pg 1-5 Electrical Inspection, Testing and Documentation – Module 6
Page 1 – Introduction and Commissioning
Module Context
Module: Domestic Electrical Installer – Section 1 Part A – Module 6.
Topic: Electrical Inspection, Testing & Documentation – the backbone of ensuring a safe, compliant electrical installation.
All content aligns with the IET Wiring Regulations (BS 7671) and legal duties under UK legislation (e.g.
Electricity at Work Regulations 1989).
Why the Topic Matters
Electrical inspection & testing is described as “the most important aspect of an electrician’s work.”
A structured process guarantees that:
The installation is free from defects before energisation.
All results are fully documented, creating a legal and technical record.
Commissioning = complete package of:
Full visual inspection (verifying workmanship & design).
All mandatory tests prior to first energisation.
Key Idea – Planning & Documentation
Planning ensures that every test/inspection is executed systematically and in the correct order.
Correct documentation:
Creates a baseline record for the owner and future electricians.
Demonstrates compliance if legal issues arise.
Page 2 – Need for Inspection & Testing
Human-error Mitigation
Even experienced electricians make mistakes: wrong polarity, loose connections, incorrect CPC size, etc.
Each new installation or alteration/addition therefore must be inspected & tested.
Statutory & Regulatory Framework
BS 7671 Part 6: sets out detailed requirements for inspection & testing.
Reference to Chapter 13 – Fundamental Principles reinforces its universal importance.
BS 7671 134.2.1 – Initial Verification:
During erection and on completion… appropriate inspection and testing shall be carried out by competent persons to verify that the requirements of this standard have been met before it is put into service.
Documentation as Evidence:
Acts as a condition report at the moment the installation is put into service.
Provides reference for assessing future wear & tear.
Protects the installer legally.
Electricity at Work Regulations (EAWR) 1989 – Regulation 29 Defence: It shall be a defence… to prove that all reasonable steps and due diligence were exercised.
Proper inspection/testing records are central to that defence.
Practical Significance
Without proper records, future alterations become guess-work → increased risk & cost.
For insurers & landlords, the existence of valid test certificates may be a condition of cover/tenancy.
Page 3 – Documentation, Periodic Inspection & Visual Checks
Documentation Mandate
BS 7671 132.13 – Documentation: “Every electrical installation shall be provided with appropriate documentation.”
BS 7671 135.1 – Periodic Inspection & Testing: recommends regular checks under Chapter 62.
EAWR 4(2): systems shall be maintained to prevent danger as far as is reasonably practicable.
Ageing & Deterioration
All equipment degrades over time (heat cycles, mechanical wear, environmental factors).
Electrical Installation Condition Report (EICR) provides:
Snapshot of current safety.
Schedule of recommended remedial works.
Next-inspection interval.
Competence: Carried out by experienced persons who understand age-related faults (e.g.
insulation embrittlement, high-resistance joints).
Ordered Sequence of Inspections (Visual/Physical)
Connection of conductors.
Identification (colour coding, markers).
Cable routing in safe zones or mechanical protection.
Adequate CCC (current-carrying capacity) & acceptable voltage drop \Delta V.
Single-pole devices connected in line conductors only.
Correct termination of accessories/equipment.
Page 4 – Further Visual Checks & Mandatory Tests
Additional Visual Items
Presence of fire barriers & seals; protection against thermal effects.
Verification of shock-protection methods (SELV, PELV, ADS, etc.).
Prevention of mutual detrimental influence (e.g.
segregation of Band I/Band II circuits).Adequate isolation & switching devices (main switches, DP isolators).
Under-voltage protection where required.
Correct labelling of devices, switches, terminals.
Equipment selection to suit external influences (IP rating, temperature rating, corrosion resistance).
Sufficient access & working space around switchgear.
Presence of danger notices (e.g.
“LIVE PARTS”, “ISOLATE ELSEWHERE”).Availability of diagrams, instructions, O&M manuals.
General erection methods (support, glanding, containment).
Core Electrical Tests (Part 6 BS 7671)
Continuity of CPCs (including main & supplementary bonding).
Continuity of ring final circuit conductors (live & CPC loops).
Insulation Resistance between:
Live conductors to earth.
Live conductor to live conductor.
Polarity (socket outlet polarity, correct functional connections).
Earth-Fault Loop Impedance Z_s.
Functional Testing (operation of devices):
• RCDs – trip time & current (I{\Delta n} & t{\text{trip}}).
• AFDDs – functional self-test.
Test Schedule
Results are recorded on a Generic Schedule of Test Results (DB reference, circuit details, R1 + R2, Z_s, insulation values, remarks, signatures, dates).
Provides traceability & comparison over the installation lifetime.
Page 5 – Alterations & Design Questions
BS 7671 132.16 – Additions & Alterations
“No addition or alteration… shall be made unless it is ascertained that the rating & condition of any existing equipment… will be adequate for the altered circumstances.”
Earthing & bonding must remain adequate for the new protective measure.
Pre-design Checklist for a Final Circuit
Load current I_b – what is the expected steady-state demand?
Assess diversity where applicable.
Capacity of Distribution Board & Supply – can it accept the new load?
Choice of Protective Device (type & characteristics):
MCB Type B/C/D, RCBO, RCCB + MCB, AFDD, etc.
Cable Type & Installation Method – PVC-T&E in stud wall, SWA buried, MICC, etc.
Protective Device Rating In – choose the next standard rating \ge Ib while ensuring In \le Iz (cable CCC after derating).
Earthing Arrangement (TN-S, TN-C-S, TT) – influences Z_e limits & RCD use.
Practical Implications
Failure to verify any of the above can result in:
Nuisance tripping, conductor overheating, or shock risk.
Non-compliance leading to insurance or legal issues.
Cross-links & Real-world Context
Guidance Note 3 (Inspection & Testing): Offers test methods and recommended periodicities (e.g.
domestic – 10 years or change of occupancy).On-site Guide (OSG): Provides ready-reckoner tables for Z_s, RCD trip times, maximum disconnection times.
18th Edition Amendment 2 introduces AFDD requirements for certain circuits → captured under functional testing.
Legal Duty vs. Contractual Duty: Even private domestic work, though not always notified under Part P, still falls under EAWR for those at work.
Summary of Core Principles
Plan → Inspect → Test → Document (PITD) cycle secures electrical safety.
Competence is a recurring theme: only qualified persons should perform or sign-off testing.
Legal & technical records (EIC, MEIWC, EICR) protect both the installer and the end user.
Visual inspection precedes testing – many faults are found without instruments.
Tests follow a logical sequence to avoid damage (e.g.
insulation before live tests).Any change to an installation demands reassessment of all protective measures – never assume existing systems are adequate.
"Inspection without testing is incomplete; testing without inspection is unsafe." – Paraphrase of industry adage