Capacity is checked at the inverter's full sizing current (incl. backup mode — backup current crosses the sub-mains to reach backed-up circuits). Vrise uses grid-tied current; the static export limit does not apply here, since it's measured at the point of supply and MSB loads can absorb generation upstream of it. Also confirm the sub-main protective device at the MSB against the added inverter current.
Consumer Mains Check & Voltage Rise (AS/NZS 4777.1)
Select the size and install method you can observe at the board. Parallel mains (common as 2 × 4 mm² or 2 × 6 mm²) doubles capacity less a 0.8 grouping factor (Table 3.33) and halves the current per cable for Vrise. With a mains length entered, the tool budgets the 2% total voltage rise across mains + inverter circuit.
Export limit: per AS/NZS 4777.1:2024 cl 3.3.3(b) and Energex FAQ 18, mains Vrise may be calculated at the export-limited per-phase current — static limits only (not dynamic/flexible exports), and the inverter circuit itself is always sized at full inverter current. Overhead/catenary service mains aren't covered — assess those manually.
Result
Cable Size
–
mm² copper
Circuit Breaker
–
A
Voltage Drop
–
–
Current-carrying capacities and voltage-drop values from AS/NZS 3008.1.1:2025 — multicore: Tables 3.15/3.16/3.18/3.19 + 4.17(B);
single-core (SDI): Tables 3.9/3.10/3.12/3.13 + 4.15(B) (laid flat touching / in common enclosure; buried = together in one conduit).
40 °C ambient air / 25 °C soil, copper conductors, no grouping derating on the inverter circuit (dedicated run).
Parallel mains: 2 × Iz × 0.8 grouping factor (Table 3.33, two circuits bunched/enclosed); Vrise on half current per cable.
Total voltage rise (mains + inverter circuit) budgeted against 2% per AS/NZS 4777.1:2024 cl 3.3.3;
mains segment may use the static export-limited per-phase current per cl 3.3.3(b) and Energex FAQ 18.
Protection coordination per AS/NZS 3000 (Ib ≤ In ≤ Iz); dedicated inverter supply circuit per AS/NZS 4777.1.
Inverter ratings from manufacturer datasheets (worst-case grid-voltage figures). Verify site conditions before installation.