Bs7671 Cable Sizing _top_ ⟶ [TOP]

| Factor | BS 7671 Ref | Applies to | |--------|-------------|-------------| | ( C_a ) | Table 4B1 | Ambient temperature ≠ 30/40°C | | ( C_g ) | Table 4C1 | Grouping of circuits (mutual heating) | | ( C_d ) | Table 4B2 | Buried cables (soil thermal resistivity) | | ( C_i ) | Table 4B3 | Thermal insulation (e.g., in a stud wall) | | ( C_c ) | Regulation 433.1 | Protective device type (e.g., BS 3036 semi-enclosed fuse: 0.725) |

[ S = \frac\sqrtI^2 tk ]

[ Z_s = Z_DB + (R_1 + R_2) \times L ]