Disclaimer

Estimates, not compliance

Every calculator on Wire Math is an estimator. Results are intended to support understanding, quoting, and conversation — not to certify that a circuit, cable, or installation meets BS 7671 or any other regulatory requirement.

A green result on this site does not mean a design is compliant. A red warning does not mean a design is non-compliant. The compliance question always belongs to a qualified person working from the current regulations and the specific installation context.

What is out of scope

• Cable derating for grouping, ambient temperature, soil thermal resistivity, or installation method.
• Protective device coordination, fault current, earth-loop impedance, and disconnection times.
• Volt-drop limits applied as a pass/fail. We surface common UK design references (3% lighting, 5% other final circuits) as context only.
• Project-specific advice. Wire Math has no view of your actual installation, environment, or load profile.

Use at your own risk

The calculators are provided "as is" without warranty of any kind. Wire Math accepts no liability for losses arising from reliance on a result, whether the result was correct, incorrect, or correctly computed from incorrect inputs.

If you spot a number that looks wrong, please report it via /contact with the build identity from the footer attached.

UK-specific framing

Defaults across the site are UK-typical: metric units (mm², mm, m, V, A), 230 V single-phase / 400 V three-phase, copper as the default conductor, and the BS 7671 CSA ladder in selectors. UK spelling is used in the interface (metre, aluminium, optimise). None of this constitutes a claim that a result is BS 7671 compliant.