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Generator safety

By Queenstown Gaffer Brett Mills

All generators used on a film set must comply with electrical standard A/NZS 4249.9 which says a Residual Current Device (RCD) must be used with the correct types and fitted to the generator.

Now that most lighting crews use and accept RCD’s (1) for personal protection, the weakest link in the chain of electrical safety are the small generators.

According to the relevant codes of practice, (3) all power circuits on a film site (2) must be protected by an RCD. This includes all small generators.

RCD’s are the first line of defence for electrical safety. They are designed primarily to protect life. I believe if every circuit on set is protected by an RCD, then most of your electrical safety fears can be allayed. I can only feel comfortable when things turn nasty electrically (ie. sudden downpour, dodgy piece of borrowed equipment, that gets pulled out at the last second) when we have total RCD protection.

By the nature of our work, the small generators are often used in isolated situations where a person inadvertently coming in contact with a live wire may not have help at hand.

All single-phase generators must be fitted with an RCD, ie. the small generator running a computer,the unit, the caterers, smoke machine, lights or the monitor. This includes generators hired from hire companies, owned by production companies or individual crew members.

Previously, I believed that an in-line breaker was sufficient protection, however, I’ve since found they do not give any protection when plugged into certain generators and are made for using off house power or in situations when the neutral is earthed.

Another confusing factor is the testing of RCD’s. The test button only tests the mechanics of the device, not the electrical ability (the test button could lead one to believe that the RCD is offering the required level of protection when in fact it is not) (4). Testing should be done with a proper RCD tester every three months or prior to every hire for a hire company. From now on, any production that I am involved with in the capacity as Gaffer, I will be insisting that all electrical equipment comply with the relevant codes of practice and specifically generators requiring RCD’s. Perhaps it would be prudent for production companies to do the same and include in their safety notes, words to the same effect.

To those people in the film industry who own small generators, I would suggest having an RCD permanently fitted. It costs around $100 for the breaker and is quite easy to fit. Often an easy solution is a socket outlet with an RCD built into it. HPM makes one especially for generators. A good all-round breaker is a FUJI fg32r which can be mounted from the front or rear.

The most common cause for RCD tripping is plugging into a camper or makeup bus where they have an earth-neutral link in place. When hiring a bus or camper it is advisable to inform the hire company that you wish to run it from an RCD-protected supply.


(1) An RCD is a Residual Current Device also referred to as an Earth Leakage Breaker or a Ground Fault Interrupt. It is a device inserted into the electrical circuit primarily to protect life by isolating the supply when the current flow to earth exceeds a predetermined value, usually 30 mA).

(2) A film site, according to the NZF&VTG Safety Code of Practice, is “any place, interior or exterior, permanent or temporary, where film, television or video production takes place."

(3) AS/NZS 4249:1994 Electrical Safety Practices – Film, video and production sites, states in Clause 13.3 “All generators used on a film site shall have an earthing system suitable to operate an RCD…”

(4) The NZ Electrical Code of Practice for Electrical Installations – Supply by Generating Systems Not Exceeding Low Voltage, (NZCEP 4:1993) clause 2.6.2 says that the only time a winding of a single-phase generator may be earthed is on the primary side of an RCD. (Electrolink 9-10/99)

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