A single-phase, 208-volt load drawing 14 amps with 12 AWG copper conductors cannot exceed what circuit length to limit the voltage drop to 3%?

To determine the maximum circuit length for a single-phase 208-volt load drawing 14 amps that limits voltage drop to 3%, it's important to understand how voltage drop is calculated and how conductor size affects it.

Voltage drop can be calculated using the formula:

[ \text{Voltage Drop} = \frac{2 \times \text{Length} \times \text{Current} \times \text{Resistivity}}{1000} ]

where:

• Length is the one-way length of the conductor,

• Current is in amps,

• Resistivity is based on the type of conductor (copper in this case).

For 12 AWG copper wire, the resistance is approximately 1.93 ohms per 1000 feet. To find the maximum allowable voltage drop, you multiply the total circuit voltage by the allowable percentage:

[ \text{Maximum Allowable Voltage Drop} = 208 \times 0.03 = 6.24 \text{ volts} ]

Using the above formulas, this allows you to calculate the length beyond which the voltage drop exceeds 6.24 volts:

Starting with:

[ 6.24 = \frac{2 \times \text{Length} \