How to Install a Dimmer Switch for LED Lights

LED dimmer switches are a great way to save on electricity and set the right ambiance for your home. Contrary to popular belief, it is possible to put a dimmer switch on LED lights without the help of a professional. However, you need to familiarize yourself with ways to safely install a dimmer switch to ensure that it adheres to the National Electrical Code requirements.

Here are step-by-step instructions that will help you install a dimmer switch for LED lights in your home.

Step-by-Step Guide

Tools Required:

Before you start, you will need these handy tools:

• 4-in-1 screwdriver
• Non-contact voltage tester
• Electrical tape
• Wire stripper/cutter
• Needle nose pliers

Materials Required:

• Dimmer switch
• Wire connectors

Step 1: Choose a Dimmer

There are many types of dimmer switches in the market to choose from. This includes 3-way dimmers, LED, and CFL dimmer switches. For this project, you will need LED compatible dimmers.

There are 2 common household dimmers: leading-edge dimmers and trailing edge dimmers. Leading-edge dimmers are designed to work with incandescent bulbs while trailing edge dimmers work well with LED bulbs. Trailing edge dimmers have a lower wattage range and can easily read and control LED bulbs.

In addition, a single-pole dimmer is a great choice if you intend to switch the light on and off from one switch. However, if you want the light to be controlled from 2 or more switches, consider buying a three-way dimmer switch.

Step 2: Turn off Power

Before you start to do any repair or installation, make sure that the power of the circuit is turned off. To do this, simply follow these steps:

• Turn off the power to the electrical circuit of the switch. You can turn off the circuit breaker or unscrew the fuse until the light goes off.
• Use a non-contact voltage detector to help you detect the voltage and check if there are any hot wires. We recommend using a non-contact voltage detector because it helps check the voltage and potential hot wires without making any direct contact with the metal conductor.
• Once you have ascertained that the power is off, the next step is to take out the switch’s cover plate and pull the switch away from the box. Use the detector to probe for hot wires inside the electrical box. If it doesn’t light up, you can be certain that the power is off.

Step 3: Figure Out the Minimum Box Size Required

You need to determine the minimum box size that is necessary for the electrical code. This is important because too many wires in a box can increase the risk of short-circuiting, overheating, and even fires. In order to reduce this risk, the National Electrical Code spells out minimum box sizes. Some of the common metal box sizes include (measured in inches):

• 3 x 2 x 2-1/4
• 3 x 2 x 2-1/2
• 3 x 2 x 2-3/4

The volume of steel boxes is usually specified in the electrical code while that of plastic boxes is stamped inside.

To help determine the minimum box size for your electrical code, be sure to add 1 for all ground wires combined, for all clamps combined, and for every neutral and hot wire going to the box. Add 2 for every device including receptacle or switch that is installed in the electrical box.

To get the minimum volume of the box in cubic inches, multiply the figure by 2.25 for 12-gauge wires and 2 for 14-gauge wires. You will know the gauge of the wire by checking the amperage of the fuse or circuit breaker of the electrical service panel. Once you get the figure, compare it with the volume of the box.

It is also important to know that a 15-amp circuit breaker will require a 14-gauge wire while 20-amp circuit breakers will need a 12-gauge wire or heavier.

Step 4: Determine the Box Volume

If you are using a steel box, take measurements of the height, depth, and width to determine its volume and ensure that it’s large enough. This may not be necessary for plastic boxes as the volume is usually stamped inside. Make sure that the box is large enough. If it is too small, you could replace it with a larger model by removing a 16-inch square of plaster or drywall.

Step 5: Test Your Ground

New dimmers typically come with a green grounding wire that is connected to a grounding source. If your house has bare copper ground wires, you need to first test it with the help of a neon voltage tester to verify if it’s connected to a ground before connecting it to a dimmer switch.

If your wiring system uses a metal conduit, you first need to test the metal box to determine if it’s grounded. Use a neon voltage tester for this. If the metal box is grounded, attach a short ground wire to it using a green grounding screw or metal grounding clip. You will then attach it to the dimmer.

However, what if your switch box is not grounded? Mostly, older homes may have switches that are not grounded. Luckily, an article in the National Electric Code provides provision for dimmers to still be installed without a connecting ground wire.

Firstly, such a dimmer is required to have a cover plate that is non-combustible and is made of plastic. You must also make certain that the bare metal parts are not exposed. To test for ground, switch on the power.

After that, position the leads of the voltage tester between the metal box and screw terminal. You will know that the box is grounded when the tester lights.

Step 6: Install the New Dimmer and Grounding Clip

The process of installing a dimmer switch for LED is the same as that of installing a switch. Use a screwdriver to press the metal grounding clip and bare copper wire (6 inches) to the grounded metal box. Cut a little section of the drywall beneath the box so as to provide a way for the clip.

Step 7: Bench and Pinch Wire

Using needle-nose pliers, bend and pinch the wire onto the metal grounding clip.

Step 8: Strip the Wire

Use a wire stripper to strip 3/8 inch of the wire insulation. It is recommended to check the manufacturer’s instruction to avoid stripping off too much of the wire insulation. Similarly, you can watch this video to know how to properly strip a wire.

Step 9: Connect the Wires

If you are using stranded switch wires, ensure that they are protruding about 1/8 of an inch and connect them using plastic connectors. Twist the connectors clockwise to connect the wires. The size of the wire connector you choose will be determined by the number of wires you intend to connect. You may also want to check the package for the manufacturer’s provisions.

On the other hand, if the new dimmer has screw terminals, strip about 3/4 inch of the insulation. Afterward, bend each loop using needle-nose pliers and place them clockwise on the screw terminals and tighten the screws.

After connecting the wires, only the bare or green ground wire should be visible. Otherwise, no other bare or wire filaments should be left noticeable. Besides, it is a good idea to secure the connections with electrical tape.

Step 10: Tuck the Wires

After connecting the wires, carefully and neatly tuck them back to the electrical box. Attach the dimmer to the box with the help of mounting screws provided.

Step 11: Place the Dimmer’s Cover Plate

Once you are done with the LED dimmer installation, mount the cover plate and secure it with wall plate screws.

Step 12: Test the Dimmer Switch

Lastly, turn on the power at the electrical service panel to test the new dimmer switch. You are set to go if the lights turn on. However, if the switch doesn’t work, turn off the power and scout for any incomplete connections. Some of the possible problems and solutions for a dimmer that doesn’t work correctly include:

• Check if the LED bulb is burned out and replace it
• Ensure that the LED bulb you use is dimmable
• The fuse may be burned out or the circuit breaker tripped. To solve this, be sure to reset the breaker

If the lights flicker, here is how to troubleshoot the problem:

• Check for loose wire connections in the switch box
• A poor bad connection can cause the lights to the fixture. To solve this, tighten the bulb in the socket.

Conclusion

Make sure that the LED bulb you use doesn’t have a wattage that is higher than what is specified for the fixture. Basically, most dimmers are designed to accommodate the load of 600 watts. There are also heavy-duty dimmers that can handle 1000 to 1500 watts. You should, therefore, add all the wattage of the LED lights you intend to dim  so you can find the right dimmer for your needs.

Also, if you are not handy enough at installing a LED dimmer switch, it is ideal to hire a professional installer to handle the job safely and correctly.