Cable size calculator to calculate the required cable sizes for various types of cables, installation methods, correction factors and protective devices. 18th edition version.

Carry out on the spot instant cable calculations, great for electrical surveys, condition reports, circuit design and cable sizing on the go.

Also checks the volt drop and max Zs and applies the relevant correction factors from an easy to select list of options.

The cable size calculator calculates the required cable size, r1+r2, volt drop %, PSSC, and determines what the the Zs value will be.

Calculate circuit cable sizes for final circuits, distribution circuits and sub main electrical supplies.

Can also be used to check the electrical cable ratings for different electrical installation methods to ensure existing cables or wires are compliant on existing installations for an Electrical Installation Condition Report (EICR) including volt drop and Max Zs.

You can also use this app to check existing installed cable sizes and circuits to check for compliance and to confirm the correct cable size for the type of cable, installation method and length of circuit has been selected and installed correctly.

Functions Include:
+ Verification checks and helpful hints
+ Support for manufacturer specific BS EN 60947-2
(max Zs) MCCB's & ACB's
+ Support for RCD's in TT Earthing Systems

This app also takes into account and applies the following factors for it's cable size calculations:
+ Volt drop
+ Correction factors
+ Maximum disconnection times
+ Length of circuit
+ Various installation methods
+ Various cable types
+ Tabulated Current
+ Maximum Zs Values
+ Calculates Zs
+ Calculates r1+r2
+ Calculates volt drop
+ Calculates PSSC
+ Adjusted required minimum required cable ratings
+ Calculates cable size

Correction Factors Include:
+ Cg - Grouping
+ Ca - Ambient air temperature
+ Ca - Ambient ground temperature (if cable is buried
or in a duct)
+ Ci - Thermal insulation
+ Cf - BS 3036 semi-enclosed fuses (re-wireable

Mobile cable sizing software for iPhone and iPad.

Also check out our new 'Pro Certs' app for iPad. Produce professional electrical certificates on the go and print blank certificates for site use on to plain paper.

Check out our suite of other electrical apps @

What’s New

Version 1.3.1

This new update includes bug fixes and design improvements for a swifter experience.


Pro Certs Software Ltd
4.4 MB

Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.



Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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