Solution Summary: Safe Work Practices When Using Portable Generators
Portable generators are gasoline-powered equipment used to generate electricity for various construction tools and equipment and can present various hazards if used incorrectly. The common causes of injuries and fatalies that arise from using these equipment are electrical and fire hazards and exposure to carbon monoxide. This solution outlines some general safe work practices to help reduce these hazards for the user and utility line workers if they are working to restore power during an outage.
Work Practices to Reduce Electrical and Fire Hazards
In order to help prevent electrical hazards, always maintain and operate portable generators (figure 1) according to the manufacturer's guidelines and recommended use such as utilizing ground-fault circuit interruptors. In general, it is important to plug electrical appliances directly into the generator using the appliance manufacturer's cords. In the event that extension cords need to be used, be sure they are heavy-duty and are of the grounded type (3-pronged). They must be rated for the application and the load to be served to avoid overloading the extension cord. Caution must also be taken to avoid exceeding the capacity of the generator. In addition, always uncoil cords and lay them in flat open locations as cords can get hot and become a fire hazard.
Figure 1. Portable generator. (Photo courtesy of ELCOSH)
Proper grounding and bonding can help prevent electrical hazards from using portable generators. Under OSHA 29 CFR 1923.404, the generator's frame itself may serve as the ground without the need to use a grounding electrode system (such as a ground rod). The reason is because the generator's noncurrent-carrying metal components (such as the fuel tank, the engine, and the housing) and the component's grounding conductor terminals are typically bonded to the generator's frame. However, if there is no bonding of these components, then a grounding electrode system is required.
It is NEVER recommended to connect portable generators directly to the electrical main panel of a structure. In the event of a power outage, never backfeed a generator to the home electrical wiring system since this could result in backfeeding utility lines endangering utility workers trying to restore normal power. Temporary connections of this type can feed electrical power back through the main breaker to the transformer, which then converts it back to high voltage and can energize the connected utility lines. Thus, when utility line workers are restoring power, they are subject to the risk of electrocution. Conversely, if normal power is restored, the utility power can backfeed to generator which may cause a potential electrical arc which could result in fire and explosion since portable generators have integral mounted gasoline tanks. If a portable generator must be connected to a structure, then the electric power must be connected through a power transfer switch (properly installed by a qualified electrician) to isolate the utility systems from the home electrical wiring. The portable generator must also be bonded to a grounding electrode system if used in this manner.
Work Practices to Reduce Carbon Monoxide Exposure
Recognizing carbon monoxide (CO) toxicity symptoms and monitoring CO levels while using gasoline-powered portable generators are work practices that can reduce or eliminate health risks from CO exposure. The exposure levels will vary depending on the type of ventilation and work setting. Because of this variability and the ability of CO to accumulate without warning, it is recommended that users follow some general guidelines:
- Not operate portable generators indoors or in partially-enclosed areas unless the engines can be located outside away from air intakes so that engine exhaust is not drawn indoors where the work is being done. However, an exception to this rule might be during an emergency rescue situation in which other options are not available provided that equipment operators, assisting personnel, and the victim are donning supplied-air respirators
- Learn to recognize the signs and symptoms of CO overexposure which may include headache, nausea, weakness, dizziness, visual disturbances, changes in personality, and loss of consciousness
- Use personal CO monitors (see below) where potential sources of CO exist. These monitors should be equipped with audible alarms to alert workers when CO concentrations are too high or when it exceeds the NIOSH CO Ceiling limit at 200 parts per million
Personal CO Monitoring Instruments
While this is not a comprehensive list of commercially-available options, here are a couple of personal CO monitors from two manufacturers:
SENSIT P100 Personal CO Monitor
- Measuring Range (PPM): 0-999
- Visual, vibrating, and 90 dB audible alarms for high, low, STEL (Short Term Exposure Limit), and TWA (Time-weighted Average)
- Datalogging: Up to 100 alarm events (downloaded through SmartLink Software)
BW Technologies GasAlert Extreme Single Gas (CO) Monitor
- Measuring Range (PPM): 0-1000
- Visual, vibrating, and 95 dB audible alarms for high, low, STEL (Short Term Exposure Limit), and TWA (Time-weighted Average)
- Approved for Class I, Div 1 and CLass II, Div 1 environments
- Replaceable batteries and sensors
- Includes calibration cap and hose
- Optional: BW Technologies Infrared Connectivity Kit and Software is available for linking to a computer for data downloads and access to instrument set up options
Contact with electric current is a major cause of injury and death among construction workers (Janicak 2008). In 2012, the Census of Fatal Occupational Injuries (CFOI) data produced by the Bureau of Labor Statistics (BLS) indicated that contact with electric current was the fourth leading cause of work related deaths—after falls, transportation incidents, and contact with objects and equipment (BLS 2012). Electricity can cause electric burns, electrocution, shock, arc flash/blast, fires and explosions. Incorrect use of portable generators can contribute to the risk of electrical hazards.
One of the major causes of an electrocution hazard is contact with overhead power lines and energized sources. Overhead power lines are particularly hazardous since they carry high-voltage electricity. Although electrocution is considered the main risk, other important hazards of working near or on high-voltage lines include electrical shock, burns, and falls to lower levels. These types of hazards happen when the body becomes part of the electric circuit, whether by direct contact with an energized source or by contact with a conductive material that has become energized. The severity of the electrical hazard depends on several factors, including the length of exposure time, energy deposited into the body, the pathway through the body, wetness or dryness of the surface and the amount of current. Utility line workers repairing power lines may unexpectedly encounter high voltage and suffer a fatal shock through portable generator backfeed.
Carbon monoxide (CO) is a poisonous, colorless, odorless, and tasteless gas. Although it has no detectable odor, CO is often mixed with other gases that do have an odor. CO results from the incomplete burning of natural gas and any other material containing carbon such as gasoline, kerosene, oil, propane, coal, or wood. In construction, it is common to use gasoline-powered equipment that can lead to the risk for carbon monoxide toxicity, especially in poorly ventilated or confined spaces.
How Risks are Reduced:
Adhering to the portable generator's manufacturer guidelines and use recommendations can reduce the risk of electrical hazards through making proper grounded connections of tools and applicances. In addition, the practice of not connecting a portable generator to a structure (without a power transfer switch installed) eliminates the risk of electrocution for utility line workers.
By taking a proactive approach in recognizing symptoms and monitoring CO levels before and during the operation of portable generators, the risk for CO toxicity can be reduced or eliminated.
- Before the use of portable generators, inspect for damage or loose fuel lines
- Always keep portable generators dry and never operate under wet conditions
Le, Jean Christophe, MPH - CPWR - The Center for Construction for Research and Training
CPWR Hazard Alert Card
To obtain information, visit Carbon Monoxide Poisoining
To obtain information, visit BW Technologies GasAlert Extreme Single Gas Monitors or contact 1-877-723-2878 firstname.lastname@example.org
To obtain information, visit Grounding Requirements for Portable Generators