Residual Current Circuit Breaker (RCCB), or Moulded Case Circuit Breaker (MCCB) is a device that quickly breaks an electrical circuit to prevent serious harm from an ongoing electric shock. These electrical devices are designed to quickly and automatically disconnect a circuit when it detects that the electric current is not balanced between the supply and return conductors of a circuit.
Contactor is an electrically-controlled switch used for switching an electrical power circuit. A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch. Unlike relays, contactors are designed to be directly connected to high-current load devices.
Multimeters & Clamp Meters
A digital multi-meter is essentially a voltage-measuring tool with some current abilities. A clamp meter is basically a current-measuring tool with some voltage abilities. They are distinctly different instruments, each with its own advantages.
Switches are an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of switch is an electro-mechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow.