Power Up Your Future: Master Electrician Practice Exam 2025 – Shockingly Good Prep!

To determine the approximate voltage drop for a 90 ampere, 240-volt load located 225 feet from a panelboard using 3 AWG copper conductors, one must use the formula for voltage drop in an electrical conductor:

Voltage Drop (V) = 2 × Length (L) × Current (I) × Resistance per unit length (R)

The resistance per unit length for 3 AWG copper wire is approximately 0.00328 ohms per foot. Given that the circuit is 225 feet long, the calculation for voltage drop would be as follows:

1. Calculate the total length of the circuit: since voltage drop occurs over both the outgoing and return paths, the total length is 2 × 225 feet = 450 feet.

2. Apply the values into the voltage drop formula:

- Length = 450 feet

- Current = 90 amperes

- Resistance = 0.00328 ohms/foot

Thus, the voltage drop can be calculated as:

Voltage Drop = 2 × 225 × 90 × 0.00328 = approximately 10.5 volts.

This value closely aligns with the choice of 10 volts, acknowledging potential variations due to rounding