Interrupter Can Prevent Electric Shock

Electricity and water are a dangerous combination.

To guard against a potentially serious shock, you can substitute ground-fault interrupter receptacles for standard receptacles in any area, such as a bathroom, where water might come in contact with an electrical outlet or appliance.

A ground fault is the technical name for a leakage of current. It occurs when a loose hot wire comes in contact with, say, a metal switch box or the metal housing of a grounded power tool.

Unlike the large surge of current produced by a short circuit, the misdirected current in a ground fault may not be enough to shut down a circuit, but can give you a bad shock. If you are standing in water, the shock can be fatal.

A ground-fault interrupter, or GFI, is a highly sensitive device that monitors the current flowing through a circuit’s hot and neutral wires. In normal operation, the current is the same in both wires.

But even a slight imbalance causes the GFI to cut power to the protected receptacle within a fraction of a second, well before the current flow can shock.

A GFI is so sensitive it can detect a difference of 0.005 ampere--slightly above the threshold of sensation.

A GFI not only protects against shocks, but also senses ground faults in three-wire grounded appliances and shuts down the power even though there is no direct threat of shock to the user.

Nearly all local electrical codes now require that receptacles in bathrooms and sometimes other parts of newly constructed homes be equipped with GFIs. Besides bathrooms, the places where it makes sense to install GFIs are kitchens, garages, workshops and outdoor areas.

Three types of GFIs are available:

A GFI receptacle is the most common type. It is installed in an electrical outlet box as a replacement for a standard receptacle. Depending on how it is wired, a GFI receptacle can protect all receptacles farther along on the same circuit.

A portable GFI is an adapter that plugs into a three-slot receptacle and protects anything that you plug into it. Some portable GFIs are in the form of multi-outlet strips.

A GFI breaker is a combination GFI and circuit breaker that is installed in your home’s central service panel by an electrician. It protects all the receptacles on the circuit.

Caution: Before working on a receptacle, turn off the power to its circuit. Then test the receptacle with a lamp that you know is working to be sure the power is really off.

Installing a GFI receptacle is no more difficult than installing standard receptacles.

The GFI screw terminals or wires marked “Line” are connected to the black and white feed cable wires that bring current into the box. The GFI screw terminals or wires marked “Load” are connected to the black and white cable wires going to other receptacles on the same circuit. Follow package directions or have an electrician install it.

The GFI has two buttons. One is a test button that simulates a current leak when pushed. If the GFI is working properly, the other, reset button will pop out. Push the reset button in to reset the GFI.

If the reset button doesn’t pop out when you push the test button, or if a test lamp lights when the reset button is out, turn off the power to the circuit and call an electrician.