The circuit protective conductor (CPC) is the dedicated ground wire in a circuit that connects the exposed metallic parts of electrical equipment to the main earthing terminal. Under normal conditions, it carries no current. In the event of a fault where a live wire touches a metal casing, the CPC channels the resulting high current safely to ground, forcing the breaker to trip and preventing electric shock.
Heard on the job
Make sure you sleeve the bare CPC with green and yellow tubing before terminating it in the back box.
Insider tip
In the UK, the CPC is often a bare wire inside twin-and-earth cable, requiring sleeving at the terminations.
Also heard as
- earth wire
- ground wire
- equipment grounding conductor