I don't think this gets discussed enough on the forum.
Personally I think a 30 amp ring circuit in 2.5 mm2 is better than one or more 20 amp radials in 2.5 mm2.
The ring obviously has more capacity than one 20 amp radial.
It can serve a larger floor area.
One ring will take up fewer fuseways at the board than say two or more 20 amp radials needed to match capacity.
If a cable in a ring somehow gets damaged, the circuit could be converted into one or two 20 amp radials with minimal damage and disruption.
One unnoticed fault in the cpc will still mean each socket has an earth connection.
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What about 30 amp radials in 4 mm2?
They are ok, but no one wants to spend extra money on 4 mm2, then struggle getting three or four wires into a terminal.
Personally I think a 30 amp ring circuit in 2.5 mm2 is better than one or more 20 amp radials in 2.5 mm2.
The ring obviously has more capacity than one 20 amp radial.
It can serve a larger floor area.
One ring will take up fewer fuseways at the board than say two or more 20 amp radials needed to match capacity.
If a cable in a ring somehow gets damaged, the circuit could be converted into one or two 20 amp radials with minimal damage and disruption.
One unnoticed fault in the cpc will still mean each socket has an earth connection.
***
What about 30 amp radials in 4 mm2?
They are ok, but no one wants to spend extra money on 4 mm2, then struggle getting three or four wires into a terminal.