Journeyman Electrician Practice Exam

What type of wire is typically used in most residential branch circuits?

1. Aluminum wire

2. Plastic-coated wire

3. Copper wire

4. Lead wire

The correct answer is: Copper wire

Copper wire is typically used in most residential branch circuits due to its excellent conductivity, flexibility, and durability. Copper has a high tensile strength which allows it to withstand the mechanical stresses associated with installation and use. Additionally, it offers lower resistance compared to other materials, allowing for efficient transmission of electricity with minimal energy loss. This quality is especially important in residential settings where safety and efficiency are paramount. While aluminum wire can also be used in certain applications, it has drawbacks such as susceptibility to oxidation and a higher coefficient of expansion, which can lead to loose connections over time. Plastic-coated wire refers to the insulation on the wire rather than the type of wire itself, and lead wire is generally not used in electrical applications due to its toxicity and poor conductivity compared to copper. Thus, copper wire is the preferred choice in residential wiring.