Abstract: A battery terminal and door latch for battery operated devices. The battery terminal and door latch assembly prevents the closure of a battery compartment door when one or more batteries are missing from the battery operated device. In the embodiment, the terminal includes an aperture for engaging a latch on the compartment door. When a battery is installed the terminal is deflected so that the aperture engages the latch to close the door. Without an installed battery, the terminal is biased to prevent the aperture from engaging the latch. The open battery compartment door provides a readily discernible indication that batteries have not been installed. The terminal and door latch assembly is suitable for use with smoke detectors, carbon monoxide detectors and the like.

Abstract: A rotatable and interchangeable electrical plug for an electronic device which plugs directly into a receptacle. The electronic device comprises an enclosure with a socket for receiving the plug. The plug includes a detent which fits into one or more indents in the socket for determining the orientation of the plug. The plug can also be rotated in the socket to positions defined by the indents, which allows the orientation of the electronic device to be changed once plugged into the receptacle. In another aspect, the receptacle cover includes a safety catch which is engaged when the device is rotated to a lock position. In another aspect, the electronic device is fastened to a plate, the plate being received in a slot in the receptacle cover.