Enter the —a breed of software, spreadsheets, and mobile apps designed to simplify the tabular method outlined in Appendix C of AS/NZS 3000.
Introduction: The Critical Role of Maximum Demand In Australian electrical contracting, few calculations are as routinely performed—or as routinely misunderstood—as Maximum Demand (MD) . Under Clause C5 of AS/NZS 3000 (the Australian/New Zealand Wiring Rules), calculating maximum demand is not just a technical exercise; it is a legal and safety requirement. Under-sizing leads to nuisance tripping, voltage drop, and fire risk. Over-sizing leads to wasted copper, oversized switchboards, and unnecessary costs. maximum demand calculator australia
| Load category | Engineer’s manual calc (kVA/phase) | Free Excel (error) | Mid-range App | Premium Suite | |---------------|-------------------------------------|--------------------|---------------|----------------| | Lighting (LED + few fluoros) | 3.2 | 4.1 (didn’t apply Table C1 diversity correctly) | 3.3 | 3.2 | | Socket outlets (15 general, 5 dedicated) | 6.8 | 10.2 (summed all at 10A each) | 7.0 | 6.8 | | Welder (15A, intermittent) | 2.5 (demand 0.3) | 7.5 (peak) | 2.8 | 2.5 | | 3-phase AC unit (10kW cooling) | 5.8 | 5.8 | 5.8 | 5.8 | | Hot water (3.6kW x 2) | 5.2 | 7.2 (no diversity) | 5.1 | 5.2 | | | 22.8A | 32.1A (over by 40%) | 23.1A | 22.9A | Enter the —a breed of software, spreadsheets, and
A good maximum demand calculator turns a tedious, error-prone 30-minute manual calculation into a 3-minute data entry task. It reduces the risk of under-specifying (fires, trip issues) and over-specifying (cost blowouts). For a $15–$25 monthly subscription, most electricians will recoup that in the first hour of saved time on a single job. Under-sizing leads to nuisance tripping, voltage drop, and