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Section 5 Applying Technology: Producing Products and Structures
Most 110-volt circuits are limited to 15
or 20 amps. Therefore, a number of differ-
ent circuits are required to supply various
parts of the home. A kitchen might have
one or two circuits because of how many
appliances are used there. One circuit
might feed two bedrooms because there
are few appliances in these rooms.
Plumbing systems
The plumbing system has two sepa-
rate parts. One part supplies potable water.
See Figure 17-20. Potable water is safe
for drinking. The other part of the system
carries away wastewater. Plumbing fix-
tures and systems are designed to prevent
mixing of potable water and wastewater
and to stop sewer gas from leaking into the
dwelling.
The potable-water system starts with
a city water supply or a well for the house.
The water enters the house through a
shutoff valve and might pass through a
water conditioner to remove impurities,
such as iron and calcium. The waterline
is split into two branches. One line feeds
the water heater. The other line feeds the
cold-water system. Separate hot and cold
waterlines feed fixtures in the kitchen,
bathrooms, and utility room. Toilets, how-
ever, receive only cold water. Most water-
lines have shutoff valves before they reach
the fixture. For example, the waterlines
under a sink should have a shutoff valve.
The valve allows repairs to be made with-
out stopping the water flow to the rest of
the house.
The second part of the plumbing system
is the wastewater system. This system car-
ries used water away from sinks, show-
ers, tubs, toilets, and washing machines.
The wastewater is routed to a city sewer
line or to a septic system. At each fixture
and appliance, a device called a trap is pro-
vided. A trap is a U-shaped piece of pipe
that remains full of water. The water in
the line stops gases from the sewer system
Incoming
power
Outlets
Switch
Light fixture
Wire Colors
Black
White
Green or bare
Circuit
breaker
box
Figure 17-19. A 110-volt electric circuit. Note how the switch controls the light, but not
the outlets.