rsd@sei.cmu.edu (Richard S D'Ippolito) (01/18/91)
In article <5884@exodus.Eng.Sun.COM> Michael Bender writes: >In article <1948@umriscc.isc.umr.edu> Rob Fugina writes: >->Ground and neutral are exactly the same thing. If you were to trace the >->wires back to your breaker box, you would find bare wires (ground) and >->white wires (neutral) both connected to a grounding strip. > ^^^^^^^^^^^ Well, they aren't the same. Ground is the wire that connects to the earth, neutral is usually the vector reference of a multiphase (three-phase is most common) ciruit, doesn't always physically exist, and doesn't have to be connected to earth ground when it does. The name has sort of transfered (permanently) by analogy to the (usually grounded) center-tap return of a single-phase three-wire curcuit, and now by analogy to circuits which have no connection to ground at all, although the return for your 240V dryer is another hot connection! What could 'neutral' possibly mean on a single-phase or DC circuit? Fixtures and conduits are grounded for safety in case a hot wire comes in contact with them (the intent is to trip the fault protection device). The ground is actually made at every utility pole transformer, where you will find the wire leading down the pole into the ground. >anyone know why they choose BLACK for the hot wire and WHITE for >neutral? I always associated black wires with ground. Sure. Take a look at very old wiring (especially in the dark) -- what color is dirty insulation? So, if you open a junction box and all of the wires are black and you know that dark colors are not safe, you won't touch any of them without testing first, will you? The electronics industry didn't do anybody any favors. I used to use white for common in the equipment that I built. Remember, the black wire will never fade or soil to white. Rich