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VISUAL INSPECTIONS
Electrical Installation System
VISUAL INSPECTION
The Wiring Regulations require that every new installation, an extension or alteration to an
existing installation must be inspected and tested on completion and before being put into service
to verify that the requirements for the regulations have been met. This is to give the client some
guarantee that ‘good workmanship and the use of approved materials’ will provide an installation
which is safe to use and reduces to a minimum all risks against electric shock, fire and burns.
Before any inspection and test can be carried out, some information must be available which
includes drawings showing the positions of isolators, switches, outlet points, the type and rating
of protective devices and the size and type of conductors. Inspection must precede testing and
must normally be done with the part of the installation under inspection disconnected from the
supply.
The main purpose of inspecting an electrical installation: complies with recognized standards of design in accordance with BS 7671.
 to ensure that correct materials (designed to recognized standards) have been selected and
erected in accordance with the IEE Regulations for Electrical Installations,
 to ensure that connected equipment is seen to be undamaged and appropriate for the
environmental conditions.
 is not visibly damaged, defective or unsafe.
The visual inspection of a complete installation includes:1. checking the connections of conductors and their correct identification (by colours or
numbers)
2. the correct size of conductors must also be checked to ensure that they are able to carry
the designed load current and the voltage drop within the limits.
3. all single –pole control devices (switches) and protective devices (fuses, MCBs) must be
connected to the phase conductors only.
4. the correct protective devices are being used.
5. ‘Polarised’ wiring accessories (such as socket-outlets and Edison screw (ES) lamp
holders) must be correctly terminated.
6. presence of fire barriers, suitable seals and protection against thermal effects.
7. methods of protection against electric shock.
8. all relevant parts must be labeled such as labeling of protective devices including circuitbreakers, RCDs, fuses, switches and terminals, main earthing, etc.
9. presence of appropriate devices for isolation and switching correctly located.
10. Selection of equipment and protective measures appropriate to external influences.
11. all diagrams and instructions are available or places where required.
12. danger notices and warning signs have been fitted.
13. adequacy or capability of access to switchgear and equipment
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VISUAL INSPECTIONS
Electrical Installation System
In working areas there must be provided switches for isolation (e.g. in a motor circuit) and
emergency switching. All distribution boards and consumer units must have circuit charts giving
details of the function of final circuits, their conductor sizes and the type and rating of the
protective devices.
The visual inspection must also include checks such simple things like; no burrs are left inside
conduit; all cables are protected against mechanical damage; cables are securely fixed with
correct distances between their supports; and all materials used in the installation have been
correctly chosen to operate in the working conditions which obtain once the installation has been
energized or put into service.
The following are some of the points which the inspecting electrician should look for:
1. Flexible cables not secure at plugs.
2. Frayed cables
3. Cables without mechanical protection
4. Use of Unearthed metalwork
5. Circuits over-fused
6. Poor or broken earth connections, and especially signs of corrosion
7. Unguarded elements of radiant fires
8. Unauthorized additions to final circuits resulting in overloaded circuit cables
9. Unprotected or unearthed socket-outlets
10. Appliances with earthing requirements being supplied from two-pin BC adaptors
11. Bell-wire (with extra-low voltage insulation) used to carry mains voltages
12. Use of portable heating appliances in bathrooms
13. Broken connectors such as plugs
14. Signs of heating at socket-outlet contacts.
In installing wiring systems, electrical accessories and equipment, the electrician is building into
the installation all the fundamental requirements for electrical safety, which in a practical form
the requirements include as follows:1. Ensuring that all conductors are sufficient in cross sectional area for the design load
current of circuits.
2. All equipments, wiring systems and accessories must be appropriate to the working
conditions.
3. All circuits are protected against overcurrent using devices (fuses, MCBs) which have
ratings appropriate to the current-carrying capacity of the conductors.
4. All exposed conductive parts (i.e. all metalwork associated with the electrical
installation) are connected together by means of CPCs.
5. All extraneous conductive parts (i.e. metalwork not directly associated with the
installation, such as water pipes, structural steelwork and services fed by metal pipes) are
bonded together by means of main bonding conductors and supplementary bonding
conductors, and that these conductors are taken to the installation main earth terminal.
6. All control and overcurrent protective devices are installed in the phase conductor.
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VISUAL INSPECTIONS
Electrical Installation System
7. All electrical equipment has the means for their control and isolation.
8. All joints and connections must be mechanically secure and electrically continuis and be
accessible all times.
9. No additions to existing installations should be made unless the existing conductors are
sufficient in size to carry the extra loading.
10. All electrical conductors have to be installed with adequate protection against physical
damage and be suitably insulated for the circuit voltage at which they are to operate.
11. In situations where a fault current to earth is not sufficient to operate an overcurrent
device, an RCD must be installed.
12. All electrical equipment intended for use outside the equipotential zone (i.e. the premises
where all metalwork is both bonded and earthed) must be fed from sockets-outlets
incorporating an RCD.
13. The detailed inspection and testing of installations before they are connected to a mains
supply, and at regular intervals thereafter.
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