The junction boxes have both European (TUV) and domestic (UL) ratings.  NEC 2008 code will require latching connectors that must be disconnected with a tool. The safety clip accomplishes that by requiring the use of a small, flat-blade screw driver to open the squeeze-to-release part of the connector.  Positive connectors have a (+) sign molded on and a red ring on the female connector. Negative connectors have a (-) sign molded on and a blue ring on the female connector.