REPLACING 2 PRONG RECEPTACLES
Old fashioned two prong receptacles connected to two-wire cables don’t have the ground wires that protect people and electrical devices in case of a fault. Luckily, it is possible to convert these receptacles to three prong or GFCI receptacles using the same outlet box without any re-wiring, as long as the box itself is grounded. A ground fault occurs whenever electricity escapes the confines of the wiring in an appliance, light fixture, or power tool and takes a shortcut to the ground. When that shortcut is through a human, the results can be deadly. About 200 people in the USA die each year from ground faults which accounts for 2/3 of all electrocutions occurring in our homes.
The Ground Fault Circuit Interrupter (GFCI) was invented by Charles Dalziel in 1961. Without doubt, this is one of our greatest safety inventions. The GFCI will shut off the flow of electricity any time the flow of electricity exceeds 5 milliamps. This generally occurs within .025 seconds.
GFCI’s are required by the National Electrical Code in all new kitchens, bathrooms, crawl spaces, basements, garages and outdoor receptacles. The great thing about GFCI’s is they can protect you whether or not your wiring is grounded. However, you should note the GFCI receptacle will not protect electronic devices such as computers on an ungrounded circuit.
Metal boxes attached to armored, or BX, cable – a type of wiring commonly found in old houses – generally are grounded. The cable’s flexible metal jacket serves the same purpose as a dedicated ground wire.
To switch out your receptacles, follow these simple steps:
1. Check for ground. Insert one prong of a circuit tester into the receptacle’s hot slot (the shorter slot) and touch the other to a screw that secures the cover plate. The tester should light up. If it does not, the box is not grounded. You can install a GFCI or call an electrician to fix the wiring.
2. Remove the old receptacle. Turn off the power at the breaker panel or fuse box. Unscrew the old receptacle from the box and detach the wires.
3. Connect the new receptacle. Attach the black (hot) wire to the brass terminal and the white (neutral) wire to the silver. On a GFCI, use the terminals in line with the “line” label on the back of the receptacle. (If your box is not grounded, skip to Step 6).
4. Fasten the ground screw. This green screw, sold in hardware stores, fits in a threaded hole in the back of the box. Hook one end of an 8-inch green grounding wire or pigtail (also available at hardware stores) to the screw and tighten it.
5. Ground the receptacle. Secure the other end of the 8-inch grounding pigtail to the green grounding terminal on the 3-prong or GFCI receptacle. Insert the receptacle into the box.
6. Turn on the power. Use a circuit tester to make sure the circuit is working properly.
Although this procedure is relatively easy to follow, if you have no experience with electricity, please consider hiring an electrician. The actual cost for professional assistance is low – around $25.00 to $30.00 per outlet.