Quote: "The AC ground should never be tied to the DC ground - the AC ground should only be tied to the ground through the shore power cord."
ABYC E-11(nl)11.5.2.7. DC System Negative Connections
11.5.2.7.1. If an alternating current (AC)(nl)system is installed, the main AC system grounding bus(nl)shall be connected to
11.5.2.7.1.1. the engine negative terminal or the(nl)DC main negative bus on grounded DC systems, or
11.5.2.7.1.2. the boat’s DC grounding bus in(nl)installations using ungrounded DC electrical systems.