An method for automatically testing an arc flash detection system by periodically or continually transmitting electro-optical (EO) radiation through one or more transmission cables electro-optically coupled to respective EO radiation collectors. A test EO signal may pass through the EO radiation collector to be received by an EO sensor. An attenuation of the EO signal may be determined by comparing the intensity of the transmitted EO signal to an intensity of the received EO signal. A self-test failure may be detected if the attenuation exceeds a threshold. EO signals may be transmitted according to a particular pattern (e.g., a coded signal) to allow an arc flash detection system to distinguish the test EO radiation from EO radiation indicative of an arc flash event.