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The 13th Ed. makes absolutely no mention of cable lengths. The maximum floor area served by a ring final is no more than 1000 ft², or 92.9m².
Radial socket wiring regs were more complicated, depending on whether it was feeding a kitchen, the size of the room and the number of socket outlets installed.
Interestingly, the maximum number of socket outlets (other than clock connectors) connected to a ring final circuit installed in a non-domestic premises was 10.
A41 of the 14th Ed. has the same limit regarding floor areas covered by ring final circuits.
Radial socket circuit regs were slightly relaxed in comparison to the 13th.
But nowhere in the 14th can I find any mention of cable length. Floor areas served, yes, but not cable length.
Appendix 5 in the 15th Ed. says "..a single 30A ring circuit may serve a floor area of up to 100m², but consideration should be given to the loading in kitchens which may require a separate circuit.
A 30 or 32A 4 milli radial should cover no more than 50m² and a 20A 2.5mm² radial no more than 20m².
I cannot find anything in the 15th that refers to cable length.
The 16th Ed. has increased floor area served by a 20A 2.5mm² radial to 50m².
There seems to be no mention of cable length in the 16th, nor in the OSG (The 16th Ed. was the first edition of the regs to have an accompanying OSG).
The 17th Ed. does not list maximum cable lengths for circuits. Table 7.1 of the 17th Ed. OSG does. However, the circuit length is dependent upon the CPD type, the presence of RCD protection (BS7671:2008 [2011]), installation method and Zs limitations.
The maximum cable lengths for ring final circuits fed by 30 or 32A CPDs varies from 1m to 183m (using my Amd no. 1 17th Ed. OSG).
I cannot comment on the 18th Ed., as I have not yet got a copy.
Radial socket wiring regs were more complicated, depending on whether it was feeding a kitchen, the size of the room and the number of socket outlets installed.
Interestingly, the maximum number of socket outlets (other than clock connectors) connected to a ring final circuit installed in a non-domestic premises was 10.
A41 of the 14th Ed. has the same limit regarding floor areas covered by ring final circuits.
Radial socket circuit regs were slightly relaxed in comparison to the 13th.
But nowhere in the 14th can I find any mention of cable length. Floor areas served, yes, but not cable length.
Appendix 5 in the 15th Ed. says "..a single 30A ring circuit may serve a floor area of up to 100m², but consideration should be given to the loading in kitchens which may require a separate circuit.
A 30 or 32A 4 milli radial should cover no more than 50m² and a 20A 2.5mm² radial no more than 20m².
I cannot find anything in the 15th that refers to cable length.
The 16th Ed. has increased floor area served by a 20A 2.5mm² radial to 50m².
There seems to be no mention of cable length in the 16th, nor in the OSG (The 16th Ed. was the first edition of the regs to have an accompanying OSG).
The 17th Ed. does not list maximum cable lengths for circuits. Table 7.1 of the 17th Ed. OSG does. However, the circuit length is dependent upon the CPD type, the presence of RCD protection (BS7671:2008 [2011]), installation method and Zs limitations.
The maximum cable lengths for ring final circuits fed by 30 or 32A CPDs varies from 1m to 183m (using my Amd no. 1 17th Ed. OSG).
I cannot comment on the 18th Ed., as I have not yet got a copy.
