The old porcelain fused boards went out of production years ago and have been replaced by circuit breakers (MCBs) and residual current devices (RCDs). These devices are designed to protect users in the event of over current or an imbalance between phase and neutral.
So while new houses have this type of protection, older houses will not. Your house can be upgraded.
Contact Cal on 03 436-0063 to get a quote.