If the connection of an A/C supply to the HAL 104 is required using an isolation transformer, the following rules should be applied.
One side of the secondary winding of the A/C supply should be connected to the protective Earth from the incoming supply.
This provides a simulated TN system.
The A/C secondary supply should then be connected to the 4mm aux supply inputs on the rear panel of the ClareHAL 104.
Fig 1 below shows the type of connection used.