What does it mean for a conductor when it is referred to as covered?

When a conductor is described as covered, it indicates that it has an outer layer that does not qualify as insulation according to the National Electrical Code (NEC). This means that while the outer layer may provide some degree of mechanical protection or may serve to protect against moisture or other environmental factors, it does not offer the electrical insulating properties necessary to prevent the conduction of electricity through it.

In the context of the NEC, electrical insulation is specifically defined and must meet certain criteria to be considered as such. Therefore, a covered conductor is different from one that is insulated, as the latter would have a layer recognized by the Code as capable of preventing electrical current from escaping.

Understanding this distinction is vital for ensuring safe electrical installations, as using a covered conductor in situations where full insulation is required could lead to electrical hazards.