To provide a communication equipment for an air conditioner having a power supply for easily confirming an operation after a repair by preventing a fault due to an error of an installing work and easily recognizing the fault.

A power supply 2 for supplying power to a transmission line 1 has a power supply means 7 of a power supply source, a current sensing means 10 for sensing an output overcurrent of the means 7, and a power supply interrupting means 9 for interrupting the power supply to the line 1. The means 10 interrupts the power supply from the means 7 to the line 1 by the means 9 at the time of detecting the output overcurrent of the means 1. The equipment also has a display means for displaying the interrupted state of the means 9 and a reset means for resetting to operate the means 10 from an initial state, a constitution of operating the means 9 by sensing a temperature of the means 7 instead of the means 10 and a constitution of operating the means 9 by detecting a voltage drop of the means 7.