Understanding the Ampacity of a #1 THW Copper Wire for Residential Wiring

What is the ampacity of a #1 THW copper wire used for the 120/240, 3-wire single phase service for a single family dwelling?

1. 110 amps
2. 115 amps
3. 130 amps
4. 150 amps
Final answer:

Answer:

The ampacity for a #1 THW copper wire used in residential wiring is typically around 130 amps, in compliance with safety guidelines that stipulate continuous load should not exceed 80% of a wire's rated capacity.

Explanation:

The ampacity of a #1 THW copper wire used for 120/240, 3-wire single-phase service for a single-family dwelling varies depending on the electrical codes and tables used for reference, such as those provided by the National Electrical Code (NEC). However, since none of the options provided is directly sourced from the NEC tables and this is a hypothetical exercise, it's important to note that the ampacity must be chosen to meet the demand safely without exceeding the wire's capacity. THW insulation is typically rated for a maximum temperature of 75°C. Consulting a comprehensive ampacity chart that factors in this temperature rating would give a precise answer which should be coherent with safety guidelines that indicate a continuous load should not exceed 80% of a wire's rated ampacity. For a #1 THW copper wire, common ampacity values found in the NEC could range around 130 amps, which is suitable for a host of residential applications while allowing for safe operating conditions.