When performing household renovations, you are likely to encounter electrical outlets, switches or other fixtures that will either need to be relocated or deactivated. The process of deactivating a connection is known as capping-off, and it can be either on a long-term basis or permanently out-of-service. The main goal of capping-off is to isolate bare electrical wire ends so they don't accidentally make contact with a person, structure, or one another. Accidental contact can be destructive and even deadly; electrocution, fires and damage to electrical systems are all possible outcomes.
That's why you should know how to properly cap-off a bare electrical wire end; it's not difficult, but it requires following accepted procedures that are proven to prevent harm. Below is what you should know:
Tools and materials needed
Electrical tape - spend a few extra dollars to purchase high-quality electrical tape manufactured by a known, reputable company. Many cheap tape brands are prone to lose their adhesive qualities over time and cause wrapped wires to unravel. This can lead to failed connections and endanger both property and life.
Wire nuts - these plastic connectors contain internal wire threads that are designed to twist bare wire ends together. Be sure to match the wire size in your home with the appropriate wire nut; ones that are too small or too large can weaken the connection.
1. Turn off the electrical power at the main circuit breaker panel - before performing electrical work of any kind, including capping-off connections, you must turn off the power to the circuit that contains your fixture. If you are in-doubt, then test the wire ends with an electrical multimeter to check for voltage before proceeding.
2. Clean-up the wire ends - once the power is disconnected, then the next step is to create a neat, clean wire end. This helps prevent any possible short circuits and ensures a stronger connection. To clean-up the wire end, remove old electrical tape, paint and other residue. Rubbing alcohol is excellent for this type of cleaning duty, as it cuts through adhesives and also dries quickly.
If the bare end of the wire is nicked, broken or sharply bent, then you should cut-off the damaged wire and strip away about ¾-inch of insulation before proceeding. This will provide you with a fresh, clean wire end to use.
3. Install the wire nuts - after you have clean working ends, you are ready to place the wire nuts in position. Starting with the black-colored wire, which is the 'hot' connection, slip a wire nut over the bare end until it can't be pushed further down onto the wire. If any bare wire can still be seen protruding beneath the bottom of the wire nut, then remove the wire nut and trim the wire so it is concealed.
Next, cut off about five inches of electrical tape and wrap it tightly around the wire nut first; use a couple of wraps to hold the tape in-place and then wrap the remainder of the tape around the wire itself. Keep the tape pulled tightly throughout the wrapping process.
Once you finish wrapping the black wire, move on to the white wire, the neutral connection, and install a wire nut in the same manner as you did with the hot connection. Finally, install a wire nut on the grounding wire; this is usually a bare copper wire, but you don't need to worry about wrapping the entire wire with tape.
4. Finish the capping-off procedure - after all the wire nuts are in-place and taped securely to the wire ends, the last step is to tie everything together. Bundle the wire nuts together and wrap them with a 12-inch length of electrical tape. Inspect the entire assembly for signs of any exposed wiring and neatly coil the bundle into the fixture's electrical box.
If you need professional assistance, call a residential electrician near you.