A. The typical electrical circuits to be found in a house (e.g. 2 x ring
mains, 2 x lighting, 1 x cooker etc...). I want to find a list of
appliances
that would have their own circuit protection.

Technically, you have a maximum of 100m2 for a ring circuit. However, it is
better to anticipate the likely load and use this as maximum. In particular,
a well stocked kitchen often has more equipment than should be installed on
a single ring main, especially if, like me, you cycle the machines all
simultaneously whilst cooking.

As an example, my house has the following circuits installed into a 16
outgoing way Contactum CU. TN-S earthing, 100A DP switch incomer. (60A
cutout). RCBOs are double width, as they were the cheapest Type B RCBOs I
could find.

1. B32A/0.03 RCBO. Ring main for entire house except kitchen. (May split
into two RCBO circuits in future when loft conversion built).

2. B32A/0.03 RCBO. Ring main for kitchen. (including 2.2kW dual fuel cooker)

3. B32A/0.03 RCBO. External electrics (outside socket, outside lighting,
future shed supply)

4. B32A MCB. Radial circuit for kitchen fixed integrated appliances.
(dishwasher, washing machine, dryer) remotely switched sockets concealed
under worktop.

5. B16A MCB. Radial circuit for fridge/freezer only. Reduces risk of
defrosting, as only a fault on that circuit, or the main service fuse will
cut the power.

6. B16A MCB. Heating system. (Immersion, central heating, heat bank).

7. B6A MCB. Most of house lighting circuit.

8. B6A MCB. New lighting circuit (kitchen only currently)

9. B6A MCB. Alarms (Interlinked smoke/heat detectors + intruder alarm)

If I had an electric hob, there would be a separate B32A MCB circuit for it.
When I moved in, the house had 3 operational circuits, a single ring main, a
single lighting circuit and a cooker circuit used solely to power the skanky
fridge freezer they left behind, as only 2 double sockets were installed in
the entire kitchen.

If designing from scratch, rather than upgrading the previously stingy, but
safe and well executed system, I would use at least two lighting circuits.
It is traditional to do upstairs/downstairs split. However, I would prefer
to randomise the circuits, so in the event of the MCB popping, a nearby
light will work. It does have the disadvantage that someone might assume the
upstairs/downstairs thing and work on a live circuit, though. Quite frankly,
if you make assumptions like those, a quick jolt could help you change your
attitude!

I would also split the rest of the house ring main into two. However, there
is no real reason to change my preexisting circuit. It comes well within the
100m2 requirement. Loading is likely to be very light, with no fixed
appliances or heating loads expected. The major requirement is during a gas
failure, where I might use up to around 5kW of electric heating. My entire
house heating requirement at -3C outside is only 8kW, so it would be
difficult to blow the ring using thermostatically controlled heaters anyway.

B. The relative merits of RCDs and RCBOs.

30mA RCD (whole house) = BAD!!!

30mA RCD (split load) = Much cheaper than RCBOs

30mA RCBO = Much less prone to nuisance tripping. Tripping has fewer
consequences. Warm feeling of having done it right.

Obviously, if a TT earthing system, the 100A DP incomer switch should be
exchanged for a 100A/100mA time delay RCD. The use of split load RCD/RCBO
would remain exactly the same, though. If I had such a system, I would also
consider using an RCBO on the kitchen radial, to prevent any earth leakage
in the kitchen fixed appliance heating elements taking out my lighting and
heating.

As for your list of appliances:

electric cooker = Own dedicated circuit on B32A MCB. Do not install cooker
unit with built in socket. They look bad and trail leads over the cooker.

boiler = put on a dedicated central heating circuit MCB (not RCBO). Can
share with immersion, especially if sharing controls, such as programmers.
All central heating valves, programmers and other controls should be from
the same central heating circuit. The CH side (as opposed to the immersion)
should be fused down to 3A, either internally in the boiler or in a separate
FCU. If there is no immersion on this circuit, use a B3A MCB instead, and a
DP switch to isolate the entire circuit next to the boiler.

water softener = 3A FCU off nearby ring main/kitchen fixed appliance radial.
Some softeners don't require electrical supply.

waste disposal = 3A FCU (or as advised in installation instructions) off
nearby ring main/kitchen fixed appliance radial

central heating pump = off same circuit as boiler. Will be internal to
boiler, or connected directly to it in a modern system.

fire alarms = either wire from a regularly used lighting circuit, or give
own small radial circuit (i.e. B6A or B3A MCB).

outside socket in the garden shed = separate RCBO circuit only shared with
other outside electrics. DO NOT spur from internal socket circuits. DO NOT
share the RCD/RCBO with any other circuit or appliances. The outside socket
should be off a 13A DP switched FCU rather than directly on the radial. This
enables you to turn it off inside, preventing nuisance RCD trips and
electricity theft.

Christian.