What size copper conductors are needed to supply a 3-phase, 208-volt, 200-ampere load at a distance of 250 feet with a maximum of 3% voltage drop?

To determine the appropriate size of copper conductors needed to supply a 3-phase, 208-volt, 200-ampere load located 250 feet away, while maintaining a maximum voltage drop of 3%, several steps are considered based on electrical principles.

First, it is important to calculate the allowable voltage drop. For a 208-volt system, 3% translates to:

[

0.03 \times 208 \text{ volts} = 6.24 \text{ volts}

]

So, the conductors must be able to carry the load while ensuring the voltage drop does not exceed 6.24 volts.

Next, we use the formula for calculating voltage drop in a 3-phase system, which is given by:

[

V_d = \frac{ \sqrt{3} \times I \times L \times R }{1000}

]

Where:

• ( V_d ) is the voltage drop,

• ( I ) is the current (200 Amps),

• ( L ) is the one-way length of the conductor (250 feet, but for a round trip, you double it for the formula, giving you 500 feet), and

• (