Feature Article   Working With Portable Generators [ 2 ] [ 3 ] [ 4 ]

Last month we found out the benefits of using a power generator and a little about the required wattage output needed to run different items that require power to operate. But, we also need to consider some other very important points. Proper wiring and the safe use of generators. If you use a standby generator during power outages, remember that improper generator hookup can create serious problems in safety and service. It is absolutely essential that a generator only be connected to the electric service through a double-pole, double-throw switch. The double-pole, double-throw switch is necessary to make it impossible to mistakenly connect the generator so it would feed electricity back on the power line. A feedback would run the generator output backwards through the service transformer. This would increase the 120/240 volts to 7,200 volts and energize the power line. If a line crew was attempting to repair the line and had cut off all known power sources, they would be electrocuted. The double-pole, double-throw switch makes it impossible to have both the generator and the power supplier service connected at the same time. It simply opens one to close the other. The generator may be connected to the main service, to the service entrance of an individual building, or into an individual circuit servicing one or two essential operations. It should be emphasized again, however, that these interconnections must only be made when permanent, double-pole, double-throw transfer switches are installed to break the existing service connection when the generator is connected. No matter how small the generator’s output is, the energy fed out through the primary side of the service transformer is potentially very deadly. Therefore, the first thing we will cover is the correct way to wire a portable generator for use.   Installation Because gasoline-powered generators exhaust carbon monoxide, they must be operated outdoors. It is a good idea to house your generator in an attached garage or shed, then move it outside when you need it. To make the electrical connection to the panel as simple as possible, put the generator hookup for an outside wall of the garage near the garage door. Mount a box and receptacle that's wired to the new transfer switch panel. Then make a 6-ft. extension cord to connect the generator to the outdoor receptacle.

Some local electrical codes may require that the cord to the generator be hardwired to the house electrical system. In this case a strain-relief device should be used at the connection.   Mounting the new panel Shut off power to the main panel at its disconnect switch and remove the cover from the panel. Remember that while service panels are designed for safety, they should be approached cautiously. Even when switched off, terminals at the main disconnect will be hot and must be avoided. With the panel exposed, break a 1-in. knockout from the side of the box and mount a short threaded nipple in the hole (Photo 1).   1   Connect the new switch panel to the opposite end of the nipple and anchor it to the wall with heavy screws (Photo 2).   2   The grounding bus for the new panel comes uninstalled and there are three locations where you can secure it. Use screws to mount the grounding bus in the position that's most convenient for you (Photo 3).   3