- Electrical codes today specify a three-wire, grounded system for all installations. A typical household cable contains three wires--red or black for "hot", which carries the current; white for neutral or common, which completes the circuit; and a bare ground wire, which helps prevent shocks.
- Most household circuits are 115 volts, commonly referred to as 110 circuits. An electrical circuit is formed by wires that carry current to and from a central source. These plug into three-pronged outlets, which consist of two vertical holes (the left one slightly larger) and a round one below and between the other two. Circuits for electric ranges, clothes dryers and some other major appliances are 240 volts, usually referred to as 220 circuits. These use larger three-pronged plugs with different configurations depending on the amperage of the circuit. Amperage is a measurement of the intensity of an electrical circuit, adopted as an international standard in 1803.
- Some 110- and 115-volt circuits use special "ground fault interrupter" (GFCI) outlets. These look like regular three-wire outlets except for a button on the front. These circuits are wired with a type of mini-circuit breaker that detects when there is a problem or ground fault. The circuit breaker trips (pushing the button out) and disconnects power to the circuit. It is an added protection against a short circuit. Most building and electrical codes now require GFCI plugs in new kitchens, bathrooms, crawl spaces, unfinished basements and outdoor receptacles.
- A variation of the three-wire outlet is the 20-amp, 120-volt type used for heavy appliances, including refrigerators, washing machines and microwave ovens. It also has three holes, but the left one is "T" shaped to accommodate a special prong. This provides protection against plugging the appliance into an inappropriate circuit or plugging another device into an inappropriately powerful circuit.
- There are three versions of 240-volt receptacles. A 20-amp version has a "T" slot on the left, a horizontal slot on the right and a round slot below. A 30-amp version has a reverse L-shaped slot at the top and two rectangular slots positioned at angles below. A 50-amp variety has four slots, the top three rectangular, the bottom one with a rounded top. These are protective measures to prevent devices from being plugged into the wrong type of circuit.
- Learn the identifications on outlets. One marked "AL-CU" can be installed with either aluminum or copper wire; one marked CU, or that has a slash through the AL, can only be installed with copper wire. Receptacles also may be labeled residential, commercial, contractor, industrial or spec. These may perform in a similar manner, but those labeled contractor, industrial or spec are usually of higher quality.
- Not all countries use the same electrical standards as the United States. Overseas travelers who wish to use their computers or other electrical devices need to check the standards for the areas they will visit and buy special adapters to use their devices.
next post