A question on radials

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Subneural

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I'm due to add some sockets to a commercial unit but I'm struggling with the logistics.

The board is at the rear of the premises on the left and the sockets are to run down the right side all the way to the front. My inital thought was to run a 20A radial down the right side as the cable length from board to final socket will be 40m.

BUT, the floor area of this works out at 112 m2 and Appendix 15 states that 'Historically (or 'rule of thumb' depending on the update) this should be limited to 50 m2

Is it ok or not to run a radial around a floor area this size or do I need to add an extra board and a submain, effectively the first 14m of cable runs from the board to the first socket.

 
If we apply common sense and ignore the first 14m as it's not 'serving' anything?

Or run 2 radials splitting the loads between then so they have roughly 50m2 each?

 
4mm on 32a mcB (A2 circuit) can serve 75 square metres - assuming Ib is 25A Voltdrop would be about 11v

 
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