How many maximum conductors are allowed in a metal box, according to the NEC?

The maximum number of conductors allowed in a metal box according to the National Electrical Code (NEC) is determined by the gauge of the conductors. The NEC establishes specific fill calculations based on the size and type of conductors used, which affect how many can safely fit into a given box without risking overheating or creating a hazard. These calculations take into account the volume of the box and the volume displacement of each conductor, as well as the inclusion of devices like switches or receptacles.

For example, larger gauge conductors may occupy more space in a box, thus reducing the total number of conductors that can be installed without exceeding the box's volume. This ensures that the conductors remain safe, accessible, and in compliance with electrical codes. Understanding these guidelines is crucial for maintaining safe electrical installations and preventing issues such as conductor damage or fire hazards due to overcrowding in electrical boxes.