Residential Wiring Described

Residential Wiring Described

Modern residential wiring uses a minimum of three wires encased in a plastic sheathing. This is commonly called "two wire" because it has two conductors. The third, ground wire, is not counted.

PHOTO HERE

Modern 2 wire - Typical #12 or #14

Older residential wiring using only two wires and lacking a third grounding circuit is dangerous and should be replaced by a licenced, qualified electrician.

Two wire, Knob & Tube. REPLACE Immediately!

Outlets with only two slots, lacking a center ground connection are a giveaway that you have only two wires. An outlet with two slots and a center ground connection should have three wires connected however the outlet should be tested to ensure a third (ground) wire is connected and operating properly.

Within the plastic sheating of modern wire, two wires are individually insulated, one black and one white in color. A third uninsulated wire has a paper wrapping. All three are within the plastic sheathing.

The black wire is "hot" being connected at one end to a circuit breaker in the Breaker Box. The white wire is "neutral" and is connected to the grounding bar also within the Breaker Box.

The uninsulated wire is "ground" and is also connected to the grounding bar within the Breaker Box. Residential electricity is usually supplied to outlets and fixtures at 110 volts and is "Alternating Current" or AC. (220 volts are present within the breaker box used in three wire applications for heavy duty)

Alternating Current means that the flow of electricity alternates direction. In the United States and Canada, AC changes direction 60 times per second. So, AC current is described as 110 volts, 60 cycles.

Electricity flows through the black wire into the electrical device or "load" such as a light bulb, and out the white wire. This flow alternates, changing direction and flowing the other way repeatedly. In the ultimate display of indecisiveness, it changes direction sixty times every second.

220 Volts 3 wire.

When a heavy duty appliance like a clothes dryer or electric stove requires greater current (amps) and voltage, a three wire cable is used. The third conductor wire is insulated and colored red. In a three wire cable, both black and red are "hot" being connected to seperate breakers fixed side-by-side. From the panel, they appear to be seperate breakers (and function as such) but they are "ganged" with their switch levers connected. Turning off, or tripping one, forces the other to turn off or trip as well. Within the Breaker Box, side-by-side breakers take their current from different sides of the box.

These sides are "out of phase" meaning the alternating (reversal) of current every 60 seconds does not happen at the same time. Four wire cables are generally #10 wire or larger.

Size	Amps	Use
#14	15A	Outlets, lights. (most household circuits)
#12	20A	A/C, Radial or Table saw
#10	30A	Clothes Dryer
#8	40A	Electric Stove
#6	60A	Branch Circuit
#3	100A	Branch Circuit

Wire smaller than #14 is not used to carry 120volt current. Smaller wires may be used for door bells and thermostats.