If a 215-ampere load is supplied by a single-phase, 460-volt branch circuit, what is the voltage drop using 4/0 AWG THWN copper uncoated conductors?

If a 215-ampere load is supplied by a single-phase, 460-volt branch circuit, what is the voltage drop using 4/0 AWG THWN copper uncoated conductors?

• A. 2.5 V
• B. 3.085 V
• C. 3.5 V
• D. 4.1 V

Answer: (B)

To find the voltage drop across a conductor, you can use the formula: \[ \text{Voltage Drop} = \frac{2 \times I \times L \times R}{1000} \] where: - \( I \) is the current in amperes, - \( L \) is the one-way distance in feet, - \( R \) is the resistance in ohms per 1000 feet of the conductor. For 4/0 AWG copper THWN conductors, the resistance is typically around 0.0001 ohms per foot. Assuming a typical length of the circuit, let's say 100 feet for this example: 1. Calculate the total resistance for a one-way distance of 100 feet: \[ R_{\text{total}} = \text{Resistance per foot} \times L = 0.0001 \, \Omega/\text{ft} \times 100 \, \text{ft} = 0.01 \, \Omega \] 2. Now, using the formula for voltage drop with \( I = 215 \, A \) and \( R = 0.01 \, \Omega \):

To find the voltage drop across a conductor, you can use the formula:

[

\text{Voltage Drop} = \frac{2 \times I \times L \times R}{1000}

]

where:

• ( I ) is the current in amperes,

• ( L ) is the one-way distance in feet,

• ( R ) is the resistance in ohms per 1000 feet of the conductor.

For 4/0 AWG copper THWN conductors, the resistance is typically around 0.0001 ohms per foot.

Assuming a typical length of the circuit, let's say 100 feet for this example:

1. Calculate the total resistance for a one-way distance of 100 feet:

[

R_{\text{total}} = \text{Resistance per foot} \times L = 0.0001 , \Omega/\text{ft} \times 100 , \text{ft} = 0.01 , \Omega

]

2. Now, using the formula for voltage drop with ( I = 215 , A ) and ( R = 0.01 , \Omega ):