Three phase equipment RCD protection on a TT system

[IAmSparkytus!]

TT system, existing three phase fuse board recently installed by another spark which only has single phase circuits terminated into individual RCBOs

Required to install three phase circuits for new equipment, is there a better way of doing this than fitting a 4pole RCD ahead of the main switch?

Conscious that this is going to cause total loss of power if a problem ever occurs.

No space nearby to install a seperate DB for the three phase equipment only.

 

[pc1966]

If your circuits are 32A or less you must achieve a 0.2 disconnection time, not always possible with time delayed devices.

True, though the disconnect time is for typical fault currents which would usually be much higher than In for the RCD.

Still, not many MFT can test at high currents, I think mine maxes out at 500mA so OK for checking ultimate disconnect time for a 100mA device but not really for a 300mA device.