Kōwhiri taura māmā
Pānuitia ngā ripanga reiti taputapu me te heke voltage o Appendix C.
Reads AS/NZS 3000:2018. Tables checked 26 Sept 2026.
Whakamātau mahi 6
Ka whakakī ia mahi i ngā uara tauira. Whakakapia ērā ki ō uara.
- Match a breaker to a 2.5 mm² cableThe largest breaker for a 2.5 mm² cable partly in ceiling insulation over 30 m.
- Match a breaker to lighting cableThe largest breaker for 1.5 mm² over 35 m.
- Match a breaker to 4 mm²The largest breaker for 4 mm² over 25 m.
- Match a breaker to oven cableThe largest breaker for 6 mm² over 15 m.
- Check a three‑phase 10 mm² circuitThe largest breaker for 10 mm², three phase, over 40 m.
- Match a breaker in full insulationThe largest breaker for 2.5 mm² fully in insulation.
Ngā whakauru
He tauira mahi me ngā whakauru taunoa.
- Rahi taura
- 2.5 mm²
- Ngā wāhanga
- Kotahi wāhanga, 230 V
- Āhuatanga whakauru
- Kore kēhi i te hau
- Iahiko hoahoa
- 20 A
- Te roa o te ara
- 25 m
- Rohe heke voltage
- 5 %
Ine taputapu teitei rawa
25A
- Heke voltage
- 3.91%
- Mita-ampia
- 500
- Rahi mō te rohe o te heke whakahiato
- 2.5mm²
He āwhina hoahoa tēnei hua. Manatokohia ki te paerewa o nāianei.
Ngā hīkoi tātaitanga
- Reiti taputapu nui rawa InHua25A
AS/NZS 3000:2018 Tables C6 and C7
- Mita-ampia500
AS/NZS 3000:2018 Table C8
- Mita-ampia ia ōrau mō tēnei rahi128
AS/NZS 3000:2018 Table C8
- Heke whakahiato3.91%
AS/NZS 3000:2018 Table C8
- Mita-ampia ia ōrau e hiahiatia ana mō te rohe100
AS/NZS 3000:2018 Table C8
- Te rahi iti rawa mō te rohe heke o te hiko2.5mm²
AS/NZS 3000:2018 Table C8
Mō tēnei tātaitai
How this is calculated
The tool reads the simplified tables of AS/NZS 3000 Appendix C. They cover copper cable from 1 mm² to 25 mm². They give the largest device rating and the voltage drop in one pass.
- Maximum device rating. The tool reads the rating for your size, phases and installation condition from Tables C6 and C7.
- Ampere metres. It multiplies the load current by the one-way length.
- Ampere metres per percent. It reads the value for your size from Table C8.
- Voltage drop. It divides the ampere metres by that value. The result is the drop in percent.
- Size for the limit. It divides the ampere metres by your limit. It then picks the smallest size from Table C8 that meets the figure.
| Step | Table or clause | What it decides |
|---|---|---|
| Device rating | AS/NZS 3000 Tables C6 and C7 | The largest device for the size and condition |
| Drop and size | AS/NZS 3000 Table C8 | The drop for the run and the size for your limit |
Worked example
- 2.5 mm² on one phase over 25 m at 20 A. The cable is in unenclosed air. The maximum device rating is 25 A. The run is 500 ampere metres. The drop is 3.91 %, inside the 5 % limit. The size for the limit is 2.5 mm².
Limits
The tables assume one circuit on its own. Where circuits are grouped, use the cable size calculator. The tool does not apply correction factors. It does not read AS/NZS 3008.1 tables. It stops at 25 mm².
See also: Cable size for a 32 A single‑phase run of 25 m, AS/NZS 3000 Clause 3.6.2 voltage drop limit and Voltage drop basics.
Pātai
He āwhina hoahoa te hua. Manatokohia ki te paerewa o nāianei.
He aha te mahi a te Simplified Selector?
Ka pānui te taputapu i AS/NZS 3000:2018 Tables C6 me C7 mō te taputapu whakamaru nui rawa e taea ai e tētahi taura 1 ki te 25 mm² te kawe. Kātahi ka pānui i Table C8 mō te heke voltage i te ara, me te rahi iti rawa e tutuki ai te tepe.
Āhea me whakamahi au i te taputapu Rahi Taura katoa hei utu?
Whakamahia te taputapu rahi taura ina whakarōpūtia ngā ara iahiko, ina kore te pāmahana taiao e 30 degrees, ina kore te taura he PVC rua-kaikawe, whā-kaikawe me te whenua, ina neke atu rānei te rahi i te 25 mirimita tapawhā. E whakaaro ana a Appendix C kei a ia anake tētahi ara iahiko.
Me pēhea te tātai i te heke voltage?
Whakareatia te iahiko hoahoa ki te roa o te ara hei tiki i ngā ampere mita. Wehea taua mea ki ngā ampere mita ia ōrau mō te rahi i Table C8. Ko te hua ko te heke hei ōrau o te 230 volts wāhanga kotahi, te 400 volts wāhanga toru.
Ko tēhea āhuatanga whakaurunga me kōwhiri au?
Hāngaitia te āhua o te taura e noho ana. Ko tētahi taura e piri ana ki te hau kore kōpaki ka pānuitia hei kore kōpaki. Ko tētahi taura i roto i tētahi conduit, tētahi awaawa, tētahi kōpaki pakitara ka pānuitia hei kōpaki ki te hau. Ko tētahi rere tanu ka pānuitia hei kōpaki ki te whenua. Ko te insulation e karapoti ana i te taura ka pānuitia hei karapoti wāhi, karapoti katoa rānei. Ko Note 3 ki Table C6 te mahere katoa.
Ngā Clause me ngā Table e pānuitia ana e tēnei taputapu
- AS/NZS 3000:2018 Table C6, C7Simplified protective device selection for 1 to 25 mm² cables
- AS/NZS 3000:2018 Table C8Simplified voltage drop, ampere metres per percent
Ia Clause me Table, me te pēhea i manatokotia ai ia tētahi
Ngā tūtohi i arotakehia whakamutunga i te 26 Sept 2026.
Ngā taputapu hononga
- Tātaitai rahi tauraFind the smallest cable size that passes each check.AS/NZS 3008.1.2AS/NZS 3008.1.1AS/NZS 3000
- Arotake ara iahiko o nāianeiCheck an installed circuit: cable, device, drop and Zs.AS/NZS 3008.1.2AS/NZS 3008.1.1AS/NZS 3000
- Tātaitai Iahiko Uta KatoaCalculate full load current from power, voltage and phase.Kāore he paerewa
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