Correct Type-S Upfront RCD for 3Ph TT System

[JosephandAmber]

Yes, so long as the RCD has some form of 100A limiting there such as from the DNO fuses, or sum of down-stream OCPD.

What are your thoughts on placing the RCD prior to the meters?

Supply head > RCD > Meters > Switched Fuse > Sub main

I know that technically that's the meter companies side, however, I have little choice given the split of the three phases occurs before the meters. The other option would be to install 5 x 2 pole RCDs with 63Amp MCBs. No way the landlord would be willing to pay for that. Stuck between a rock and a hard place.

 

[pc1966]

I don't know.

If it was some sort of BNO arrangement then I guess you would be entitled to putting a disconnecter of some sort before the split/distribution to the meter but I don't think this is the case you are discussing?

The other thought is why TT? It is purely historial reasons and now you get the DNO to make it a PME system to have a low impedance earth instead of the RCD?