ElecAS
Earthing Cable Size Calculator
Determine minimum protective earthing conductor sizes using AS/NZS 3000 Table 5.1 criteria.
Why this page matters
Determine minimum protective earthing conductor sizes using AS/NZS 3000 Table 5.1 criteria. This static content is published so the canonical route has meaningful crawlable HTML even before the interactive application hydrates.
Who this page is for
Designers checking protective earthing conductor sizing against active conductor and device conditions.
Relevant standards
- AS/NZS 3000 Table 5.1
What this tool helps with
- Look up protective earthing conductor sizes from active conductor data.
- Use the result during final circuit design and compliance review.
- Connect earthing outcomes with cable sizing and demand calculations.
Frequently asked questions
How is the protective earthing conductor size determined?
- AS/NZS 3000:2018 Table 5.1 gives the minimum protective earthing conductor cross-sectional area as a function of the active conductor size. Larger active conductors require larger earthing conductors, with a minimum of 2.5 mm² for installations with mechanical protection.
Can the earthing conductor be smaller than the active?
- Yes, for active conductors above 35 mm² Table 5.1 allows the earthing conductor to be one size smaller, provided the prospective earth fault current and protective device disconnection time still satisfy the adiabatic equation in Clause 5.3.3.
Does the earthing conductor need to be the same material as the active?
- Not necessarily. AS/NZS 3000 Table 5.1 has separate columns for copper and aluminium. When mixing materials, apply the equivalent cross-section conversion.