Grouping rating factor used for calculatingminimum required cable size. For cables installed in air, values for this factor are given BS7671:2018,Tables4C1,4C4,4C6.For ground installations, values are
The rating factor Cf = 0.725 is applied to cable sizing calculations for any circuit protected by a semi-enclosed fuse to BS3036.
The rating factor Cd is applied to cable sizing calculations for cable installed in the ground. Its value varies according to the depth of lay
The rating factor Cc = 0.9 is applied to cable sizing calculations for cables installed in the ground (Installation Methods 70 to 73). See BS7671:2018,Appendix
Circuit-breaker manufacturers publish tables showing combinations of pairs of circuitbreakers, one upstream,one downstream,where the downstream device can be used at a location where the prospective
k2s2 its an Energy withstand of cable in A2s. For example,a cable with a withstand of 12 x 104 A2s, can sustain without permanentdamage,a fault
Ambient temperature rating factor used for calculating theminimum required cable size. For cables installed in air, values for this factor are given in BS7671:2018 Table4B1.For
The breaking capacity of a circuit-breaker is themaximum level of fault current (kA) it cansafely interrupt. Each circuit-breaker has two breaking capacities: Ultimate BreakingCapacity (Icu)
Protection against electric shock under fault-free conditions;use of barriers,placing out of reach,and so forth.
The temperature of the free air surrounding a cable,or in the case of cables installed in the ground, the temperature of the surrounding soil.For an
