What must be true of completed wiring installations according to the NEC?

The requirement that completed wiring installations must be free from short circuits is crucial for ensuring the safety and reliability of electrical systems. Short circuits can cause excessive current flow, leading to potentially dangerous situations such as overheating, fires, and equipment damage. The NEC emphasizes the importance of proper installation practices and adherence to specifications that prevent conditions which could result in a short circuit.

Proper wiring techniques, including correct conductor sizing, securing connections, and using appropriate materials, all contribute to minimizing the risk of short circuits. Ensuring that installations are free from these conditions is critical for maintaining electrical safety standards.

Other options, while addressing important aspects of electrical installations, do not encompass the fundamental requirement of ensuring that no short circuits are present. For instance, grounding connections are essential for safety, but an installation could still have short circuits. Similarly, intentional ground faults are designed for specific scenarios and should not be present in general installations. The use of aluminum conductors is irrelevant to the basic requirement of eliminating short circuits, as both copper and aluminum conductors can be installed in ways that either create or prevent short circuits. Thus, the principal focus should remain on ensuring installations are devoid of short circuits for safety compliance.