Reverse polarity protection kit comprising changeover contactor & buzzer for mounting in a suitable DIN rail enclosure or switchboard. Disconnects the power to the caravan, boat, RV or transportable if the supply lead is wired incorrectly, designed to assist compliance with AS/NZS3001-2022 requirements for transportable electrical installations. Activated by voltage between neutral & earth (reverse polarity fault condition), disconnecting the supply and illuminating a warning LED. Backup buzzer sounds continuously in the event of a failure of the relay.