What is the maximum length that 18 AWG fixture wire may be tapped to a 20 ampere rated branch-circuit conductor?

The maximum length for tapping 18 AWG fixture wire to a 20 ampere rated branch-circuit conductor is based on National Electrical Code (NEC) guidelines, which ensure safety and proper functioning of electrical systems. According to the NEC, the ampacity of 18 AWG wire is typically limited due to its smaller diameter; therefore, it can safely carry current only up to a certain distance when tapped to a higher rated conductor.

For a 20 ampere circuit, the maximum tap rule indicates that the smaller wire, in this case, 18 AWG, can be tapped for a distance of up to 50 feet from the 20 ampere branch circuit. This limit is established to prevent overheating of the 18 AWG wire and ensure it operates within a safe temperature range, as longer distances could lead to excessive voltage drop and potential hazards.

Understanding the context of this regulation is key for anyone working in the electrical field, as it helps maintain the integrity and safety of electrical installations.