Use a double-throw type transfer switch if you’re connecting a standby generator directly to an existing electrical wiring system to provide power for a home, farm or small business. A double-throw switch allows you to place or “throw” the switch into two different positions.
One position feeds normal power from the utility line to the load, such as the household or building circuit just like the power flows under normal circumstances. In the other position, it disconnects the utility line and feeds power from the standby generator to the household or building circuit.
Remember, anytime a standby generator is wired or directly connected into a household or building wiring system, a transfer switch must be used for the connection.
A double-throw type transfer switch is required by the National Electric Code and by electrical utility companies for two very good reasons. First, it prevents power back flow from the standby generator through the utility power line. This prevents possible electrocution of utility linemen working to restore service to the power lines. Second, it prevents damage to the standby generator when electrical service is restored; otherwise, the generator could be damaged extensively when power is reestablished.
You won’t need to use a double-throw type transfer switch if you’re plugging individual appliances like a refrigerator, freezer, sump pump or power tools directly into a small portable generator.
These are some more safety considerations to remember when using standby generators:
Ground the generator using number six copper wire and an eight-foot ground rod that is properly bonded to the electrical grounding system.
To avoid the possibility of carbon monoxide poisoning, never operate a standby generator in a basement or other enclosed area. Locate the generator away from buildings to prevent exhaust fumes from entering the building through the crawl space or open doors or windows.
Use extreme caution when operating the generator in wet conditions.
Use only approved containers to store fuel.
Never refill fuel when the generator is running or while the engine is hot.
Do not shut off the generator under load.
For more information on transfer switches and other necessary measures for safe installation and use of standby generators, contact your local electrical utility company or a qualified electrician.
For more information contact the Harlan County Extension Service at 573-4464 or visit our website at http://ces.ca.uky.edu/harlan/.
Educational programs of the Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability or national origin.