An arc fault detector, as a stand alone device or in combination with a circuit interrupting device such as a ground fault interrupter, protects from potentially dangerous arc fault conditions. More particularly in variable bit rate compression such as a video signal via MPEG-2, this is hard to forecast. User information, at least at the venue, is provided to users for transmitting electronic signals to the central communication point. When the system runs in the distributed group key management mode, a Group Security Association is established by all the group members together at the beginning of the group communication.