Distribution circuit fro Henley bocks

[equitum]

The customer would like to convert detached garage to an office/small gym As there is no gas supply he wants an electric shower and a water heater for a basin. My plan is to take a feed from the existing meter tails via Henley blocks to a small CU with a 80A mcb acting an OPD for a 3 core 16mm SWA feed (10M) to the garage. Then at the garage install a dual 100A RCD board for the final circuits (lights, radial socket circuit, smoke) with a 3KW water heater on one side and a 9KW shower on the other. The supply at the house is 100A TN-CS singe phase. Are there any issues with the 100A cutout rating given it would be supplying a second 80A mcb ?

 

[Taylortwocities]

Do not use an MCB at the origin.
Use a switch fuse.
https://www.tlc-direct.co.uk/Main_Index/Distribution_and_Switchgear_Index/Hager_SP_1/index.html
It’s very difficult to get discrimination between MCBs.

PS - in case you were going to ask - no RCD is needed at the origin if you are using SWA.

 

[AndyPRK]

didn't realise an 80A fuse was suitable for 16mm

 

[RF Lighting]

 

[equitum]

Thanks for replies - He has a point - buried in ground as intended reference method D is only 78A current carryring capacity for 16mm SWA

 

[EFLImpudence]

Use a 60A fuse, then.