Cable Sizing (AS/NZS 3008)

Cable size and voltage drop calculators for Australian projects

Use Tenselo's Australian cable size calculator and voltage drop calculator to compare stated inputs and methods for pump stations, bores, irrigation solenoids and treatment plants.

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Explore the methods and required inputs below. Running a calculation requires an approved Tenselo account with access to the relevant calculators.

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Electrical & solar in Tenselo

A short introduction to what Tenselo covers in this category.

Video summary: Voltage drop, cable sizing, irrigation solenoid wire selection, valve-circuit distance, motor current, generator duty and solar-pumping inputs.

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A result preview

10 mm² Cu cable

AS/NZS 3008 · 40 A Type C MCB · 415 V 3-phase

A preview of the result layout with selected inputs. It is not a complete design example; review the full inputs, method, assumptions and warnings when assessing your own site.

Inputs

Load current 40 A

Supply 415 V 3-phase

Install method Enclosed in wall

Conductor Copper

Results

10 mm²

Phase cores

10 mm²

Neutral

4 mm²

Earth (T5.1)

40 A

MCB Type C

415 V

3-phase AC

Conductor

Why it matters on the job

Cable selection checks

Review current-carrying capacity and voltage drop against the selected AS/NZS 3008 basis, with earth sizing referenced to AS/NZS 3000 Table 5.1.

Review protective devices

Compare protective-device ratings with the load and cable. Verify coordination against the selected equipment and site conditions.

Arc-flash & fault aware

Assess fault-loop impedance and arc-flash calculations with their stated assumptions. Installation testing and certification remain separate requirements.

Choosing an electrical calculator for an Australian site

Inputs for an Australian cable size calculation

Before comparing cable sizes, record the supply and phase arrangement, design current, one-way route length, conductor material and insulation, installation method, grouping, ambient conditions, protective device and permitted voltage drop. Keep the selected standard edition and correction-factor basis with the result. The responsible electrical professional must also confirm fault protection, coordination and the requirements that apply to the installation.

Voltage drop and cable sizing answer different questions

The voltage drop calculator checks the voltage lost along a cable run. Start with the supply voltage and phase arrangement, load current, one-way route length, conductor material and size, operating temperature and power factor. For a pump installation, record the actual cable route to the motor rather than the straight-line distance across the site.

The AS/NZS 3008 cable sizing calculator also considers current-carrying capacity and the installation conditions. Cable insulation, grouping, ambient temperature and the installation method can change the selection. A cable that meets a voltage-drop target may still fail another design check.

Voltage rise calculator for inverter export circuits

The ELE-006 voltage rise calculator checks single-phase or three-phase inverter export circuits. Enter the nominal voltage, export current, one-way cable length, conductor material, cable size, power factor and permitted rise. The result reports volts, percentage rise and the smallest cable that meets the selected limit.

Voltage rise is only one part of the design. Confirm the inverter manufacturer's limits, network connection requirements, cable current capacity, protection, installation conditions and the standard edition that applies to the project.

Fault loop impedance: check the complete circuit

Record the voltage-drop allowance available to this circuit, including upstream losses. Check motor starting separately from normal running duty. Use the fault loop impedance calculator to examine the relationship between loop impedance and the selected protective device; use motor overload and protection for the motor protection calculation.

Start with the protective device and its rating, the supply arrangement and the circuit being assessed. Keep the assumed loop impedance and the device operating basis with the result. ELE-018 addresses the stated MCB tripping check; it does not establish every protection requirement for the installation. Review the manufacturer's device data and the applicable requirements, and verify the completed installation through the required inspection and testing.

Solenoid cable sizing for irrigation valves

For ELE-011, record the controller supply, solenoid model, one-way cable route and the valves energised together. Include an additional master valve when it operates with the zone valve. Check both the active and common conductors and review the voltage available at the coil during inrush and holding.

The Hunter solenoid cable example at 160 m shows the stated inputs, conductor selection and both voltage checks. It is a conventional single-valve example with no additional master valve. A different controller supply, valve load or simultaneous-valve arrangement needs its own calculation; the example is not a universal cable-size recommendation.

Keep the standard and assumptions with the result

Confirm the standard edition, table basis, site inputs and warnings shown with the calculation. The WA electrical regulator describes the 2025 cable-selection standard update, including changes to DC coverage and installation scenarios. Check the requirements that apply to your jurisdiction and project.

A calculation supports design review; it does not certify an installation. Review Tenselo's scope and design responsibilities, and have the responsible electrical professional verify the design, equipment and site conditions.

For the wider pump-station design, see pump selection, solar pumping and the irrigation pump sizing guide.

Hunter solenoid cable at 160 m

View the worked sample and downloadable PDF for the inputs, calculation result, manufacturer references and limitations.

What is in this category

23 Electrical Power & Cable calculators

Every calculator in this category, by its reference code. Running them requires an approved Tenselo account with access to the relevant calculators.

ELE-001 Arc Flash (IEEE 1584-2018)

Incident energy, arcing current & arc-flash boundary - IEEE 1584-2018 empirical model
ELE-002 Arc Flash Incident Energy (Ralph Lee)

Incident energy & arc-flash boundary by the IEEE 1584 Lee method (conservative screening)
ELE-003 Generator Fault Current

Sub-transient / transient short-circuit current from Xd'' and Xd'
ELE-004 Transformer Calculator

kVA, full-load current (primary & secondary), kW and turns ratio
ELE-005 Transformer Fault Current

Symmetrical 3-phase fault at the LV terminals from kVA and %Z (infinite or finite source)
ELE-006 Voltage Rise (inverter export, AS/NZS 3008/4777)

Inverter export voltage rise 1ph/3ph, % of nominal, and the smallest cable for the limit
ELE-007 Cable Sizing (AS/NZS 3008)

Current rating, voltage drop, earth-fault loop, short-circuit + step-by-step calculations, to AS/NZS 3008.1.1 + 3000
ELE-008 Cable Sizing (quick)

Motor FLA + voltage drop (AS/NZS 3008 mV/A.m method)
ELE-009 Cable Tray Sizing & Selection

Size or check a cable tray from the cable runs - width, depth, support span, load, material for the environment and fasteners (AS/NZS 61537 / 3000 / 1170)
ELE-010 Conduit Fill

Minimum conduit for any AU cable - single-core (Cu/Al, PVC/XLPE) or multicore circular (orange PVC, XLPE) - real ODs, AS/NZS 3000 space factors
ELE-011 Solenoid Cable

Size the field cable, or check a size -- voltage at coil
ELE-012 Voltage Drop (AS/NZS 3008)

Cable volt drop 1ph/3ph with R & X at operating temperature, % of nominal, and the smallest size for the limit
ELE-013 Motor Full-Load Current & Starting

FLC, input kW, start current & speed (50 Hz)
ELE-014 Motor Overload & Protection

Overload setting/class, AC-3 contactor & SCPD for a 3-phase motor (AS/NZS 3000 / IEC 60947-4-1)
ELE-015 Power Factor Correction

Capacitor kVAR & uF to reach a target power factor
ELE-016 Single Phase Capacitors

Start & run capacitor selection for 240 V pump motors
ELE-017 Earth Electrode Resistance

Driven earth rod(s) resistance from soil resistivity (Dwight; AS/NZS 3000 / AS 1768)
ELE-018 Fault Loop Impedance

Max Zs for an MCB to trip instantly (AS/NZS 3000 Cl 5.7.4)
ELE-019 Generator Sizing

Size a diesel generator off max site amps + pick an Able Power model
ELE-020 Lighting / Luminaire Count (Lumen Method)

Number of luminaires for a target lux over a floor area (shed, pump room, plant)
ELE-021 Maximum Demand

AS/NZS 3000 App C max demand - domestic & commercial, 1ph/3ph
ELE-022 UPS / DC Backup Battery Sizing

Battery capacity (Ah) to back a load for a set time, with depth-of-discharge & ageing derating
ELE-023 Electrical Formulas (Ohm's Law & Power)

V, I, R, P, kVA, kVAR & kW<->HP for DC / 1ph / 3ph

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