BS 7671 reference
Subject
Summary of notable change / new content
717.55.3
Mobile or transportable units
New requirement. Automatic means of disconnecting the supply from generator sets mounted in the unit, other than those providing SELV or PELV supply, in the event of the unit being involved in an accident. Where this is difficult to achieve, an easily accessible emergency switch is to be provided.
Figs 717.1; 717.2; 717.3; 717.4.
Mobile or transportable units
Conductive external staircase (steps into vehicle) added to figures.
Fig 717.4
Mobile or transportable units
New example of connection to a fixed installation for a unit using simple separation and an internal IT system with or without an earth electrode.
Fig 717.6
Mobile or transportable units
Example of connection to a fixed electrical installation for a unit using simple separation and an internal TN system. Was previously Fig 717.4
Fig 717.7
Mobile or transportable units
New diagram. Example of connection to a fixed electrical installation for a unit using an IT system without automatic disconnection in the event of a first fault.
721.1
Caravans
The three-phase nominal a.c. voltage changed from 440 V to 400 V.
Section 729
Operating and maintenance gangways
New section added, Operating and maintenance gangways.
753.410.3.6
Floor and ceiling heating systems
New requirement. The fault protective measure of earth-free local equipotential bonding shall not be employed for floor and heating systems.
Appendix 1
Standards referred to in BS 7671
List of British and other standards to which reference is made in the Regulations has been updated.
Appendix 2
Statutory Regulations etc
Names of various government department and titles of posts therein updated.
Appendix 3
Time/current characteristics
Changes made in line with changes made to the standards covering cartridge fuses.
Appendix 4
Current-carrying capacity and voltage drop for cables
New section 2.4 with table containing correction factors to be applied when determining current-carrying capacity and voltage drop for cables having flexible conductors, using data for cables having solid or stranded conductors in Tables 4D1, 4D2, 4E1 and 4E2. Five Rating factors added/amended, which are used in equations within this Appendix. New section 5.5, Rating factors for triple harmonic currents in four-core and five-core cables with four cores carrying current and 5.6 Harmonic currents in line conductors. (Expanded version of text that was in Appendix 11 previously). New section 6.4, Voltage drop in consumers’ installations. (Text was in Appendix 12 previously). Amendments made to descriptions in Table 4A2 for installation methods specifically for flat twin and earth cables in thermal insulation. New Table 4B4, Rating factors for depths of laying other than 0.7 m for direct buried cables and cables buried in ducts. New Table 4B5, Rating factors for cables having more than 4 loaded conductors. Table 4C2, Rating factors for more than one circuit, cables laid directly in the ground – Reference Method D in Tables 4D4A to 4J4A now only applicable to multicore cables. Table 4C3, Rating factors for more than one circuit, cables in ducts buried in the ground – Reference Method in Tables 4D4A to 4J4A now only applicable to multicore cables. New Table 4C6, Rating factors for cables enclosed in infloor concrete troughs (Installation Methods 118 to 120 of Table 4A2).
Appendix 5
External influences
Part B, Utilisation. Table amended. Part C, Construction. Table amended.
Appendix 6
Model forms for certification and reporting
Original Schedule of Inspections. Modified to be applicable for use with Electrical Installation Certificate only. Introduction of Electrical Installation Condition Report to replace Periodic Inspection Report. Introduction of Condition report inspection schedule for domestic and similar premises with up to 100 A supply. A number of changes made to Generic Schedule of Test Results. Introduction of generic list of Examples of items requiring inspection for an electrical installation condition report.
Appendix 16
Protection against overvoltage
New Appendix added Devices for protection against overvoltage.
Note. Many of the minor editorial and similar changes introduced by Amendment 1 are not included in this table. www.niceic.com
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