On construction sites, portable generators are often used to power work lights and tools such as table saws, compressors and belt sanders. Portable generators are generally easy to operate, but it's important to follow some simple safety practices that can help prevent a few common hazards associated with them: carbon monoxide poisoning, electric shock and fire.
Carbon Monoxide Poisoning
Carbon monoxide can be produced anywhere that combustion is taking place, such as in a portable generator. If the generator engine is not operating correctly, higher levels of carbon monoxide can be produced. Carbon monoxide is a colorless, odorless gas that can quickly cause illness and death. The symptoms of carbon monoxide poisoning include headache, nausea, dizziness and tiredness. These symptoms can be mistaken for cold, flu or other illness. If you or anyone in the area where a portable generator is running begin to feel sick or have symptoms of carbon monoxide poisoning, leave the area immediately and seek medical attention.
Follow these steps when using a portable generator to help prevent carbon monoxide poisoning:
- Never use a portable generator inside an enclosed or partially enclosed space—not even in a building with the windows open or in a garage with the door open.
- Never run a generator near the windows, doors or vents of an enclosed space.
- If you're providing power to a home after a natural disaster, the Centers for Disease Control and Prevention (CDC) recommends placing the portable generator in open air at least 20 feet from any door, window or vent. If you think you may use a portable generator for backup power in your home, plan ahead to help minimize the hazards:
- Install a battery-powered or battery backup carbon monoxide detector in your home, as recommended by the CDC.
- Make sure to have either a generator cord or an appropriately rated extension cord that will allow you to place the generator at least 20 feet from any occupied building.
- Think about how you'll secure your portable generator during use. Fear of theft is one reason that people are tempted to run their generators in basements, garages and other unsafe places where harmful carbon monoxide can easily build up. Anchoring the generator to a fixed location with a heavy chain and lock can help prevent portable generator theft. Removing the wheels from the generator can also deter thieves by making it more difficult to move.
You can use a portable generator to supply power to a trailer, office or other structure—but only when there's a properly installed, code-compliant transfer switch or interlock device connecting to the structure's electrical panel. Connecting a generator to the structure's electrical system in any other way can be illegal and dangerous to you and to anyone working on nearby utility lines.
Follow these steps when using a generator to help prevent electric shocks:
- Plug tools and appliances into the generator directly or using grounded (three-prong) extension cords that are appropriately rated for the amperage or wattage of those devices and suitable for outdoor use.
- Use ground fault circuit interrupters (GFCIs), which help prevent electric shock, especially in damp conditions, by cutting the power as soon as electricity begins to flow outside its intended path. The GFCIs can be integrated into longer extension cords.
- Ensure that the generator is properly grounded according to the manufacturer's instructions and OSHA guidance on portable generator grounding.
- Keep the generator dry. Don't use the generator if your hands are wet or you're standing in water.
- Start and stop the generator only when there's nothing connected to it.
Also, to avoid damaging the generator and the appliances or other devices drawing power from it, make sure the generator is appropriately sized for the load you expect it to handle.
Portable generators get hot when they're running, and they need time to cool down. Take these precautions to help prevent fires when using portable generators:
- Don't refuel the generator while it's running or while the engine is hot.
- Don't overfill the fuel tank. Allow some space for the fuel to expand.
- Don't put anything flammable near the generator while it's running.
- Make sure the generator has three or four feet of clearance on all sides and on top. This will help engine cooling and also allow for rapid ventilation of the exhaust.
- Let the generator cool before moving it inside for storage.
- Store fuel only in approved containers, away from living areas.
- Don't smoke near the generator or its fuel.
- Always read and follow the instructions in the owner's manual and on the generator's safety labels.
- Before using the generator, inspect it for damage or loose fuel lines. Inspect any extension cords for fraying or other signs of damage.
For more information, see the OSHA portable generators fact sheet.