from Transformer/Distro. Right: 4Kw and 1800W HMI ballasts powered from Transformer/Distro.​

Finally, in her situation, Isabelle can ground the transformer via the grounding conductor of the 50A/240V receptacle that she plugs it into. And, if she uses an all weather rated transformer, like the 60A Full Power Transformer/Distro we provide for modified Honda EU6500is generators, the transformer windings, core, and lead connections will be sealed in epoxy inside a tough, waterproof casing, and it will be able to withstand the wettest outdoor conditions without creating an electrical hazard.

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