简易电缆选型
查阅附录 C 中的保护装置额定值和电压降表。
Reads AS/NZS 3000:2018. Tables checked 26 Sept 2026.
尝试一个工程 6
每项工作都会预填示例数值。请替换为您自己的数值。
- 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.
输入
使用默认输入值的示例计算。
- 电缆截面
- 2.5 mm²
- 相
- 单相，230 V
- 安装条件
- 空气中未封闭
- 设计电流
- 20 A
- 路径长度
- 25 m
- 电压降限值
- 5 %
最大装置额定值
25A
- 电压降
- 3.91%
- 安培米
- 500
- 按压降限值选择规格
- 2.5mm²
此结果仅供设计参考。请对照现行标准进行核验。
计算步骤
- 装置最大额定值 In结果25A
AS/NZS 3000:2018 Tables C6 and C7
- 安培米500
AS/NZS 3000:2018 Table C8
- 该规格每百分比的安培米数128
AS/NZS 3000:2018 Table C8
- 电压降3.91%
AS/NZS 3000:2018 Table C8
- 达到限值所需的每百分比安培米数100
AS/NZS 3000:2018 Table C8
- 满足电压降限值的最小规格2.5mm²
AS/NZS 3000:2018 Table C8
关于此计算器
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.
问题
结果仅供设计参考。请依据现行标准核对。
简易选型工具有什么作用？
工具读取 AS/NZS 3000:2018 Tables C6 和 C7，以获得 1 至 25 mm² 电缆可承载的最大保护装置。随后读取 Table C8，获得线路的电压降以及满足限值的最小截面。
何时应改用完整的电缆截面工具？
当回路成组敷设、环境温度不为 30 °C、电缆并非 PVC 双芯或四芯带接地，或截面超过 25 mm² 时，请使用电缆截面工具。Appendix C 假定单独一个回路敷设。
电压降如何计算？
将设计电流乘以线路长度，得到安培米。再除以 Table C8 中该截面每百分比的安培米数。结果即为占单相 230 V 或三相 400 V 的压降百分比。
应选择哪种安装条件？
按电缆的敷设方式对应。在空气中明敷卡固的电缆视为非封闭。穿于线管、管道或墙腔中的电缆视为封闭于空气中。埋地敷设视为封闭于土壤中。电缆周围有隔热材料时，视为部分或完全被隔热材料包围。Table C6 的注 3 给出完整对应关系。
本工具读取的条款和表格
- 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
表格最后核对于 26 Sept 2026。
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