Series C: Voltage Drop Calculation
As most motors are designed to operate with a 5% voltage drop, divide volts lost by line voltage to determine if a larger
conductor or additional feed points are required.
Determining Amperage:  The national electric code suggests loads:
 For one motor, use 100% of motor nameplate full load ampere rating.
 For multiple motors on a single crane or hoist, the minimum circuit ampacity of the power supply conductors on a crane or
hoist shall be the nameplate full load ampere rating of the largest motor or group of motors for any single crane motion, plus
50% of the nameplate full load ampere rating of the next largest motor or group of motors.
 For multiple cranes and/or hoists supplied by a common conductor system, compute the motor minimum ampacity for each crane
as in step (2), add them together and multiply the sum by the demand factor from the following table:
Number of cranes 
2 
3 
4 
5 
6 
7 
Demand factor 
.95 
.91 
.87 
.84 
>.81 
.78 
 For constant loads such as magnets, lights and air conditioners, etc., plus high duty cycles, use full load amperage, in
selecting conductor size.
