Series H:
Determining Amperage
Determining Amperage: - The national electric code suggests the following when determining motor amperage
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.
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