Power Transfer Switches (Manual / Automatic)
Practical Considerations - Do you need one?
If you experience frequent power outages, or your local area is susceptible to severe weather, a power transfer switch is a must for your home emergency generator installation. Emergency generators can provide comfort, safety and security during power outages and emergencies, and can be installed temporarily during these situations. However; any emergency generator must be connected properly to protect electrical utility workers, family members and property. Improper connection of your emergency generator and/or failure to install a transfer switch system could void your homeowner's insurance in case of accident or injury.
A power transfer switch is the key to safe and convenient operation of emergency / backup generators for standby power. By isolating those circuits using generator power, a transfer switch eliminates the risk of back feeding the electrical utility, which can cause injury to workers and property damage.
Manual Power Transfer Switches
A "Manual" transfer switch is a device that requires the operator to switch the load from the utility service to the emergency generator "by hand",( i.e., personally go do it yourself). By installing a manual transfer switch at your breaker box and connecting a portable generator to the transfer switch, you can run selected circuits for appliances such as a furnace, well pump, sump pump, refrigerator, television, computer, printer or lighting circuit during a power outage, depending on the capacity of your generator. Since many portable generators cannot handle all of these loads at the same time, the transfer switch allows you to manually transfer each of these loads separately whenever you need them.
Automatic Power Transfer Switches
An automatic power transfer switch is a device that monitors incoming voltage from the utility line, around the clock, and when the utility power is interrupted, the automatic transfer switch immediately senses the problem and signals the generator to start. Once the generator is running at the correct speed, the automatic transfer switch safely disconnects the utility line and simultaneously opens the generator power line from the generator. With this system in place, your generator system begins supplying electricity to the critical emergency circuits of your home or business. The transfer switch continues to monitor the utility line conditions. When the automatic transfer switch detects that the utility line voltage has returned (continuously), it will re-transfer the electrical load back to the utility line and resumes monitoring for subsequent utility loss. The generator will continue to run for an engine cool-down period, prior to shut-down, while the entire system stands ready for the next power outage. If you are installing a larger emergency backup generator (not a portable generator) the use of an automatic transfer switch is what you really want to have installed, (not a manual switch)!
Transfer Switch Safety Issues
Determining which circuits you will require during a power outage is the first step in selecting the proper wattage generator and transfer
The best way to use these generators is to install them safely and to use only as much power as is absolutely necessary. For example, if you only need to provide electricity to your refrigerator and a few lights during an outage, the simplest and safest way is to run an extension cord of the correct gauge directly from the generator to the appliance.
Electrical current from the generator may "back feed" into the home's electrical system and cause damage or fire and ruin equipment if it is not properly installed. It is recommended a qualified electrician install a generator to a home electrical system.
Some transfer switches automatically trip to generator power if there is a power failure while others must be switched manually. A transfer switch works by isolating a few of the electrical circuits in the home from the incoming electrical service. If the generator is running and power is restored, the power company's electricity cannot get to those isolated circuits until the generator is turned off and the transfer switch is reset to the non-backup position.