The DET-6-C is a 6-channel EOL transmitter in cottage shell housing. It includes a CAM loc, AC transformer, standby battery, and built-in charger. The unit is housed in a durable cottage shell enclosure suitable for outdoor mounting. Telegraph codes unique to each of the six zones for Trouble, Alarm, Secure, as well as Tamper and Low Battery are transmitted over 100 milliampere circuit using positive non-interfering successive (PNIS) line current detection to avoid clashes between more than one transmitting box. Automatic ground return, a watchdog timer, and a jumper selected internal trouble buzzer assure continued main system operation and operator notification in the event of box failure. A built-in trouble relay output (form C) and the ground and code relay (grounding, opening, or no effect on the 100MA line) are activated by the watchdog timer ensuring reliable failure detection in the event of malfunction.