In Auckland most domestic houses are protected by 63 Amps HRC fuses in pillars via underground supplies, or 63A rewirable Crown lynn fuses via overhead supply.
In the Waitemata Electric Power Board days pre 1991, if you had a 6 kW Spa heater a 63 Amps MCB was fitted in series with the main switch and meter to avoid blowing especially the rewirable pole fuse, and could easily be reset by the home owner if they had the spa and electric range on at the same time, and other heating in winter.
A 63 Amps HRC in the pillar would usually go before the braker tripped but was easily replaced by the faultman. After the deregulation in 1992 the old 03 tariff disappeared for controlled fixed wired heating appliances and so did new installation of these MCB's.
Regards Raymond
