What is fixed wire testing?

Fixed wire testing is the testing of the wiring within the fabric of a building.

Is it necessary?

Yes. It is a mandatory requirement of the "Electricity at Work Regulations 1989".

What happens if we fail to have it tested?

Failure to carry out such testing is likely to invalidate your insurance cover in the event of a claim. Also, you may have a personal duty of care to the employees and by endangering their lives you could be held responsible and prosecuted, under the HSE laws. The HSE inspectorate carries out routine inspections.

How often should it be done?

In a normal office environment, combined inspection and testing should be carried out no less than once every five years, with a yearly visual inspection. Some larger buildings have 20% inspected and tested every year, with a 100% visual, to cover the five-year cycle.

Who does it?

A competent person, with knowledge of the electrical system, will carry out all works. (See competency section towards the end of this guide). The engineer will have all the relevant qualifications appertaining to the works undertaken in accordance with BS 7671 Guidance Note 3.

What does it entail?

A full operational process can be found at the end of this guide.

How long does it take?

That depends on the size of the building and the intricacies of its electrical system.

Is it done during normal office hours?

This may be possible, but most works are effected outside of normal working hours to minimalise disruption to customers and staff.

Does it entail the powering down of our supply?

Quite simply - yes. Testing involves the testing of the circuits both when they are ‘live’ and when they are ’dead’.

How long for?

Sometimes for as little as 10 –15 minutes, but in order to verify that the incoming supply is safe you should allow for a total power-down of the system for approximately 1 hour. Please note that individual circuits will be isolated from the supply intermittently throughout the works, not just for this initial 1-hour period.

What are the implications for our I.T systems?

Many of today’s IT systems are server based, often with the server itself benefiting from a UPS (Uninterrupted Power Supply). Whilst the UPS system provides a temporary back-up supply, the servers themselves should be shut down during testing works to enable the testing of the final sub-circuits. Usually where we find comm’s and computer rooms, these areas are tested first to enable IT Managers to reboot all their computer systems and minimise disruption.

What happens if faults are found?

These are recorded and presented to the client in the form of a defects report. A plan of action is formulated and remedial works are carried out. If a fault is found to pose a danger to the building or the people in it, we will seek authorisation to carry out emergency repairs without the need to lock off the system.

Are any records kept, and if so by whom?

Both parties will keep a copy of all test results, defects reports and certificates as proof of maintenance


General Inspection of Installations

Installation will be visually inspected to check for correct installation, assembly and mounting. Missing bolts, unfilled cable entry holes, broken corners, damaged cables, open panel doors, etc., will be identified and reported.

Conductors and Terminations

Exposed conductors will be identified and tested to prove whether they are LIVE or DEAD. If they are LIVE, or can be made LIVE, we will indicate whether sufficient barriers, screens or divisions can be positioned to prevent   touch. We will also indicate whether the conductor can be placed out of reach. generally we would identify any LIVE conductors, which were not already protected by enclosures to IP2X (BS 5490-Degree of Protection of Enclosures) and suggest course of action to rectify. All cable entries to enclosures will be inspected to make sure that they are properly glanded with no inner cores exposed. Flexible conduits and tubing containing electrical cables will be checked for damage.

Electrical Protection

Circuits will be inspected to ensure that they are adequately protected to clear overloads, earth faults and short circuits. Protective devices will be identified (e.g., circuit breaker or relay) and tested to ensure they clear the above faults. Results will be compiled and copies supplied if required. The protection system will be checked to ensure that faults are cleared locally and do not cause interruption or other circuits.

Joints and Connectors

Joints and connectors will be inspected to assess whether they meet the requirements of electrical conductivity and insulation. Connectors will be checked for corrosion, electrolytic action, overheating and security of connection.

Isolation and Cutting Off Supply

Machinery will be checked for means of isolation (e.g., one stop button) and its accessibility. The isolators’ condition and operation will be inspected to check for broken handles, etc., or any impediment in the operation. The system will be inspected to ensure the circuit is provided with adequate means of isolation at the mains switch room and at the respective distribution points.
All isolation points will be inspected to ensure that they are clearly marked for the circuits they control, (this will also include identification of fuse ways within distribution boards).
All circuits will be checked to ensure that they have a means of switching off.


All conductive parts, i.e., pipes, radiators, taps, etc., will be checked to ensure they are efficiently connected to earth. If visible, the earthing protective conductor will be examined for tightness and the colour coding of the earthing protective conductor will be checked to make sure it is green, or green/yellow. Earthing from the supply authority will be identified and the Earth Loop Impedance will be tested. Results will be compiled and copies supplied to your organisation.
In accordance with the law, all work by TCS will be done with the supply removed, i.e., DEAD.
TCS will implement a “SAFE SYSTEM” to ensure that when the supply has been removed for work to be done on dead conductors, it remains off until all works are completed. If a “safe system” is already in place, TCS will require a demonstration of its effectiveness.

Safe System Procedure

• Where possible, all circuits to be worked on will be clearly identified.
• Circuits to be worked on will be isolated and locked off.
• The circuit will be proved to be dead before work commences.
• Warning notices will be used in work areas.
• Engineers will use personal earthing equipment where necessary.
• Where possible, switch rooms will not be accessible to anyone but the
engineers who will carry keys.
• Where testing requires more than one engineer, constant communication
will be kept via hand held 2-way radios.


Fixed wire test engineers are fully qualified to 17th Edition standards and hold a BS2391 certificate. At anytime there will be at least one fully qualified engineer to BS2391 on site. In addition, all engineers who complete testing and inspection will: -
• Be aware of the dangers and how to avoid them.
• Be happy with their levels of training.
• Know what is expected of them.
• Be confident that they can complete the job without risk to themselves or
• Be provided with all the necessary information to do the job safely.
• Be satisfied with supervision provided.