Adding electric wiring - here is an excellent illustrated guide

Installing outdoor wiring and lighting
 

What do numbers on electrical cable mean?

They refer to the number and types of wire inside the cable. For example, 14-2 means the cable has two 14-gauge wires inside. 12-3 G means the cable has three 12-gauge wires plus a bare ground wire.

How large of a cord should I use when wiring an appliance?

Use cords with 16-gauge wire for appliances pulling less than 15 amps and 12-gauge wire for appliances pulling up to 20 amps.

What do the colors of the plastic insulation mean on wires?

They are designed to indicate their use, but be careful because they are not always hooked correctly. Hot wires, those carrying current at full voltage, are usually black, red or white with black marks. Neutral wires are usually white or gray. Ground wires are usually either green or bare copper.

What does gauge mean?

Wires have size numbers that express their diameter. These are even numbers from 0 to 18, and smaller numbers indicate larger diameters that can carry more power.

I am putting a couple of more outlets in my garage. Can I use 14-gauge wire?

While 14-gauge wire is the minimum for most house wiring, it can only be used for 15-amp circuits. Number 12-gauge wire is recommended for general home use. There is often a chart on boxes of wire that will show you recommended gauges for specific applications.

I am running an underground cable in my lawn. What should I use to connect the wires?

You can use waterproof wire nuts if you do not have a waterproof box.

How is UF electric wire different from regular Romex cable?

If you lay cable underground, it must be UF (underground feed) cable, which has each individual wire insulated and has plastic wound around the insulated wire for weather and sunlight protection. Romex has a paper product around the wires.

What type of wire should I use for a 220-volt outlet?

The best choice is a three-wire cable with a ground. Also, make sure it's rated for the amperage you need.

Which color of wire nut do I need?

Check the package. It will tell you what size and how many wires each color of nut will hold.

Is there a special extension cord for my window air conditioner?

Yes, you need to use a major appliance cord. A regular extension cord doesn't have heavy enough wire to safely conduct the necessary current.

What is the difference between an extension cord rated for outdoor use and a standard one?

The outer coating of the insulation on the outdoor-use cord is weather and sunlight resistant.

What tool should I use to strip the plastic sheathing off wire?

A combination tool has openings that fit different sizes of wire. When a wire is put into the correct one and pulled, it will remove the covering without damaging the wire.

Is there a tool for removing the outer sheathing on cables such as Romex?

A utility knife will work, but an inexpensive cable ripper is designed for the task and will not damage the wires inside.

How do I use a wire nut?

Strip off about 1/2" of insulation from the wires you want to connect. Hold these wires next to each other and twist clockwise. Screw on the wire connector using only your hand strength. Make sure no bare wire is exposed.

I need to run some wire through my wall. Do you have any suggestions?

Instead of trying to feed the wire through, use a fish tape. This tool is a small wire on a reel that is easier to feed through. Once you have fed it through the wall, attach the wire and pull the tape back through.

I think there is a short in a wire running to one of my rooms. Is there some way to test it to find out?

A continuity tester will let you know if there is a short. It is a tool that includes a battery so that it can supply a low-voltage current to devices and wires to see if there is a complete circuit.

I want to run a new wire to install some additional outlets. Do I have to run these wires through the wall?

You can use surface wire channels that allow you to run the wire on the outside of the wall and still maintain an attractive appearance.

What is BX cable?

This is a trade name for an armored cable that wraps the wires in a flexible metal sheathing.

Do you have something I can use to insulate and repair cords and wire with?

You can use heat-shrink tubing. It's designed to fit something half its size in diameter.

Do I need special tape for wiring?

Yes, you should use electrical tape.

Adding New Wiring From a Junction Box

§ New wiring can also be tied into a junction box, unless the wiring in the junction box is already at maximum capacity.

§ Before tying in at a junction box, always trace the cables leading to the box to check the voltage. Be sure you are not connecting a 120-volt outlet to a run of wire providing 240 volts for larger appliances.

§ To tie in new wiring at a junction box, first shut off the current at the service panel.

§ Locate the main supply cable coming into the junction box from the service panel. Locate the supply wire by tracing the white wires. All white wires in the junction box will be attached to the white wire on the supply line.

§ Knock out the unused plug on the junction box and run the new line from the box. Be sure to use a cable clamp to secure the cable to the junction box.