Job Safety Analysis and Activity Hazard Analysis considerations for Non-Electrical and Electrical Hazards Associated with Portable Electric Generators

Portable electric generators can range from small units generally used on rare occasion, such as in emergencies or when camping, to very large semitruck size units capable of powering a remote work location supporting hundreds of workers.

Large Diesel Powered Portable Electrical Generator Image Source

There is a wide variety of users of portable electrical generators that include:

  • Commercial
  • Residential
  • Industrial
    • Construction
    • Mining
    • Oil & Gas
    • Television and Film

Many of the electrical hazards are similar if not the same as when working with commercially supplied power. However portable generators do have additional risks and hazards that are specific to the transit nature of these devices that need to be evaluated in the Job Safety Analysis.

Smaller, residential portable generators are often used in times of emergencies, such as after a storm or earthquake. In these situations, the user may not be that familiar with the hazards associated with the generator because it is used so infrequently. One of the main hazards is using the generator in doors or too close to a building where the exhaust from the engine accumulates inside and leads to buildup of carbon monoxide (CO) inside the building. Carbon monoxide poisoning is a leading cause of death related to the improper use of residential portable electrical generators. The Centers for Disease and Prevention (CDC) has a Carbon Monoxide - Generator Safety Fact Sheet that should be reviewed when preparing the Job Hazard Analysis.

Typical Residential Size Portable Electrical Generator Image Source

The use of extension cords with portable electrical generators can create a number of different hazards and so it is appropriate to have a discussion during the Job Hazard Analysis regarding these risks and hazard mitigation regardless if the generator is used in a residential or commercial environment. In emergencies it is common to connect extension cords to the generator and route the extension cords to various parts of the building. These cords can be a tripping hazard so how the cords are routed should be considered before someone trips or falls and becomes injured.

There are many factors that should be considered when selecting an extension cord to use with a portable electric generator. How long will the cord need to be to reach the device to be powered? How many amps or watts are required by the device or devices? How long will the extension cord be required to power the devices at the maximum load? The following table can be used as a first cut approximation to determine the correct wire size for the given distance and load that is anticipated to be powered by the extension cord.

Length (Feet) 16 AWG 14 AWG 12 AWG 10 AWG
Amps Watts Amps Watts Amps Watts Amps Watts
25 13 1560 15 1800 15 1800 15 1800
50 12 1440 14 1680 15 1800 15 1800
100 9 1080 12 1440 14 1680 15 1800

Please note that this table is only an approximation for extension cords that are generally used in residential situations. Each specific use case requires a detailed hazard analysis to determine the appropriate cord. For commercial and industrial environments that require much larger current carrying capacity, each situation should be evaluated by an electrician or someone trained and certified. Make sure to consult the manufacture of the extension cord for their specifications and maximum usable loads. The use of extension cords for high current devices is not recommended. Some examples of high current devices include portable space heaters, microwave ovens, and air conditioners. Consult the device manufacture for their recommendations. It cannot be over emphasized that exceeding the amperage and wattage ratings of the extension cord has a very high likely hood of causing a fire due to overheating of the extension cord, plug, or socket.

Portable generators produce heat when they are running. The heat can cause burns to people working around the generator and the heat is also a potential ignition source for fires, especially, but not limited to, refueling operations. Overloading a generator can lead to fires so make sure you follow the manufacture's instructions regarding the maximum allowable load. The exhaust from a generator has the potential to start a fire, particularly if there is dry weeds and brush nearby. The United States Forest Service has requirements for motorized equipment that specifically require the use of spark arresters. Information on the USFS spark arrester requirements can be found in in their guidance "An Introduction to Spark Arrestors SPARK ARRESTERS AND THE PREVENTION OF WILDLAND FIRES".

Water presents other hazards associated with generators. Water can be a conductor of electrical energy, so there is an increased risk of electrical shock or worse when using a generator during a storm or in areas where there is standing water. Water and moisture can also damage the generator hardware. Generators should always be properly grounded before using. The Occupational Safety and Health Administration (OSHA) has guidelines and requirements for grounding portable generators.

Noise from the portable generator is a hazard that should be considered during setup and placement of the unit.

When a generator is to be used in large commercial and industrial setting for extended periods of time, it is advised that a certified electrician be consulted to evaluate the specific needs and to assure compliance with all applicable regulations and permitting requirements. Consider hardwiring the generator to reduce or eliminate the need and use of extension cords.

A good resource that can be consulted during the Job Safety Analysis is from the office of Cybersecurity, Energy Security, and Emergency Response, which has a web page titled "Using Portable/Emergency Generators Safely" that contains safety tips for residential users in emergencies such as hurricanes and earthquakes.

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