Regulations, Standards and Legal Framework for Electrical Installations
This domain checks that you know what BS 7671 is, what it is not, how it relates to national law, and which document goes with which job. Expect questions on the structure of the standard, definitions, the certificate family and the role of product standards.
Status of the standard
BS 7671 is not an Act or a Regulation. It is a national standard, harmonised with HD 60364 and IEC 60364, and it becomes legally significant through contract, through the statutory electricity legislation administered by the Electromechanical Services Department, and through its use as evidence of the standard reasonably expected of a competent person. Saying it is law is a mark-losing answer.
Structure you should be able to navigate
- Part 1 scope and fundamental principles; Part 2 definitions such as competent person, skilled person and instructed person.
- Part 3 assessment of general characteristics: maximum demand, earthing arrangements, supply characteristics.
- Part 4 protection for safety; Part 5 selection and erection of equipment, including wiring systems and isolation.
- Part 6 inspection and testing; Part 7 special locations such as bathrooms, swimming pools, construction sites and solar installations.
- Appendices carry the tabulated values used in design, the model forms and the schedule of inspection.
Documents
Initial verification produces an Electrical Installation Certificate with schedules of inspections and test results. Alterations produce a Minor Works Certificate. Periodic inspection produces an Electrical Installation Condition Report with classification codes C1, C2, C3 and FI. Commonly adopted intervals are 10 years for owner-occupied domestic, 5 years for rented domestic and commercial, and 3 years for industrial, always overridden by the designer's recommendation.
Product standards
BS EN 60898-1 for MCBs, BS EN 61009-1 for RCBOs, BS EN 61439-3 for distribution boards, BS EN 60529 for IP ratings, BS 6004 for PVC cables, BS 5467 for armoured cables, BS EN 61008 for RCCBs, BS EN 60947 for switchgear. A device without the correct standard marking cannot be assumed to give the breaking capacity or tripping characteristic the design relies on.
Worked example
A client asks whether a 15-year-old installation must be rewired by law. The answer: no automatic legal time limit exists. The condition is judged by inspection and testing, producing an EICR with codes; C1 and C2 require action, C3 is improvement recommended. Any new work must comply with the current standard, and a change of use or a significant load increase can invalidate the original design assumptions.
Traps
Calling BS 7671 legislation; treating an EICR as pass or fail; using a Minor Works Certificate for a new circuit; over-coding C3; issuing a certificate without the design and supply characteristics.