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How to enjoy snow and not let it kill you.


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#1 Brian Yankou

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Posted 07 January 2011 - 04:45 PM

Hey everyone!

I'm working as an electric on a short film up in the mountains where we'll be dealing with portable generators (6500 and 2000 watts) in snow. The gaffer, director, producer, etc. talked to a faculty member/ gaffer from their school who advised that we ground the generator and each of the instruments (one 2.5K and two 1.2K HMIs) and put the stands on plywood boards with rubber matting. We're also planning on visqueening and taping all the connections and raising them up on apple boxes and covering lights with celo. We'll also be using rubber gloves and rubber boots. In doing my own research, it seems like a ground fault interrupter (GFI) is recommended in any situation where you're potentially mixing water and electricity but they've been told that it's not necessary and will trip too easily or too often.

I've never worked with a GFI or shot very much in snow so I put it to you, the experts: are GFIs absolutely necessary, just a good idea or a waste of time?

Also, do you have any other tips about shooting/ running power in snow?

Any pointers or trade secrets on grounding lights and generators?

Thanks in advance. I look forward to your responses.
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#2 John Sprung

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Posted 07 January 2011 - 06:01 PM

A lot depends on the temperature range you'll have. Will there be a significant amount of liquid water? Drive pieces of rebar about 3 ft. into the ground, one for each item. Have a few extra sticks of rebar handy so you don't have to mess with pulling them out during the shooting day. Since you're grounding the stands, having them up on rubber mats is pointless. Isolating the spider boxes or whatever you're using for connections is where you want the mats. Neutral and ground are tied together at the generator, and nowhere else.




-- J.S.
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#3 Ed Conley

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Posted 07 January 2011 - 06:15 PM

You do not need to Ground the gensets nor the Stands- the only protection you get from Grounding-actually sticking Mother Earth with a ground rod is from Lightening strikes or if by some chance a High Voltage line drops down on your generators- but you'll probably die from a Heart attack if that ever happens anyways :ph34r:


You really need to pound the rod 8' inna ground to make a ground path anyways- you gonna do that for every piece o' equipment?


The Gensets are "grounded" thus the 3 prong receptacle.

The Equipment is grounded Via the Ground wire in the cord. If for some reason you are missing a Ground prong on a Cord- REPLACE the cord!!!

Check yer Cords and cables and you'll be good to go.


What is really happening is more of a BONDING dealeo.

GROUNDING

The purpose of grounding is safety. In all discussions concerning electrical wiring you will regularly meet the term ground, grounded and grounding. They all refer to deliberately connecting parts of a wiring system to a grounding electrode or grounding electrode system.

Grounding falls into two categories:

Systems Grounding and Equipment Grounding

Systems Grounding – is accomplished by attaching one current carrying conductor of an electrical system to ground or earth at the source of power, this is called the neutral or common leg.

Equipment Grounding – is accomplished by attaching all of the non-current carrying metal parts of a system together and connecting to the same systems ground at the source of power (neutral and ground).

The ground can be the earth or in the case of portable generators, the frame of the generator which will serve as a large conducting body that serves in place of the earth.

Equipment grounding it the intentional connecting of all metal parts of a system together through a ground wire. Its purpose is to have all exposed conducting surfaces at the some potential, so that some touching any two metal surfaces will not experience any difference in potential; in other words, so that the individual will not feel a shock and get knocked on his tail or worse.

The other intentional grounded conductor of the system is the neutral or common conductor. This is a circuit conductor, not an equipment ground, and it is grounded to keep it at the some potential as earth, or ground as with a generator. It should be grounded at the source and nowhere else.

An unintentional ground is known as a ground fault. This occurs when a live conductor accidentally comes into contact with a metal surface. This type of ground fault is usually arcing and is extremely destructive. When a ground fault occurs in a grounded system the safety device (fuse or circuit breaker) will activate which opens the circuit and current will not continue to flow.

http://www.dadcopowe...ribution-system


The 6500 can sit on the ground since it will be elevated by the wheels and frame- if you want to place Pancakes under the wheels and frame go ahead but I wouldn't worry too much about it.

Place the 2000's on full 1/4 or Full apple boxes or a Milk Crate with a Pancake on top.
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#4 Ed Conley

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Posted 07 January 2011 - 06:23 PM

GFI's are a different beast- they don't really measure a ground fault- they just measure the fact that the Power ain't going where it is supposed to be going and since that could be YOU- they trip and shut off the power.

Ground wire don't even have to be connected in a GFI circuit.


Anyhoo- iffin' yer gonna be around water it is a good ideer But they sensitive little beeches and do nuisance trip so again just make sure all your cords are in good shape and you'll be good.
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#5 John Sprung

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Posted 07 January 2011 - 07:06 PM

The reason for driving ground rods is capacitance coupling from the hots to the earth. It can give you a shock because the voltage can be fairly high, but the impedance is also so high that you won't usually draw a lot of current. Often annoying, rarely fatal. If things are a little slushy, I'd do it. If everything's totally frozen dry, probably not. Building codes require a rod 8 ft. deep, but about 2-3 ft. in wet ground works fine for temporary stuff. It's kinda like putting those red foam balls on the ends of C-stand arms at eye level.




-- J.S.
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#6 Guy Holt

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Posted 09 January 2011 - 08:13 PM

GFI's are a different beast- they don't really measure a ground fault- they just measure the fact that the Power ain't going where it is supposed to be going and since that could be YOU- they trip and shut off the power. Anyhoo- iffin' yer gonna be around water it is a good ideer But they sensitive little beeches and do nuisance trip so again just make sure all your cords are in good shape and you'll be good.


Check your local municipal electrical code – many municipalities require the use of GFCIs outdoors. It is especially a good idea to use GFCIs with HMIs if there is standing water or slush because of the high voltages that HMIs use to strike. If because of moisture, the striking voltage arcs to ground in the head, the amperage is not enough to kill you, but it will give you a nasty shock and likely damage the ballast. So you want to make sure your equipment grounding is in good condition and use GFCIs when possible.

The problem is that GFCIs are, as Ed Conely says “sensitive little beeches,” and can slow production down by constantly tripping. I have found that it makes a difference if you use magnetic or electronic HMI ballasts on GFCIs. What type of ballasts are you using on the 2.5kw and 1.2kw HMIs? And are they Power Factor corrected? Will you be running the 2.5kw at 120V or 240V. Which lights do you plan to run on the 6500W Honda? And, what model of Honda 6500 are you using. These are all factors when it comes to running HMIs on GFCIs on portable generators in the snow.

- Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental in Boston
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#7 Ed Conley

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Posted 10 January 2011 - 03:24 PM

Just a heads up- the Honda 2000's are not gonna do ya much good unless you are using them to power up different electronic item besides the 1.2HMI's

Honda 2000's are only rated at 13.3 amps continuous load- you could parallel 2 with the simple banana plug and get the full 20amps from one receptacle but I imagine you'll have a Truck so might as well get another 6500watt and run the 2 1.2's off of it.

The 6500 that you rent will need to have the 60amps Bates Receptacle modification- not all Honda 6500's available for rent have this.


Where are you located?
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#8 Ed Conley

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Posted 10 January 2011 - 03:29 PM

What do you guys use for a 60amp bates for GFI

I know you can get 100amp GFI's- have used those and then split it out to 2 60amp bates but can't seem to find a 60amp Bates GFI

http://www.littelfus...block-GFCI.html
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#9 Guy Holt

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Posted 10 January 2011 - 06:37 PM

Just a heads up- the Honda 2000's are not gonna do ya much good unless you are using them to power up different electronic item besides the 1.2HMI.


Not necessarily. If the 1200s have the newer Power Factor Corrected ballasts they will draw 11.5 Amps and will run no problem on the 2000s. If they have magnetic ballasts they will draw 13.5 amps and will likewise run without a hitch on the 2000s.

The 6500 that you rent will need to have the 60amps Bates Receptacle modification- not all Honda 6500's available for rent have this.


Not necessarily. You can use a 240-to-120 Step-Down Transformer to step down the 240 output of any Honda 6500w to a single 120 circuit. If the Honda is one of the modified EU6500is that have an enhanced output of 7500W at 240V, a Step-Down Transformer will give you a 60A circuit. If it is an unmodified Honda 6500W (any model) it will give you a 46A circuit which is still enough to run your 2.5kw HMI but not much more. The modified Honda EU6500is with Transformer will enable you to not only run the 2.5kw, but also both 1200s if the ballasts of all the HMIs are Power Factor Corrected. There are a number of other benefits to using Transformers with Hondas (use this link for details.)

Posted Image

A single 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.


In this case, one big benefit is that Brian can use standard film style distribution (like 60A Bates Extensions, 60A Bates Siameeses (sp?), and 60A Bates-to-Edison breakout boxes) to distribute power from the transformer. The benefit to using standard film distro is that it will allow him to use the 100A "Shock Block" (pictured above) that Ed mentions in-line with the step-down transformer (rewired w/ 60A Bates connectors) to provide ground fault protection for the entire distro system. That way Brian has GFCI protection for the larger 2.5kw HMI and avoids the pesky 20A GFCIs that will trip constantly with the smaller HMIs.

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.

Posted Image


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.screenlig...generators.html.

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston
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#10 Brian Yankou

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Posted 21 January 2011 - 02:02 PM

Hey everyone! Thanks for all of your input on this thread!

I'm happy to report that the shoot went off without incident, as far as electricity and lights are concerned; no shocks, no arcs, no green flames . Fortunately (for me) the temperature was consistently below freezing for the entire week so we didn't have standing puddles or slush to worry about. We did have a lot of wind and snow, but between the cello, sealing our connections with garbage bags and electrical tape (a method we started calling "Tootsie-Rolling"), and using extra sandbags and safety lines, we were able to neutralize these safety concerns.

We grounded the generator and the light stands to copper spikes that were pounded into the frozen ground by a local electrician who used an auger to get the holes started. We ran 14 gauge wire from the light stands to the grounding spikes. The stands were placed on rubber matting and plywood.

The generator we were using for most of the production was a Honda EU 6500is which we often used to power all three HMI's. The 2.5 was powered through a three-prong twistlock 30A outlet on the genny. We plugged in a twistlock to bates adapter and ran bates for the 2.5. The 1.2's were powered by the two 20A Edison courtesy outlets on the genny. The only time the other generator (Honda EU 2000i) came into play was on a day when we wanted the 2.5 and a 1.2 on opposite sides of an active snowmobile path, which we couldn't run cable across. We didn't use any GFCIs.

One thing i'm not sure of is whether we had power factor corrected ballasts for the HMIs. How can you tell? Does "EB" stand for "electronically balanced" or something? The ballasts we were using looked similar to these:


Posted Image
Posted Image


Does the One other question that came up was "Is it safe to refuel a generator while it is running?" We had opposing viewpoints on this. Let me know if I missed one of your questions with this response.

Thanks again, everyone!
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#11 John Sprung

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Posted 22 January 2011 - 08:17 PM

"Is it safe to refuel a generator while it is running?"


It varies from generator to generator. Diesel is intrinsically safer than gasoline. Big generators by virtue of their size generally have the fuel cap farther from any source of ignition than a little putt putt. Though it's one of those things that you might very often get away with, it's also something that with reasonably good planning you should be able to avoid. Keep it topped off and you won't need to.




-- J.S.
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#12 JD Hartman

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Posted 23 January 2011 - 11:22 AM

Does the One other question that came up was "Is it safe to refuel a generator while it is running?" We had opposing viewpoints on this. Let me know if I missed one of your questions with this response.

Thanks again, everyone!


Generally, never safe to refuel any small gasoline engine, while it's running or hot. You have to consider that the fumes are explosive as well as any spilled fuel, combustible.
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#13 Guy Holt

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Posted 23 January 2011 - 03:33 PM

One thing i'm not sure of is whether we had power factor corrected ballasts for the HMIs. How can you tell? Does "EB" stand for "electronically balanced" or something? The ballasts we were using looked similar to these:


EB stands for Electronic Ballast. Arri non-Power Factor Corrected (PFC) Ballasts look identical to PFC Ballasts or as Arri calls it Active Line Filtration (ALF.) The ballasts you used had to be PFC Ballasts, otherwise you could not have run them all on the EU6500is. For instance, a non-PFC 2.5kw would have drawn about 35 Amps and would never have run on the 120V/30A twist-lock on the generator. Likewise with the 1200 ballasts: had they been non-PFC they would draw about 19 Amps a piece and the accumulative 38 Amps of the two of them on the other leg of the generator would have overloaded that leg. A PFC 2.5 drawing 26 Amps would fit comfortably on one leg of the generator, and the accumulative load of two PFC 1.2 ballasts would balance the generator with a draw of 23 Amps (2 x 11.5A) on the other leg. The continuous load rating for an unmodified Honda EU6500is is only 45 Amps, so even with PFC ballasts ( a total load of 49Amps) you were pushing the generator to its’ maximum capacity. It would never have been a able to support the 73 Amp load of non-PFC ballasts

One other question that came up was "Is it safe to refuel a generator while it is running?" We had opposing viewpoints on this. Let me know if I missed one of your questions with this response.


Countless personal injuries have resulted from fires that have started from fuel spilled on a hot generator while refueling. For this reason we have developed an extended run auxiliary fuel tank system for the Honda EU6500is.

Posted Image
An Extended Run Fuel Tank enables the safe refueling of Generators while running.


By eliminating the need to refuel the generator in the course of a production day, our extended run fuel tank eliminates the extreme fire hazard inherent in refueling a hot generator. And, if for some reason you do have to refuel the generator, you can do so at a safe distance by refueling the Extended Run Fuel Tank rather than the generator fuel tank.

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

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Posted 01 February 2011 - 12:02 PM

I'm happy to report that the shoot went off without incident, as far as electricity and lights are concerned; no shocks, no arcs, no green flames . ... We grounded the generator and the light stands to copper spikes that were pounded into the frozen ground by a local electrician who used an auger to get the holes started. We ran 14 gauge wire from the light stands to the grounding spikes. The stands were placed on rubber matting and plywood. .. The generator we were using for most of the production was a Honda EU 6500is ...


Brian did the right thing to Earth Ground the Honda EU6500is, even though it sounds like it wasn’t easy with the ground frozen. The question whether to ground portable generators, and the effectiveness of GFCIs used in connection with them, have been debated in the industry. Some technicians, like Ed, believe that Honda portable gas generators, like Crawford Studio units, do not require grounding and that GFCIs will function regardless of the grounding arrangement. What fuels the debate is a general ignorance that there are two distinct types of portable gas 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 http://www.screenlig...ard Protection'>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 condition. 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; and 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), Floating Neutral generators require that at least the frame of the generator to be bonded to earth ground for reasons we will explore shortly. This involves putting a rod 8’ into the earth and attaching a ground cable from the rod to the generator frame.

There is no question that a generator system with a Floating Neutral requires grounding with a grounding electrode. Remember that OSHA guidelines for the grounding of portable generators does not allow for isolating the generator from ground when the Neutral conductor is not bonded to the frame along with the equipment grounding conductors. The reason being, over-current breakers offer no protection in the event of a double ground fault when the Neutral is not bonded to the equipment grounding system. To understand why this is the case, it helps to understand first why technicians are not endangered by electrocution from current going to ground if there is only one fault in the system.

In a Floating Neutral system, technicians are not endangered by electrocution from current going to ground as long as there is only one fault in the system. Since the ground wire and the neutral wire are not bonded at the generator bus, the equipmet grounding wire does not offer a path for the fault current to complete the circuit back to the generator windings. In effect an open circuit, current will not travel it and so the fault current does not even go to ground. The figure below, illustrates why that is the case.

Posted Image



1) A fault in a metal fixture energizes the entire housing as soon as the circuit is turned on.
2) Since the ground wire and the neutral wire are not bonded at the generator bus, and the generator is not grounded to earth by an grounding electrode, the equipmet grounding wire does not offer a path for the fault current to complete the circuit back to the generator windings. Therefore, the fault current does not go to the equipment ground wire.
3) If the generator frame is completely insulated from the ground (a Floating Ground), an individual making contact with the energized housing does not present an alternate path for fault current back to the generator windings. An open circuit, the fault current does not go through the individual and ground back to its source.

But, in the event of a double ground fault - one on the Hot, and a second in the Neutral - a path (circuit) can be created for fault current to return to the generator windings through an individual making contact with the energized housing and through the ground if the generator frame becomes grounded (either through moisture or contact with the ground.) Since the equipmet ground wire is not bonded to the generator windings, it does not offer in the event of a double fault an alternate path of lower resistance. Where the individual/ground route is now the path of least resistance, the fault current travels through the individual and the ground back to the generator windings through the second fault - delivering a shock to the individual. If either of the faults is high resistance, the current will not be high enough to open the breaker, and the individual will receive a sustained shock that can be potentially fatal. The Figure below illustrates why an individual receives a shock when there are two faults.

Posted Image



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. If either of the faults is high resistance, the current will not be high enough to
open the breaker. However, the currrent will be high enough if the grounding conductor is faulty (the grounding
pin is broken or there is a bad connection) to give the individual touching the housing a shock.
4) The generator’s circuit breaker may trip in response, but only if enough current flows through the
second fault to create an over-current situation.
5) The worker, however, is exposed to electrical shock until the breaker operates because no GFCI is present.

The inherent risk in using Floating Neutral generators lies in the fact that the neutral of the generator winding is neither grounded to the generator frame nor to the grounding pin of the receptacle. This deficiency makes operation of the protective device (breaker or fuse) unreliable because in a two Fault situation, fault current has no definite path as it does in a Bonded Neutral generator. For example, a fault current that, under these circumstances, is too low to trip a breaker or blow a fuse will also travel through an individual making contact with the energized housing and deliver a potentially life threatening shock. Since all equipment leaks some current, it is not uncommon to have two Faults in a system. A defect in the generator, a poorly insulated or defective extension cord, defective insulation in a lamp housing, or defective plug, can all produce Faults - to name just a few causes. And, since it is difficult to completely insulate a portable generator from ground (wet ground, rain, or even high humidity can cause a generator to be inadvertantly grounded) the risks of shock greatly increases (see the study by The Construction Safety Association of Ontario (CSAO) below). Floating Neutral generators are deceptive because they give the appearance of a safely grounded system when, in fact, they are not. Their receptacles accept a plug with a grounding pin, but in the receptacle the grounding pin is connected only to the generator frame and not to the generator winding (neutral). The user is given a false sense of security.

Grounding Floating Neutral generators to earth with a grounding electrode offers some degree of protection from electrical shock in the event of a double ground fault – and for this reason it is mandated by OSHA (use this link for the complete guidelines.) 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. The individual making contact with the energized housing will receive a lesser shock, because the bulk of the fault current will now travel through the equipment grounding wire instead.

Simply using a GFCI on a Floating Neutral generator will not ensure a safe system, and can in fact lead to unnecessary and costly production delays. Tests recently conducted by The Construction Safety Association of Ontario (CSAO) uncovered significant problems in using GFCIs on ungrounded portable generators with Floating Neutrals (use this link for the complete report.) A GFCI will only operate reliably if one side of the 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. GFCI test circuits can also be misleading when they are used on Floating Neutral generators. On a Floating Neutral generator, the test button will draw power from the Hot through the toroid and back to the Neutral without going through the toroid again and the sensor will initiate the GFCI to trip. The false positive received by GFCI test circuits on ungrounded Floating Neutral generators does nothing to eliminate faulty equipment and only causes unnecessary and costly production delays. A combination of grounding the generator winding (grounding the Neutral) and adding a GFCI is necessary. For this reason OSHA requires both on worksites.

For the reasons illustrated above, OSHA requires that all portable generators on work sites have their Neutral bonded to the equipment grounding system and be equipped with GFCI protection. 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 http://www.screenlig...horInverter Gen '>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 work 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 should a film electrician do when filming will take place in wet hazardous conditions?

Posted Image


One approach that meets OSHA requirements is to use a Floating Neutral generator with a grounded Transformer. Since Transformers bond the Neutral to Ground on the secondary load side they provide a low resistance path (illustrated below) for fault current back to the Transformer windings. And, if the Transformer has a breaker wired into it ( like our 60A Full Power Transformer/Distro) that will trip from the over-current situation, it offers more protection against faults than does the generator used alone.

Posted Image



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 a 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).
4) If enough current flows through the ground wire, the circuit breaker on the transformer pops in response – shutting off power to the distribution system.


Since a Transformer bonds the Neutral to Ground, to completely comply with the OSHA requirements for the use of a EU6500is on work sites all you need to do is use 20-Amp GFCI protected cords. Since the Neutral and Ground are bonded in the Transformer, GFCIs will operate reliably even when the power is being generated by a Floating Neutral generator like the EU6500is.

The ability to use GFCI protection in wet conditions or locations has got to be one of the greatest benefits to using a Transformer/Distro with a Honda EU6500is Generator. Not only can you use a generator that is quiet and produces clean power, but it also makes it possible to use GFCI technology, like a 100A shock block pictured below, that is specifically designed for motion picture applications.

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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 the nuisance tripping that electronic Kino & HMI ballasts can cause with standard GFCIs, film style shock blocks like the one pictured above 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), our 100A GFCI includes 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. Placed immediately after the secondary load side of a Transformer, a 100A shock block will provide safe and secure ground fault interruption for the entire distribution system – eliminating the need for finicky individual 20A GFCI outlets. Used in-line with our 60A Full Power Transformer/Distro, a 100A shock block will provide a larger GFCI protected circuit than is available on any other portable generator (by comparison the largest GFCI circuit available on a Honda EB6500 is only 30Amps.) In fact, it enables the operation of even 4k HMIs with GFCI protection. Specifically tailored to the type and size loads used in motion picture production, a film style 100A shock block provides reliable ground fault protection for larger lights, or more smaller lights, than has ever been possible on a portable gas generator when used on our modified Honda EU6500is with our 60A Full Power Transformer/Distro.

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 http://www.screenlig...ard Protection'>use of portable generators in motion picture lighting.

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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.screenlig...generators.html.

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

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Posted 22 February 2011 - 11:13 AM

Specifically tailored to the type and size loads used in motion picture production, a film style 100A shock block provides reliable ground fault protection for larger lights, or more smaller lights, than has ever been possible on a portable gas generator when used on our modified Honda EU6500is with our 60A Full Power Transformer/Distro.


A quick note to wrap up this thread. The problem with Shock Blocks is that they don’t come smaller than 100Amps. So, unless you tie-in to the location service head, they can’t be used on “house power” unless used with a 240-to-120V step down transformer on a 240V Range or Dryer plug. Among the many benefits to using transformers/distros on common residential 240V circuits is the ability to use film style shock blocks. GFCI protection is a must when working around water even if it is in-doors. In any situation - whether it is a bath scene, a kitchen scene, or a scene washing a car in a driveway - where people and equipment are likely to get wet, there needs to be ground fault protection for the reasons discussed above. The problem with home style GFCIs is that they are prone to tripping with HMIs & Kinos, and they have limited capacity (20A max.) The benefit to using a transformer/distro, like the one we manufacture for our modified 7500W Honda EU6500is generators, on residential 240V circuits is that it will step the 240Volts of a 50/30AmpRange/Dryer down to a single 100/60A 120V circuit that you can plug a 100A shock block into. Used inline with a transformer, a 100A GFCI 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 the house 20A GFCIs that are prone to tripping when used with harmonic generating loads like non-PFC HMI & Kino Ballast, & LED Power Supplies. Used in-line with a transformer/distro, a 100A shock block will also provide a larger GFCI protected circuit than is commonly available in homes. In fact, it enables the operation of even 4k HMIs on wall outlets with GFCI protection.

A good example of this approach is an independent film that recently shot in our area that we equipped. The film is loosely based on a “This American Life” radio segment about a family that lived year round in the boatyard of a marina because they were fugitives from the FBI because of the father’s drug conviction for raising marijuana. Finding usable power in the boatyard and on the marina’s docks was a problem for the production because most of the 20A Edison receptacles had GFCI protection. This was a problem because, like common household GFCIs, marine style GFCIs are prone to tripping when used to power HMIs and Kino Flos (use this link for the reasons why that is.) But they needed the GFCI protection because they were shooting in, on, and around the water.

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(photo courtesy of Isabelle Landers)

The 50A/240V Nema 14-50 receptacle that supplied power to the Transformer/Distro


The solution to their problem was to use one of the 60A Full Power Transformer/Distros, that we manufacture for our 7500W modified Honda EU6500is generators, to step down the 240V power from a 50A Nema 14-50 receptacle (pictured above) wired into a little shed on the deck of the marina’s guest house for the water heater of a hot tub/Jacuzzi. Our Transformer/Distro stepped down the 50A 240V output to a single 60A/120V circuit that was capable of operating not only a 4k HMI Par, but also a 1800W Baby Max, and Kino on occasion. And, because our Transformer/Distros are outfitted with standard film style Bates receptacles, they could use a Film Style GFCI that was not prone to nuisance tripping from the harmonics their HMIs and Kinos kicked back into the power stream. (use this link for details.)

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(photo courtesy of Isabelle Landers)

The cart outfitted with 60A Transformer/Distro, 100A Shock Block, and 4/2.5kw & 1800W ballasts that the crew called the E-Cart.
Note: that the 1800W Ballast is plugged directly into a 60A Woodhead w/3 20A circuits.


As an added benefit, the heavier-gauge Twist-lock cable we use to supply the transformer, eliminated the voltage drop they would have experienced if they instead had run multiple stingers to wall outlets to power their 1800W Baby Max. And, the slight voltage boost that we design into our Transformer/Distros assured that the supply voltage on set did not drop far below 120V causing the 1800W ballast to draw more than 19.5 Amps (use this link for details.) In fact, the crew was able to run 200’ or more of Twist-lock cable to the cart from the shed without there being an appreciable voltage drop.


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(photo courtesy of Isabelle Landers)

A 100A Shock Block provides reliable GFCI protection to a 4/2.5kw HMI Ballast and 60A Woodhead supplying the 1800W ballast and audio cart.


Finally, since our 60A Transformer/Distro is compatible with standard film distribution equipment, the crew could use 60A Bates Extensions to run power down to the lights on the docks (breaking out to 20A Edison pockets next to the ballast with 60A Splitters and 60A Snack Boxes), rather than having to run multiple stingers from the ballast back to the Transformer/Distro. By eliminating the line loss from long cable runs, increased resistance from overheated plug ends, and voltage drop in this fashion, our 60A Transformer/Distro assured that both the HMIs and the GFCI operated reliably throughout the production.

For more detailed information on using transformers with film style GFCIs to provide ground fault production on “house power”, I would suggest you read the article I wrote on the use of portable generators in motion picture production.


Guy Holt, Gaffer, SceenLight & Grip, Lighting and Grip Rental in Boston.
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