Adiabatic Equation Calculator: Precise BS 7671 Compliance for Electrical Professionals

Adiabatic Equation for calculating the minimum cpc (circuit protective conductor) and earth minimum csa sizes of earthing conductors, S = √(I²t) / k. This Adiabatic Equation Calculator takes into account the following parameters: t = Disconnection time (seconds). k = Conductor k value (From BS 7671 tables). la = Fault current (PEFC in Amps). I² = la x la. Results with the minimum CSA mm². Values of K are obtained from the tables within BS 7671: - Table 54.2 : Conductor not incorporated in a cable and not bunched with cables. - Table 54.3 : Conductor incorporated in a cable or bunched with cables. - Table 54.4 : Sheath or armour of a cable. - Table 54.5 : Steel conduit or trunking. Disconnection times (t) are obtained from the maximum operating time/current characteristics tables within BS 7671: - Fig 3A2 (a,b) : BS 3036 semi-enclosed fuse. - Fig 3A3 : (a,b) : BS 88-2.2. - Fig 3A4 : BS EN 60898 / 61009-1 MCB/RCBO type B. - Fig 3A5 : BS EN 60898 / 61009-1 MCB/RCBO type C. - Fig 3A6 : BS EN 60898 / 61009-1 MCB/RCBO type D. - BS 1361 Fuse. How to use the Adiabatic Equation App: 1) Input your voltage value. 2) Input your Zs value. 3) Select protective device. 4) Select protective device rating. 5) Select conductor type. 6) Select conductor material. 7) Tap calculate.