shall not be required for submers- ible types of motors.
(B) Open Motors. Open motors that have commutators or collector rings shall be located or protected so that sparks cannot reach adjacent combustible material.
Exception: Installation of these motors on wooden floors or supports shall be permitted.
430.16 Exposure to Dust Accumulations. In locations where dust or flying material collects on or in motors in such quantities as to seriously interfere with the ventilation or cooling of motors and thereby cause dangerous temperatures, suitable types of enclosed motors that do not overheat under the prevailing conditions shall be used.
FPN: Especially severe conditions may require the use of enclosed pipe-ventilated motors, or enclosure in separate dust-tight rooms, properly ventilated from a source of clean air.
430.17 Highest Rated or Smallest Rated Motor. In de- termining compliance with 430.24, 430.53(B), and
430.53(C), the highest rated or smallest rated motor shall be based on the rated full-load current as selected from Table 430.247, Table 430.248, Table 430.249, and Table 430.250.
430.18 Nominal Voltage of Rectifier Systems. The nominal value of the ac voltage being rectified shall be used to determine the voltage of a rectifier derived system.
Exception: The nominal dc voltage of the rectifier shall be used if it exceeds the peak value of the ac voltage being rectified.
II. Motor Circuit Conductors
430.21 General. Part II specifies ampacities of conductors that are capable of carrying the motor current without over heating under the conditions specified.
The provisions of Part II shall not apply to motor cir- cuits rated over 600 volts, nominal.
The provisions of Articles 250, 300, and 310 shall not apply to conductors that form an integral part of equipment, such as motors, motor controllers, motor control centers, or other factory-assembled control equipment.
FPN No. 1: See 300.1(B) and 310.1 for similar requirements.
FPN No. 2: See 110.14(C) and 430.9(B) for equipment device terminal requirements.
FPN No. 3: For over 600 volts, nominal, see Part XI.
430.22 Single Motor.
(A) General. Conductors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125 percent of the motor's full-load current rating as determined by 430.6(A)(1).
Exception: For dc motors operating from a rectified single-phase power supply, the conductors between the field wiring terminals of the rectifier and the motor shall have an ampacity of not less than the following percent of the motor full-load current rating:
(a) Where a rectifier bridge of the single-phase half-wave type is used, 190 percent.
(b) Where a rectifier bridge of the single-phase full-wave type is used, 150 percent.
(B) Multispeed Motor. For a multispeed motor, the selec tion of branch-circuit conductors on the line side of the controller shall be based on the highest of the full-load current ratings shown on the motor nameplate. The selection of branch-circuit conductors between the controller and the motor shall be based on the current rating of the winding(s) that the conductors energize.
(C) Wye-Start, Delta-Run Motor. For a wye-start, delta-run connected motor, the selection of branch- circuit conductors on