Excellent post there Dave, my boys have applied the 20A MCB route many times.Plusses and minuses for both methods.Have done a lot of emergency cover work - and I have had to split rings up into 2 radials due to cable breakdown/nails through cables etc on many occasions.
Arguably a ring gives you the chance to recover from this fault condition which a radial doesn't.
On the other hand - if I was doing a new build or a rewire I wouldn't be doing such a lousy job in the first place!
Fitting 2 x 4mm wires into a termination + spur could be a problem.
With a radial you know what fusing to use. In an existing installation it's hard to tell if a ring has a spur with several sockets on it.
Perhaps the safest and most repairable circuit is a ring with 20A MCB!
PMSLI know it wasn`t originally an option, but my pref. is for 2.5 radial on 16/20; with the exception of the kitchen fixed appliances / utility which I`ll generally use a ring for. (primarily because 4mm can be such a cow to work with (no offence intended to apache!!!)
Mmm..Well - I foresee all rings in the UK being wired in 4mm in the future - because of all this routed through insulation - derating factors.
and actually being radials.!Well - I foresee all rings in the UK being wired in 4mm in the future - because of all this routed through insulation - derating factors.
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