Help with discrimination

[IQ Electrical]

All enclosures of RCDs or consumer units incorporating RCDs in TT installations should have an all-insulated or class 2 construction, or additional precautions, as recommended by the manufacturer, need to be taken to prevent faults to earth on the supply side of the upstream 100mA, S type, RCD.

That's why we're suggesting a 'front end' RCD.

 

[Chr!s]

If its a large installation you could go with a 300 mA time delayed, the front end RCD sees everything, capacitance, resistive leakage, appliance leakage etc, if the 100 trips first it may be because its already near its threshold?