A connection system for establishing one or more electrical connections through a barrier, the system comprising: a first connector including: a first-connector housing defining a cavity ; a slideable end piece captively but slidingly disposed over a distal-end portion of the first-connector housing; a cable extending from said slidable end piece having a first electrical lead coupled to a distal-end portion of the first-connector housing ; and at least a first piercing element connected to the first electrical lead, the first piercing element configured to enter the cavity and pierce the barrier when the barrier is disposed in the cavity and the slideable end piece is advanced toward a proximal-end portion of the first-connector housing during a transition from a safety state to an operable state of the first connector ; and a second connector including: a second-connector housing ; and at least a first receptacle within the second-connector housing configured to form at least a first electrical connection of the one or more electrical connections with the first piercing element when the transition from the safety state to the operable state of the first connector is complete. a first connector including: a first-connector housing defining a cavity ; a slideable end piece captively but slidingly disposed over a distal-end portion of the first-connector housing; a cable extending from said slidable end piece having a first electrical lead coupled to a distal-end portion of the first-connector housing ; and at least a first piercing element connected to the first electrical lead, the first piercing element configured to enter the cavity and pierce the barrier when the barrier is disposed in the cavity and the slideable end piece is advanced toward a proximal-end portion of the first-connector housing during a transition from a safety state to an operable state of the first connector ; and a first-connector housing defining a cavity ; a slideable end piece captively but slidingly disposed over a distal-end portion of the first-connector housing; a cable extending from said slidable end piece having a first electrical lead coupled to a distal-end portion of the first-connector housing ; and at least a first piercing element connected to the first electrical lead, the first piercing element configured to enter the cavity and pierce the barrier when the barrier is disposed in the cavity and the slideable end piece is advanced toward a proximal-end portion of the first-connector housing during a transition from a safety state to an operable state of the first connector ; and a second connector including: a second-connector housing ; and at least a first receptacle within the second-connector housing configured to form at least a first electrical connection of the one or more electrical connections with the first piercing element when the transition from the safety state to the operable state of the first connector is complete. a second-connector housing ; and at least a first receptacle within the second-connector housing configured to form at least a first electrical connection of the one or more electrical connections with the first piercing element when the transition from the safety state to the operable state of the first connector is complete. <EOS>