jeh@cmkrnl.uucp (05/15/91)
*** WARNING TO U.S. READERS: FOLLOWING THE ADVICE IN THE BELOW-QUOTED *** ARTICLE COULD VERY WELL GET YOU KILLED. In article <2953@odin.cs.hw.ac.uk>, adrian@cs.hw.ac.uk (Adrian Hurt) writes: > 2. If you see blue, it's almost certainly neutral. AARRGGHH! Never heard of U.S. practice for three-phase, have you??? > [...] > 4. What the black wire does, depends on what other colours are present. If > there's a white or grey wire present, then black is live, and white is > neutral. If there are two wires (black and red) or three wires (black, red > and green) then black is neutral. If there are three wires (black, red and > white) then black is live, white is neutral and red is earth! AARRGGHH!!!! NO! NO! NO!!!! Never heard of U.S. practice for 240V outlets in residential three-wire service, have you??? > [...] > > Adrian Hurt | JANET: adrian@uk.ac.hw.cs > UUCP: ..!ukc!cs.hw.ac.uk!adrian | ARPA: adrian@cs.hw.ac.uk I don't know about the very latest revisions to the code, since I don't work in the field. But I've looked over enough trained shoulders to know that, at least in recent years... In standard (three-wire) residential wiring where both 120-volt legs are present in the same outlet box (e.g. a 240V socket for a clothes dryer), black and red are the two hot legs (240V between them, 120V from either to neutral), and white is neutral and green is ground as usual in the rest of the house. A black-red-white-green run may also be used for the link between a pair of three-way switches, with black and red being the two "switched hot" leads. So much for note 4. Black is NEVER neutral and red is NEVER earth in the u.s. And in three-phase wiring, the three hot leads are red, blue, and black; again, white (if present, ie in wye systems as opposed to delta) is neutral, and green is ground. So much for note 2. Either what I've just said is correct, or about a dozen different electricians on a dozen different job sites, PLUS the folks who did the original wiring at all of those sites, were wrong, and furthermore were all wrong in the same way. My advice: If you need to rely on an article in sci.electronics to tell you this stuff, stay the hell out of those outlet boxes. No, don't trust your life to THIS article either. Hire an electrician to do your wiring for you. I'm not kidding. 120VAC can kill you, especially if it shows up where you don't think it will be. The electrician might "not know anything about electricity", from the perspective of an electronics student, but otoh if a mistake is made it won't be on YOUR head. (Looking over the electrician's shoulder and asking polite questions in order to understand what's going on, especially if you see something that doesn't seem to make sense, is of course perfectly reasonable.) And, please, those of you who don't know what you're talking about: PLEASE stop posting misinformation that can cause fires or get people killed. --- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA Chair, VMS Internals Working Group, U.S. DECUS VAX Systems SIG Internet: jeh@dcs.simpact.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com Uucp: ...{crash,scubed,decwrl}!simpact!cmkrnl!jeh