What is the minimum size of electrical conductors for feeders and branch circuits when made of copper?

The minimum size of electrical conductors for feeders and branch circuits made of copper is 6 AWG. This specification is established based on common practices in residential and commercial electrical design, considering both the current-carrying capacity and safety standards outlined in the National Electrical Code (NEC).

In residential applications, the 6 AWG copper conductors are typically used because they can handle a sufficient amount of current for various circuits while minimizing the risk of overheating. This size is particularly important for feeders, which carry power from the main service to subpanels, as well as for branch circuits supplying outlets and lighting in different areas of a building.

Using conductors that are too small can lead to increased resistance, which may cause overheating and potential fire hazards, while larger sizes than necessary can lead to increased costs and complexity in installations. Therefore, the 6 AWG size balances safety, performance, and cost which is why it is identified as the minimum requirement in many scenarios.