What is the maximum fuse size that should be used for a two-wire lighting circuit when using number 14 wire?

In a two-wire lighting circuit utilizing number 14 wire, the maximum fuse size that should be used is 15 amperes. This is grounded in the National Electrical Code (NEC), which establishes guidelines for electrical safety and ensures that wiring and components can safely handle the electrical load without risk of overheating or starting a fire.

Number 14 wire is typically rated for a maximum current carrying capacity of 15 amperes in residential applications. Using a fuse size larger than this, such as 20 or 25 amperes, would allow more current to flow through the wire than it can safely handle, potentially leading to overheating and damage to the wire insulation.

The choice of a 10-ampere fuse, while safe, does not provide the necessary capacity for typical lighting loads that could be connected safely to a 15-ampere circuit, contributing to inefficient circuit operation. Therefore, 15 amperes represents the optimal balance of safety and functionality for a lighting circuit with number 14 wire. This knowledge is crucial for ensuring both compliance with electrical codes and the safe operation of electrical systems in residential and commercial settings.