The FDB range of single phase transformer complete with RCD protection, fulfils a need often found in schools, laboratories, test areas, hospitals, workshops, mortuary's etc where electrical equipment is in use. It can easily be forgotten that RCD protection on the supply to a transformer does not reach "beyond it" and that therefore, the transformers output needs additional RCD protection.

The secondary winding of all FDB 3 units is centre-tapped to earth, thus reducing the possible shock level and providing the opportunity to restrict any fault currents, by connection of a limiting resistor in the centre tap.