Final answer:
The correct option when dealing with more than three current-carrying conductors in a wireway is c) The National Electrical Code (NEC), which provides safety guidelines for electrical installations.
Step-by-step explanation:
The National Electrical Code (NEC) is what shall only be applied when the number of current-carrying conductors in a wireway exceeds three. The NEC provides guidelines, including derating factors, to ensure safe electrical installations where multiple conductors are present in a single conduit or wireway. This is important as the increase in the number of conductors can cause excessive heat build-up due to mutual heating effects, potentially leading to insulation damage and electrical fires.
Kirchhoff's first rule, also known as the junction rule, is pertinent when examining a junction or node involving current in three or more wires and is based on the principle of conservation of charge. However, when it comes to the specific logistics of wiring, the regulations and precautions outlined in the NEC are what directly address the situation in question.
It is fundamental to comply with the NEC when installing or examining electrical systems to ensure safety and maintain efficiency, which becomes particularly crucial when the conductor count exceeds three in a confined space.