NZ Electrical Calculators

Quick tools for NZ electricians, built around AS/NZS 3000, AS/NZS 3008 and AS/NZS 5033. Every calculator is free, needs no login, and shows the formula and clause behind its answer so you can put the working on your design records.

• Voltage Drop — calculate voltage drop for any cable and load against the 5% AS/NZS 3000 Clause 3.6.2 limit, with a 3% lighting design target shown as an advisory, plus the maximum run length and load for the cable.
• Maximum Demand — total maximum demand for a domestic or commercial installation using the AS/NZS 3000 Appendix C tables, with pre-loaded templates for typical NZ loads and a main-switch recommendation.
• Cable Sizer — pick your circuit type, enter the length, and get the recommended cable size from AS/NZS 3008 with current-carrying capacity, voltage drop and short-circuit checks.
• Circuit Check — verify an existing circuit: enter cable size, breaker, length and load for an instant pass/fail on the Clause 2.5.3.1 coordination rule (IB ≤ IN ≤ IZ) and voltage drop.
• Earth Fault Loop Impedance — check measured or calculated Zs against the AS/NZS 3000 Table 8.1/8.2 maximum values for MCB Types B, C and D, with the 80% rule and prospective fault current.
• Solar String Sizing — minimum and maximum modules per string with AS/NZS 5033 cold-Voc temperature correction, the MPPT voltage window and the 1.25 × Isc current check.
• Ohm's Law — enter any two of volts, amps, ohms or watts and the other two compute live. Used for design current, voltage drop, fault current and power dissipation work.

New to the calculators? The calculators guide walks through each one with worked examples.

Free NZ electrical calculators: cable sizing, voltage drop, maximum demand, earth fault loop, solar string, Ohm's Law. AS/NZS 3000 / 3008 / 5033.