Three wire connection of RCDs
Our Technical Team have received a number of enquiries regarding three wire connection of RCDs.
A RCD will still function without a neutral connection, however the test button may not operate.
Some RCDs have the trip test circuit connected between phases while others are between phase and neutral. There will be a circuit diagram on the RCD which will show the trip circuit configuration.
In the case of a RCD with a phase to phase test circuit, there are no special requirements and the test function will operate with a three wire connection.
RCDs with a phase to neutral test circuit will require the connection of a resistor between the load side neutral terminal and a load side phase that is not connected to the test circuit - see wiring diagram below.
