At 09:20 AM 2/7/02 +1100, Sean Alcorn - Avion Sydney wrote: >As an Australian and too young to remember anything OTHER than a 3-wire MEN >system, I am curious about the US 3-wire system. Is the White leg >(equivalent to what we term a neutral, I assume) connected to Earth at some >point in the building's electrical system or is it floating? > >ie; in a new building with 3-wire outlets throughout, is the white neutral >leg tied to earth back at the distribution board? Yep - in 2 places (redundant): inside the meter box (usually on the outside of the building) and inside the main disconnect (usually part of the main breaker panel). The meter box earth - neutral connection is accomplished by stripping the insulation from the neutral conductor and clamping under a robust ground clamp. The main disconnect accomplishes the same thing by having a screw connect the neutral bar to the case. The neat thing about the meter box neutral ground is that you don't cut the neutral in order to ground it; in fact, the neutral must be a continuous (no splices) conductor from the service connection to the disconnect. The bonding screw inside the disconnect is removable for those cases where the panel is used as a sub-panel being fed the main panel but must NOT be removed if the panel is in fact the main panel. >Also is the colour coding still Black, White and Green? The Green/Yellow >combination is not used? I'm now starting to see green / yellow wire instead of solid green in modern line cords. In addition, when we build and wire racks to be used in industrial plants, we are allowed to use green / yellow in place of solid green. I assume (but don't know for a fact) that at some point all ground conductors with insulation will be green / yellow. dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads