The peripheral edge of the upper face (31A) of a plate-shaped portion (31) of a holding member (30) confronts a terminal exposing through hole, cast through holes, and the inner periphery of an upper housing (10), i.e., a portion defining the terminal exposing through hole and the cast through holes. The upper face (31A) of the plate-shaped portion (31) defines a passage for passing rain water having flown from the terminal exposing through hole and the cast through holes into a housing space (1a). The lower end of the passage forms grooves (30a) and communicates with stepped through holes (12a) formed in the upper housing (10), so that the rain water is released from the stepped through holes (12a) to the outside of the upper housing (10).