A plug (1), socket (30) and connection apparatus for making an electrical connection. The plug (1) can hold a wire (20) and be received within a socket (30) having a conductor (37) and sealant (39), for making a waterproof electrical connection. The plug (1) comprises a plug body (2) and a passage (7) extending axially within the plug body (2) for receiving a wire (20), wherein the plug body (2) is configurable in a first wire-receiving configuration so that a wire can be placed within the passage (7) and a second clamping configuration so that the plug body (2) can clamp to and retain the wire (20) within the passage (7) when received within the socket (30).