The Occupational Safety and Health Administration (OSHA) offers the following cautions on the use of gas-powered generators and other tools:

Shock and Electrocution

• Never attach a generator directly to the electrical system of structure (home, office, trailer, etc.) unless a qualified electrician has properly installed the generator with a transfer switch.
• Always plug electrical appliances directly into the generator using the manufacturer’s supplied cords or extension cords that are grounded (3-pronged). Be sure to inspect the cord to make sure they are fully intact and not damaged.
• Never use frayed or damaged extension cords.

Carbon Monoxide Poisoning

• Never use a generator indoors or in enclosed spaces like garages, crawlspaces and basements.
• Make sure a generator has three to four feet of clear space on all sides and above to make sure there's adequate ventilation.
• Be careful when using a generator outdoors so it's not placed near doors, windows and vents which could allow CO to enter and build up in occupied spaces.
• If anyone shows symptoms of CO poisoning (dizziness, headaches, nausea, tiredness) get to fresh air ASAP and seek medical attention. Do not re-enter any area until it is determined to be safe by trained and properly equipped personnel.

Fire Hazards

• Generators become hot while running and remain hot for long periods after they have been shut off. Generator fuels (gasoline, kerosene, etc.) can ignite when spilled on hot engine parts.
• Before refueling any generator, shut down the generator and allow it to cool.
• Gasoline and other generator fuels should be stored and transported in approved containers that are designed and marked for their contents and vented.
• Keep fuel containers away from flame-producing and heat-generating devices such as the generator itself, water heaters, cigarettes, lighters and matches. Do not smoke around fuel containers.

Noise and Vibration Hazards

• Generator engines vibrate and create noise.
• Excessive noise and vibration can cause hearing loss and fatigue that may affect your job performance.
• Keep portable generators as far away as possible from work areas and gathering spaces.
• Wear hearing protection if this is not possible.

The National Fire Protection Agency Provides These Tips

• Generators should be operated in well-ventilated locations outdoors away from doors, windows and vent openings.
• Never use a generator in an attached garage, even with the door open.
• Place generators so that exhaust fumes can’t enter the home through windows, doors or other openings in the building.
• Make sure to install carbon monoxide (CO) alarms in your home or business. Follow the manufacturer's instructions for correct placement and mounting height.
• Turn off generators and let them cool down before refueling. Never refuel a generator while it is running or hot.
• Store fuel for the generator in a container that is intended for the purpose and is correctly labeled. Store the containers outside of living areas.