CPC
CPC turns up in 2 fields: electricians, telecom & it. Here is what it means to the people in each one.
CPC in electricians
The circuit protective conductor, which provides a safe path for fault current to ground.
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.
"Make sure you sleeve the bare CPC with green and yellow tubing before terminating it in the back box."
CPC in telecom & it
A momentary drop in line voltage used to signal that the calling party has hung up.
Calling Party Control is a line disconnect signal sent by a central office to customer equipment. It briefly drops the direct current on the telephone line to zero volts, typically for a few hundred milliseconds. This tells automated answering equipment like PBX systems and voicemail machines to release the line and reset for the next call.
"The answering machine keeps recording dead air because the PBX isn't passing the CPC signal down to the analog ports."