Home Is Where the Hearth Is - When Disaster Strikes - page 76

Medium-sized generators run from the smaller “jobsite” generators (see fig. 4-4 ) , like my
9-horsepower 4 kW gasoline-powered generator, to the large models such as the 15-horsepower
7.5 kW (9.4 kW at temporary peak load) model HW7500E made by Honeywell. These generat-
ors typically offer both standard household-style 120-VAC outlet sockets and high-amperage
“screw lock” 240-VAC sockets. Standard North American household wiring is powered by two
opposite phased 110-VAC main lines coming into the home. These two oppositely phased
110-VAC lines provide the two “hot” legs of your home's 220-VAC circuits (the red and black
wires) that carry power to major 220-VAC appliances such as electric water heaters, kitchen
ranges, and large air-conditioning units.
Note: If the following discussion means something to you, congratulations! If not, please
play it safe and keep it simple. Plug a power strip and/or extension cords into your generator to
power your appliances, and leave it to the professionals to hook up anything more complicated.
The advantage of hooking your generator directly into your home's power system is that
you can avoid the clutter and physical hazard created by running power cords thorough open
windows and hallways to hook into different appliances, and simply use your home's electrical
system and switches to power your lights, refrigerator, TV, computers, furnace, etc. However,
electrical codes require that whenever a generator is hooked into a building's electrical system,
the connection must pass through a “transfer switch” to guarantee that when the generator is
powering your home, the home will be disconnected from the grid (see fig. 4-10 ) .
Figure 4-10. Generator plugged into an outdoor power-outlet box that is wired to a transfer switch next to a load
center located in the garage. Illustration courtesy of Reliance Controls