Page 133 - Pipeline Rules of Thumb Handbook

120 Pipeline Rules of Thumb Handbook

National Electrical Code Tables

Table 430–150 Table 310–16
Full-Load Current* Three-Phase Alternating-Current Ampacities of insulated Conductors Rated 0-2000 Volts,
Motors 60° to 90°C (140° to 194°F) Not More Than Three
Conductors in Raceway or Cable or Earth (Directly
Buried), Based on Ambient Temperature of 30°C (86°F)

* These values of full-load current are for motors running at speeds
usual for belted motors and motors with normal torque characteristics.
Motors built for especially low speeds or high torques may require more
running current, and multispeed motors will have full-load current
varying with speed, in which case the nameplate current rating shall be
used.
† For 90 and 80 percent power factor the above figures shall be multi-
pled by 1.1 and 1.25 respectively.
The voltages listed are rated motor voltages. The currents listed shall
be permitted for system voltage ranges of 110 to 120, 220 to 240, 440
to 480, and 550 to 600 volts.

† Unless otherwise specifically permitted elsewhere in this Code, this
overcurrent protection for conductor types marked with an obelisk (†)
shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and
30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25
amperes for 10 AWG aluminum and copper-clad aluminum after any
correction factors for ambient temperature and number of conductors
have been applied.

Reprinted with permission from NFPA 70-1990, The National Electrical Code®, Copyright © 1988, National Fire Protection Association, Quincy,
MA 02269. This reprinted material is not the complete and official position of the National Fire Protection Association, on the referenced subject
which is represented only by the standard in its entirety.