Understanding Generators
Written by Elizabeth Wood
Editor In Chief, United Home Improvement

Generators are great way to add comfort and security during a power outage. During times of inclement weather and other interruptions, you want to be prepared for a possible power outage. There are three different ways in which your generator can bring power to your house.

• Plug in loads directly, using extension cords if necessary. This may be the simplest of the three options. This method is used when there is no electrical wiring present or in standby situations. With this method, electrical loads are removed from your wall outlets and plugged into your portable generator by means of extension cords. With portable generators, lights, pumps and small appliances can be plugged directly into outlets. For safety purposes, look for the Underwriters Laboratories-listed, three-prong extension cords. Make sure to plug the appliance into the extension cord first, and then plug the extension cord into the generator outlet.

• You also have the option of using a circuit transfer switch, designed primarily for portable generators. With is method, you only hookup the circuits that you think you will need in an emergency. These panels hook up to your main breaker panel as a sub-panel. Depending on the capacity of your generator, a circuit transfer switch allows you to run selected circuits (6 or 10) for appliances such as a refrigerator, furnace, well pump sump pump, television, and computer, printer or lighting circuit during a power outage. The transfer switch breaks the connection from one source to another, eliminating the chance of the power coming together.

• A large transfer switch works in the same ways as a circuit transfer switch, except it allows you to switch the whole house over. They are available in manual (MTS) and automatic (ATS) transfer switch options. They are costly to install, but essential for protecting your home. With a transfer switch, when power is restored with an improper connection, electrical currents from the generator can cause a short circuit with your utility line. This can often lead to a fire in the electrical system.

With automatic transfer switches, when utility power is interrupted, the problem is immediately sensed and the generator is signaled to start running. The ATS will know when the generator is running at the correct speed, and at this point it will shut off the utility power supply and let the generator take over. The ATS will monitor the entire process from start to end.

Transfer switches are required by the building code electrical codes in most areas and must be installed by a qualified electrician.

Generator Upgrade

If you are thinking of upgrading your generated power unit, you must consider the type of generator you need, determine your wattage requirements, and select appropriate features.
To begin this process, you must first consider what items you are planning to have run on your generator and what their power requirements are. Generators are rated in terms of the amount of power they can produce and are measured in Watts or Kilowatts. Watts are units of electrical power (Volts x Amps = Watts.)
Some household items list their power requirement in Watts; typically light bulbs and small appliances. Others only list Amperes (A or Amps). Most household electrical loads run on 120 Volts, but large heating and cooling appliances such as fans and well pumps will sometimes use 240 Volts.

In order to determine what size generator you need to upgrade to, you will need to add up the wattage required by each electrical load that you plan to use. A load is the amount of electricity required to run an appliance. Make sure to include the starting power required by the largest motor and any others that will be started at the same time. If a generator is too small for its load, the voltage will drop. A 5,000-7,500 running watt generator will run an average home's essential appliances.

Cost will vary depending on size, reliability and special features. Also, cost will depend on whether you are interested in a portable standby system or a permanently installed standby system.

• ($400-$600) Small portable units. Less than 2 kW
• ($500-1,500) Midsize portable units. 4-10 kW
• ($2,000-$5,000) Large trailer-mount units without engines. 15-60 kW
• ($2,000-$5,000) Large trailer-mount. 10 kW or more.
• ($4,000-$12,000) Ê Large standby units designed for permanent installation. 5-40 kW or more.
• (5,000-20,000) Permanent generators for residential use. 5-10 kW

Special features can make operating your generator extremely convenient. Features can be divided into Engine Features and Generator Features.

Generator Power

Generators can be useful during long power outages by providing power to run essential equipment, such as furnaces, lights, security systems, medical equipment, computers, refrigerators, freezers, lighting, water pumps and sump pumps. They are also useful for providing power where it is inconvenient, costly, or impossible to bring commercially produced power.

For residential use, generators can be installed for temporary or for permanent use. They can be run by natural gas, LP propane, or diesel. All types must be installed by a licensed contractor. Installations must meet the National Electrical Code. There are many important safety issues that need to be taken into account before and after installation, which includes getting a generator with enough power.

It is extremely important to determine your wattage requirements. For a general idea, 1000w or less can power lights, clocks, battery chargers, radios and other small appliances. 1500w or more can also power a computer, small freezer or refrigerator. 3500w 120v can power almost any plug-connected appliance with a standard 120V plug. 5000w 240v or more will handle nearly all the loads of a typical household. Make sure to never connect loads to the generator that are too large for its capacity.

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