The connector has a base with hooked side boards for joining a top cap. A partition board is placed between the side boards so as to form two slots for housing two metallic plates and two supporting pieces with slant top faces. The metallic plates have two upwardly extended conducting pins. Wires of exposed cores are placed on the supporting pieces. When the top cap is joined to the base, the wires are tightly locked by the top cap and the partition board while the conducting pins firmly contact with the cores. The connector can be quickly configured on a string of lamps and can be conveniently used to cascade multiple strings of lamps.