Many thanks yet again Engineer 54.
There is a Thanks button at the bottom left of every post, ...lol!!
So this is my latest proposed installation.
1/ Main Supply into a 80A fused switch mounted in a box.
Could be rated smaller, say 40A or 63A max, seeing as you only have a 30A supply into the house. Either way, the suppliers cutout fuse is going to operate before yours will. lol!!
2/ Then L and N into (2) 2 way commoning blocks mounted in a box.
3/ These to be mounted in the roof space near the loft access.
4/ Each set of L & N then to run into an MK 16 way split consumer unit. Main switch 63A.
5/ Earth Rods to be 4 metre deep with minimum spacing of 4 metres. Set about 1.2 metre from house wall. Managed to get one rod in to 2 metres so far but not rushing it. Really expensive – 2 metre x 5/8 rods cost about £65 each.
6/ Earth cable to be 10 mm. Run into 2 way commoning block and then into each consumer unit.
You may only need one 4m earth rod, but the only way you would know that, is if you test it with an ELI TESTER (see earlier post) If at all possible try and increase the distance between rods to 1.5 times the driven depth, (eg 6m). It is sometimes useful to excavate a 1m deep X .5m hole then drive the rod in the ground and backfill/compact. If two rods are being used, link the two rods out with the 10 mm cable and take a single 10mm earth conductor back to the CU's. Are you using an S D type drill (set to rotation off) ?? It will make short work of driving those rods in the ground and make life a lot easier than a club or sledge hammer....
7/ 2 No. lighting circuits including Ceiling and Wall Fans. Cable to be 1.5 mm. Ceiling lights will be downlighters that do not have an earth connection. MCB = 6A.
Connect the earth cable (CPC) at the ceiling lights into a connector, for future use.
8/ 5 No. Air Con circuits – 1 for each Air Con. Cable to be 4.5 mm. MCB = 20A.
9/ 1 No. Cooker circuit. Cable to be 6 mm. 2 Pole switch. MCB = 32A.
10/ 2 No. Shower circuits. Cable to be 4.5 mm. 2 pole switch. MCB = 32A.
11/ 6 No. Main circuits. Cable to be 4.5 mm. MCB = 20A.
How many socket outlets are you going to connect to each of these circuits, you shouldn't need 6 socket outlet circuits. Say 1 circuit for the all the bedrooms, 1 circuit for the lounge and dining room. 2 circuits for the Kitchen.... Total 4 radial circuits should be more than ample for your needs.
12/ 1 No. external supply to water pump and external socket. Feed will run into small consumer unit with RCBO. MCBs to be 10A.
If the supply cable from the main CU is supplied from a protected circuit (RCD) then no need for a RCD at the small CU. The two RCD's will not discriminate with each other, e.g. either or both RCDs will trip in the case of an fault fault... If supply cable is going underground then the cable should be Steel Wire Armour (SWA) cable.
13/ Cable joints to be Wago connectors. Only lighting circuits to have joins (switches).
14/ All cables to include earth wire.
15/ Sockets and accessories to be rated at least 240V / 16A.
Total number of MCBs is 17 which seems high for a relatively small bungalow but It helps to keep things simple.
Up to you really, but that sounds like an awful lot of circuits to me!!!
I've got some contacts for what should be good electricians – from supply company's inspection dept or local skilled labour centre.
