From American Electricians' Handbook, Fourteenth Edition

MOTOR CIRCUITS

370. National Electrical Code rules definitely specify certain requirements with respect to the size and location of the component parts of motor branch circuits. The following tables and rules are in accordance with the 2002 edition of the Code. Certain cities have adopted motor wiring tables and rules which may be more exacting than those required by the Code. In such communities these local requirements should be followed in preference to the tables presented herein.

Section 370 through 395 are the rules for conventional motors and motor circuits. Sections 396 through 404 are the rules for air-conditioning and refrigerating equipment which includes a hermetic refrigerant motor-compressor. See Sec. 396.

In the following sections the terminology of the National Electrical Code with respect to within sight is adhered to. A distance of more than 15 m (50 ft) is considered equivalent to being out of sight, even though there may be no obstructions between the two points. several motors but no other equipment except that directly associated with the motors, and (3) a branch circuit supplying one or more motors, lamps, receptacles, and/or electric heaters, etc. (combination load).

Full-Load Motor Currents. According to the National Electrical Code, whenever the current rating of a motor is used to determine the ampacity (current-carrying capacity) of conductors or the ampere ratings of switches, branch-circuit overcurrent devices, etc., the values given in Tables 7 to 10 of Div. 12, including footnotes, should be used in...

Copyright The McGraw-Hill Companies, Inc. 2002 under license agreement with Books24x7

Products & Services
Motor Contactors
Motor contactors are relays with large current capacity for connecting and disconnecting a motor from the power supply. Typically, motor contractors are multi-pole for control of all current carrying conductors.
Stepper Motor Drives
Stepper motor drives power unipolar and bipolar stepper motors in full step, half step, and microstep motion control applications.
AC Motors
AC motors include single, multiphase, universal, induction, synchronous, and gear motors. They also include servomotors.  

Topics of Interest

CONTROL CIRCUITS 393. Electric control circuits constitute a broad subject, and the reader is urged to refer to special books devoted to this important phase of motor circuitry. Two such books are...

Table No. Table Title 1 Standard Sizes of Lamps for General Illumination, in Watts 12.3 2 to 6 Demand Factors and Data for Determining Minimum Loads 12.4 7 to 10 Full-Load Currents of Motors 12.10...

The shaft of a stepper motor moves between discrete rotary positions typically separated by a few degrees. Because of this precise position controllability, stepper motors are excellent for...

Overview This chapter focuses on the wiring and devices used in residential and office branch circuits. It starts by reviewing the National Electrical Code (NEC 2002) branch circuit requirements and...

National Electrical Contractors Association, Inc. Washington, D.C. GLOSSARY Frequently used terms are defined here. More complete definitions are available in the latest edition of the National...