Circuit protective device (CPD)
A fuse or circuit-breaker providing overload and fault current protection.
Day: 5 February 2023
Consumer Unit
Atype of single-phase board for the control and distribution of electrical energy, principally in domestic premises. In the ProDesign software,a consumer unit (CU) can be split into three sections,each with different types of residual current protection.
Competent person
Aperson who possesses sufficient technical knowledge, relevant practical skills and experience for the nature of the electrical work undertaken and is able at all times to prevent danger and,where appropriate, injury to themselves and others.
Circuit Protective Conductor (CPC)
Acircuit protective conductor (CPC) connects exposed-conductive-parts* of equipment to themain earthing terminal. *Conductive part of equipment,which can be touched and which is not normally live,but which can become live when basic insulation fails.
Thermal insulation rating factor (Ci)
Ci Rating factor used for calculating theminimum required cable size for cables run in thermal insulation. See BS7671:2018 Table52.2.
Harmonic rating factor (Ch)
Ch Rating factor used for calculating theminimum required cable size in the presence of harmonic currents.See BS7671:2018,Appendix 4, section 5.5.
Grouping rating factor (Cg)
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 given in Table4C2. Grouping a circuit with others will result in a lower rating factor Cg. Thismay result in an increased cable size.
Semi-enclosed fuse rating factor (Cf)
The rating factor Cf = 0.725 is applied to cable sizing calculations for any circuit protected by a semi-enclosed fuse to BS3036.
Depth of lay rating Factor (Cd)
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 installed. See BS7671:2018,Table4B4. Indicates the depth of installation for cables installed in the ground. The rating factor Cd is applied in cable sizing calculations to account for different installation depths.For […]
Ground rating factor (Cc)
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 4,Sections3,4 and 5.1.1.
