In Enphase installations, the single-phase Q Relay (network system relay controller) acts as a galvanic disconnection device. It is designed for single phase use and has built in contactors. During specified grid abnormalities, the Q Relay disconnects the Enphase Microinverters from the AC grid, and when the voltages return to normal and the grid frequency is in the acceptable range, the Q Relay reconnects the microinverters to the AC grid. The Q Relay has built in current sensing that can detect DC current injection required by VDE V 0126-1-1 requirements. The Q Relay works together with the Envoy-S to meet the need to break both line and neutral per grid requirements. See full installation instructions for the Enphase Envoy-S and/or Enphase Microinverters at: enphase.com/support. It is best practice to install the Q Relay when installing the Envoy-S and before commissioning the system. The Q relay is IP-20 rated. You must mount it in an environmentally protected enclosure.