hoist, the minimum ampacity of the power supply conductors shall be the name-plate full-load ampere rating of the largest motor or group of motors for any single crane motion, plus 50 percent of the nameplate full-load ampere rating of the next largest motor or group of motors, using that column of Table 610.14(A) that applies to the longest time-rated motor.

(3) Multiple Cranes or Hoists on a Common Conductor

System. For multiple cranes, hoists, or both, supplied by

a common conductor system, calculate the motor minimum ampacity for each crane as defined in
610.14(E), add them together, and multiply the sum by the appropriate demand factor from Table 610.14(E).

(F) Other Loads. Additional loads, such as heating, light ing, and air conditioning, shall be provided for by application of the appropriate sections of this Code.

(G) Nameplate. Each crane, monorail, or hoist shall be provided with a visible nameplate marked with the manufacturer's name, rating in volts, frequency, number of phases, and circuit amperes as calculated in 610.14(E) and (F).

Table 610.14(E) Demand Factors

Number of Demand

Cranes or Hoists Factor

2 0.95

3 0.91

4 0.87

5 0.84

6 0.81

7 0.78

610.15 Common Return. Where a crane or hoist is operated by more than one motor, a common-return conductor of proper ampacity shall be permitted.

III. Contact Conductors

610.21 Installation of Contact Conductors. Contact conductors shall comply with 610.21(A) through (H).

(A) Locating or Guarding Contact Conductors. Runway contact conductors shall be guarded, and bridge contact conductors shall be located or guarded in such a manner that persons cannot inadvertently touch energized current-carrying parts.

(B) Contact Wires. Wires that are used as contact conductors shall be secured at the ends by means of approved strain insulators and shall be mounted on approved insulators so that the extreme limit of displacement of the wire does not bring the latter within less than 38 mm (l'/a in.) from the surface wired over.

(C) Supports Along Runways. Main contact conductors carried along runways shall be supported on insulating supports placed at intervals not exceeding 6.0 m (20 ft) unless otherwise permitted in 610.21(F).

Such conductors shall be separated at not less than
150 mm (6 in.), other than for monorail hoists where a
spacing of not less than 75 mm (3 in.) shall be permitted.
Where necessary, intervals between insulating supports
shall be permitted to be increased up to 12 m (40 ft), the
separation between conductors being increased proportionately.
(D) Supports on Bridges. Bridge wire contact conductors shall be kept at least 65 mm (2Vi in.) apart, and, where the span exceeds 25 m (80 ft), insulating saddles shall be placed at intervals not exceeding 15 m (50 ft).

(E) Supports for Rigid Conductors. Conductors along runways and crane bridges, that are of the rigid type specified in 610.13(B) and not contained within an approved enclosed assembly, shall be carried on insulating supports spaced at intervals of not more than

80 times the vertical dimension of the conductor, but in
no case greater than 4.5 m (15 ft), and spaced apart
sufficiently