Pairing PLC devices

A first pass-through power line communication device capable of pairing with a second pass-through power line communication device, the first device comprising:

• a pass-through power connection,
• a power line communication unit;
• a sensor unit to sense a pass-through connection with said second device, wherein said sensor unit comprises an inner sensing unit at an inner location of said first device to sense if said first device is plugged into said second device and an outer sensing unit at an outer location of said first device to sense if said second device is plugged into said first device;
• a pairing unit to enter an appropriate pairing initiation state upon triggering of said pairing initiating state responsive to receiving an indication from said sensor, said pairing initiation state being either an add device state or a join device state;
• and
• a network key unit to control a network key as a function of which of said sensors is activated.