MEASURING DEVICE

PROBLEM TO BE SOLVED: To provide a measuring device capable of being mounted on any existing circuit breaker of ordinary construction without shutting off the current flowing to the wirings nor requiring any wiring works. SOLUTION: The measuring device is composed of a part whereto mounting is made 45 to be fitted in a cover mounting hole 14b provided in the circuit breaker 10, a resilient conductor 25 located to generate a pressure attachment to a terminal 13d of the circuit breaker 10 when the part 45 is fitted in the hole 14b, a clamp type current transformer 21 located to allow insertion of a wiring 17b connected to the terminal 13b when the part 45 is fitted in the hole 14b, and a transmitting terminal 48 to send out the voltage value taken in by the resilient conductor 25 and the current value taken in by the clamp type current transformer 21.