Abstract: A lamp disconnection detecting device includes a magnetic core with a gap; a plurality of detecting coils the number of turns of which are different from one another and are proportional to 2.sup.n (where n=0, or positive integers), and a magnetic response section provided in the gap of the magnetic core.

Abstract: Electric current, flowing through a penetration conductor extending through a main housing, is detected by a non-contact current detection unit incorporated in the main housing. Connector housings are provided respectively at those portions of opposite sides of the main housing through which the penetration conductor extends, and opposite end portions of the penetration conductor as connector terminals are disposed within the connector housings, respectively. Each of the connector housings and the associated connector terminal received therein jointly constitute a connector.