Recessed Lighting Wiring Instructions

Recessed lighting fixtures make an elegant addition to any room, creating the potential for subdued, indirect lighting with a cozy, comfortable feel.

From a string of pot lights under the eaves around your house to mood lighting in your den, recessed lighting offers a sleek, warm alternative to more exposed fixtures. Here's how to go about installing your own.

Safety Note: Electrical work is dangerous. Don't try it unless you have professional skills.

1 - Planning the Layout

Step 1.1 - Pick Locations

Whatever the objective when you install a “string” of lights overhead, the very first step is to determine which areas are to be illuminated by that specific circuit and how many fixtures will be required with their ideal locations to ensure proper illumination coverage.

Using painter’s tape to temporarily mark the location of each fixture will give you the opportunity to shift some of them while selecting the proper spots, without leaving any unnecessary markings on the ceiling.

Step 1.2 - Choose Fixtures

Shop around and decide on the type of fixtures you want. Knowing the rating and the number of fixtures you plan to install will let you determine the combined maximum power of all the fixtures so that a properly sized breaker and wiring can be decided upon—as halogen and incandescent lights consume much more power than LED lights and can let you downsize from 20 amps to a 15 amps circuit.

Step 1.3 - Plan Switches

You will then decide where the switching needs to originate from—are you going to use an already existing switch or, if it’s to be a new install, how much wire will you need to reach the electric panel and how much more to reach the closest light fixture of the new circuit.

Step 1.4 - Plan Cable Layout

You can marginally reduce the overall cost of the project by avoiding ill-conceived runs if you carefully plan your work beforehand. So this is where you figure out the most effective way to inter-connect all the fixtures together and to a power source or activation switch.

Figure 2 shows how the power is fed from the electric panel to the timer/switch, then to a junction box conveniently added to split the feed to multiple branches of that particular circuit and laid out in different directions.

A) With the 120 Volts Source Coming from the Switch

If the shortest distance brings the switch cable to the fixture at one end of the circuit, the cable from the switch will simply be inserted into its electrical box and hooked up to the fixture itself but also to the line leading (or feeding) the next fixture in the circuit—making sure all the white wires are connected together, all the black wires are together, and the Gnd and green wires pigtailed together and connected to the ground in the junction box (Fig.2).

If the cable from the switch needs to be fed to one of the intermediate fixture’s junction boxes because of its proximity, but where two cables are already inserted, one coming from one end of the circuit, the other from the other end, along with the 3^rd set of wires from the fixture itself, making the cable from the switch provide the 4^th set of wires inside that box, it will make it a bit more crowded but the wiring is still done as described above with every matching wire connected together.

B) With the Live Cable Feeding Directly from the Electric Panel

If the shortest distance or some other complication causes you to feed the cable from the electric panel to one of the fixtures instead of the switch, it will make the wiring connections slightly more complicated and hazardous but possible, providing that both the power cable and the switch cable are routed to the same junction box.

This will add another set of wires into that junction box, where the connections will be as described previously EXCEPT for the Black from the panel and the White from the switch which will be singled out and pigtailed together while making sure that black electrical tape is wrapped around the white wire from the switch to indicate that the wire is in effect another Live line and not Neutral.

Understanding this, you can now measure the length of cable needed to join the switch box to the appropriate fixture. You will also have to measure and add to it the distances between each subsequent light fixture in every branch.

To this total, you can finally add an additional two feet (600 mm) minimum for every cable joining two junction boxes to provide about 8-10 inches (200-250 mm) of slack at each box to make the connections of each fixture and switches in that circuit.

Step 1.5 - Choosing the right cable and breaker

If you were to use of 14-gauge wire to power your circuit, it will require the use of a breaker with a maximum rating of 15-Amps which is therefore the maximum load to be used on that circuit (measured in Watts).

So the number of fixtures that a 14-gauge wire can handle is based on the combined wattage of every fixture in your circuit. Using the basic formula to determine the maximum possible wattage of a circuit: Watts = Volts x Amps.

A 120 volts circuit on 14/2 cables can only allow 1800 Watts of power (15 rated amps) through it. So if you’re planning to install enough lighting to draw more than 15 amps, you’ll need 12/2 cables and a circuit breaker upgrade to 20 amps.

With that information gathered, you can now shop around for the best fixtures for your money, and the right size cables and breaker.

Caution! - If you should add one or several outlets to that particular circuit, the wiring should also be upgraded to 20 amps, since you cannot predict what type of appliance will be plugged into it at any time.

2—The Installation

Step 2.1 - Pick Your Spots

Using a stud-finder, make sure to check around each spot to locate joists and trace out the best location for the fixtures so you don’t inadvertently cut on the framing grid which would block the placement of the fixture’s electrical box.

The recessed light kits normally come with a template that you now place on the spot where the painter’s tape is to trace the opening’s cut out. If you’re installing a new switch box, identify where and mark its location.

Step 2.2 - Cut Access Points

The openings can then be cut out using a rotary tool with a special bit, a keyhole saw, or a utility knife. You will need to drill access holes to pass cables through wall plates and sills, joists, and possibly wall studs.

Step 2.3 - Power Down

Before proceeding further with wiring to an existing switch, make sure that you turn off the power to that switch from the circuit breaker. Measuring between each of the switch’s terminals and ground with a multimeter will tell you if the circuit is still Live.

Step 2.4 - Run the Cords

You can now run the wires across each and every opening following your planned layout, leaving about a foot (300 mm) hanging out for connections later.

If there is an attic overhead, the job should be easier done, where otherwise, some fishing may be required to get the cables across to all the fixture openings and to the switch box.

Step 2.5 - Prep the Wires

Remove about 6 inches (150mm) of the jacket from each cable ends coming out of every fixture opening, exposing the color-coded wires, then remove about 1/2-inch (12mm) of insulation from each insulated wire.

Step 2.6 - Run Into Junction Boxes

For every junction box, remove a knock-out plug for each of the cables coming out of each of the openings, from the same side of the boxes, keeping the wiring together as much as possible to provide a slimline assembly to gain an easier insertion through the openings.

Fig. 3 shows how the cables are inserted into the junction box through knock-outs next to each other to keep them together.

Step 2.7 - Apply Connectors

You can then add the cable connectors to their junction boxes and secure about 8 inches (200 mm) of wire through its respective cable clamp.

Step 2.8 - Insert Boxes

The wires from the recessed fixture can then be added into each respective junction boxes, and the wires connected together as described in Step 1.4. Once complete, add and secure the cover plate on the junction box and insert it through the opening in the ceiling.

Note: If you get fixtures that have a “built-in junction box” (Fig 4). They only provide a very restricted space for the connections, however, and could require the installation of an additional junction box.

Step 2.9 - Fasten

Recessed fixtures usually come with some kind of fastening clips. Refer to the instructions to adjust the clips properly, and insert the fixture inside its opening making sure all is secure and safe.

Step 2.10 - Run the Final Cord

You can finally run the last length of cable to the electric panel if it's going on a dedicated breaker. But before removing the panel’s cover, turn OFF the main breaker for the panel.

You can then put in the new cable through a cable connector, secure the ground wire to the Gnd bus bar, connect the white neutral wire to the neutral bus bar, insert the breaker into place, and secure the black Hotwire to the breaker’s terminal.

Step 2.11 - Reset Power

Once the cover is reinstalled on the panel, you can turn OFF all the breakers and switch them ON starting with the main breaker and following with the rest of the breaker—this will prevent a power surge within the system. With your new breaker switched ON, you can now test your recessed lighting.