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Old 08-13-02, 02:36 AM
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nelsonj
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dumb question

what are the disignations of the red / black / and white wires in and electrical system
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Old 08-13-02, 06:38 AM
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Red and black are both hot (officially "ungrounded conductors"). White is normally neutral ("grounded conductor"), but can be used as hot when remarked in a switch loop or in a 240-volt circuit.

Within these guidelines, the electrician can do anything he wants. Therefore, you cannot draw any reliable information from whether a wire is red or black, since they both follow the same rules.

Having said that, there are conventions that many electricians follow that can give you hints at the purpose of a wire, based on color. Red wires are often used for switched hots when the black is unswitched hot. Red wires are also often used as travellers between 3-way switches. In 240-volt circuits that use separate neutral and grounding, red wires are almost always one of the two hot legs. But none of this information can be relied on without further investigation, since it may not be that way. Code allows you to use a red wire for any purpose that a black wire can be used for.

Note that in areas that use NM cable, red and black are the only two typical choices for hot wires. This means that an electrician must reuse these colors for many purposes. But in areas that use conduit, most of the colors of the rainbow are available (except green white and grey) for any ungrounded conductor you want. If you're lucky, your electrician used lots of colors which makes it easier to follow the wires.
 

Last edited by John Nelson; 08-13-02 at 06:54 AM.
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