buildings [over 11 m (35 ft) high at walls], where conditions of maintenance and supervision ensure that only qualified persons service the systems, conductors tapped to a feeder shall be permitted to be not over 7.5 m (25 ft) long horizontally and not over 30.0 m (100 ft) in total length where all of the following conditions are met:
a. The ampacity of the tap conductors is not less than one-third that of the feeder conductors.
b. The tap conductors terminate with a single circuit breaker or a single set of fuses complying with (1) Part IV, where the load-side conductors are a branch circuit, or (2) Part V, where the load-side conductors are a feeder.
c. The tap conductors are suitably protected from physical damage and are installed in raceways.
d. The tap conductors are continuous from end-to-end and contain no splices.
e. The tap conductors shall be 6 AWG copper or 4
AWG aluminum or larger.
f. The tap conductors shall not penetrate walls, floors, or ceilings.
g. The tap shall not be made less than 9.0 m (30 ft)
from the floor.
430.29 Constant Voltage Direct-Current Motors — Power Resistors. Conductors connecting the motor controller to separately mounted power accelerating and dynamic braking resistors in the armature circuit shall have an ampacity not less than the value calculated from Table 430.29 using motor full-load current. If an armature shunt resistor is used, the power accelerating resistor conductor ampacity shall be calculated using the total of motor full-load current and armature shunt resistor current.
Armature shunt resistor conductors shall have an ampacity of not less than that calculated from Table
430.29 using rated shunt resistor current as full-load current.
Table 430.29 Conductor Rating Factors for Power
Resistors
Time in Seconds Ampacity of
Conductor in
Percent of
On Off Full-Load Current
5 75 35
10 70 45
15 75 55
15 45 65
15 30 75
15 15 85
Continuous Duty 110
III. Motor and Branch-Circuit Overload Protection
430.31 General. Part III specifies overload devices in- tended to protect motors, motor-control apparatus, and motor branch-circuit conductors against excessive heating due to motor overloads and failure to start.
FPN: See the definition of Overload in Article 100.
These provisions shall not be interpreted as requiring overload protection where it might introduce additional or increased hazards, as in the case of fire pumps.
FPN: For protection of fire pump supply conductors, see 695.7.
The provisions of Part III shall not apply to motor cir- cuits rated over 600 volts, nominal.
FPN No. 1: For over 600 volts, nominal, see Part XI. FPN No. 2: See Annex D, Example No. D8.
430.32 Continuous-Duty Motors.
(A) More Than 1 Horsepower. Each motor used in a continuous duty application and rated more than 1 hp shall be protected against overload by one of the means in 430.32(A)(1) through (A)(4).
(1) Separate Overload Device. A separate overload de vice that is responsive to motor current. This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate