No emergency generator, whatever its size, should ever be connected directly to household or farm wiring. Any emergency power system must be directly connected only to those appliances or equipment it serves unless that generator is connected to a properly installed and operable double-throw transfer switch. Such a switch is not optional.
Backfeed
When any generator, no matter how small, is connected directly to a home’s wiring, say by being “plugged’ directly into an electrical outlet the energy produced by that generator can “back-flow” through the household wiring, the service wire and even through the transformer serving that home or farm. Transformers work both ways. It takes 14,000 volts from a power line and reduces it to the 120-volts used in your home. But 120 volts generated by an emergency generator, when it “back-flows” through that same transformer, is transformed into 14,000 volts that will travel for miles along what should be a “dead” power line.
Line crews working to restore service miles away on what should be a “dead” line risk death or injury from this current; and so do your neighbors who touch a downed power line. Children, pets, and livestock can all be endangered when a generator is connected to household current without proper safeguards. If the power comes back on while that generator is improperly connected, appliances and electrical equipment can be damaged by power surges.
Safety Double-Throw Transfer Switch
All generators are sold with instructions that outline their safe and proper use and installation. No generator should ever be connected to household wiring without using a special Safety Transfer Switch. Take time to read and obey safety material that comes with standby generators.
The double-throw switch is not optional equipment. This transfer switch permits a safe changeover from utility service to an on-site power supply. The National Electrical Code requires a double-throw switch on a standby generator installation. Otherwise, individual appliances should be plugged into the generator. Never connect a generator to household wiring that cannot be isolated from the utility system by a transfer switch.
Generator Instructions & Safety Tips
Proper standby generator hookup is vitally important.
- Deficient or improperly installed generators can cause damage to the generator, the appliances connected to it, utility equipment and could cause injury or death to service personnel or the public.
- Installation is not a do-it-yourself project. Rely on the expertise of a professional.
- No matter who does the installation, make certain your generator has a double-throw (transfer) switch.
- Follow all regulations established by your local utility company when using emergency generators.
Once installed, operate the generator according to manufacturers’ recommended installation procedures (proper ventilation, limited load, and preventive maintenance are all essential to safe operation).