Hi Mike,
Just checked my old revised edition 1987 of the Handbook to the Electrical Wiring Regulations 1976.
under reg 100. the plug arrangements were shown. ( instead of reg 99 )
under reg 50. the ring mains circuit was explained with the same diagramme.
under reg 163. Test of ring circuit was quoted.
Even then this system was still OK to install although I have never seen it used in NZ.
