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Ring circuit intelligence

Ring Circuits in Pirform 2025.1 and Later Versions

Pirform version 2025.1 made significant updates to the cable-sizing intelligence and has changed how ring circuits are handled. Read how to handle ring circuits in Pirform 2025.1 and later versions here. Read more about the cable-sizing intelligence improvements here.

Ring Circuits in Pirform Versions Before Version 2025.1

The remaining content on this page applies to Pirform versions before 2025.1.

By default, Pirform treats all circuits as radial unless specified otherwise.

Marking a Circuit as a Ring

To mark a circuit as a ring, include the word ring in its circuit designation.

According to Regulation 433.1.103, socket outlets can be supplied by ring final circuits, protected by a 30A or 32A device conforming to:

  • BS 88-2.2, BS 88-6
  • BS 1361
  • BS 3036
  • BS EN 60898
  • BS EN 61009-1 RCBO

The circuit must use 2.5 mm2 copper conductors (or 1.5 mm2 for MICC), with cables rated to carry at least 20A in the installed condition, to allow the use of a 30A or 32A overcurrent protective device.

Example:

For example, consider a 2.5 mm2 Twin and Earth cable installed using Reference Method 101 (see Table 4D5, BS 7671) with a 32A BS EN 60898 protective device.

In this case, the cable can carry only 17A and does not meet the specific requirements of Regulation 433.1.5 outlined above.