Electrical 3: Home Wiring Tips

VERY IMPORTANT! Before working on any electrical modifications of your home read the first article in this series: Electrical 1: Electrical Safety.


Lights and plugs (duplex receptacles) circuits are 15 amp # 14 wire and can have up to 12 plugs or lights combined. It is best to combine plugs and lights, then if the circuit blows, some lights are still left on another circuit, so you are not totally in the dark. When connecting lights and plugs, keep them polarized with the black wire going to the brass screw and the white wire connecting to the silver screw. Only one black and white wire per fixture. To carry on to another fixture use a short wire, called a pigtail, to connect back to the circuit wire by using a marrette, or wire nut. Don't connect another wire to the double screw in the plug or light receptacle.

GFCI Rules

All plug outlets within 118" of a tub or shower must be a GFCI (Ground Fault Circuit Interrupter). All plug outlets within 118" of a wash basin must be GFCI. These first two do not apply to the washing machine or dryer plugs installed in a combined washroom, or bath and laundry room. All carport plugs must be GFCI.

All outdoor plugs are GFCI, except for the Christmas lights receptacle, in the soffit, if over 8' above the ground. All outdoor plugs should be on one circuit by themselves up to 12 plugs. Install the GFCI in the first receptacle from the panel, which will protect the entire circuit. Use only a 2 wire cable, a GFCI won't work with a 3 wire cable. Lights only, are not required to be protected by a GFCI.

Kitchen Plugs

Kitchen counter plugs are normally #14 - 3 wire 15 amp, split receptacle and should be within 36" of each other along the same counter. If the counter top is more than 12" wide it needs its own plug. These plugs are on a separate circuit, only 2 per circuit and not adjacent to each other.

A split receptacle is when the brass side of the receptacle is split, removing the tie between the two screws. Just twist it off with pliers. This creates two circuits - a black wire is attached to the one screw and a red to the other. The black and red wires are called the load and are directly attached to two separate breakers in the panel. The white wire is attached, as usual, to the silver screw with the tie left attached.

Notice on the panel the two main vertical bars on which the breakers are attached. Unless you shut off the main breaker, these are hot so don't touch them and hang onto the panel at the same time. Notice that the breakers attach to each of the bars alternatively.

When installing a double breaker for 220 volt or a split receptacle for two circuits, be sure to install the breaker so that the connections of the breaker attaches to alternate bars. Each bar is 110 volts. The black or red wire attaches to the breakers and the white wire attaches to the neutral bar obtaining 110 volts. For 220 volts the red and black are attached to opposite bars through the breaker without a neutral, the ground is attached to the ground or bonding bar.

In a dryer connection you need the red and black wires for the 220 volt element as well as the white for the neutral for 110 volt to run the motor and timers, light, etc. The 110 volt is obtained internally off the terminal block inside the dryer. 20 amp plugs are allowed in the kitchen, but must be wired with #12 wire and have a special 20 amp receptacle, only one 20 amp receptacle per circuit.


Receptacles around a room must be no further than 6' away, along a wall; most lamps, etc. have 6' cords. For these areas, don't count the swing of the door against a wall, windows that extend to the floor, fireplaces, or other permanent installations which limit the use of a wall.

All walls more than 36" need their own plugs. Bedroom plugs must now be protected with an arc-fault type breaker. A normal breaker will only trip with an overload, not a short. This new type will trip with both. Check this out in your area.

Hallways have their own rule, one plug within 15 ft of each other without going through a doorway.


Microwaves require their own circuit if installed in a built in cavity, or microwave shelf. These are 15 amp 14 wire. Otherwise, a counter plug will do.


Fridges should be on there own 15 amp, #14 wire circuit. A clock receptacle is also allowed on this same circuit.

Junction Boxes

No hiding junction boxes, they should always be accessible.

Protective Plates

Nail protective plates over any wire less than 1 1/4 inches from the stud surface.

Hot Tub

A hot tub needs its own circuit, which depends on the size of its motor and heater. Contact your dealer for this. A GFCI breaker is also required. The heater is usually 220 volt, possibly needing 2 circuits, if the motor is 120 volt.

Wire Size

Amperage in relation to wire size. A 15 amp circuit at 120 volts is 1800 watts and requires a #14 wire. A 20 amp circuit at 120 volts is 2400 watts and requires a #12 wire. A 30 amp circuit at 240 volts is 7200 watts and requires a #10 wire and a 40 amp circuit at 240 volts is 9600 watts and requires a #8 wire.

If not absolutely sure of what you are doing while wiring your house, hire an electrician. Don't put your family and property at risk.

Better safe than sorry.


(Ask Dave) (About Dave)

Your source for building tips, woodworking & furniture plans, house plans and building advice directly from Dave...

Hi, I'm Dave Osborne. With over 50 years experience as a journeyman carpenter, foreman and contractor in heavy construction I enjoyed working with apprentices and sharing the tricks of the trade that others shared with me. Now I get emails from Members all over the world and we include many of my answers in our Free Monthly Newsletters. Some of my answers include drawings and instructions specific to a project, but may also answer your questions. I use correct construction terminology, so you can confidently inform your building supply dealers or contractors exactly what you need.


The Benefits of Membership

Membership gives you full access to our hundreds of how-to articles, woodworking plans, converters, calculators and tables. Our Stair Calculator is one of the most popular on the internet. We have projects you can build for (and with) your kids, furniture for your wife, and sheds and gazebos. If you run into a problem or need advice your Membership includes unlimited email questions to me through our Ask Dave quick response button.

Join us!