--- title: "Cable Size Calculator: AS/NZS 3008.1.1:2025 Cable Sizing for Australia" url: "https://scaleset.com.au/calculator/cable-selection" description: "Free AS/NZS 3008.1.1:2025 cable size calculator: size copper or aluminium cables for capacity, voltage drop, short circuit and earth loop impedance." updated: "2026-10-13" standards: - "AS/NZS 3008.1.1:2025 (Cable Selection: Tables 3.9 to 3.20 capacity, 3.33 to 3.48 derating, 4.1 to 4.10 impedance, 5.1 k-values)" - "AS/NZS 3000:2018 (Wiring Rules, including Clauses 2.5.3, 3.4, 3.6, 5.7.2 and Appendix B4)" - "AS/NZS 3000 Table 5.1 (Earthing Conductor Sizing)" - "AS/NZS 3000 Table 8.1 (Maximum Earth-Fault Loop Impedance)" - "AS/NZS 3013 (Fire-Rated Wiring Systems: WS Classification)" - "AS 60038 (Standard Voltages: 230 V +10% / -6%)" - "National Construction Code (NCC): essential services" author: "Wisam Tozah (B.Eng (Electrical), MIEAust, CPEng, NER, NSW DBP, NSW PRE, APEC, IntPE(Aus))" site: "ScaleSet" license: "https://scaleset.com.au/terms" usage: "Cite and link. Do not reproduce or train on this content." --- # Cable Size Calculator: AS/NZS 3008.1.1:2025 Cable Sizing for Australia Source: https://scaleset.com.au/calculator/cable-selection Free, browser-based AS/NZS 3008.1.1:2025 cable size calculator built for Australian electrical engineers, designers, electricians, estimators and contractors. Enter your design current, supply phase, conductor material, insulation, construction, installation method, route length and protection device. The calculator returns the smallest compliant cable size after running every check that AS/NZS 3000 and AS/NZS 3008.1.1 require: current-carrying capacity with k1 ambient, k2 grouping, k3 soil thermal resistivity and k4 depth-of-burial derating; protection coordination Ib ≤ In ≤ Iz; voltage drop against your per-segment limit and the AS/NZS 3000 Clause 3.6.2 envelope (5%, or 7% under AS/NZS 3000 Cl. 3.6.2 Exception 3 where supply is from a dedicated on-site substation); device breaking capacity against the prospective fault current; the I²t ≤ k²S² adiabatic short-circuit withstand check on both the active and the earth conductor using AS/NZS 3008.1.1:2025 Table 5.1 k-values (111.2 Cu/PVC, 142.9 Cu/XLPE, 73.7 Al/PVC, 94.6 Al/XLPE), with the earth conductor checked at both ends of the run; and earth-fault loop impedance computed from the full R + jX cable loop per the AS/NZS 3000 Appendix B4 framework, with the trip current Ia pulled directly from the linked Schneider Electric circuit protection database (Im for thermal-magnetic MCBs and MCCBs, Ii for electronic-trip MCCBs and ACBs). Three conductor types (Copper (Cu), Copper Flexible, Aluminium (Al)), and five insulation classes (V-75 PVC, X-90 XLPE, R-90 elastomeric, and the two fire-rated 110 °C classes, X-110 XLPE and R-110 elastomeric) are supported, every class for aluminium as well as copper, along with every installation method the AS/NZS 3008.1.1 rating tables publish, from unenclosed in air to buried in an underground enclosure. Auto insulation uses V-75 up to 16 mm² and X-90 above, and Auto sizing checks each candidate size against the V-75 or X-90 table it would be supplied in; construction Auto uses multicore up to 95 mm² and single cores from 120 mm², and a 110 °C class is picked from the Insulation selector for fire-rated and essential-services sections. Built-in support for parallel sets, earth conductor sizing from AS/NZS 3000 Table 5.1, full project metadata capture and a branded PDF cable selection report you can drop straight into a design submission. ## Key facts - Cable sizing in Australia is governed by two standards working together: AS/NZS 3008.1.1:2025, written AS3008 or AS 3008 on most drawings, supplies the tables, and AS/NZS 3000:2018 supplies the compliance limits those tables are checked against. - A compliant cable must pass six checks: current-carrying capacity after derating, protection coordination (Ib ≤ In ≤ Iz), voltage drop, device breaking capacity, short-circuit thermal withstand (I²t ≤ k²S²) and earth-fault loop impedance. - Current ratings come from the AS/NZS 3008.1.1:2025 Section 3 tables (AS/NZS 3008.1.1 Tables 3.9 to 3.20), voltage-drop impedances from AS/NZS 3008.1.1 reactance Tables 4.1 and 4.2 and a.c. resistance Tables 4.5, 4.7, 4.9 and 4.10, and the k1-k4 derating factors for ambient temperature, grouping, soil resistivity and burial depth from AS/NZS 3008.1.1 Tables 3.33 to 3.48. - The minimum earth conductor follows AS/NZS 3000 Table 5.1 and must also pass the adiabatic and loop-impedance checks. - Ze and the fault level are taken at the board the cable leaves. For a final subcircuit on a distribution board, Ze includes the consumer mains and every submain upstream; the network figure alone reads Zs low. - A four- or five-core cable is rated on three loaded conductors, a balanced load. Where third harmonic current exceeds 15% of the phase current, AS/NZS 3008.1.1 Clause 3.5.9 and Table 3.4 take 0.86 up to 33%, and above that the cable is sized on the neutral current. - The voltage drop pass is for this cable against the share you set for it. AS/NZS 3000 Clause 3.6.2 limits the drop from the point of supply, so the drop upstream is added to check that clause. - The switchboard end of the cable is covered by AS/NZS 61439.1: Table A.1 gives the conductor sizes a terminal must accept for its rated current (6 to 25 mm² at 63 A, 16 to 50 mm² at 100 A, 70 to 150 mm² at 250 A), and the report notes when a single copper cable falls outside the range for its device rating. - The earth-fault trip current Ia is read from a linked Schneider Electric circuit protection database: Im for MCBs and thermal-magnetic MCCBs, Ii for electronic-trip MCCBs and ACBs. - It is an AC cable size calculator for both supply types: single-phase 230 V and three-phase 400 V. A 3 phase cable size is read from the three- and four-core columns of the tables, and its voltage drop uses √3 in place of the 2 used for single-phase; the cable size chart further down gives the amps for the common sizes before derating. ## Who this page is for Electrical engineers, designers, electricians, estimators and contractors sizing copper, copper flexible or aluminium conductors for consumer mains, submains, final subcircuits, motor circuits and essential / fire-rated services under AS/NZS 3000:2018, AS/NZS 3008.1.1:2025, AS/NZS 3013 and the National Construction Code (NCC). ## Relevant standards - AS/NZS 3008.1.1:2025 (Cable Selection: Tables 3.9 to 3.20 capacity, 3.33 to 3.48 derating, 4.1 to 4.10 impedance, 5.1 k-values) - AS/NZS 3000:2018 (Wiring Rules, including Clauses 2.5.3, 3.4, 3.6, 5.7.2 and Appendix B4) - AS/NZS 3000 Table 5.1 (Earthing Conductor Sizing) - AS/NZS 3000 Table 8.1 (Maximum Earth-Fault Loop Impedance) - AS/NZS 3013 (Fire-Rated Wiring Systems: WS Classification) - AS 60038 (Standard Voltages: 230 V +10% / -6%) - National Construction Code (NCC): essential services ## What this tool does - Runs every AS/NZS 3000 and AS/NZS 3008.1.1:2025 cable selection check in one pass: current carrying capacity (with full k1·k2·k3·k4 derating), Ib ≤ In ≤ Iz protection coordination, voltage drop, breaking capacity, I²t ≤ k²S² thermal withstand on the active and the earth conductor, and earth-fault loop impedance. - Applies the four AS/NZS 3008.1.1 correction factors from Tables 3.33 to 3.48 (ambient air or soil temperature (k1), grouping (k2), soil thermal resistivity (k3) and depth of burial (k4)): type the combined factor into the Correction Factor field, or open its Wizard to build it from the tables, and tick Auto beside it to apply the grouping factor for parallel sets. - Three conductor options (Copper (Cu), Copper (Flexible) and Aluminium (Al)), with aluminium rated from 16 mm² in every insulation class, the 110 °C classes included, as AS/NZS 3008.1.1:2025 publishes it (AS/NZS 3008.1.1 Tables 3.11, 3.14, 3.17 and 3.20). - Five insulation classes: V-75 PVC, X-90 XLPE, R-90 elastomeric, X-110 XLPE and R-110 elastomeric. The two 110 °C classes are the fire-rated options, for circuits such as fire pumps, smoke control fans and fire-mode lifts that have to keep running in a fire. - Auto insulation uses V-75 PVC up to 16 mm² and X-90 XLPE above, and Auto sizing checks every candidate size against the table for the insulation it would be supplied in; construction Auto uses multicore up to 95 mm² and single cores from 120 mm². A 110 °C class is picked from the Insulation selector for fire-rated sections. - Ten construction layouts covering single-phase and three-phase: 2C+E, 2C, 2x1C+E, 2x1C, 4C+E, 3C+E, 4C, 4x1C+E, 3x1C+E and 4x1C, with the calculator counting loaded conductors when it pulls the AS/NZS 3008.1.1 capacity table. - Every installation method the AS/NZS 3008.1.1 rating tables publish (unenclosed spaced or touching, exposed to sun, enclosed in conduit, in thermal insulation, buried direct and in underground enclosures), with the single-core arrangement (trefoil, flat touching or spaced) feeding the impedance lookup. - Voltage drop calculated by the impedance method Z = √(R² + X²) per AS/NZS 3008.1.1, with a one-toggle switch to the actual-PF projection Vc = R·cosφ + X·sinφ for tighter sizing on known-PF loads, and the per-segment limit checked against your design split (typically 1% mains, 1.5 to 2% submains, 2 to 2.5% final subcircuits inside the 5% AS/NZS 3000 Cl. 3.6.2 envelope, or 7% under its Exception 3 for a dedicated on-site substation). - Earth-fault loop impedance computed from the full cable impedance loop Zs = Ze + √((R_loop·L)² + (X_loop·L)²) per the AS/NZS 3000 Appendix B4 framework, with the trip current Ia pulled from the linked Schneider Electric circuit protection database (Im for MCB / thermal-magnetic MCCB, Ii for electronic-trip MCCB / ACB) and the AS/NZS 3000 Table 8.1 figure for a fuse. - Parallel sets per AS/NZS 3000 Cl. 3.4.3: Auto uses the fewest sets that pass under the Max size, or set the count with Sets beside a pinned size. Earth Size defaults to Auto, from AS/NZS 3000 Table 5.1 and upsized for the fault checks, and parallel sets carry one earth per set or one earth for all, its size shown beside the AS/NZS 3000 Table 5.1 figure for the whole group. A project metadata block (project name, number, address, designer, revision) flows into the exported PDF cable selection report. - Built and reviewed by a Chartered Professional Engineer (CPEng, NER, NSW DBP, NSW PRE, APEC, IntPE Aus): see the Verification page for the testing and review process. ## How to size a cable under AS/NZS 3008.1.1 and AS/NZS 3000 1. **Enter design current (Ib)** — Enter the maximum continuous design current the circuit will carry. For motors use the nameplate full-load current; for distribution circuits use the maximum demand from AS/NZS 3000 Section 2. 2. **Select phases and protection device** — Set System Type to 1 Phase (230 V) or 3 Phase (400 V) and pick the upstream protective device (MCB curve B/C/D, MCCB, ACB or fuse). The device rating In must satisfy Ib ≤ In ≤ Iz per AS/NZS 3000 Cl. 2.5.3.1. 3. **Choose conductor, insulation and construction** — Pick Copper (Cu), Copper Flexible or Aluminium; pick V-75, X-90, R-90, X-110 or R-110 insulation (or leave Auto); pick a multi-core or single-core construction with the appropriate number of cores for the loading. 4. **Choose AS/NZS 3008.1.1 installation method** — Select unenclosed in air, enclosed in conduit, buried direct or in underground enclosure to match the physical install. 5. **Apply derating factors** — Enter the combined factor in the Correction Factor field, or open its Wizard and set the ambient temperature, the grouping arrangement and number of circuits and, for a buried cable, the soil thermal resistivity and depth of burial. The Wizard reads k1, k2, k3 and k4 from AS/NZS 3008.1.1 Tables 3.33 to 3.48 and applies their product to the field. 6. **Set route length and voltage drop budget** — Enter the cable route length in metres and the per-segment voltage drop allowance: typically 1% for consumer mains, 1.5 to 2% for submains and 2 to 2.5% for final subcircuits, inside the AS/NZS 3000 Cl. 3.6.2 5% envelope (or 7% under its Exception 3 for a dedicated on-site substation). 7. **Enter fault current and clearing time** — Enter the prospective fault current at the cable origin in Source Fault. Leave Fault Duration blank to use the selected catalogue device’s breaking time, its short-time delay, or the device class figure (20 ms for an MCB or RCBO, 40 ms for an MCCB or HRC fuse, 60 ms for an ACB), or enter the clearing time read off the device curve. The calculator runs the adiabatic I²t ≤ k²S² check on the active and the earth conductor. 8. **Set external impedance Ze for Zs check** — Enter Ze, the earth fault loop impedance at the board the cable leaves: the supply and consumer mains, plus every submain upstream for a circuit on a distribution board (0.38 Ω for a residential final subcircuit or 0.02 Ω at an on-site substation, from the supply presets). The calculator adds Ze to the full cable loop R + jX as a vector and verifies Zs ≤ U₀/Ia against the AS/NZS 3000 Cl. 5.7.2 disconnection time. 9. **Review pass/fail pills and export the PDF report** — Each compliance check shows a pass/fail pill. When every check passes, fill in the project metadata block and export the branded PDF cable selection report for submission. ## Cable sizing under AS/NZS 3008.1.1:2025: practical guide ### Standards and methodology The ScaleSet cable size calculator reads tabulated values directly from the current Australian/New Zealand standards: no rules of thumb and no interpolation beyond the published data. AS/NZS 3008.1.1:2025, written AS3008 or AS 3008 on most drawings and specifications, is the dominant reference: current-carrying capacity comes from the AS/NZS 3008.1.1 Section 3 tables (Tables 3.9 to 3.20 for the supported constructions) selected by the chosen installation method, conductor and insulation; voltage drop uses the impedance values published in AS/NZS 3008.1.1 reactance Tables 4.1 and 4.2 and a.c. resistance Tables 4.5, 4.7, 4.9 and 4.10 (R and X per kilometre at the conductor operating temperature); derating factors come from AS/NZS 3008.1.1 Tables 3.33 to 3.48; and short-circuit k-values for the adiabatic check come from AS/NZS 3008.1.1 Table 5.1. AS/NZS 3000:2018 (the Wiring Rules) drives the compliance checks. AS/NZS 3000 Clause 2.5.3.1 sets protection coordination Ib ≤ In ≤ Iz. AS/NZS 3000 Clause 3.5.1 and Table 3.3 fix minimum conductor sizes. AS/NZS 3000 Clause 3.4.3 governs parallel runs. AS/NZS 3000 Clause 3.6.2 sets the 5% voltage drop limit from the point of supply, raised to 7% by its Exception 3 where the point of supply is a substation on the premises dedicated to the installation. AS/NZS 3000 Appendix B4 frames the earth-fault loop impedance requirement: the tool computes the full R + jX loop rather than the resistance-only shortcut. AS/NZS 3000 Clause 5.7.2 sets disconnection times (0.4 s for socket-outlet final subcircuits up to 63 A, hand-held Class I and portable equipment; 5 s for other circuits). AS/NZS 3000 Table 5.1 fixes the minimum earthing conductor and AS/NZS 3000 Table 8.1 publishes the corresponding maximum Zs values. AS 60038 sets the nominal voltage envelope (230 V +10% / −6%) that the 5% drop limit feeds into. ### The six compliance checks A cable size is not one number. The cable calculations behind a compliant result are six separate checks, and the governing one changes with the circuit: capacity governs short hot runs, voltage drop governs long ones, and thermal withstand or loop impedance governs where fault levels are high. The calculator verifies current-carrying capacity with correction factors, voltage drop, short-circuit thermal withstand and earth-fault loop impedance/disconnection time. It also verifies protection coordination per AS/NZS 3000 Cl. 2.5.3.1 (Ib ≤ In ≤ Iz) and short-circuit breaking capacity at the device. Each check is reported with its own pass/fail pill in the result summary. Capacity is the cable’s tabulated rating after the four derating factors are applied (ambient temperature k1, grouping k2, soil thermal resistivity k3 and depth of burial k4). The thermal withstand uses the adiabatic equation I²t ≤ k²S² on both the active and the earth conductor with the AS/NZS 3008.1.1 Table 5.1 k-value matched to the resolved insulation, and the earth conductor is checked for a fault at both ends of the run. The earth-fault loop impedance check computes the full impedance loop Zs = Ze + √((R_loop·L)² + (X_loop·L)²) and verifies Zs ≤ U₀ / Ia for the disconnection time required by AS/NZS 3000 Cl. 5.7.2. ### Voltage drop split across the path AS/NZS 3000:2018 Cl. 3.6.2 limits the total drop from the point of supply to any load to 5% of nominal when the supply comes from the network: 11.5 V on a 230 V single-phase circuit and 20 V line-to-line on a 400 V three-phase circuit. Where the point of supply is the low voltage terminals of a substation on the premises and dedicated to the installation, AS/NZS 3000 Cl. 3.6.2 Exception 3 raises the limit to 7%. The total is a budget for the whole path. A conservative allocation that gives sensible headroom at the final outlet is roughly 1.0% on consumer mains, 1.5% to 2.0% on submains, and 2.0% to 2.5% on final subcircuits. The calculator’s Maximum Voltage Drop field is the per-segment limit you want this cable checked against. ### Conductor, insulation and construction choices Copper is the default in Australia. Aluminium is offered from 16 mm² and is chosen for large mains and submains where weight and cost favour it, but it has only about 60% of copper’s conductivity, cold-flows under terminal pressure, oxidises and reacts galvanically with copper. Every insulation class is available with aluminium: AS/NZS 3008.1.1:2025 rates aluminium at 110 °C as well (AS/NZS 3008.1.1 Tables 3.11, 3.14, 3.17 and 3.20). V-75 PVC is the calculator’s default for lighting, general power and small submains; the Auto rule selects V-75 for any size up to 16 mm². X-90 XLPE carries about 14 to 28% more current than V-75 in the same cross-section in air or in conduit, and 10 to 18% more buried (AS/NZS 3008.1.1:2025 Tables 3.9 to 3.19), with a higher AS/NZS 3008.1.1 Table 5.1 k-value (142.9 against 111.2 for copper); Auto selects X-90 once the cable is larger than 16 mm². The calculator rates an X-90 cable at 90 °C. AS/NZS 3008.1.1 does not cover the temperature rise at equipment terminals (AS/NZS 3008.1.1 Clause 1.1 refers it to AS/NZS 3000 and the equipment Standards), so check the terminal rating of the breakers and lugs the cable lands on; AS/NZS 3008.1.1 Table 3.1 says a 110 °C cable should only connect to equipment suitable for that temperature. The two 110 °C classes are the calculator’s fire-rated options: X-110 (X-HF-110) and R-110 (R-HF-110 / R-E-110 elastomeric). Pick the one specified from the Insulation selector for essential-services sections. Construction Auto resolves to multicore up to 95 mm² and single cores from 120 mm², each with an earth conductor (a +E construction). ### Derating and installation methods Enter the combined correction factor in the Correction Factor field, or open its Wizard and set the four AS/NZS 3008.1.1 factors: k1 for ambient air or soil temperature (AS/NZS 3008.1.1 Tables 3.44 and 3.45), k2 for grouping of circuits (AS/NZS 3008.1.1 Tables 3.33 to 3.43), k3 for soil thermal resistivity on buried cables (AS/NZS 3008.1.1 Table 3.48) and k4 for depth of burial (AS/NZS 3008.1.1 Tables 3.46 and 3.47). Their product multiplies the tabulated rating. Tick Auto beside the field to apply the grouping factor for parallel sets. AS/NZS 3008.1.1 rates every buried cable at a soil thermal resistivity of 1.2 K·m/W, an average that assumes the soil at its driest at times of maximum load (AS/NZS 3008.1.1 Clause 3.5.5). Clay or peat can be as low as 0.8 K·m/W, and well-drained sands under constant load 2.5 K·m/W and above. Measure the soil along the route where possible and take the AS/NZS 3008.1.1 Table 3.48 factor for that value; a stabilised backfill improves the rating but does not earn back the 1.2 K·m/W figure. The Installation Method selector maps the physical install to the AS/NZS 3008.1.1 current-carrying-capacity column. Unenclosed covers tray, ladder or clipped direct; Enclosed in air covers surface or in-wall conduit and trunking; Buried direct covers cables in a trench; and Underground enclosure covers cables in buried conduits or ducts. Buried installations do not automatically mean smaller cables. ### Short-circuit thermal withstand and earth-fault loop impedance Short-circuit withstand tends to govern when prospective fault currents are high and the upstream protection has a relatively slow clearing time. Left blank, Fault Duration takes the selected catalogue device’s breaking time, its short-time delay, or the device class figure: 20 ms for an MCB or RCBO, 40 ms for an MCCB or an HRC fuse and 60 ms for an ACB. The presets beside the field offer the same figures, plus 80 ms for an electronic-trip MCCB held on a short-time delay. The adiabatic equation I²t ≤ k²S² is applied to both the active and the earth conductor with k from AS/NZS 3008.1.1:2025 Table 5.1: 111.2 for copper PVC (≤300 mm²; 98.5 above), 142.9 for copper 90 °C XLPE/elastomer, 131.8 for the copper 110 °C classes, 73.7 for aluminium PVC and 94.6 for aluminium XLPE. The earth conductor is checked for a fault at both ends of the run. For earth-fault loop impedance the calculator implements the AS/NZS 3000 Appendix B4 framework with the full cable impedance: Zint = √((R_loop·L)² + (X_loop·L)²) / 1000, Zs = Ze + Zint, and the pass condition is Zs ≤ U₀ / Ia with U₀ = 230 V. The trip current Ia is read from the linked Schneider Electric circuit protection database: Im for MCBs and thermal-magnetic MCCBs, Ii for electronic-trip MCCBs and ACBs, and for a fuse the AS/NZS 3000 Table 8.1 0.4 s figure for its rating, or a trip multiple read off its curve where one is entered. ### Earth conductor sizing and parallel runs The minimum copper protective earthing conductor comes from AS/NZS 3000 Table 5.1. The calculator’s Earth Size selector defaults to Auto and follows the table: 1, 1.5 and 2.5 mm² actives keep an earth equal to the active; from 4 to 10 mm² the earth steps down (4 and 6 mm² actives resolve to 2.5 mm² earth, a 10 mm² active to 4 mm²); from 16 mm² upwards the earth is roughly a quarter to two-fifths of the active CSA (50 → 16 mm², 95 → 25 mm², 150 → 50 mm², 240 → 95 mm²). AS/NZS 3000 Table 5.1 caps the copper earth at 120 mm² for 300 to 630 mm² actives (25% of the active above 630 mm²), and the calculator follows that cap. With aluminium actives AS/NZS 3000 Table 5.1 permits a smaller copper earth at the same active size. AS/NZS 3000 Table 5.1 is only the minimum: the earth still has to pass the adiabatic check I²t ≤ k²S² at both ends of the run and the Zs loop check, which the calculator runs automatically, upsizing the earth (never beyond the active size) if needed. On Auto the calculator uses the fewest parallel sets that pass, starting another set when one cable would exceed the Max size beside Conductor Size; with a size pinned, set the number of identical sets with Sets beside it, and each set carries Ib / n. AS/NZS 3000 Cl. 3.4.3 requires every set to be no smaller than 4 mm² and identical in length, cross-sectional area, conductor material and installation method. Sets run side by side are grouped, each counting as a circuit (AS/NZS 3008.1.1 Clause 3.5.2.8): tick Auto beside the Correction Factor field to apply the grouping factor for them. ### Fire-rated and essential-services cables A fire-rated wiring system keeps circuit integrity for a set time in a fire, so the equipment it feeds keeps running. AS/NZS 3013 classifies the complete system, cable, supports, fixings and enclosure together, with a WS code that AS/NZS 3000 Appendix H explains: the first numeral is the time circuit integrity is held in the fire test (1 for 15 minutes up to 5 for 120 minutes), the second the mechanical impact it withstands (1 light to 5 extremely heavy), and a trailing W means it then held integrity when hosed with water. WS52W is 120 minutes of fire, moderate impact and the water test. AS/NZS 3000 Clause 7.2 covers safety services: fire detection, warning and extinguishing systems, smoke control, evacuation systems and emergency lifts. AS/NZS 3000 Appendix H lists the ratings the equipment Standards call for, among them WS5X for hydrant and hose reel pumpsets (AS 2941), WS5X for circuits that run in smoke-control mode (AS/NZS 1668.1), WS51W for fire-rated circuits of a fire detection system (AS 1670.1), WS4X for the submains of a central emergency lighting system (AS 2293.1), and WS52W, or WS53W where vehicles could hit it, for wiring to a substation or main switchboard that supplies emergency equipment under the NCC. AS/NZS 3000 Clause 7.2.2.1, which requires a safety service’s wiring to keep supplying it in a fire, does not apply to fire detection, alarm and intercom systems with battery backup to AS 1670. The supports belong to the classification. AS/NZS 3000 Appendix H asks the supplier to state the fixing and support method the system achieved its WS classification with, and the installer to follow it; tested supports and fixings of equivalent or greater classification and load capacity may be substituted. Where the wiring passes through a fire-rated wall or floor, the fire rating of that element is reinstated around it (AS/NZS 3000 Clause 3.9.9.3). ### Cable size chart: amps for common copper cables in Australia The chart below is the quick reference most people are looking for when they search for an electrical cable size chart: the AS/NZS 3008.1.1:2025 current-carrying capacity, in amps, of the everyday copper multicore sizes, before any derating. Single-phase (two-core and earth) and three-phase (three- or four-core and earth) AC cables sit in different tables because the extra loaded cores run hotter, so a 3 phase cable size is always read from its own column. The in-conduit figures are the ones that decide most final subcircuits and submains; the buried-direct column shows how much more a cable can carry in the ground. Read the chart as a starting point, not the answer. A 6 mm² X-90 single-phase cable rated 46 A in conduit is a 37 A cable once one other circuit shares the conduit (k2 = 0.8, AS/NZS 3008.1.1 Table 3.33), and about a 44 A cable on its own at a 45 °C ambient (k1 = 0.95). The calculator applies those k1 to k4 factors from the AS/NZS 3008.1.1 tables, then runs the voltage drop, short-circuit and earth-fault loop checks that a chart cannot. Enter the design current above and it returns the size that passes all of them. ## Key terms - **Current-carrying capacity (CCC)** — The continuous current a cable can carry without exceeding its insulation temperature rating, read from AS/NZS 3008.1.1 tables and reduced by the applicable derating factors. - **Derating factor** — A multiplier, usually below 1.0, applied to the tabulated current rating for grouping, ambient temperature, soil thermal resistivity or burial depth. Multiple factors multiply together. - **Adiabatic check** — The short-circuit thermal withstand test I²t ≤ k²S²: the fault energy let through by the protective device must not overheat the conductor before the fault clears. - **External loop impedance (Ze)** — The earth fault loop impedance at the board a cable leaves, everything upstream of that cable. At the main switchboard it is the supply and consumer mains; at a distribution board it also includes every submain back to the main switchboard. The Zs of a submain is the Ze of the board it feeds. - **Third harmonic neutral current** — Current at three times the supply frequency from non-linear loads such as LED drivers, drives and switch-mode supplies. It adds in the neutral of a three-phase circuit instead of cancelling, so AS/NZS 3008.1.1 Clause 3.5.9 and Table 3.4 derate or re-size four- and five-core cables where it exceeds 15% of the phase current. - **Earth-fault loop impedance (Zs)** — The total impedance of the earth-fault path. It must be low enough that the protective device trips within the AS/NZS 3000 Clause 5.7.2 disconnection time (0.4 s for socket outlets up to 63 A, 5 s for fixed circuits). - **V-75 and X-90** — Common Australian insulation classes: V-75 is PVC rated 75 degrees Celsius; X-90 is XLPE rated 90 degrees Celsius. The class sets the temperature column used in the AS/NZS 3008.1.1 tables. ## Frequently asked questions ### What size cable do I need? The smallest cable whose derated current-carrying capacity is at least the rating of its protective device, and which still passes voltage drop, short-circuit withstand and earth-fault loop impedance for its length and fault level. As a first guide for copper enclosed in conduit at 40 °C with no grouping (AS/NZS 3008.1.1:2025): 2.5 mm² for a 20 A single-phase circuit and 6 mm² for 32 A in two-core and earth, then for three single-core cables 16 to 25 mm² at 63 A, 35 mm² at 100 A and 95 to 120 mm² at 200 A (X-90 at the smaller size, V-75 at the larger). Grouping, a hot ambient, a long run or a high fault level push the size up. Enter the design current, installation method and route length above and the calculator returns the size that passes every check, with the table each figure came from. ### What standards does the ScaleSet cable size calculator use? AS/NZS 3008.1.1:2025 supplies the current carrying capacity tables (AS/NZS 3008.1.1 Section 3: Tables 3.9 to 3.20 for the supported constructions), derating factors (AS/NZS 3008.1.1 Tables 3.33 to 3.48), conductor R and X values for voltage drop (AS/NZS 3008.1.1 reactance Tables 4.1 and 4.2, a.c. resistance Tables 4.5, 4.7, 4.9 and 4.10) and short-circuit k-values (AS/NZS 3008.1.1 Table 5.1). AS/NZS 3000:2018 drives compliance: AS/NZS 3000 Cl. 2.5.3.1 protection coordination, AS/NZS 3000 Cl. 3.4.3 conductors in parallel, AS/NZS 3000 Cl. 3.5.1 and Table 3.3 minimum conductor sizes, AS/NZS 3000 Cl. 3.6.2 voltage drop limit (5% from the point of supply, or 7% under Exception 3 where the point of supply is a dedicated on-site substation), AS/NZS 3000 Cl. 5.7.2 disconnection times, the AS/NZS 3000 Appendix B4 earth-fault loop framework, AS/NZS 3000 Table 5.1 earth conductor sizing and AS/NZS 3000 Table 8.1 maximum Zs. AS/NZS 3013 covers fire-rated wiring systems and AS 60038 sets the 230 V +10% / -6% voltage envelope. ### What checks does the cable size calculator run? Six checks on every result: (1) current carrying capacity after k1·k2·k3·k4 derating; (2) protection coordination Ib ≤ In ≤ Iz per AS/NZS 3000 Cl. 2.5.3.1; (3) voltage drop against your per-segment limit and the AS/NZS 3000 Cl. 3.6.2 envelope; (4) device breaking capacity against the prospective fault current; (5) the adiabatic I²t ≤ k²S² short-circuit thermal withstand check on both the active and the earth conductor using AS/NZS 3008.1.1:2025 Table 5.1 k-values, with the earth checked at both ends of the run; and (6) earth-fault loop impedance computed from the full R + jX cable loop, Zs = Ze + √((R·L)² + (X·L)²), against the AS/NZS 3000 Cl. 5.7.2 disconnection time. ### How does the cable sizing calculator pick a size on Auto? Auto mode works out the cable, the earth and the protective device from the design current: it picks a breaker rated at or above Ib, then the smallest copper cable that passes all six checks at that rating, using V-75 PVC up to 16 mm² and X-90 XLPE above, multicore up to 95 mm² and single cores from 120 mm². When one cable would exceed the Max size (240 mm² unless you change it) it uses the fewest parallel sets that work. The fault level and Ze come from an indicative supply preset chosen by the load, so switch to Advanced to enter measured figures, choose aluminium, pin a size or pick a specific breaker. ### How much voltage drop is allowed under AS/NZS 3000, and how do I split it across consumer mains, submain and final subcircuit? AS/NZS 3000:2018 Cl. 3.6.2 limits the total drop from the point of supply to any load to 5% of nominal when the supply comes from the network: 11.5 V on a 230 V single-phase circuit and 20 V line-to-line on a 400 V three-phase circuit. Where the point of supply is the low voltage terminals of a substation on the premises and dedicated to the installation, AS/NZS 3000 Cl. 3.6.2 Exception 3 raises the limit to 7%. The total is a budget for the whole path, not a per-segment limit. A conservative allocation is roughly 1.0% on consumer mains, 1.5% to 2.0% on submains, and 2.0% to 2.5% on final subcircuits. The calculator’s Max Drop field (3% by default) is the per-segment limit checked against this cable, so set it to the share of the budget this run is given. ### What size cable do I need for a 32A circuit in Australia? For a single-phase 32 A circuit in copper V-75, the AS/NZS 3008.1.1:2025 tables give 4 mm² unenclosed (34 to 37 A spaced or touching) but 6 mm² enclosed in conduit (4 mm² tabulates 30 A enclosed, just short of 32 A). A three-phase 32 A circuit derates further because three conductors are loaded, and longer runs or tighter voltage-drop allowances often push the result up a size. Re-run the calculator for your actual phasing, length, ambient temperature and grouping, then verify short-circuit withstand and Zs against the upstream device. ### What size cable do I need for a 63A circuit? 16 mm² X-90 or 25 mm² V-75 copper, for three single-core cables enclosed in conduit at 40 °C with no grouping (AS/NZS 3008.1.1:2025 Tables 3.12 and 3.13): 10 mm² X-90 tabulates 56 A and 16 mm² V-75 62 A, both short of a 63 A breaker. Unenclosed on a tray, or buried, the size can drop; grouping, a hot ambient, dry soil or a long run push it back up. Enter the real installation method, correction factor and route length and the calculator also checks the size for voltage drop, short circuit and earth-fault loop impedance. ### What size cable do I need for a 100A submain? A 100 A copper submain typically falls around 25 to 35 mm² depending on installation method, insulation type, conductor arrangement and derating. Three single-core copper V-75 cables in conduit on a wall land at 35 mm², which tabulates exactly 100 A at reference conditions (no headroom for derating). Aluminium will generally require a larger size (around 70 mm² in the same scenario since 50 mm² aluminium tabulates 92 A enclosed in conduit). Voltage drop becomes the governing constraint on long runs or where the upstream allowance is tight. ### What size cable do I need for 200A consumer mains? 120 mm² V-75 or 95 mm² X-90 copper, or 185 mm² V-75 aluminium, for three single-core cables enclosed in conduit at 40 °C with no grouping (AS/NZS 3008.1.1:2025 Tables 3.12 and 3.13): 95 mm² V-75 tabulates 183 A, 70 mm² X-90 183 A and 150 mm² aluminium 190 A, each short of 200 A. Consumer mains are often long enough for voltage drop to govern, so hold this segment to about 1% and leave the submains and final subcircuits their share of the 5% budget. ### How do I derate a cable for grouping and ambient temperature? Enter the combined factor in the Correction Factor field, or open its Wizard and set the ambient air or soil temperature (k1, AS/NZS 3008.1.1 Tables 3.44 and 3.45), the grouping arrangement and number of circuits (k2, AS/NZS 3008.1.1 Tables 3.33 to 3.43) and, for buried cables, the soil thermal resistivity (k3, AS/NZS 3008.1.1 Table 3.48) and depth (k4, AS/NZS 3008.1.1 Tables 3.46 and 3.47), then apply the result. The calculator multiplies the tabulated rating by that factor and sizes the cable so the derated capacity Iz is at least the protective device rating In, which is at least the design current Ib (AS/NZS 3000 Cl. 2.5.3.1). Parallel sets can take their own grouping factor automatically: tick Auto beside the Correction Factor field. ### Which AS/NZS 3008.1.1 installation method should I select? The one that matches how the cable is actually run, because each option reads a different AS/NZS 3008.1.1 current-rating column. Unenclosed Spaced, Spaced from Surface or Touching covers cables on cleats, trays, ladders or fixed to a wall; Unenclosed Exposed to Sun covers outdoor runs; Enclosed in Air covers conduit, trunking or duct above ground; the thermal insulation options cover cables partly or wholly in building insulation; and Buried direct, Underground wiring enclosure or Underground separate conduits covers cables in the ground. Buried ratings assume 1.2 K·m/W soil at 25 °C and 0.5 m deep, so enter the real soil and depth in the Correction Factor Wizard. ### Copper vs aluminium: which conductor should I size with? Copper, unless aluminium is a deliberate cost or weight choice on a large main or submain. Aluminium has about 60% of copper’s conductivity, so it needs one or two sizes larger for the same current, and it needs aluminium-rated terminals, torque-controlled lugs and bimetallic joints where it meets copper. AS/NZS 3008.1.1:2025 rates aluminium from 16 mm² in every insulation class, the 110 °C classes included. Auto mode assumes copper: switch to Advanced and choose Aluminium (Al) in the Conductor selector. The earth beside an aluminium active is a copper conductor, sized from the aluminium column of AS/NZS 3000 Table 5.1. ### V-75 (PVC) vs X-90 (XLPE): which insulation should I pick? X-90 XLPE when capacity is tight, V-75 PVC for smaller everyday circuits. X-90 runs at 90 °C, so the same conductor carries roughly 15 to 25% more current and has a higher short-circuit k-value (142.9 against 111.2 for copper, AS/NZS 3008.1.1:2025 Table 5.1). On Auto the calculator uses V-75 up to 16 mm² and X-90 above, checking each candidate size against the table for the insulation it would be supplied in. In Advanced you can also pick R-90 elastomeric for harsh or vibration-prone runs, and X-110 or R-110 for fire-rated circuits or where 90 °C is still short. Check the terminal rating of the breakers and lugs the cable lands on: AS/NZS 3008.1.1 Table 3.1 says a 110 °C cable should only connect to equipment suitable for that temperature. ### Single-core vs multi-core cables: which should I pick? Multicore up to about 95 mm², single cores above. A multicore cable keeps every conductor in one sheath, so it is quicker to install and terminate; single cores are easier to pull and bend at large sizes and are what most large parallel feeders use. Auto follows that split: multicore to 95 mm², single cores from 120 mm² (the multicore tables stop at 500 mm²). For single cores the Conductor Arrangement selector sets trefoil, flat touching or flat spaced, which sets the reactance read from AS/NZS 3008.1.1 Table 4.1(A). Parallel sets of either kind must be at least 4 mm² and of the same material, size, route and length (AS/NZS 3000 Cl. 3.4.3). ### How do I size a fire-rated cable for a fire pump or essential services? Size it like any other circuit, in the 110 °C insulation the specification names. In Advanced, pick XLPE (110 °C), which is X-HF-110, or Elastomeric (110 °C), which is R-HF-110 or R-E-110, from the Insulation selector; every check then runs on the 110 °C current-rating, impedance and k-value tables (k = 131.8 for copper). Fire rating is for loads that must keep running from the mains during a fire with no battery of their own: fire pumps, essential mechanical services such as smoke control fans, fire-mode lifts and fire detection or warning systems without a battery-backed head end. The AS/NZS 3013 wiring system classification, the supports and the penetration seals are specified separately, from the fire engineering report. ### When is short-circuit thermal withstand the limiting factor? When the prospective fault current is high, close to the transformer or on a large on-site substation, and the protection is slow to clear it. The Source Fault field carries the prospective Isc where the cable starts, and Fault Duration is how long the protection takes to clear it: left blank it follows the device class (20 ms for an MCB or RCBO, 40 ms for an MCCB or HRC fuse, 60 ms for an ACB), a committed short-time delay is charged in full, and an 80 ms preset covers a trip unit held on a short-time delay. For a fuse, a far-end earth fault near its trip current is charged the 0.4 s that AS/NZS 3000 Table 8.1 reads Ia at. The check is I²t ≤ k²S² on the active and on the earth (at both ends of the run), with k from AS/NZS 3008.1.1:2025 Table 5.1: 111.2 for copper PVC (98.5 above 300 mm²), 142.9 for copper 90 °C XLPE or elastomer, 131.8 for the copper 110 °C classes, 73.7 for aluminium PVC and 94.6 for aluminium XLPE. A manufacturer let-through I²t entered for the device replaces Isc² × t. ### How does the calculator check earth-fault loop impedance under AS/NZS 3000? The calculator implements the AS/NZS 3000 Appendix B4 earth-fault loop framework using the full cable impedance: Zint = √((R_loop·L)² + (X_loop·L)²) / 1000, where R_loop and X_loop sum the active and earth conductor values per kilometre at operating temperature (AS/NZS 3000 Appendix B4 lets reactance be ignored at 35 mm² or less where the active and earth run close together, so on small cables this is the familiar resistance-only method). The total loop impedance is Zs = |Ze + Zint|, the supply and cable impedances added as vectors, with Ze the earth fault loop impedance at the board the cable leaves: the supply and consumer mains, plus every submain upstream when the cable leaves a distribution board (presets from 0.02 Ω at an on-site substation MSB to 0.38 Ω at a residential final circuit). Entering the network’s Ze for a circuit on a distribution board leaves the submains out and reads Zs low. The pass condition is Zs ≤ U₀ / Ia with U₀ = 230 V: Ia is 4, 7.5 or 12.5 × In for a type B, C or D MCB (AS/NZS 3000 Table 8.1 and Paragraph B4.5), 1.2 × Im for a thermal-magnetic MCCB, 1.1 × Ii (or 1.1 × Isd on a short-time stage) for an electronic-trip MCCB or ACB, and, for a fuse, a trip multiple read off its curve where you enter one, else the AS/NZS 3000 Table 8.1 0.4 s figure for ratings from 6 to 200 A and 10 × In outside them. The earth beside an aluminium active is the AS/NZS 3000 Table 5.1 copper conductor and is taken into the loop as copper. The disconnection time required by AS/NZS 3000 Cl. 5.7.2 is 0.4 s for socket outlets up to 63 A and portable equipment, and 5 s for fixed and distribution circuits. ### What size earth conductor do I need? At least the AS/NZS 3000 Table 5.1 size for the active, and larger if the fault checks need it. For copper actives AS/NZS 3000 Table 5.1 gives an earth equal to the active up to 2.5 mm², 2.5 mm² for 4 and 6 mm², 4 mm² for 10 mm², 6 mm² for 16 and 25 mm², 16 mm² for 50 mm², 25 mm² for 70 and 95 mm², 50 mm² for 150 mm², 95 mm² for 240 mm² and 120 mm² from 300 to 630 mm². An aluminium active takes a smaller copper earth from the table’s second column, and an earth run as a separate single-core cable is never below 2.5 mm² (AS/NZS 3000 Cl. 5.3.3.4). The calculator’s Earth Size selector defaults to Auto: it starts from AS/NZS 3000 Table 5.1 and upsizes the earth, never beyond the active, until it passes the adiabatic check at both ends of the run and the Zs check. ### What is the smallest cable allowed under AS/NZS 3000? 1 mm² copper for most final subcircuits and 2.5 mm² copper for socket-outlet circuits, under AS/NZS 3000:2018 Clause 3.5.1 and Table 3.3, whose exceptions allow less in limited cases. The same table sets 0.5 mm² for signal and relay control circuits, 0.75 mm² for insulated flexible cords, and 6 mm² copper or 16 mm² aluminium for aerial wiring. Mains and submains have no AS/NZS 3000 Table 3.3 minimum of their own: capacity, voltage drop, short circuit and Zs set their size, and the local service and installation rules can set a floor for consumer mains. The calculator offers 1 to 630 mm², and parallel sets start at 4 mm². ### How do I size a cable for a three-phase motor? Enter the motor’s full-load current from the nameplate as the design current, set System Type to 3 Phase (400 V) and, in Advanced, choose a 3C+E or 3x1C+E core arrangement, since a balanced motor needs no neutral. The starting current is not the design current: the motor protection is set to ride through it. Where a specification asks for a margin, such as 1.25 × full-load current for continuous duty, enter that figure instead. On long runs voltage drop usually governs, because low voltage at the motor terminals costs starting torque. ### How do I size parallel cable runs? On Auto the calculator splits a large load into the fewest parallel sets that pass, starting a new set when one cable would exceed the Max size, so lower Max to get more, smaller sets. With a size pinned, set the number of sets beside it. AS/NZS 3000 Cl. 3.4.3 lets parallel cables share the load when each is at least 4 mm² and they are the same material, size, route and length, joined at each end; each set then carries the circuit current divided by the number of sets, and AS/NZS 3000 Cl. 3.6.3 takes the voltage drop of one set at that share. Sets run side by side are grouped: tick Auto beside the Correction Factor field to apply the AS/NZS 3008.1.1 grouping factor for them. ### Why is the Design Current (Ib) input capped at 4000 A? 4000 A is the practical ceiling for cable-fed feeders in Australian LV switchboards. Above that, the standard solution is busbar trunking (busduct) rather than parallel cables: manufacturers publish busbar systems up to 6300 A and beyond, and the switchgear that lands on them (ACBs, fixed-pattern boards) is built around that interface. By 4000 A you are already running roughly 8 × 630 mm² parallel runs per phase, and beyond that so many cables run side by side that the derating tables stop being reliable and you cannot be confident the runs are sharing current evenly. The cap is a design judgement rather than a search limit; designs that need more capacity should be modelled as busbar, since AS/NZS 3008 does not cover busduct and the tested rating tables from the manufacturer apply instead. ### Which MCB protective device curve should I use: B, C or D? C for general circuits, B for lighting and resistive loads, and D only for high inrush such as transformers and motors. The curve sets the trip current Ia in the earth-fault loop check Zs ≤ U₀ / Ia, and the calculator takes Ia as 4, 7.5 or 12.5 × In for curve B, C or D, the AS/NZS 3000 Paragraph B4.5 figures behind Table 8.1. A higher curve therefore allows a lower maximum Zs, so a D curve that fails Zs where a C curve passes needs a lower curve, a larger cable or an electronic-trip device with a lower instantaneous setting. Pick the curve in the Device type list in Advanced. ### Does the calculator handle four-core cables and neutral derating? Yes. The Core Arrangement selector (in Advanced) covers four single-phase layouts (2C+E, 2C, 2x1C+E, 2x1C) and six three-phase layouts (4C+E, 3C+E, 4C, 4x1C+E, 3x1C+E, 4x1C). For a balanced three-phase load with no neutral (most three-phase motors) pick a 3C+E or 3x1C+E construction; for any submain feeding single-phase loads downstream pick a 4C+E or 4x1C+E so a neutral is included. The calculator counts loaded conductors when it pulls the AS/NZS 3008.1.1 capacity table: three loaded actives in a 4C+E cable are rated lower than two loaded actives in a 2C+E. Where the load is harmonic-rich (LED lighting, drives, IT equipment), AS/NZS 3008.1.1 Clause 3.5.9 and Table 3.4 apply: 15 to 33% third harmonic takes a factor of 0.86 on a 4-core cable’s rating, and above 33% the phase and neutral conductors are sized on the neutral current, with 0.86 up to 45% and 1.0 above. The calculator does not apply AS/NZS 3008.1.1 Table 3.4 itself: for 15 to 33% enter 0.86 in the Correction Factor field, and above 33% enter the neutral current as the design current, with 0.86 in the Correction Factor field up to 45%. ### Is the ScaleSet cable size calculator free? Yes. Sizing a cable is free and needs no account: the page runs in your browser and the calculation runs on the ScaleSet server, which holds the AS/NZS 3008 tables. Downloading the cable selection PDF report needs a free account, and the project details you enter (project name, number, address, designer, revision) print on it. Saving the job as a project file needs no account. ### Will my cable fit the circuit breaker terminal in the switchboard? AS/NZS 61439.1 Annex A Table A.1 lists the copper conductor sizes a terminal for external conductors must accept for its rated current, one cable per terminal: 1.5 to 4 mm² at 16 A, 6 to 25 mm² at 63 A, 16 to 50 mm² at 100 A, 35 to 95 mm² at 160 A, 70 to 150 mm² at 250 A and 95 to 240 mm² at 315 A, with a narrower range for flexible conductors. Above 315 A terminals are by agreement. When a single copper cable falls outside the range for its device rating the report says so under Assumptions, so the switchboard builder can confirm the terminal or fit a lug or adaptor. ### Is there an electrical cable size chart for Australia showing amps per cable size? Yes. The guide above includes a cable size chart with the AS/NZS 3008.1.1:2025 current-carrying capacity in amps for the common copper multicore sizes from 1.5 mm² to 120 mm², single-phase and three-phase, in conduit and buried direct. It shows the table value before derating; the calculator then applies the grouping, ambient, soil and depth factors and runs the voltage drop and fault checks for your actual circuit. ### How do I calculate cable size in Australia? Work out the design current Ib (maximum demand or motor full-load current), pick a protective device with In ≥ Ib, then find the smallest cable whose derated current-carrying capacity Iz is at least In in the AS/NZS 3008.1.1 table for your conductor, insulation and installation method. Check that the voltage drop over the route length stays inside the AS/NZS 3000 5% budget, that the cable survives the prospective fault current for the device clearing time (I²t ≤ k²S²) and that the earth-fault loop impedance lets the device trip in time. Enter the same inputs above and the calculator does all six checks and shows the working. ### Can I use this as a single phase or 3 phase cable size calculator? Yes. Set System Type to 1 Phase (230 V) or 3 Phase (400 V). Single-phase reads the two single-core and two-core ratings (AS/NZS 3008.1.1 Tables 3.9 to 3.11 and 3.15 to 3.17) with a voltage drop factor of 2; three-phase reads the three single-core and three- and four-core ratings (AS/NZS 3008.1.1 Tables 3.12 to 3.14 and 3.18 to 3.20) with √3, and rates a four-core cable on three loaded conductors, a balanced load. Where third harmonic current exceeds 15% of the phase current, AS/NZS 3008.1.1 Clause 3.5.9 and Table 3.4 apply and are entered by hand in the Correction Factor field. ### Is this an AC cable size calculator, or does it cover DC as well? It sizes AC cables: single-phase 230 V and three-phase 400 V at 50 Hz. AS/NZS 3008.1.1:2025 rates d.c. circuits in tables of their own (AS/NZS 3008.1.1 Tables 3.21 to 3.26 for current, and d.c. resistance and voltage drop tables in Section 4), which this calculator does not read, so size a solar string or battery cable from those. The Voltage Rise Calculator covers the inverter’s AC side. ## Related ScaleSet pages - [Voltage Rise Calculator (AS/NZS 4777.1)](https://scaleset.com.au/calculator/voltage-rise) - [Solar & Battery ROI Calculator](https://scaleset.com.au/calculator/solar-roi) - [Voltage Drop Calculator](https://scaleset.com.au/calculator/voltage-drop) - [Correction Factor Calculator](https://scaleset.com.au/calculator/correction-factor) - [Conduit Sizing Calculator](https://scaleset.com.au/calculator/conduit-sizing) - [Cable Tray Sizing Calculator](https://scaleset.com.au/calculator/cable-tray) - [Earthing Cable Size Calculator](https://scaleset.com.au/calculator/earth-cable-size) - [Maximum Demand Calculator](https://scaleset.com.au/calculator/max-demand) - [Switchboard Sizing Calculator](https://scaleset.com.au/calculator/switchboard-sizing) - [Selectivity Calculator (Breaker Discrimination)](https://scaleset.com.au/calculator/selectivity) - [EleCAD Single Line Diagram Builder](https://scaleset.com.au/elecad) - [PowerCAD Alternative](https://scaleset.com.au/powercad-alternative) - [Design Guides](https://scaleset.com.au/design-guide) - [AI Mode](https://scaleset.com.au/ai) - [Voltage Rise Design Guide (worked example)](https://scaleset.com.au/design-guide/voltage-rise) - [AS/NZS 3000 Table C1 Domestic Maximum Demand](https://scaleset.com.au/calculator/c1) - [Calculation Verification](https://scaleset.com.au/verification) ## About this page Methods built and reviewed by Wisam Tozah (CPEng, NER, MIEAust), Sydney, Australia. How the methods are tested and reviewed: https://scaleset.com.au/verification. ScaleSet is a design aid: your inputs and results are not reviewed or certified, and responsibility for the design stays with the engineer who issues it. Profile: https://scaleset.com.au/creator. Usage: this page may be read, indexed, retrieved and cited, including as grounding for an AI answer, with attribution to ScaleSet and a link to https://scaleset.com.au/calculator/cable-selection. Reproducing it, training a model on it, or using it to build a derivative or competing site is not licensed. Terms: https://scaleset.com.au/terms. Machine-readable policy: https://scaleset.com.au/ai-usage-policy.json Site index for assistants: https://scaleset.com.au/llms.txt — full content: https://scaleset.com.au/llms-full.txt