ElecAS
Voltage Drop Calculator
Calculate cable voltage drop using Australian cable data, installation methods and load inputs.
Why this page matters
Calculate cable voltage drop using Australian cable data, installation methods and load inputs. This static content is published so the canonical route has meaningful crawlable HTML even before the interactive application hydrates.
Who this page is for
Electrical designers checking voltage performance against supply and final subcircuit limits.
Relevant standards
- AS/NZS 3008
What this tool helps with
- Estimate voltage drop from cable impedance, load current and circuit length.
- Compare installation methods and conductor selections for Australian projects.
- Use results alongside cable sizing and maximum demand calculations.
Frequently asked questions
What is the maximum allowable voltage drop in Australia?
- AS/NZS 3000:2018 Clause 3.6 limits total voltage drop from the point of supply to any load to 5% of nominal supply voltage. For 230 V single-phase, that is 11.5 V; for 400 V three-phase, 20 V. Final subcircuits commonly target a 2.5% allowance.
How is voltage drop calculated for AC cables?
- Voltage drop is calculated using Vd = (I × L × Z) / 1000, where I is load current (A), L is one-way cable length (m), and Z is the cable impedance per metre from AS/NZS 3008.1.1 (combining Rc and Xc adjusted for power factor and operating temperature).
Does cable temperature affect voltage drop?
- Yes — conductor resistance rises with temperature. AS/NZS 3008.1.1 tables list impedance at the maximum operating temperature for each insulation type (75 °C for V-75/PVC, 90 °C for X-90/XLPE). The ElecAS calculator applies the correct value automatically.
What is the difference between voltage drop and voltage rise?
- Voltage drop occurs on cables supplying loads (consumer to load). Voltage rise occurs on cables exporting from generation (e.g., solar inverter back to the point of supply) and is governed by AS/NZS 4777.1 with a 2% inverter-path limit.