When you’re connecting a wire to an electrical outlet, it’s vital that you have a ground wire. This prevents the outlet from becoming live and presenting the risk of electrocution when you plug something into the outlet. Ground wires can also help to prevent fire. Connecting a ground wire correctly avoids these pitfalls and helps keep you safe. It’s a skill that most electricians learn at the start of their careers so it is a basic skill, but if you’re doing electrical work yourself, pay attention to the ground wire in a sensible and professional manner.
Step 1 - Which is the Ground?
An electrical cable will contain three wires. One will be black and this is the live wire. The white wire will be neutral and the bare wire is the ground. Both the black and white wires are insulated and you’ll need to strip back the insulated ends to attach them to the terminals. There is usually no insulation on the ground wire. If there is, it will usually be green.
Before doing any electrical work, make sure the circuit on which you’re working is turned off at the breaker. If you’re not certain, turn off the electricity to the entire house before you begin working.
Step 2 - Receptacles and Outlets
Your electrical receptacle attaches to the junction box with screws above and below the outlets. There are also screws on the sides. One side will contain a brass screw and you will need to screw the black wire to this. On the other side, there will be two screws. One will be silver and this is for the white, or neutral, wire. The other screw should be green. You will screw the ground wire to this.
Step 3 - Junction Box
The junction box and receptacle need to be fully connected to the grounding system within the building. If the junction box holding the receptacle is metal instead of plastic, you need to ground the incoming wire to this as well. To do this, you'll need to attach the incoming ground wire to the box's ground screw with the leftover piece going to the receptacle's ground screw. If there’s no ground screw in the junction box, there should be a grounding clip to secure the ground wire to the edge of the metal junction box.
You can’t just connect the ground to the receptacle and believe that the screws connecting the receptacle to the box will make an adequate ground. This is not allowed under the National Electrical Code.
Step 4 - Ground Fault Protection
Under the National Electrical Code, outlets in certain locations that could be hazardous, such as in bathrooms, kitchens, and garages, must be fitted with ground fault circuit interrupters (GFCIs). This way, if a ground fault is detected, special circuitry switches power off at the outlet. You will need to consult the instructions for the GFCI regarding wiring a ground wire to it. This method can also be applied when wiring an electrical point outside of your home.