MCB tripping RCD

Installed a Memera2000 B6 MCB (used) into Memera2000 CU. Only thing connected to it is a BG bell transformer (https://www.screwfix.com/p/british-...ll-transformer-module/8707p?_requestid=119382) which connects to a Google NEST Hello. When you turn on the B6 MCB, it trips the 100a RCD that is protecting the sockets and cooker. Upstairs/Downstairs/Smoke Detector and Water Heater MCBs all remain on. Transformer has been replaced so I know that’s not the problem. Nest wire is not connected so that is not the problem either.

Cable from MCB to Transformer is a 1.5mm2, not sure where I should put the earth on the transformer side though so att the moment I have got the earth connected to a 2-lever Wago Connector. Transformer is housed in a Wylex DIN enclosure (https://www.screwfix.com/p/wylex-ese2-ip40-2-module-unpopulated-din-enclosure/32311).

Anyone have any ideas of what I should try next?

Also, would a Eaton B6 MCB or Eaton C6 MCB be compatible with the Memera 2000 CU (https://www.screwfix.com/search?search=eaton+6a+mcb). Is it okay to have 1 type C MCB in the CU when the rest are type B?

Apologies, I am a DIY electricians, trying to educate myself.

 

Hi Deleted member 11267

Thanks for the quick reply. I think its in the correct neutral bar, but will need to double-check. If it is in the correct side, what else would you suggest?

 

Thanks guys, you were correct. Traced where the other MCBs were going on the unprotected side and was going to a different neutral bar. Connected to this one and no tripping...hooray .

Tested the Google Nest and it’s working too.