Abstract: An intrinsic barrier made up of active and passive electrical components which combine to maintain the power in the output lines below a predetermined level in order to prevent the possibility of explosion if the output lines or any circuit electrically connected therewith comes in contact with a potentially explosive atmosphere. Specifically, the intrinsic barrier includes a transistor and a first zener diode combination which serve as a source of controlled voltage to the output lines of the barrier and which combination is protected on the input end by a fuse and also protected on the output end of the barrier by two zener diodes having voltage ratings equal to or greater than the first zener diode mentioned and also having, under prescribed test conditions, destruction times which are significantly greater than the blow time of the fuse and which output line further contains a resistor which has been selected such that the energy level is maintained at a safe level.