When can a raised plaster cover increase the maximum number of conductors permitted in an outlet box?

A raised plaster cover can increase the maximum number of conductors permitted in an outlet box when it is marked with its cubic-inch volume. This marking indicates the additional volume that the plaster cover can provide for conductors, allowing for a higher capacity in the outlet box.

The sizing of outlet boxes and their covers is crucial for ensuring safety and compliance with the National Electrical Code (NEC), which stipulates how many conductors can fit in a box based on its volume. When a raised plaster cover has a specific cubic-inch volume marking, it becomes permissible to account for that additional volume in the overall calculation, effectively allowing more conductors to be accommodated within the outlet box.

This facilitates proper installation while ensuring that heat dissipation and electrical safety requirements are met. The method for determining maximum allowed conductors considers the physical space available, so any additions to that space, recognized through a clear marking, are significant in adjusting capacity.