EUGENE WATER  &  ELECTRIC  BOARD

When properly installed and operated -- offer a safe, convenient means of powering equipment when electricity is unavailable. However, if improperly installed and operated, generators can be dangerous to EWEB's line crews, your neighbors, and you.

Backfeeding is a very dangerous condition in which electricity from your generator flows back through your electrical panel and meter into EWEB's electrical system. Backfeeding can occur when a generator is connected to your home wiring system without disconnecting from EWEB power. The most common way this could occur is if you directly connect a generator to your electrical panel or to a circuit in your home. If you feed power back into the utility system during an outage, you will energize the transformer serving your house. This poses an electrocution hazard for EWEB's line crews and for your neighbors who may not know the lines are energized. If EWEB power is restored while your generator is backfeeding, your generator may be severely damaged.

The simple answer is to always keep generator power and EWEB power isolated from each other.

• Permanent generators are isolated from EWEB's electrical system with a transfer switch installed between the generator and the electrical panel. The transfer switch allows power to be fed from only one source at a time.
• Portable generators are usually connected directly to an appliance or piece of equipment through an extension cord. As long as the equipment is not hard-wired to the building's electrical panel, there is no path back to the panel. Transfer switches are available to safely connect portable generators to building electrical systems.

Transfer switches work by opening the connection to the utility before closing the generator connection. Diagram A shows the two switch positions and power flow for each condition.

Switch Positions

Diagram A

Transfer switches become part of your building wiring system. They require an electrical permit and must be installed by a licensed electrician. The National Electrical Code requires transfer switches for permanently installed generators. Diagram B shows a typical installation for a transfer switch.

Typical Transfer Switch Installation

Diagram B

For economic reasons, generators are not typically sized to handle all the loads in a home or business. To prevent generator overloading, only certain circuits or equipment can be operated at one time during an outage. In diagram B, for example, only the circuits fed from the sub-panel will be powered by the generator.

In addition to installing your generator safely, there are several important safety rules to follow when you are operating the generator.

• Always read and follow the guidelines in your operator's manual. Know how to shut the generator off quickly in case of emergency. Never modify a generator in any way. Never refuel a generator while it is running or hot.
• Periodically run the generator to assure it will start and run properly.

For portable generators a few additional safety rules apply.

• Use adequately sized extension cords. Operate the generator in the open -- never in a building or enclosure. Set the generator on a firm, level surface.
• Operate the generator in a dry location.

If you intend to run your generator during an electrical outage, give us a call at (541) 484-2300, so we can alert our crews.

Contact EWEB Energy Management Services at (541) 685-7000, if you have questions or would like additional information.

Generators take mechanical energy from a spinning shaft and turn it into electrical energy. For most home applications, the mechanical energy is supplied from an internal combustion engine.

Generators are available in many sizes, voltages, and fuel types. Sizing a generator for your application is a critical step and should be done in consultation with a reputable generator supplier or a licensed electrician. Portable generators are typically used to power tools or equipment in locations where no utility power is available.

Permanent generators are installed in homes and businesses to provide backup power during electrical outages.