Electrical Wiring: Updating for the 21st. Century!
Common Problems Found in Older Homes
- Inadequate Amount of Electric Service
- Too Few Outlets & Not Enough Circuits
- Few or No Grounded Electrical Outlets
- Worn or Undersized Electrical Wiring
WARNING: When working with electricity, removing covers, or examining your wiring, be certain to turn the power
OFF first. The main power box may not have a disconnect and you may have to call the power company to pull the meter or
turn off your electricity at the pole.
CAUTION: Depending on the local building codes and laws, some or all of your work must be done by a licensed
electrician. In some areas, the homeowner is allowed to do some or all of the work when supervised by a licensed
electrician. Most likely, the work will have to be inspected by a local building inspector and if any of the work fails to pass, it will have
to be replaced and done correctly.
Inadequate Amount of Electric Service
Newer homes are normally required to have a minimum of 200 amp service. This is considered a minimum amount. If
your home has electric heat, you may need a larger service. Larger homes may require 400 amp service or greater.
When upgrading your electrical service, you may need to check with your power company for placement of the
service entrance. It's possible that you will need to move it from where it's located now. You may want to have it somewhere
else, or the power company may require it to be located in a different spot.
The service entrance includes the masthead, conduit, and wiring from the top of the masthead into the building.
The service panel or breaker panel is normally located as close as possible to the service entrance, however in some
cases you may need to locate it farther away check with local building codes before doing this.
Some breaker panels do not have as many "slots" for breakers. Normally, the price is similar no matter how many
slots there are, so it's best to get one with the most slots. Be sure the brand is popular in your area. I recommend going to
the hardware store and pricing different breakers. Some brands only accept one type of breaker, and they may be very
Breakers v Fuses is an old argument and modern breakers are actually better than fuses. The breaker has two
protections: too much current will "trip" the breaker off, and if it fails to trip, or the current is extremely large, there is a
"fuse-like" strip inside that will burn out.
How Many Circuits Do You Need?
Unless you are rewiring your entire home, you probably won't be able to split up many of the existing circuits. You
should plan ahead for circuits you may be adding during future remodeling even if you won't be adding them now.
There are four basic types of circuit breaker installations. The first two types are used for 220 volt service. One is
double width and provides two connections for wires and the other one looks like a normal 110V breaker and are used in
pairs, with a connector for pair's switches [so both wires are tripped together]. The other two types are for 110V. One has a
single breaker and the other one has two breakers built into one [duplex] so that two 110V circuits can fit into one breaker
slot [often used with small size panels with lots of circuits].
The number of circuits will depend on the size of your home. You should have at least two circuits, staggering the
connects so that if a breaker trips, adjoining rooms will still have lights. Also, if you have a wired smoke-detector [uses AC,
not batteries], these should be wired into the lighting circuits. The idea is that you are more likely to be aware of a
tripped breaker that operates lighting so that you will know there is power to the smoke-detector.
Duplex receptacles are normally places six to eight feet apart in newer homes, depending on local building codes.
The idea is to have enough circuits so that extension cords are not necessary. Ideally, each room should be on a
separate circuit. Some outlets could be switched so that a table or floor lamp could be turned off at a wall switch. Often, the
duplex outlets are split so that one "plug-in" is switched and one is not.
Bathroom Outlets & Outdoor Circuits
Ground-fault protection should be used with all bathroom and outdoor circuits. This is a special device, either in the
outlet or in the circuit breaker, which will immediately disconnect the power in case of a short, such as dropping a hair dryer in
a sink full of water. Ground-fault protection could save your life! The type used [breaker or outlet] will depend on your
local building codes be sure to check.
Modern electric appliances in the kitchen can make life easier. However, most homes don't have enough circuits in
the kitchen. If you are making coffee, using the microwave, cooking in an electric skillet, and using the toaster all at the
same time, you probably need at least two circuits. Three or four circuits are even better.
WARNING: If you don't have enough circuits in the kitchen, do NOT increase the size of the breaker or fuse. The
electric wires in the wall cannot handle more than 15 or 20 amps, depending on size.
Breakers . . . How Many Amps?
Most circuits for lighting and outlets, using 12 AWG [American Wire Gauge] wire with ground, should be 15 or 20 amps.
If you have special needs for higher amp service, for example, to operate power tools in the garage or shop, larger
size breakers should only be used with proper size wiring.
Special outlets and circuits for appliances will require larger wiring and breakers. Electric furnaces vary in size and
the breaker and wiring size will depend on the furnace requirements. Central air conditioning requires a breaker and wiring
of the size recommended by the manufacturer.
Most electric water heaters and electric clothes dryers each need a 30A, 220V, breaker. Kitchen ranges require a 50A
to 60A, 220V, breaker. A dishwasher usually requires 20A, 110V breaker. Special appliances like a sauna, or hot tub
require ground-fault interrupt protection; the size of the wiring and breaker should be the size recommended by the manufacturer.
Few or No Grounded Electrical Outlets
Most older homes do not have grounded outlets. By grounded, it means that there are three wires: a hot wire, a
neutral wire, and a grounding wire [normally bare, or with green insulation]. The electric for a 110V circuit travels in the hot
wire [normally black insulation], and back out on the neutral wire [normally white insulation]. The ground wire is used in
the event of a fault in the appliance or device. Grounded outlets also provide better protection against plugging the cord
To add grounded outlets, the wiring must be replaced first. Changing to grounded outlets, so that a three prong plug can
be used, does NOT provide ground protection unless you have it connected to a ground, plus hot and neutral wires.
A ground-fault interrupt outlet is a special grounded outlet that will turn off the power at the outlet if the appliance is faulty
or gets wet. It must have grounded wiring for it to work properly.
Worn or Undersized Electrical Wiring
This is probably one of the biggest causes of fires in older homes. Building codes for electrical wiring and devices
are taken from NFPA the National Fire Protection Association who publishes guidelines for safety. Everything is
covered from out buildings [like chicken houses and barns] to modern sky scrapers.
The only solution is to replace the wiring. Normally, most 110V lighting and outlet circuits in homes require at least
#12 AWG wiring with ground. Some areas may allow #14 AWG for connecting switches [switch-leg of circuit]. It's best to use
all copper wiring. Some use of aluminum wiring is allowed when special outlets and switches are used, however, what
little money is saved on wiring is lost on the extra cost of devices.
The physical size of the wire gets greater as the gauge gets smaller. While it's not exact, a rule of thumb is that #12
AWG will handle up to 20 amps, #10 up to 30A, #8 up to 40A, #6 up to 50A, for common household wiring. Higher gauges
don't follow the rule the same, and even the rule of thumb presented here should be checked to make sure you are in
compliance with local building codes.
Common Questions & Answers
How do I figure the size breaker I need from wattage?
The formula is VxA=W and W/V=A. For example, a 100 watt bulb takes almost one amp. Divide 100 watts by 110
volts. This will work for most "resistive" loads, such as light bulbs and toasters. Electric motors also have something called
a "power factor" which makes it a little different, but most motors are rated in amps, too.
What's the difference between 110 and 120?
Actually, it's historical. Originally, 110 volts and 220 volts were supplied. The power companies have increased the
voltage and in most parts of USA, it is called 120 and 240, or 125 and 250, yet it is common to actually have 127 volts and
254 volts. The actual amount will vary, depending on your location. During peak times, the power company may increase
How do I know if I have 220 volts?
Most households have a typical three-wire service. There are two wires that are "hot" and one wire is "neutral." By
using the two "hot" wires, you get 220V. By using either one of the "hot" and a "neutral" wire, these two wires provide 110V.
Will a window air conditioner be cheaper to run if it is 220V?
Most likely, it's cheaper to build it. The only way it would be cheaper to operate depends on the SEER the
Season Energy Efficiency Rating. If the 220V unit is less efficient than a unit that uses 110V, then it would cost more to operate
the 220V unit. Electricity costs are based on KWH the number of kilowatts used per hour. To get the wattage, a rough
figure can be had by multiplying the voltage times the amps. Sometimes, a unit comes in 220V because the 110V version
would require a 30A or larger circuit, which is not very common in homes.
How can I have more than one switch operate the same light?
You need special wiring and "three-way" switches. If you want more than two switches, an unlimited number of
switches can be used with two, three-way switches, and as many four-way switches as are needed. The wiring layout is not for
the timid; some electricians have trouble with these. To do this yourself, see related article:
"3-Way & 4-Way Switch Wiring."
My neighbor's farm has three-phase service. What is this?
It's a different way of using electricity. Most homes have single-phase. Some large motors can benefit from
three-phase. Basically, the power "spurts" through each wire at three different intervals. The best way to explain this is putting up
a circus tent. One big guy with a real big hammer, driving in a big tent-peg, is like single-phase. Or, get three little guys,
with little hammers, each taking turns, hitting it three licks for every one lick the big guy hits his peg that's three-phase.
Reprinted with permission, Homedoctor.net