Fixed wire testing is one of those things every building owner knows they should have, but few people are quite sure what it involves, how often it’s needed or what to do with the report afterwards. This guide answers all of it in plain English, from people who carry out fixed wire testing every week in offices, schools, warehouses, data centres and rented properties. It’s fully up to date with Amendment 4 to BS 7671, which has applied to all testing since 15 October 2026.
What is fixed wire testing?
Fixed wire testing is the periodic inspection and testing of the permanent electrical installation in a building. It checks that the wiring and everything connected to it is safe to keep using, and that it still meets the current wiring regulations closely enough to be considered satisfactory. The result is recorded in an Electrical Installation Condition Report, or EICR.
What counts as the fixed installation?
Anything permanently wired in, as opposed to plugged in. That includes:
- The main switchboard, distribution boards and consumer units
- Cables running between boards and out to every circuit
- Sockets, switches, fused spurs and isolators
- Fixed lighting, including emergency lighting circuits
- Hard-wired equipment such as hand dryers, water heaters, extract fans and plant
- Earthing and protective bonding to gas, water and other services
Portable equipment, anything with a plug, isn’t covered by fixed wire testing. That’s checked separately through PAT testing.
Is it called anything else?
You’ll hear fixed wire testing called lots of different names, which causes plenty of confusion. They generally mean the same thing:
- EICR (Electrical Installation Condition Report)
- Periodic inspection and testing (PIR, the old name for the report)
- Hard wire testing
- Electrical safety certificate or landlord electrical certificate
- Five-year electrical test
Is fixed wire testing a legal requirement?
For businesses, the Electricity at Work Regulations 1989 require all electrical systems to be maintained so they’re safe. The regulations don’t name fixed wire testing specifically, but a current EICR is the recognised way of proving you’ve met that duty, and it’s what the HSE, your insurer and your fire risk assessor will expect to see if anything goes wrong.
For private landlords in England, it’s explicit. The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 require an EICR at least every five years, a copy for tenants, and remedial work completed within 28 days. Our guide to whether fixed wire testing is a legal requirement covers this in more detail.
How often do you need fixed wire testing?
IET Guidance Note 3 sets out commonly used maximum intervals. Your inspector may recommend a shorter period depending on the condition of the installation and how it’s used.
- Offices, shops, restaurants and hotels: 5 years
- Schools, colleges and universities: 5 years
- Private rented homes and HMOs: 5 years
- Factories, workshops and warehouses: 3 years
- Farms and agricultural buildings: 3 years
- Theatres, cinemas and places of entertainment: 1 year
- Swimming pools and spas: 1 year
- Hospitals and medical locations: 1 year
- Construction site supplies: 3 months
- Owner-occupied homes: 10 years
You should also test sooner after a change of use, flood or fire damage, major alterations, or before buying, selling or taking a lease on a building. There’s more on this in how often does a commercial building need an EICR.
Who is responsible for arranging it?
Whoever has control of the electrical installation. In a building with one occupier, that’s usually the owner or tenant, depending on the lease. In multi-let buildings, the landlord or managing agent is normally responsible for the landlord’s supplies and common parts, while tenants look after their own areas. If your lease doesn’t make it clear, it’s worth agreeing in writing.
Who can carry out fixed wire testing?
It must be done by a competent person: someone with the right qualifications, experience and test equipment to inspect, test and interpret the results. In practice, use a contractor registered with a recognised scheme such as NICEIC or NAPIT, whose testers hold inspection and testing qualifications such as City & Guilds 2391. Registered contractors are assessed regularly, which gives you a level of assurance an unregistered electrician can’t.
What does fixed wire testing involve?
1. Planning
A good test starts before anyone arrives on site. We agree the scope, how much of the installation will be tested, access arrangements, and an isolation plan so you know when each area will lose power. On large installations, the inspector may agree a sampling approach with you, testing a representative percentage of circuits and increasing it if problems are found.
2. Visual inspection
The inspector looks for damage, wear, overheating, missing covers, incorrect or missing labelling, poor workmanship and anything that doesn’t comply with the regulations, from the main switchboard right out to the accessories.
3. Testing
Circuits are then tested with specialist equipment. The main tests include:
- Continuity of protective conductors and ring final circuits
- Insulation resistance, to check cables aren’t breaking down
- Polarity, to make sure everything is connected the right way round
- Earth fault loop impedance, to confirm protective devices will disconnect quickly enough in a fault
- Prospective fault current at the origin of the installation
- RCD operation and trip times
- Functional checks of switches, isolators and other devices
4. The report
Everything is recorded in the EICR, including the condition of the installation, any observations with their codes, the full schedule of test results and a recommended date for the next inspection.
Will testing disrupt my business?
Some disruption is unavoidable, because most tests need the circuit being tested switched off. But it should be short and planned. Each circuit is usually only off for a few minutes, and a good contractor will leave critical circuits such as servers, fridges, freezers and alarms until a quiet time, or test them out of hours. For occupied offices, schools and data centres, we routinely work evenings, weekends and holidays.
How long does fixed wire testing take?
It depends mainly on the number of circuits. A small office or shop might take half a day to a day, a medium-sized commercial building or school several days, and a large site or campus is best run as a planned programme. We’ve written a full guide on how long an EICR takes.
What do the observation codes mean?
- C1, danger present: immediate risk of injury. It should be made safe on the day.
- C2, potentially dangerous: urgent remedial action required.
- C3, improvement recommended: doesn’t meet the current regulations, but isn’t dangerous.
- FI, further investigation required: something the inspector couldn’t confirm during the test.
Under Amendment 4, only C1s and C2s make a report unsatisfactory. C3s and FIs no longer affect the overall outcome, although FIs are still worth investigating. See EICR codes explained and what Amendment 4 means for your EICR.
What if the result is unsatisfactory?
Don’t panic. It’s common, especially in older buildings. Get the C1s and C2s put right, ideally with a quote that references each observation number, and make sure you receive a certificate for the remedial work. You don’t have to use the same contractor that carried out the test. Read more in what happens if your EICR is unsatisfactory.
What’s the difference between an EICR, an EIC and a Minor Works Certificate?
An EICR reports on the condition of an existing installation. An Electrical Installation Certificate (EIC) is issued for new work such as new circuits, rewires and board changes. A Minor Works Certificate covers small alterations that don’t involve a new circuit. Our guide to EIC vs EICR vs Minor Works explains when you need each one.
How much does fixed wire testing cost?
The price depends mostly on the number of circuits and distribution boards, followed by access, out-of-hours requirements, the state of your records and the type of installation. When you compare quotes, check how many circuits are included, whether it’s a full test or a sample, and whether remedials will be quoted separately. We explain each factor in how much a commercial EICR costs.
Is fixed wire testing the same as PAT testing?
No. Fixed wire testing covers the permanent installation, and PAT testing covers portable equipment with a plug. Most businesses need both, and they’re often carried out by the same contractor to save visits. See is PAT testing a legal requirement.
How to prepare for your fixed wire test
- Find your last EICR, board schedules and any drawings.
- Tell us about anything that mustn’t lose power, such as servers, medical equipment, cold storage or security systems.
- Make sure every distribution board is accessible, including those in locked cupboards and plant rooms.
- Let staff, tenants or pupils know when testing is happening.
- Agree who the inspector should report urgent findings to on the day.
Frequently asked questions
Does an EICR expire?
Not in a strict sense, but it includes a recommended date for the next inspection, and insurers, landlords and letting agents will expect you to keep to it.
Can testing be done without switching the power off?
Not completely. Some checks can be done live, but most of the key tests need circuits isolated. Planning keeps the disruption to a minimum.
Do I need fixed wire testing if the building is new?
A new installation should come with an Electrical Installation Certificate, which sets the date of its first periodic inspection. You won’t need an EICR until then, unless something changes.
What standard should testing be carried out to?
BS 7671:2018+A4:2026, the IET Wiring Regulations with Amendment 4. It has been the only current version since 15 October 2026.
Book fixed wire testing with Martin Cook Electrical Services
We’ve been carrying out fixed wire testing since 1998, for offices, schools, universities, warehouses, landlords and live data centres across London, Bedfordshire, Buckinghamshire and Hertfordshire. We’re NICEIC approved, Safe Contractor Approved and our engineers are BS 7858 screened and enhanced DBS checked. Find out more about our inspection, testing and compliance services, request a free quote or call us on 01525 582582.
EICRs across our area
We carry out EICRs and landlord electrical safety certificates across London, Bedfordshire, Buckinghamshire and Hertfordshire, including: EICR Milton Keynes · EICR Leighton Buzzard · EICR Luton · EICR Bedford · EICR Aylesbury · EICR Watford · EICR St Albans · EICR Hemel Hempstead · EICR High Wycombe · EICR Northampton · EICR Berkhamsted · EICR Buckingham · EICR Wendover · EICR Woburn · EICR London · EICR Central London · EICR North London.
