Notably, Clause 2.5.7.2 (Residual Current Devices) is independent of MD—a reminder that earth fault protection is a separate domain from overload protection.
Your Maximum Demand is 68 Amps . Therefore, you would install a 63A or 80A Main Switch (depending on the next standard size up and the rated current of the consumer mains cable). as3000 maximum demand
This acknowledges that not every appliance runs at the same time. You don't run your air conditioning, oven, hot water system, and every light in the house all at once for hours on end. The Wiring Rules allows us to apply to account for this intermittency. Notably, Clause 2
This method is used when the specific nature of the installation makes the table-based calculation impractical. It involves a professional judgment based on the known operating characteristics of the equipment. 3. Measurement This acknowledges that not every appliance runs at