An electrical connection box for wall mounting provides a recessed external plug for receiving or transmitting power to electronic components. The connection box is configured to receive a variety of signal connection modules for interconnecting associated audio/visual electronics such as DVD players, displays and the like in adjacent apertures. The signal connection modules are inserted or extracted from the face of the connection box; replacing blanking plates, and is optionally recessed from the face of the box into the wall cut-out. The configuration and mating features of the box and modules also provides for a common and isolated ground reference for surge protection of the connected components. A signal connection module includes circuitry for surge protection of the connected A/V components receiving electrical power from an adjacent wall socket. The protection circuits in the signal connection module provides an isolated ground reference for the A/V components sharing a common ground connection at the wall socket, or a power conditioning module connected thereto.