Why do I need to tell PIRform that the circuit is a ring?
PIRform assumes all circuits are radials until you tell it otherwise.
Under Regulation 433.1.103, socket outlets may be supplied through a ring final circuit protected by a 30A or 32A protective device that complies to
BS 88-2.2, BS 88-6
BS EN 60898
BS EN 61009-1 RCBO
Providing the circuit is wired in 2.5mm2 copper conductors (or 1.5mm2 for MICC),
and providing the cable is capable of carrying no less than 20A in its installed condition,
then the overcurrent protective device rated at 30A or 32A is acceptable.
You are using 2.5mm2 Twin and Earth, installed using Reference Method 101 (See Table 4D5, BS 7671).
Your protective device is a 32A BS EN 60898.
Under these conditions, the cable is only capable of carrying 17A, and does not meet the special requirements of Regulation 433.1.5 as described above.