Re: Generator wiring?
A backup generator is usually powered by a conventional internal combustion engine.<br />The two main types of residential generators are portable and permanent standby. If you plan to power a few lights, your refrigerator and a furnace, a less expensive portable generator may provide enough power. If you intend to run your lights and furnacealong with a well pump, a freezer and other major appliancesyou will need a permanent standby model. <br />Typically such a generator is mounted on a concrete pad and connected directly to your home's electrical circuits via an automatic transfer switch that starts the generator during a blackout and shuts it off when grid power returns (more on transfer switches later). <br /><br />If your home is grid-connected, you don't need to spend a lot of money on a backup generator to weather the occasional power outage because typically, backup generators are used less than 50 hours a year. Large standby generators can cost several thousand dollars, but smaller portable models will power basic necessities and cost $1,000 or less, some as little as $400. Even a less expensive generator will run at least 500 hours, giving you about 10 years of service. But if you plan to install solar or wind power, or you live in a rural area on a distribution line that suffers frequent power outages, you will need a larger capacity generator. Those that back up renewable energy systems operate between 100 and 200 hours a year. The load is heavier because they run your household and recharge your renewable energy system's batteries at the same time. <br /><br />Regardless of what size generator you need, it is important to shop around and do your researchprices vary greatly from brand to brand and, according to Consumer Reports, some models deliver less power than they promise. Best-buy-rated models were the Generac 5500 WheelHouse and the Troy-Bilt 5550 (each $650<br /><br />SIZING YOUR GENERATOR<br /><br />It's important to match the size of your generator to your electrical needs. An undersized generator won't last long and can destroy motors and other electrical equipment that require more current than the generator can deliver. Generators are rated by their maximum electrical power output in kilowatts. (A kilowatt equals 1,000 watts, or enough energy to light 10 100-watt light bulbs.) For greatest efficiency and to prolong your generator's life, operate it at no more than 75 percent of its capacity. <br /><br />To calculate the generator size you need, total the wattage of the appliances and other items you want to simultaneously power and then double that number. If you plan to power several appliances, you need to account for their starting or "surge" requirements. You can find this information on the appliance or in its manual. <br /><br />Most homeowners will need a 5-kilowatt portable generator to power a heating system and a few other essentials (a furnace uses from about 1,800 watts to 3,500 watts, depending on the type of furnace and the size of the house). A generator of this size will cost at least $600 and, when running at 50-percent load, wlll consume about half a gallon of gasoline per hour. Larger portable generators use more fuel and cost up to $3,000. Permanent standby generators with automatic operation generally cost between $2,200 and $10,000. <br />If you are just going to power one or two appliances or a few lights, you may be able to use an extension cord to connect them to your generator. Be sure to use a heavy-duty cord that won't cause excessive voltage drop. Saving a few dollars by buying a cheap extension cord for an expensive genset is foolish and potentially dangerousan overheated extension cord is a fire hazard. Dragging extension cords out to your generator in the middle of a stormy night can be a real pain, too, but it is the cheapest approach. <br /><br />A much safer but more expensive approach is a transfer switch. If you plan to back up appliances that can't be unplugged from your home's electrical circuits such as your furnace or boileror you want to power all your household lighting, then you must have a transfer switch, also known as a bypass switch. These special electrical panels work somewhat like your main circuit breaker panel and are available in manual and automatic models. Many city and state electrical codes require a transfer switch and you may need a permit or inspection to have one installed.<br /><br />A basic manual transfer switch costs about $200 and should be installed by a licensed electrician. The installation will cost about $300 (more if extensive rewiring is needed). Your electrician will connect the circuits you want to power. In the event of a power failure, you plug your generator into the panel with a special power cord and switch the circuits from utility power to your generator. When the blackout is over, you switch the circuits back to utility power. This eliminates having both power sources on the selected circuits at the same time and the possibility of sending electricity to the grid lines when utility crews are working on them. A transfer switch also will protect your generator from surge damage when grid power is restored. <br /><br />An automatic transfer switch accomplishes the same tasks as a manual model, except, as its name implies, it functions automatically. Automatic transfer switches cost at least $600 and work with generators that turn on when the grid goes down and shut off when electricity resumes. If your stand by generator is going to power your entire house, then the transfer switch needs the same rating as your main breaker panel. If you only want to power certain circuits, a smaller-capacity transfer switch will work fine. Finally, if you have a natural gas- or propane-powered generator, you need to have a licensed plumber or pipe-fitter install the gas connections.
