A great many electrical problems around the house are traced to different versions of the same essential problem: wire connections that are made improperly or that have loosened over time. You may have inherited the problem from a previous owner or from an electrician who did an inadequate job, or perhaps it's the result of work you did yourself. Many wire connection problems are no one's fault but are simply the result of time. Wires are under a constant cycle of heating and cooling, expansion and contraction. Every time a switch is used or appliances are plugged in, and the natural result of all this usage is that wire connections can loosen over time.
Your electrical system has a lot of safeguards against danger from bad wire connections, such as its grounding system, its circuit breakers, and GFCI and AFCI protection. Still, there is danger from sparking and arcing whenever there is a loose wire connection in your system. Many of these problems are quite easy for a homeowner to spot and repair, while others are best handled by a professional electrician. Understanding where these problems commonly occur will help you decide how to handle them.
Tools and Materials
Here are six very common places that wire connection problems occur.
Loose Wire Connections at Switches and Outlets
By far the most common problem is when screw terminal connections at wall switches and outlets become loose. Because these fixtures get the most use within an electrical system, these are the places to look first if you suspect wire connection problems.
Loose wire connections at a switch, outlet, or light fixture are often signaled by a buzzing or crackling sound or by a light fixture that flickers.
To address this problem, it involves first turning off the power to the suspected wall switch, light fixture, or outlet. With the power shut off, you can remove the cover plate and use a flashlight to carefully examine the screw terminals inside where the wires are connected. If you find any that are loose, carefully tighten the screw terminals down onto the wires. In all likelihood, this will fix the problem.
Sometimes, you may find that the wire connections are made via push-in fittings on the back of the switch or outlet. This method of connection is notorious for being prone to failure—so much so that most professional electricians don't use the push-in fittings at all, but instead make all wire connections with the screw terminal connections on the sides of the switch or outlet. If you find that your device is made with the push-in fittings, you might want to remove them and reconnect the wires to the screw terminals on the device.
Finally, if there are pass-through wire connections inside the box that are made with wire nuts or another type of connector, check these to make sure the wires are tightly joined together. A loose connector is also a common source of problems.
Wire Connections Made With Electrical Tape
A classic wire connection error is when wires are joined together with electrical tape rather than a wire nut or other sanctioned connector.
To fix the problem, first, turn off the power to the circuit. Then, remove the electrical tape from the wires and clean them. Make sure there is the proper amount of exposed wire showing (for most connectors, this means about 3/4 inch), then join the wires together with a wire nut or other approved connector (there are now push-in connectors that some pros like to use).
If the wire ends are damaged, you can cut off the ends of the wires and strip off about 3/4 inch of insulation to make a proper wire nut connection.
Two or More Wires Under One Screw Terminal
Another common wire connection problem is when you find two or more wires held under a single screw terminal on a switch or outlet. This is a clear sign of amateur work and a distinct fire hazard. It is allowable to have a single wire under each of the two screw terminals on the side of an outlet or switch, but it is a code violation to have two wires wedged under a single screw. This is most often seen when two bare copper grounding wires are found under the grounding screw on the outlet or switch, but you also may occasionally find hot wires or neutral wires connected to a single screw terminal.
To fix this problem, once again, this repair involves first shutting off the power. Then, the two offending wires are removed from their screw terminal. Cut a 6-inch pigtail wire of the same color as the two wires (use a green pigtail if you are joining two bare copper grounding wires). Strip 3/4 inch of insulation from each end of the pigtail, then join one end to the two wires you just disconnected, using a wire connector (wire nut). Now, attach the free end of the pigtail wire to the screw terminal that once held the two wires.
You have essentially created a bridge, or pathway, that connects both wires to the desired screw terminal on the outlet or switch.
Note: Make sure the pigtail wire is the same wire gauge as the circuit wires. A 15-amp circuit normally uses 14-gauge wire; a 20-amp circuit uses 12-gauge wire.
It is quite common, especially with amateur electrical work, to see a screw terminal connection or wire nut connection where it has too much (or too little) exposed copper wire showing at the wires. With screw terminal connections, there should be enough bare copper wire stripped to wrap entirely around the screw terminal but not so much that excess bare copper wire extends out from the screw. The excess exposed wire can short out if it touches a metal box or other wires. Wires should be wrapped clockwise around the screw terminals; if they are reversed, they can be prone to loosening.
With wire nut connections, all of the bare copper wire should be hidden under the plastic cap, with no exposed wire showing at the bottom of the wire nut.
To fix the problem, turn off the power to the device, then disconnect the wires and either clip off the excess wire or strip off additional insulation so the proper amount of wire is exposed. Then, reconnect the wires to their screw terminal or wire nut. Tug lightly on the wires to make sure they are securely connected.
Loose Connections on Circuit Breaker Terminals
A less common problem is when the hot wires on circuit breakers in the main service panel are not tightly connected to the breaker. When this happens, you may notice lights flickering or service problems on fixtures all along the circuit. When making connections to circuit breakers, be sure to strip the proper amount of wire insulation from the wire and make sure that only the bare wire is placed under the terminal slot before tightening. Insulation under the connection slot is a code violation.
To fix the problem, repairs at the main service panel should be handled by a professional electrician. Amateurs should attempt these repairs only if they are quite experienced and knowledgeable about electrical systems.
The electrician will address this problem by turning off the breaker then unclipping it from the hot bus bar in the main service panel. He or she will check the hot wire connected to the breaker to make sure that the screw is tight and that there is no insulation under the terminal and no excess bare copper wire exposed. With repair complete, the electrician will snap the breaker back into place on the hot bus bar and turn the breaker back on.
Faulty Neutral Wire Connections at Circuit Breaker Panels
Another less common problem—and another that is usually handled by a pro—is when the white circuit wire is not correctly mounted to the neutral bus bar in the main service panel. Symptoms here will be similar to those with a faulty hot wire.
To fix this problem, the electrician will check to make sure the neutral wire is sufficiently stripped and correctly attached to the neutral bus bar.