Question

A store has 15,300 VA in non continuous loads and 18,500 in continuous loads is 240 volts, single phase. What's the feeder size for the size for the service using 75 degree wires?

Answer 1

The feeder size for the service should be at least 81.49A to accommodate the total load of the store.

Step-by-step explanation:

To determine the feeder size for the service, we need to calculate the total load for the non-continuous and continuous loads separately and then add them together. First, let's convert the VA (volt-ampere) values to watts. Since power (in watts) is equal to the volt-ampere (VA) value multiplied by the power factor, we can assume a power factor of 1 for simplicity in this case.

For the non-continuous loads: 15,300 VA = 15,300 W

For the continuous loads: 18,500 VA = 18,500 W

Adding the two loads together: 15,300 W + 18,500 W = 33,800 W

Now, to find the feeder size, we need to divide the total load by the voltage (240 V) and the current capacity (75A for 75 degree wires). Using Ohm's law, I = P / (V x √3), where I is the current, P is the power, V is the voltage, and √3 is the square root of 3 (approx. 1.732), we can calculate:

I = 33,800 W / (240 V x 1.732) = 81.49 A

Since the current capacity for the 75 degree wires is 75A, the feeder size for the service should be at least 81.49A to accommodate the total load.