Simplified Selector
Read the Appendix C device rating and voltage drop tables.
Questions
Each answer describes what this tool calculates. The result is a design aid. Verify against the current standard.
What does the simplified selector do?
The tool reads AS/NZS 3000:2018 Tables C6 and C7 for the largest protective device a cable from 1 to 25 square millimetres may carry. It then reads Table C8 for the voltage drop over the run and the smallest size that meets the limit.
When should I use the full cable size tool instead?
Use the cable size tool when circuits are grouped, when the ambient temperature is not 30 degrees, when the cable is not PVC two-core or four-core and earth, or when the size is above 25 square millimetres. Appendix C assumes one circuit on its own.
How is the voltage drop worked out?
Multiply the design current by the route length to get ampere metres. Divide that by the ampere metres per percent for the size in Table C8. The answer is the drop as a percent of 230 volts single phase or 400 volts three phase.
Which installation condition should I pick?
Match the way the cable sits. A cable clipped in free air reads as unenclosed. A cable in a conduit, a duct or a wall cavity reads as enclosed in air. A buried run reads as enclosed in ground. Insulation around the cable reads as partly or completely surrounded. Note 3 to Table C6 gives the full mapping.