Jul 22

A Gentle Introduction to Wiring

Simple Wiring

An Introduction to Home Wiring

Some people find home wiring intimidating. The truth is, wiring is similar to plumbing, the current comes in, and needs to go somewhere. Electricity does some work before leaving your house. The work is providing light, heating soup, or making your favorite tune come out of your sound system.

Many cities will require a licensed electrician to do commercial work. Each city will have a licensing bureau that will outline the requirements to obtain a license. Some of the work can be done by unlicensed personal, but must be inspected and signed off by licensed personnel. Commercial work will normally need to be inspected by the
city inspector.

Typical home circuits are 110VAC 60Hz. Batteries are normally measured in direct current (DC), and home wiring is alternating current (AC). Batteries only put out a few volts each (1.5 to 9), the home wiring is 110 volts. Batteries have a constant positive, and negative connector, where home wiring with alternating current, meaning the
positive and negative switch places, sixty times a second (the 60Hz is the frequency it changes).

Since home wiring doesn’t have a constant positive, the terms change. The one side is called the hot side, the other side is called the neutral. The hot side is usually the black wire, where the neutral is the white wire. As a safety feature, there is usually some kind of ground, indicated by an uninsulated or green wire.

The color of the wires is really the color of the insulation. The copper (or aluminum) wire is the same for all wires. Wrapping the wire in a plastic coating will prevent the electricity from leaving the wire at the wrong time, and easily mark the purpose. The electricity wants to get back to the power source as quickly as possible. When the two wires touch before the end point, the electricity takes a short cut, and we call that a short circuit.

The electricity enters the home as some very large wires. There are typically two 110V circuits on three wires. There are two hot wires, and a single shared neutral. The wires come into a distribution box (sometimes called a fuse box), that is filled with fuses or circuit breakers. The two circuits are split between the various loops in the home.

The fuses and circuit breakers are used to protect the wires. When a circuit needs too much energy, the friction in the wire can cause it to become very warm, potentially causing a fire or just melt the wire. The circuit breaker or fuse will break the circuit when the specific current limit is met. Circuit breakers are usually rated in 5 amp levels, like 10 amp, 15 amp, 20 amp, etc. The difference between a 15 amp circuit and a 20 amp circuit is the size of the wire from the distribution box and the end.

The wire is measured in guage. The larger the wire the smaller the guage number. A 0 guage wire will be about a half inch in diameter, a 30 guage wire will be about the thickness of a heavy hair.

The wire that goes from the distribution panel to the receptacles is contained in some sheathing. Older homes and commercial buildings will have a metal sheathing. The flexible metal sheathing is called greenfield, and the pipe looking sheathing is a conduit. Most homes have most of their wiring in a plastic sheathing. Various brands of
plastic sheathed wire are used, with most people using the “Romex” name for all plastic sheathed wire. All circuits start at the distribution panel and terminate in some box. A circuit is never terminated or joined outside of a box.

Before working on any electrical circuit, the circuit breaker must be turned off, or the fuse removed to prevent electrical shock to anyone touching the wiring. It is a good idea to mark any circuits that have been turned off to insure someone doesn’t accidentally turn on the circuit before the work is completed.

To make a light bulb light, the two wires are used to put electricity in, and to take it out. Once the circuit is broken, by disconnecting one of the wires, the electricity quits flowing, and the light goes out. Once that circuit is restored, the light comes on. A switch is used to break the circuit. The black wire is the one usually broken. The wires from the circuit breaker are brought near the switch. The black wire is cut, and either side is connected to the light.

Outlets are wired similar to lights. Normally, the outlet won’t have a switch to break the circuit. Unplugging the appliance will break the circuit and cause the electricity to quit flowing. Most appliances will have switches to control the electricity. The outlet has three connectors. The ones on either side are the hot and neutral, where the third connector (usually a green screw) is for the ground.

Use a proper wire stripper to get the insulation off the wire, not a wire cutter, since that may nick the wire, causing it to break. If the screws are used for connecting the wires to outlets or switches, the wire should be wrapped around the screw the way it is tightened (to the right). If slipping the wires in the “quick-wire” holes, be sure to use the right gauge wire (usually 14 gauge) and stripped to the proper length, according to the gage on the receptacle.

Receptacle connectors may take up to two wires. If more wires are needed near a receptacle, it may be necessary to use wire nuts to join the wires, and then run a single wire from the join, to the receptacle. Wire nuts are also limited to a range of connections. The package will show the limit, typically 3 or 6 or more.

Remodeling a house can sometimes be a challenge. Some houses will have aluminum wiring. It is dangerous to mix aluminum wire with copper receptacles or wire. The  aluminum and copper wire expand and contract at different rates, so when in contact, will rub, even a little bit, making the connection come loose, causing more friction, eventually causing more heat, and risking a fire. There are special wire nuts that allow mixing the wire types, without ripping the existing aluminum wire out of the house.

When adding several light fixtures or outlets are desired, it is smart and safe to start a new circuit. Adding a new circuit breaker to the distribution panel can be done if there is room in the box. Planning the new circuit should be done to insure the proper wire sizing is used. The circuit should have 12 gauge wire for a 20 amp circuit, and can get by with 14 gauge wire for a 15 amp circuit.

Simple concepts when managed can make small wiring projects easily handled by any handy person. Care must be used, to prevent injuries, like almost any project. Careful planning and working with someone experienced will allow quick learning.




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