NEC Level 4 Practice Test

To determine the total load of the feeder serving the four motors, it’s essential to understand how to convert the horsepower ratings of the motors into amps. The general formula used for this calculation is:

Total Load (in amps) = (Total HP × 746) / (Voltage × Power Factor)

In this case, to find the total horsepower, simply add the ratings of the motors together: 5 hp + 15 hp + 20 hp + 40 hp, which equals 80 hp.

Next, convert this total horsepower into watts by multiplying it by 746 (since one horsepower equals 746 watts):

80 hp × 746 = 59,680 watts.

Next, divide this total wattage by the voltage supply and the power factor to convert it into amps. Assuming a common voltage in industrial setups, such as 480 volts (and if a standard power factor of approximately 0.8 is assumed), the calculation would look like this:

Total Load (in amps) = 59,680 / (480 × 0.8) = 59,680 / 384 = approximately 155.2 amps.

However, the question may not specify the voltage or the power factor, so the answer choice that closest aligns