What is the feeder ampacity for a three-phase, 120/208V subpanel with a connected load of 84,563VA?

To determine the feeder ampacity for a three-phase subpanel, you need to calculate the total current (amps) that will load the feeder. The formula to convert from volt-amperes (VA) to amps in a three-phase system is:

[ \text{Current (I)} = \frac{\text{Total Load (VA)}}{\sqrt{3} \times \text{Voltage (V)}} ]

In this case, the total connected load is 84,563 VA, and the line-to-line voltage for a three-phase 120/208V subpanel is 208V.

Now, using the formula:

[ I = \frac{84,563 \text{ VA}}{\sqrt{3} \times 208 \text{ V}} ]

First, we calculate ( \sqrt{3} ), which is approximately 1.732. Then we calculate the denominator:

[ 1.732 \times 208 \approx 360.256 ]

Now we substitute this back into the equation for I:

[ I = \frac{84,563}{360.256} \approx 234.6 \text{ A} ]

When rounding, this value is typically rounded up to