Plug for a connector

A plug arranged to make an underwater electrical connection with a receptacle, the plug comprising:

• a housing defining an inner space that is sealably separated from the underwater environment;
• a first contact disposed within the inner space and including a first conducting region;
• a second contact disposed within the inner space and including a second conducting region;
• a third contact disposed within the inner space and including a third conducting region;
• and
• a connection cartridge selectively movable between three discrete positions without disconnecting the plug from the receptacle, wherein a first position provides an electrical connection between the first conducting region and the second conducting region and insulates the third conducting region, a second position in which the first conducting region, the second conducting region, and the third conducting region are electrically connected to one another, and a third position in which the first conducting region, the second conducting region, and the third conducting region are electrically insulated from one another.