Transcript
The hot and neutral wires must be connected to the proper terminals on the electrical receptacle.
The "hot" or "live" black wire (or red wire) should be connected to the brasscolored screw terminal on the electrical receptacle, usually marked BLACK or HOT.
The "neutral" white wire should be connected to the silver-colored screw terminal on the electrical receptacle, usually marked NEUTRAL or WHITE
The above sketch points out that the white wire, i.e. the neutral wire, will be connected through the receptacle's internal parts to the wide slot on the receptacle face in order to assure that the neutral wire side of an appliance being plugged-in there is properly connected.
What Happens When Polarity is Reversed at a Receptacle? Most electrical appliances and devices are designed so that their "on-off" switch interrupts electrical power at the point of entry into the appliance or device circuitry or components. If you switch the hot and neutral wires that may not quite be the case, and parts of the device will remain energized or potentially energized even when the electrical device switch is OFF. No electrical current may flow, but it could flow if
someone touches the wrong part of the device, or damage may be caused in other circumstances as well, as we describe next. Scenario #1: A simple light or floor lamp is less safe with polarity reversed While some devices such as an incandescent electric light may appear to work properly and safely regardless of which way the lamp's plug is inserted into the wall outlet, virtually all modern electrical appliances, even lamps, use polarized plugs. In the case of an electric light, the device will "work" properly in either position. When a lamp or light fixture is connected with proper polarity, the hot wire connects to a contact at the bottom inside center of the bulb socket or screw-in base, and the neutral wire is connected to the shell that contacts the sides of the bulb when it is inserted and screwed into the socket.
But if the lamp is plugged in with its polarity reversed the metal "shell" into which the bulb screws is energized or "hot". Because this component is much easier to touch when changing a light bulb than is the connector in the internal center of the bulb base, a shock hazard is present.
Scenario #2: The toaster You are preparing toast or toasting an english muffin, pop tart, etc. and it gets stuck in your toaster. You look in the toaster and see that the heating elements are off, so you assume it's safe to stick a knife in the toaster to get it out. You should be safe doing this, because the switch that controls the flow of electricity to the heating elements in the toaster shuts off the hot wire. Unfortunately, your toaster is plugged in to an outlet with reversed polarity, so the switch on your toaster is shutting off the neutral wire instead of the hot. This means there is always electricity at the heating elements just waiting for some poor sap to stick a knife in, and that electricity will travel up the knife, through your body, and back to the earth. Breakfast over!
Some appliances and electronic devices may be damaged if polarity is reversed Some appliances and some electronic equipment may be damaged if left connected to a reversed-polarity electrical circuit. A disassembled coffee maker that had burned-up showed that the appliance had been damaged by being left connected to its receptacle with polarity reversed. The presence of live voltage at the "wrong end" of a circuit or circuit board may cause some devices on the board to remain energized even when the device has been "switched off". A result can be overheating or electrical shock hazards.
