Circuits without RCD:
- BS8436 cable is the only practical way of no RCD in domestic, it is
supposedly available in cut lengths from www.discount-electrical.com
(Vicki Thompson was my email contact, ask for Prysmian Earthshield
2.5mm about 1.10/metre plus carriage plus VAT).
- Note protection must be a Type-B device of rating no higher than
32A, Earthshield quoted is PVC sheath so will be limited to 20A as a
radial (wiring accessories are rated to PVC BS6004 cable anyway).

SWA is out because terminations must be accessible. Pyro is very
expensive to buy (few hundred a reel now) and probably more trouble
than it is worth now. Steel conduit gets expensive and impractical
unless you are lucky with a "corridor strip kitchen" and appliances on
one side, with the CU very close.

4.0mm FTE:
- Radials with 4.0mm FTE can be easier in some circumstances, or where
someone wants several power circuits in a house but is limited on
space re number of cables (routing around 150mm zone or having to
create their own zone re sloping ceilings, doorways, chimneys etc).
- 4.0mm FTE is stranded, not solid like 2.5mm FTE, so is easier than
you may think certainly in PVC (not in Prysmian BS7211 which will be
pig rigid!)

Ring v Radial:
- Ring gives two routes for CPC, whereas radial has only one
- Ring can be split to produce two 20A radials, can be very handy for
"resiliency" with elderly so they don't lose either everything in a
house or everything in a room (taking 314.1 to its logical conclusion)
- Ring has one downside in that a double socket is rated to 19.5A
continuous yet fusing will tolerate 26A and fuse 30/32A, this one is
upsetting europe even now as a known defect with a potential counter
being "phasing out PVC and using XLPE insulation" which would require
wiring accessories to be certified to 90oC from 70oC
- Radial has one benefit in that it is fused to 20A thereby matching a
double socket 19.5A continuous limitation

One issue with a ring is ensuring the legs are reasonably balanced,
this combined with 314.1 means a "whole house ring" is now out of
favour with a kitchen now ideally on its own ring separate from the
house. Some councils require this, however its more to prevent penny
pinching and a resulting useless installation (just removed part of my
mother's original kitchen ring and the PVC cable sheath shattered
lengthways when snipped, totally unbalanced design and ring broken at
an undercounter socket).