4.2 Visual Inspection Requirements
Key Takeaways
- Visual inspection is the first stage of inspection, completed before any testing begins — it catches defects that testing alone may miss and informs the test plan
- For initial verification, visual inspection covers 100% of the new work; periodic inspection uses sampling (covered in Chapter 10)
- Key checks include conductor connections, cable selection and routing, conductor identification per BS 7671 Table 51.1, fire barriers and segregation, earthing and bonding conductor presence and size, RCD presence where required, IP rating for location, and consumer unit enclosure
- Since Amendment 2 of the 18th Edition, consumer units in domestic premises must be enclosed in a non-combustible enclosure or located in a fire-protected cabinet
- The schedule of inspections records each visual inspection item as satisfactory or notes defects for remedial action
Visual Inspection: The First Stage
Visual inspection is the first stage of the inspection process and must be completed before any testing begins. It serves two purposes: it identifies defects that testing alone may not reveal (e.g. damaged cable insulation, wrong cable routing, missing fire barriers), and it informs the test plan by flagging areas that need closer attention.
For initial verification, visual inspection covers 100% of the new work — every connection, accessory, and cable run must be checked. For periodic inspection, sampling is used (covered in Chapter 10), but the principle that visual inspection precedes testing remains the same.
A serious defect found during visual inspection should halt further testing until the defect is corrected — there is no value in testing an installation that is visibly non-compliant.
What the Inspector Checks
The visual inspection is systematic. The inspector works through the installation checking each of the following:
Conductors and Connections
- Connection of conductors — all conductors are securely and correctly connected at terminals, with no loose strands, no stray conductor outside the terminal, and correct tightening.
- Cable selection — conductor size and type are appropriate for the design current, voltage drop, and ambient conditions.
- Cable routing — cables are routed to avoid mechanical damage, heat, and where appropriate are in prescribed zones (e.g. within 150 mm of ceilings or corners — the "safe zones").
Identification and Labelling
- Conductor identification — colours and markings comply with BS 7671 Table 51.1 (brown for line, blue for neutral, green-and-yellow for protective conductors).
- Circuit labelling — each circuit is clearly identified at the consumer unit or distribution board.
- Warning notices — present where required (e.g. the RCD six-monthly test notice required by Reg 514.12.2, "Safety Electrical Connection — Do Not Remove" label on main earthing and bonding terminals).
Protection and Segregation
- Fire barriers and segregation — cables passing through fire-rated structures are sealed; Band I (ELV) and Band II (LV) circuits are segregated where required by BS 7671 Section 527.
- Presence of RCDs — where required by BS 7671 (e.g. socket-outlets rated at 32 A or less, bathrooms, outdoors, buried cables in walls).
- Methods of protection against electric shock — basic protection (insulation, barriers, enclosures, obstacles — IP2X or IPXXB, IP4X or IPXXD) and fault protection (automatic disconnection of supply, double insulation, RCDs).
Earthing and Bonding
- Presence and size of earthing conductor — checked visually for condition, routing, and connection at the main earthing terminal (MET).
- Presence and size of main protective bonding conductors — to incoming gas and water services, and other extraneous-conductive-parts.
- Adequacy of connections — clamps are tight, correctly labelled, and accessible.
Location and Environment
- IP rating and location suitability — equipment in bathrooms, saunas, swimming pools, and other special locations is correct for the zone (e.g. IPX4 in zone 2 of a bathroom per Section 701).
- Mechanical damage protection — cables in conduit, trunking, or with adequate mechanical protection where exposed.
- Accessibility — switchgear, consumer units, and accessories are accessible for operation, inspection, and maintenance per BS 7671 Section 513.
Consumer Unit Enclosure
- Non-combustible enclosure — since Amendment 2 of the 18th Edition (BS 7671:2018+A2:2022), consumer units and switchgear assemblies in domestic (household) premises must be enclosed in a non-combustible enclosure (e.g. steel), or be located in a fire-protected cabinet. This requirement, now embedded in the main body of BS 7671, remains a key visual inspection check.
Connection to the Schedule of Inspections
The items checked during visual inspection are recorded on the Schedule of Inspections — the formal document that accompanies an Electrical Installation Certificate (EIC) or Electrical Installation Condition Report (EICR). The schedule uses a tick-box format covering:
- Connection of conductors
- Cable selection and routing
- Conductor identification
- Fire barriers and segregation
- Protective conductors (earthing and bonding)
- Protection against electric shock
- Protection against thermal effects
- Switchgear and protective devices
- Labelling and warning notices
- Location and environment
Each item is recorded as satisfactory or, where a defect is found, noted for remedial action. The schedule is a mandatory part of the EIC — a certificate without its schedule of inspections is incomplete and invalid.
Visual Inspection Checklist
| Item | What to check | Standard reference |
|---|---|---|
| Conductor connections | Secure, correct, no loose strands | BS 7671 Chapter 53 |
| Cable selection | Correct size and type for load | BS 7671 Chapter 52 |
| Conductor identification | Colours per Table 51.1 | BS 7671 Table 51.1 |
| Fire barriers | Sealed penetrations, segregation | BS 7671 Section 527 |
| Earthing conductor | Present, correct size, connected at MET | BS 7671 Chapter 54 |
| Main bonding | To gas, water, extraneous parts | BS 7671 Section 544 |
| RCD presence | Where required (sockets, bathrooms, outdoors) | BS 7671 Sections 411, 415 |
| Consumer unit enclosure | Non-combustible (domestic) | BS 7671 532.6 |
| IP rating and zones | Correct for location | BS 7671 Sections 701, 702 |
| Accessibility | Switchgear accessible | BS 7671 513.1 |
| Labelling | RCD test notice, circuit schedules | BS 7671 Section 514 |
For initial verification of a new installation, what proportion of the new work must be covered by visual inspection?
Since Amendment 2 of the 18th Edition, what requirement applies to consumer units and switchgear assemblies in domestic premises, and how is this verified during visual inspection?