Journeyman Electrician Practice Exam 2025 - Free Electrician Practice Questions and Study Guide

The correct answer focuses on the ampacity limit for armored cable when it is installed in thermal insulation relative to that of conductors rated for 60°C. In this context, armored cables, when placed in thermal insulation, are subject to specific restrictions regarding their current-carrying capacity, known as ampacity.

The reasoning behind this is based on the heat generated by the current flowing through the cables. Insulation can trap heat, leading to increased temperatures that can negatively affect the performance and safety of the electrical installation. Consequently, the National Electrical Code (NEC) stipulates that the ampacity rating for armored cables must be limited to ensure safety and to prevent overheating, which is why it cannot exceed that of conductors rated for 60°C.

This limit is critical in ensuring the integrity and reliability of electrical systems installed in environments that may predispose conductors to higher operational temperatures. By adhering to this guideline, electricians maintain safety standards needed for effective and reliable electrical installations.