high-voltage direct current gives lower losses over long distances. Color codes Conductors of a three-phase system are usually identified by a color code, to allow for balanced loading and to assure the correct phase rotation for motors. Colors used may adhere to International Standard IEC 60446 (later IEC 60445), older standards or to no standard at all and may vary even within a single installation. For example, in the U.S. and Canada, different color codes are used for grounded (earthed) and ungrounded systems. See also Industrial and multiphase power plugs and sockets International Electrotechnical Exhibition Mathematics of three-phase electric power Rotary phase converter Three-phase AC railway electrification Y-Δ transform Notes References External links AC Power History and Timeline Electric power Electrical engineering Electrical wiring Inventions by Nikola Tesla AC power