Household electric outlets and circuits provide a convenient means to power devices such as lights, computers, televisions and stereo systems. However, each outlet and light fixture must be connected correctly to provide a safe way to power these devices. A fault in either the ground connection or the neutral connection can cause shock or fire hazard that can be fatal.
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Purpose of a Neutral Wire
For electricity to do work, it must flow through a closed circuit. Each circuit in a modern home contains three wires – a hot wire, a neutral wire and a ground wire. The hot wire provides electric current to the outlet or light fixture, then the neutral wire carries that electric current to electric ground, thus completing the circuit.
How a Neutral Wire Differs From a Ground Wire
While a neutral wire and a ground wire are both ultimately connected to electric ground, these wires serve two different purposes. A neutral wire completes the electric circuit by conducting current away from the plugged-in electrical device, while a ground wire is a safety device that carries electric current away from a device only when the circuit or the plugged-in device malfunctions. Many electric devices are wired with a chassis ground, which is connected to the household circuit by means of the round prong on an electrical plug. If the neutral wire suffers a fault or if the plugged-in device experiences a fault, the ground wire is designed to carry electric current away from the device, so that the device won't shock the user.
Faulty Neutral Wiring Dangers and Symptoms
The electric circuits in a building are designed to operate on a balanced system. The power coming from a building’s electric transformer is split into two 120-volt phases. When these phases are combined, the electric service can provide 240 volts of electricity to certain circuits – such as electric dryers and central air conditioners. In other parts of the home, the phases are split; thus, the first 120-volt phase powers the outlets and light fixtures on one side of the home, and the second 120-volt phase powers the outlets and fixtures on the other side.
If a neutral wire is not properly connected to an outlet or light fixture, the wire can become damaged due to heat stress and undergo a mechanical failure. If a neutral wire has become completely damaged, the outlet or light fixture will malfunction and might be unintentionally energized with the full 240-volt potential that the electrical service provides. This can damage or destroy electrical devices, outlets and fixtures and might pose a shock or fire hazard.
Faulty Ground Wiring Dangers and Symptoms
A faulty ground wire deprives the electric circuit of a critical safety device. If a damaged electric device is plugged into an outlet with a faulty ground wire, a potential for electric shock or fire exists. If the chassis on a damaged electrical device were to become energized, a person who touches the frame or any metal parts on the device and a grounded surface will become the sole path for electric current. This situation can pose a fire danger, as well as the possibility of fatal electric shock.