Yeah, I was wondering about space at the top.

 

You could of course screw a bit of DIN on to the existing back plate just for the end thingies.

My local proper electrics store didn't have them in stock when I checked last week. That's not surprising now I see that the Lazada options are all from China. I've ordered some which should arrive around the same time I'm back in Thailand. Updates to follow. Thanks again.

The din mount things hold ok. They’re really designed to have two points of contact like on a din rail. It’s not a super great hold but looks like it should do the job. 
 

Next issue is that the existing space is a bit too tight to pass the four new circuits through. I’m thinking to drill a hole in the top of the CU (or maybe one each side of the existing channel), add a grommet and feed the wires through it. Before I do that I’ll have another go getting them through how it is now. 

 

I managed to get the wires through in the end. All the new circuits are connected and I did a quick test on each one with a multimeter. Next i'll try adding a socket on each circuit and testing the RCBO with my little socket tester. The loads are balanced at L1=100A, L2= 112A, L3=104A. Tomorrow i'll post a photo of completed wall chases/ conduit and then i'll post again when the chases are filled in and the receptacles installed. Just in case anyone's interested.

 

Learning curve 

Looking good. 

You have 100A per phase in your condo?

20 minutes ago, carlyai said:

Looking good. 

You have 100A per phase in your condo?

Thanks. 50A

The finished product. Thanks again to all who replied.