Residential electrical wiring changed during the 20th
century as new appliances appeared on the scene and electricity evolved from
a luxury to a mainstay. More appliances at home led to safety improvements
and an increased number of room outlets, leaving older home wiring to play
catch-up. Although most older home electrical systems have been upgraded
over the years, safety shortcomings may still exist. Since a third of
American homes were built more than 50 years ago, home buyers and folks
living in older homes should be aware of how wiring changed during the last
Electric capacity is a major concern with older wiring
systems. Homeowners in the 1930s didn’t use a lot of electrical appliances,
except for a refrigerator, a few lights, and a radio.
An explosion of appliance purchases followed in the late
1940s and early ’50s. But the arrival of air conditioning during the 1960s
soon rendered many mid-century home electrical systems obsolete. More
recently, residences built as little as 20 years ago might be insufficient
for handling entertainment systems and personal computers.
Each year, household wiring and lighting cause an
estimated average of 32,000 home fires. On average, these fires result in
950 injuries, 220 deaths, and nearly $674 million in property damage,
according to the National Fire Protection Association.
“Residential electrical systems
are seldom inspected after they are installed and tend to be destroyed in
house fires,” explains John Drengenberg, consumer affairs manager for
Underwriters Laboratories, Inc. (UL), an independent product-safety testing
and certification organization based in Chicago, Ill.
“Homeowners should not assume all is well simply
because fuses aren’t blowing, circuit breakers aren’t tripping, or they’re
not receiving shocks or smelling burnt plastic. Inside the walls, wire
insulation could be cracking and crumbling, especially if wires are drawing
more current than they were designed to handle. The wood frame above plaster
ceilings could also become charred by light bulbs that are too close to the
ceiling or higher in wattage than the light fixture’s rating.”
To avoid such hazards, consumers should understand the
limits of home wiring systems. Often, this depends on when a home was built
or if the electrical system was upgraded. In other cases, though, telltale
signs may indicate a problem.
“Anytime you receive a shock from an electrical appliance,
outlet, or wall switch in your home, it’s a warning that you should talk
with a qualified electrician,” Drengenberg cautions. “If a fuse blows or a
circuit breaker trips right after you replace or reset it, you have trouble
somewhere. Flickering or dimming lights could mean loose connections,
overloaded circuits, improper wiring, or arcing and sparking inside walls.”
In older homes, heat means too much electrical current’s
being drawn through outlets. “If your receptacles or plugs are hot to the
touch — you can’t keep your hand on them for more than five seconds — you
may have an overload,” Drengenberg advises.
When too much current gets drawn, wires heat up, baking
and eventually weakening insulation. Wires with damaged, decayed, or brittle
insulation can lead to shocks and fires.
Another issue associated with older home wiring systems is
the number of receptacles in each room. Today’s electrical code requires
outlets be placed every 12 feet of running wall space, about one per wall in
the average 10-by-12-foot room. Houses built before 1956 were required to
have outlets placed every 20 feet, while homes built before 1935 weren’t
required to have wall outlets at all.
“Relying on extension cords is not the answer,” says
Drengenberg. “Extension cords are meant for temporary use only and should
not be a substitute for permanent wiring.”
Proper grounding, meanwhile, prevents painful or even
deadly electrical shocks when electricity flows through an improper path.
Every home electrical system should have some type of grounding.
Newer homes are wired with cables that include a ground
wire. The ground wire allows for use of three-pronged receptacles needed to
power certain appliances, particularly ones with metal shells, such as
refrigerators and washing machines.
Many wiring systems installed in the 1950s and earlier
used non-metallic wiring, which lacked a ground wire. Homes from this era
boast only two-pronged outlets, unsuitable for many modern conveniences.
Simply replacing two-pronged receptacles with three-pronged receptacles
violates the National Electrical Safety Code if no ground path exists.
In some cases, older homes may feature newer wiring
systems. But the era in which the wiring was upgraded impacts its electrical
limitations. Before buying a home, have someone certified in electrical work
inspect the wiring system carefully for safety. Visit www.inspectorseek.com