Cable Size UK is a calculation tool for UK electricians, electrical designers and competent-person scheme members. Enter the circuit details and it returns a minimum cable size with every intermediate step shown, so the result can be transcribed onto a design or certificate and explained during an inspection.
It shows its working
Free calculators give you a number. This one gives you the chain: design current, protective device rating, applied correction factors, required tabulated capacity, selected conductor size, and volt drop as a value and as a percentage of nominal. The intermediate values are what an inspector asks for.
Features
- Design current (Ib) Single and three phase, resistive and inductive loads, power factor, efficiency and diversity, with the formula shown.
- Device rating and correction factors Checks Ib against the device rating and applies ambient, grouping, insulation and rewireable fuse factors to give the required tabulated capacity.
- Volt drop Reported in volts and as a percentage of nominal, checked against the lighting and other-uses limits.
- Working shown for every result Each step labelled, ready to transcribe.
See it working
This app is a design aid.
Results must be verified against the current edition of BS 7671 and
any applicable amendments before being relied on. Responsibility for
the design, and for compliance, remains with the user. Cable Size UK
is not certified, approved or endorsed by BSI or the IET.