I need to double check grounding rules with the Victron Multiplus please… in our situation it will be used to power a coffee machine in a tent at a trade show. It will not be connected to shore power, it will only be operated in inverter mode. There is no chassis or hull to connect the Multiplus case ground point to and no connected metal parts that customers can touch, Is an earth cable to the case ground point necessary in this temporary use case?