Master Electrician Practice Exam

When can conductors other than service-entrance conductors be installed in a cable tray with service-entrance conductors?

1. When both are the same size

2. When a solid fixed barrier is installed to separate the systems

3. When they are insulated separately

4. When installed by the same electrician

The correct answer is: When a solid fixed barrier is installed to separate the systems

Installing conductors other than service-entrance conductors in a cable tray with service-entrance conductors is permissible when a solid fixed barrier is present to separate the different systems. This barrier helps prevent any potential interference between the conductors, ensuring that electrical and safety standards are maintained. Such separation mitigates risks associated with fault conditions, electromagnetic interference, and maintains a clear physical distinction between different systems that might operate under varying voltage levels or current types. While conductors may need to be the same size or insulated separately in other contexts, those criteria alone do not address the safety concerns associated with mixing different types of conductors within the same tray. Therefore, the requirement for a solid fixed barrier is a definitive measure that meets code regulations and ensures a safe installation environment.