- Multiply this figure by 2 for 14-gauge wire and 2.25 for 12-gauge wire to get the minimum box volume in cubic inches. Plastic boxes have the volume stamped inside. Once you’ve selected a power source, choose the easiest path for a 12-in. Deep trench for the new cable.
- In home run light switch wiring, each outgoing hot wire must be connected to the load terminal of the switch. The best way to do this is to make a pigtail, which means to twist all the black wires going to fixtures together with a 6-inch length of spare black wire.
If necessary, use wire strippers to remove the insulation from the light fixture’s electric wires. Wrap the copper or silver ground wires from the light fixture around the ground screw. Then, connect it to the supply ground wire of the junction box with a wire connector. Connect the black or red current wires and the white neutral wires.
Photo: Kit Stansley
Since my current residence is only half finished, there are a lot of fixture-less light boxes in the ceilings—which means I am tripping over tools in the middle of the night more often than I care to admit.
Electrical DIY projects are not a favorite of mine; probably a result of being shocked as a child by the current from a cut phone line (or perhaps the innate fear of sudden death by electrocution). But for simple electrical work around the house, a little knowledge and the right tools can make the work slightly less intimidating and—more importantly—less shocking.
Before You Begin
Here are a couple of things you should know about electricity and residential wiring before you get started.
- All electric power is fed through the meter to your breaker panel. If you shut something off at the panel there is no power to the wires or boxes in the house.
- Shutting something off at the switch does not necessarily mean that there is no power to the wires in the electrical box.
- When looking at wires, black or red is the current, white is neutral, and green or copper is ground.
- Don’t stick a bobby pin into an electrical outlet, even if your cousin dares you to.
How to Install a Light Fixture
Step 1: Shut off power
For some fixtures you can simply shut the power off at the switch, but I recommend always shutting power off at the breaker. If you’re lucky, the breakers on your electrical panel will be labeled. If not it’s a bit of a guessing game, shutting off breakers and then using the voltage detector to make sure the area you’re going to be working in isn’t “hot.” (The voltage detector will beep and light up when a current is present.) I always power down my computer before randomly flipping off breakers … just in case.
Step 2: Connect wires
A standard box for a light fixture will have three wires, a white (neutral), black (current), and copper (ground.)
Photo: Kit Stansley
How To Install A Floodlight
A permanent fixture may have a plate that will be connected to the two screw holes on either side of the box, and I find it’s easier to have that done before connecting the wires (particularly on a heavy fixture that will need to be supported while wires are being connected.)
Wires may be connected to the fixture in different ways. In this case, the wires are wrapped around screws to make a connection. There may also be wires (of corresponding colors) in the fixture that would be connected to the ceiling wires with wire nuts.
In either case, use the wire stripper to remove 3/4″ of wire sheathing. To attach to screw connections, bend the wire into a U-shape, wrap around the screw, then crimp the wire closed and tighten the screw. (White wire to silver screw, black wire to gold screw, ground to green screw.)
Photo: Kit Stansley
To attach wires to wires, twist like-colored wires together and then twist a wire nut over them.
Step 3: Attach fixture to box
This simple pull-chain fixture was attached with two screws that go directly into the box, but you may also have just one screw directly on to the mounting plate. Once the fixture is mounted, install a light bulb, turn the breaker back on, and let there be light.
Photo: Kit Stansley
By code, the number of conductors allowed in a box are limited depending on box size and wire gauge. Calculate total conductors allowed in a box before adding new wiring, etc. Check local regulations for restrictions and permit requirements before beginning electrical work. The user of this information is responsible for following all applicable regulations and best practices when performing electrical work. If the user is unable to perform electrical work themselves, a qualified electrician should be consulted. How to Read These Diagrams
This page contains wiring diagrams for adding a new light fixture to an existing circuit. There are diagrams for adding lights to a ceiling fixture you already have and for using an existing wall outlet as the source for a new switch and light. Different wiring arrangements are included to allow for either the light or the switch to come first in the circuit. Also, find a diagram for adding a light from a switched receptacle you already have to include the fixture when you turn on the room light.
How To Wire A Floodlight To An Extension Cord
Wiring a New Switch and Light from an Outlet
In this diagram power is taken from an existing wall outlet for a new switch and light fixture. The switch comes first in the new part of the circuit and new 2-wire cable is run to it from the outlet. From the switch, new 2-wire cable is run to the new light location.
The neutral for the new light is taken from the receptacle and spliced to the new white wire and to a pigtail that connects back to the receptacle. Likewise, the source hot is removed from the receptacle and spliced to the new black wire and a pigtail connecting back to the hot terminal on the outlet.
How To Wire A Floodlight To An Existing Switch
At the switch, the black wire from the outlet is connected to one terminal on the switch and the black wire running to the new light is connected to the other. The white wire from the receptacle is spliced to the white wire going to the light, it doesn't connect to the switch in this diagram. At the light, the black wire connects to the hot terminal on the fixture and the white connects to the neutral terminal.