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Installation wiring: (section 3.8.1) recommended for single phase [d] recommended for multiphase While light blue is prohibited from use for active function, dark blue is recommended for L3. usually used for "Switched Line" [19] To designate any phase, the below colours are prohibited: [d] [e] (before 1980) (before 1966) Cable identification ...
The National Electrical Code (NEC), or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment in the United States. It is part of the National Fire Code series published by the National Fire Protection Association (NFPA), a private trade association . [ 1 ]
A three-phase motor is more compact and less costly than a single-phase motor of the same voltage class and rating, and single-phase AC motors above 10 hp (7.5 kW) are uncommon. Three-phase motors also vibrate less and hence last longer than single-phase motors of the same power used under the same conditions. [32]
In addition to the current limiting function, the device serves to filter out spikes of current [7] and may also reduce injection of harmonic currents into the power supply. The most common type is designed for three-phase electric power, in which three isolated inductors are each wired in series with one of the three line phases. [8]
The neutral current can be determined by adding the three phase currents together as complex numbers and then converting from rectangular to polar co-ordinates. If the three-phase root mean square (RMS) currents are I L 1 {\displaystyle I_{L1}} , I L 2 {\displaystyle I_{L2}} , and I L 3 {\displaystyle I_{L3}} , the neutral RMS current is:
One voltage cycle of a three-phase system. A polyphase system (the term coined by Silvanus Thompson) is a means of distributing alternating-current (AC) electrical power that utilizes more than one AC phase, which refers to the phase offset value (in degrees) between AC in multiple conducting wires; phases may also refer to the corresponding terminals and conductors, as in color codes.
Marne, David J. McGraw Hill's National Electrical Safety Code (NESC) 2023 Handbook. McGraw-Hill Education. The 2023 NESC Handbook represents a next-generation tool for the professional who needs to understand the NESC. The handbook was developed for use at many levels in the electric and communication industries, including those involved in ...
A three or four-pole isolator or circuit breaker is used for three-phase loads, for devices with both permanent and switched supplies (such as bathroom extractor fans) and also at the distribution board to isolate all the phases. A three-phase installation with a TT earthing system is an example where four-pole devices would be required.