How much voltage will a 200 foot extension cord drop?

Answered by Bill Hernandez

When it comes to using a 200 foot extension cord, it is important to consider the voltage drop that may occur. The length of the cord plays a significant role in determining the amount of voltage that will be lost along the way. This is due to the resistance of the wire used in the cord.

To understand the voltage drop, it is essential to know that electrical current encounters resistance as it flows through a wire. The longer the wire, the more resistance it has, resulting in a higher voltage drop. This means that the voltage at the end of the cord will be lower than the voltage at the outlet.

The American Wire Gauge (AWG) system is commonly used to determine the appropriate wire size for different applications. In this case, we need to consider the gauge of the extension cord to estimate the voltage drop.

Assuming a standard 120V outlet and a current of 10 amps, let's explore the voltage drop for different wire gauges commonly used in extension cords.

1. #14 AWG Extension Cord:
A #14 AWG wire has a lower resistance than thinner wires and can handle up to 15 amps of current. However, for a 200 foot length, there will still be a noticeable voltage drop. The voltage will likely be approximately 10% lower than the outlet voltage. So, you can expect around 108 volts at the end of the cord.

2. #12 AWG Extension Cord:
A #12 AWG wire has a lower resistance than #14, allowing it to handle up to 20 amps of current. With a 200 foot length, the voltage drop will be slightly less than with a #14 wire. You can anticipate a voltage drop of around 6%, resulting in approximately 113 volts at the end of the cord.

3. #10 AWG Extension Cord:
A #10 AWG wire has even lower resistance and can handle up to 30 amps of current. With a 200 foot length, the voltage drop will be further reduced compared to the previous wire gauges. You can expect a voltage drop of approximately 4%, resulting in approximately 115 volts at the end of the cord.

It is important to note that these estimations are based on ideal conditions and may vary depending on factors such as the quality of the extension cord and the actual length of the cord used. Additionally, the voltage drop can be further affected by the load on the circuit and the overall electrical system in your specific situation.

Personal experience has shown that using a heavier gauge wire, such as a #10 AWG, for longer extension cords can help mitigate voltage drop issues. This is particularly important for sensitive equipment or appliances that require a stable voltage supply to function properly.

A 200 foot extension cord will experience voltage drop, and the amount of drop will depend on the wire gauge used. While a #14 AWG cord may result in a 10% drop, a #12 AWG cord may have a 6% drop, and a #10 AWG cord may have a 4% drop. These estimates provide a general idea of what to expect, but it is always recommended to consult an electrician or refer to manufacturer guidelines for precise calculations in specific situations.