Probable Effect Concentration Quotients (PECQS) Practice Test

Which of the following materials is permitted to be uninsulated for a grounded conductor?

1. Aluminum

2. Copper

3. Steel

4. Plastic

The correct answer is: Aluminum

In electrical systems, grounded conductors are those that are intentionally connected to the ground to ensure safety in case of a fault. The use of uninsulated materials for grounded conductors is based on the conductivity and corrosion resistance of the material, as well as safety standards. Aluminum is an acceptable uninsulated material for a grounded conductor because it has excellent conductivity and is often used in electrical applications, particularly in overhead transmission lines and service connections. While aluminum can oxidize, the oxide layer does not insulate the conductor perfectly, allowing for sufficient grounding. Copper, though a highly conductive material, typically requires insulation when used as a conductor because it is highly reactive with various environmental conditions, which can lead to corrosion and potentially unsafe conditions. Steel is sometimes used in grounding systems, but it generally requires insulation since it can rust and corrode, which can impair its ability to conduct electricity and provide effective grounding. Plastic, while an insulator, is not conductive, and thus cannot serve the purpose of a grounded conductor. It cannot be uninsulated for the specific role of grounding. Overall, aluminum's properties allow it to function effectively as an uninsulated grounded conductor, making it the correct choice.