Abstract: Apparatus provides for testing a fault indicator of the type which has a surge-current detection portion and a settable fault indicating portion and which is widely used in electric power distribution systems. Such a fault indicator must meet certain performance specifications including a maximum allowable reaction-time specification relating to the time required for the detection portion first to detect a surge current flowing in a conductor as a result of a down-line fault and then to set the fault indicating portion accordingly. The testing apparatus of this invention provides for effectively simulating field conditions, and to this end includes current-drive circuitry for supplying a test surge current to the fault indicator under test. Substantially simultaneously with the start of the test surge current, a timing-initiation signal is produced to enable interval-timing circuitry in the testing apparatus. To designate the end of the interval being timed, there is produced a timing-completion signal.