EV charger circuit calculator
Check EV chargers for spare capacity, cable size and RCD.
Reads AS/NZS 3000:2018. Tables checked 1 Oct 2026.
Try a job 9
Each job fills in example values. Replace them with your values.
- Charge an EV from a home socket-outletThe circuit a mode 2 charging lead needs on a home socket-outlet.
- Check spare capacity for an EV chargerWhether a 7 kW charger fits a 63 A board that already carries 40 A.
- Add EV chargers to an Australian car parkWhether four 22 kW chargers fit a 400 A board, with and without load management.
- Add a 22 kW charger to a houseThe cable, RCD and headroom for a three-phase charger.
- Add a charger with load managementThe headroom when the charger is limited to 16 A.
- Add a second charger to a houseThe headroom with two 32 A chargers.
- Choose a charger RCD without d.c. detectionThe RCD type when the station has no 6 mA d.c. detection.
- Size a long charger runThe cable for a 32 A charger 40 m from the board.
- Add six chargers to an apartment car parkThe demand and supply for six chargers in New Zealand.
Inputs
Worked example with the default inputs. The live calculator replaces it when the page loads.
- Country
- New Zealand · Clause 7.9
- Charging mode
- Mode 3
- Installation
- Domestic electrical installation
- Number of chargers
- 1
- Charger supply
- Single-phase
- Charger rated current
- 32 A
- Board supply
- Single-phase
- Main switch or supply rating
- 0 A
- Maximum demand without the chargers
- 0 A
- Load management device
- No
- Run length
- 20 m
- Installation method
- Enclosed in air
- Material
- Copper
- Insulation
- PVC 75 °C
Spare capacity
Not assessed
- Cable size
- 6mm²
- Residual current device
- 30 mA Type B, separate, in every live conductor
- Charger demand
- 32A
- Minimum single-phase final subcircuit capacity
- 32A
- Isolating switch
- 32A
- Clauses to read
- AS/NZS 3000:2018 Cl 7.9.3.3
This result is a design aid. Verify it against the current standard.
Calculation steps
- Clause read for these figures7.9.3.3
AS/NZS 3000:2018 Cl 7.9.3.3
- Minimum single-phase final subcircuit capacity32A
AS/NZS 3000:2018 Cl 7.9.3.3
- Other points on the final subcircuitNone, the clause excludes them
AS/NZS 3000:2018 Cl 7.9.3.3
- Maximum rated residual current30mA
AS/NZS 3000:2018 Cl 7.9.3.3
- Residual current device typeB
AS/NZS 3000:2018 Cl 7.9.3.3
- Residual current device arrangementSeparate device, in every live conductor, the neutral included
AS/NZS 3000:2018 Cl 7.9.3.3
- Alternative device in the ExceptionA with RDC-DD
AS/NZS 3000:2018 Cl 7.9.3.3
- RDC-DD detection level, from a NOTE6mA
AS/NZS 3000:2018 Cl 7.9.3.3
- Minimum isolating switch rating32A
AS/NZS 3000:2018 Cl 7.9.3.3
- Minimum height from the floor or ground800mm
AS/NZS 3000:2018 Cl 7.9.3.3
- Chargers counted on the heaviest phase1
- Share of rated current counted100%
AS/NZS 3000:2018 Table C1 group (j)(iv)
- Charger demand on the heaviest phase32A
AS/NZS 3000:2018 Table C1 group (j)(iv)
- Cable design current32A
- Cable size6mm²
AS/NZS 3008.1.2:2017
- Voltage drop at that size2.09%
AS/NZS 3008.1.2:2017
About this calculator
How this is calculated
The tool checks an EV charger circuit. It reads Clause 7.9.3.3 of AS/NZS 3000:2018 for the circuit, the RCD and the isolating switch. It reads Table C1 for the charger demand. It then takes a cable size from the cable size calculator.
- Circuit rules. The tool prints the minimum final subcircuit capacity and the other points allowed on it. It also prints the isolating switch rating (Cl 7.9.3.3).
- RCD. It prints the maximum rated residual current, the type and the arrangement of the device. It also lists the Exception that allows a device with RDC-DD.
- Charger demand. It counts the chargers on the heaviest phase. It applies the share of rated current that group (j)(iv) of Table C1 counts. Load management can set a lower limit.
- Spare capacity. It subtracts your maximum demand from the supply rating. It then subtracts the charger demand.
- Cable. It takes the design current for the charger. It sizes the cable and gives the drop over your run.
| Step | Table or clause | What it decides |
|---|---|---|
| Circuit and switch | Cl 7.9.3.3 | The capacity, the points and the isolator |
| RCD | Cl 7.9.3.3 | The type, the rating and the arrangement |
| Charger demand | Table C1 group (j)(iv) | The current counted for each charger |
| Cable | AS/NZS 3008.1.2 | The size and the drop for the run |
Worked example
- 32 A Mode 3 charger on a 63 A supply with a 40 A demand. The charger is 20 m from the board. The tool finds the board short by 9 A. It gives a 6 mm² cable with a 2.09 % drop.
Limits
- The tool reads the clause and prints its figures. It is a pointer to the clause, not a ruling on a design.
- Clause 7.9 adds to Sections 2 to 7. A figure the tool does not report can still come from those Sections.
- The clause prints a capacity figure for single-phase circuits only. It prints none for a three-phase circuit.
- The RDC-DD level comes from a NOTE. A NOTE is not a requirement.
- The cable uses the default inputs of the cable size tool. Open that tool to set grouping or ambient.
- The tool reads the 2018 edition with Amendments 1, 2 and 3. It does not read the supply authority rules.
See also: Clause 7.9 and EV charging in NZ, EV charging load and spare capacity and EV charger spare capacity on a 63 A main switch.
Questions
Each answer describes what this tool calculates. The result is a design aid. Verify against the current standard.
What does the EV charger tool do?
It checks chargers against the spare capacity at the board, sizes the cable and names the residual current device. In New Zealand it reads AS/NZS 3000:2018 Clause 7.9. For domestic Mode 2 it adds the 30 mA of Clause 2.6.3.3.1, which Clause 7.9.1 keeps in force. Clause 7.9.3.3 prints the 32 A capacity for single-phase final subcircuits only.
How does the spare-capacity check work?
Enter the main switch rating and the maximum demand without the chargers, per phase. The difference is the spare capacity. The tool counts every charger at its rated current on the heaviest phase: Table C1 group (j)(iv) in a New Zealand home, Appendix P Paragraph P2 elsewhere. With load management, it shows the managed case beside the unmanaged one.
What does the tool read for Australia?
Clause 2.2.1.4 points to Appendix P, which is informative. Paragraph P4.1 names a 30 mA device of at least Type A for each charging point. A Mode 3 or Mode 4 outlet adds a d.c. measure: Type B, or Type A with 6 mA d.c. detection. Where the charger detects d.c. fault current itself, Type A follows.
Which residual current device figures does the tool report for Mode 3?
Those in Clause 7.9.3.3 and its Exception. The clause sets a separate Type B device at 30 mA in every live conductor, the neutral included. For Mode 3, the Exception names Type A with an RDC-DD instead. The 6 mA RDC-DD figure sits in a NOTE, not in the clause body. The tool marks it as a note.
Is this a ruling on whether my installation complies?
No. The clause figures are pointers to the clause numbers. The spare-capacity check compares the figures you type, and the cable comes from the cable size tool. A licensed electrical worker reads the clauses and decides how they apply to the work in front of them.
Clauses and tables this tool reads
- AS/NZS 3000:2018 App P Para P2Maximum demand of charging points
- AS/NZS 3000:2018 App P Para P4.1Residual current devices for charging points
- AS/NZS 3000:2018 Cl 2.2.1.4Electric vehicle charging circuits
- AS/NZS 3000:2018 Cl 2.6.3.3.1Additional protection in New Zealand, residential
- AS/NZS 3000:2018 Cl 7.9.1Scope of Clause 7.9, electric vehicle supplies
- AS/NZS 3000:2018 Cl 7.9.2.1Source of supply for electric vehicle charging
- AS/NZS 3000:2018 Cl 7.9.2.2Socket-outlets for Mode 1 charging
- AS/NZS 3000:2018 Cl 7.9.3.2Facilities for Mode 2 charging
Every clause and table, with how each was verified
Tables last checked on 1 Oct 2026.
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