सर्किट लोडिंग कैलकुलेटर

How this is calculated#

The tool counts the points a final subcircuit can carry. It reads AS/NZS 3000:2018 Table C9. You enter the breaker rating, the cable size and the points on the circuit.

1. Lighting points. Each point adds the current that Table C9 gives for a lighting point.
2. Socket‑outlets. The tool counts 10 A, 15 A and 20 A socket‑outlets. Each group has its own contribution in Table C9.
3. Fixed and stationary load. You enter the rated current of fixed loads. The tool adds it in full.
4. Cooking and diversity. If you turn them on, the tool adds the cooking demand and applies the diversity for upstream devices.
5. Sum of contributions. The tool adds all contributions.
6. Check. It compares the sum with the breaker rating. The pair of cable size and device rating must also be one that Table C9 lists.

Worked example#

• Eight 10 A socket‑outlets on a 20 A circuit. The cable is 2.5 mm² in a domestic installation. The sum of contributions is 8 A. That is within the 20 A breaker rating, so the tool passes the circuit.

Limits#

The tool fails a circuit when the sum is over the rating. It warns when Table C9 does not pair the cable with the device. It also fails a cooking range that the table does not permit.

It counts points. It does not check the voltage drop or the loop impedance. Use the cable size calculator for those.

See also: Maximum demand with Table C1 and C2, What size breaker for 4 mm² cable and the maximum demand tool.