A commercial EICR is the periodic inspection and testing of the fixed wiring in a workplace, reported on the same BS 7671 model form as a domestic one. No regulation names it, but Regulation 4(2) of the Electricity at Work Regulations 1989 requires every system to be maintained so as to prevent danger, and the report is how a duty holder shows that. IET Guidance Note 3 recommends a maximum of 5 years between inspections for offices and shops, 3 years for industrial premises and 1 year for swimming pools and petrol filling stations. The job differs from a house in three ways: three-phase distribution, agreed sampling, and limitations set in writing before you open a board.
- Intervals come from IET Guidance Note 3 (GN3) Table 3.2, not from BS 7671: typically 5 years commercial, 3 years industrial and agricultural, 1 year for pools, petrol filling stations, caravan parks and marinas.
- The legal driver is Regulation 4(2) of the Electricity at Work Regulations 1989. The EICR is evidence of maintenance, and an unsatisfactory report left unactioned is evidence against the duty holder.
- Every distribution board gets its own schedules. Each distribution circuit (sub-main) is a circuit in its own right, with Zs at the board, prospective fault current and insulation resistance recorded.
- Agree extent, sampling, exclusions and shutdowns in writing before the visit, and name the person who agreed them on the report.
- The socket-outlet RCD exception in Regulation 411.3.3 is narrower than most people think: a documented risk assessment only helps where ordinary persons do not use the sockets.
- Under the BS 7671:2018+A4:2026 model form, FI is advisory and only C1 and C2 make the report unsatisfactory. A2:2022 is withdrawn on 15 October 2026.
Is a commercial EICR a legal requirement?
Not by name. Rented housing has the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020, which demand a report at least every 5 years. Workplaces have a broader duty. Regulation 4(2) of the Electricity at Work Regulations 1989 (EAWR) says: "As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable, such danger." The HSE's guidance on the Regulations, HSR25, treats regular inspection as an essential part of preventive maintenance and recommends keeping test records for the life of the system. Periodic inspection and testing to BS 7671 Chapter 65 is the recognised way of doing both.
The duty sits with employers, the self-employed and employees for matters within their control (Regulation 3). Offences are prosecuted under the Health and Safety at Work etc. Act 1974 and carry an unlimited fine, with up to two years' imprisonment for individuals. Enforcement is split: the HSE covers factories, construction and similar sites, and local authorities cover most offices, shops, hotels and restaurants.
| Driver | What it asks for | Who checks |
|---|---|---|
| Electricity at Work Regulations 1989, Reg 4(2) | Systems maintained so as to prevent danger | HSE or local authority |
| Electricity at Work Regulations 1989, Reg 16 | People doing the work to have the technical knowledge or experience, or be supervised | HSE or local authority |
| Regulatory Reform (Fire Safety) Order 2005 (England and Wales) | Responsible person to assess and reduce fire risk, including electrical ignition sources | Fire and rescue authority |
| Commercial insurance policy | Inspection by a competent person at a stated interval, defects rectified | Insurer, usually at renewal or claim |
| Lease | Tenant or landlord to maintain the installation and hold evidence | The other party's surveyor or solicitor |
| Premises or entertainment licence | A current report, often at a shorter interval | Licensing authority |
Regulation 16 matters to you as much as to the client. It is the reason a commercial report should be carried out by someone with periodic inspection experience on three-phase systems, and countersigned where your firm's arrangements require it. See Qualified Supervisor (QS) Sign-Off Explained.
How often does a commercial property need an EICR?
BS 7671 gives no table. Regulation 652.1 says the frequency is to be determined from the type of installation and equipment, its use and operation, the frequency and quality of maintenance, and the external influences. The figures everyone quotes are recommendations in GN3 Table 3.2, now in its 10th edition for BS 7671:2018+A4:2026. They are maximum periods for the first inspection after an installation is put into service; after that the inspector recommends the next interval on the report, with a reason if it is shorter.
| Premises | Routine check | Maximum period between inspections |
|---|---|---|
| Commercial, offices, shops, laboratories | 1 year | 5 years, or at change of occupancy for commercial lets |
| Restaurants, hotels, public houses, village halls, churches | 1 year | 5 years |
| Educational establishments | 6 months | 5 years |
| Hospitals and clinics, general areas | 1 year | 5 years |
| Hospitals and clinics, medical locations | 6 months | 1 year |
| Industrial | 1 year | 3 years |
| Agricultural and horticultural | 1 year | 3 years |
| Leisure complexes (not pools), theatres, places of public entertainment | 1 year | 3 years |
| Cinemas | 1 year | 1 to 3 years |
| Swimming pools, marinas, fish farms | 4 months | 1 year |
| Caravan parks | 6 months | 1 year |
| Petrol filling stations | 1 year | 1 year |
| Launderettes | Monthly | 1 year |
| Fixed wiring of fire alarms | Daily and weekly user checks | 1 year |
| Fixed wiring of emergency lighting | Daily and monthly user checks | 3 years |
The table is paraphrased, so check the current GN3 before quoting it in a tender. Two points get missed. First, the routine check column: GN3 expects a recorded look-over between formal inspections, which need not be done by an electrician and is not a substitute for the EICR. Second, licensed premises may have an interval set by the licensing authority that overrides the table.
Regulation 652.2 gives large sites an alternative. Where an installation is under an effective management system for preventive maintenance, periodic inspection may be replaced by continuous monitoring and maintenance by skilled persons, with records kept. A hospital estates team or a factory with its own electricians can work this way; a shop with a caretaker cannot.
A change of use, a new tenant, a significant alteration, flood or fire damage, or a request from an insurer or purchaser all justify an inspection before the interval runs out. Intervals for every property type are in How Often Is an EICR Required? Intervals by Property Type.
What is different about inspecting a commercial installation?
The form, the codes and the standard are the same as for a house, and the sequence in How to Do an EICR Step by Step: Inspector's Workflow still applies. The differences are practical.
Three-phase supply and distribution circuits
A typical commercial intake is three-phase, 400 V between lines and 230 V to earth, on TN-C-S or TN-S, with a main switch or switch-fuse and distribution circuits to several boards. Each distribution circuit gets its own line on the schedule: cable type and size, the protective device at its origin, Zs measured at the far board (often written Zdb) and insulation resistance. BS 7671 allows a 5 second disconnection time for distribution circuits on TN systems (Regulation 411.3.2.3) and 1 second on TT (411.3.2.4), so check the device against the 5 second column, not the 0.4 second one.
Measure prospective fault current at the origin and at every board, record the higher of the line-to-neutral and line-to-earth values, and for a three-phase board multiply the single-phase line-to-neutral figure by 1.73 to estimate the three-phase value. Then compare it with the breaking capacity of the devices. A board of 6 kA circuit-breakers ten metres from the transformer can easily see more than 6 kA, and unless the manufacturer's data shows the upstream fuse backs them up (Regulation 434.5.1), that is an observation. Regulation 643.9 also requires phase sequence to be verified at each three-phase board. The method is in Three-Phase Testing Basics for Domestic Electricians and What is prospective fault current (PFC)? Explained.
Where Zdb is high, every final circuit on that board inherits the problem. Investigate the distribution circuit before you code twenty final circuits one by one; the fault-finding route is in Earth Fault Loop Impedance Testing: Ze, Zs and Ipf Explained.
Main bonding is sized differently too. On a PME supply, Table 54.8 sets the minimum main protective bonding conductor by the supply neutral: 10 mm² copper for a neutral up to 35 mm², 16 mm² up to 50 mm², 25 mm² up to 95 mm², 35 mm² up to 150 mm² and 50 mm² above that. The 10 mm² that is right for a house is undersized on a 200 A commercial intake.
One set of schedules per board
Every distribution board has its own schedule of test results and its own inspection items, headed with the board designation, location, the device that supplies it, Zdb and prospective fault current. Circuits are identified by the board's own numbering, so the chart on the door matters. Regulation 514.9.1 requires one, and a board with no chart, or a chart that has not survived three fit-outs, is the first observation on most commercial reports. Column-by-column help is in How to Fill In a Schedule of Test Results, Column by Column.
Sampling
Opening every socket-outlet and luminaire in a 200-desk office is not practical, and Regulation 651.2 allows inspection without dismantling, or with partial dismantling as required. GN3 describes the method: agree an initial sample, spread it across the installation including the far end of circuits, and increase it when defects turn up, to 100 per cent if they keep appearing. A common starting point is 20 per cent of socket-outlets and 10 per cent of luminaires per circuit, but the figure is yours to agree and record. Sampling applies to accessories and terminations. It does not mean leaving circuits out of the test schedule. Full detail is in EICR Sampling and Limitations Explained: Extent, LIM and N/V.
Isolation, access and live work
Regulation 14 of the EAWR prohibits work on or near live conductors unless it is unreasonable for them to be dead, it is reasonable to work live, and suitable precautions are taken. Live measurement inside a board meets that test only with barriers in place, leads and probes to HSE guidance note GS38, and a competent person holding the probes. Regulation 13 covers the other half: equipment made dead must be secured against being re-energised, which on a multi-tenant site means locks and tags, not a note on the door.
Agree shutdown windows before you quote. The table shows which tests need them.
| Test | Circuit dead or live? | Commercial practice |
|---|---|---|
| Continuity of protective conductors and ring finals | Dead | Done in the agreed shutdown, board by board |
| Insulation resistance | Dead | 500 V d.c., minimum 1 MΩ. Where equipment cannot be disconnected, Regulation 643.3.2 allows 250 V d.c., still with a 1 MΩ minimum; test live conductors joined together to earth to protect electronics |
| Zs at boards and final circuits | Live | Measured, or calculated from Zdb plus R1+R2 where a live test is not sensible |
| Prospective fault current | Live | At the origin and every board |
| RCD operation | Live, and it trips the circuit | Warn the occupier; one a.c. test at rated residual current (Regulation 643.8), plus the test button |
| Phase sequence | Live | Every three-phase board and three-phase outlet |
| Thermal imaging | Live and under load | A useful supplement for busbars and terminations; not a substitute for any test above |
Circuits that cannot be released, such as servers, refrigeration, security and process plant, are recorded as limitations with the reason, and should be picked up at the next planned shutdown. Test methods are in Insulation Resistance Testing Guide: Voltages, Minimums, Method and RCD Testing Explained: Types, Test Currents and Trip Times.
What should be agreed in writing before the inspection?
Regulation 653.2 requires the report to state the extent of the installation covered and the limitations of the inspection and testing. The model form asks for the agreed limitations, the reasons for them and who they were agreed with, and separately for operational limitations met on the day. On a commercial job, settle the first group by email before you arrive:
- Extent: which buildings, floors and boards are included, and whether tenant fit-outs, outbuildings, external lighting, car park supplies and EV charge points are in or out.
- Sampling: the percentage of accessories per circuit type, and the rule for increasing it.
- Circuits that cannot be isolated: what they are, who decided, and what will be done instead.
- Exclusions: emergency lighting (BS 5266-1), fire detection and alarm (BS 5839-1), lightning protection (BS EN 62305), lifts, machine wiring, generator and UPS outputs, high-voltage switchgear, solar PV and battery systems if they are to be reported separately, and portable appliances.
- Access: locked rooms, ceiling voids, risers, roofs, plant rooms and anything needing a permit to work.
- Records: previous reports, certificates, board schedules and drawings the client can supply.
State on the report what was excluded and why, and recommend that the client holds current certificates for the excluded systems: Emergency Lighting Certificate: BS 5266-1 Testing and Records, Fire Alarm Certificate BS 5839-6: Grades and Categories and PAT Testing Guide UK: Intervals, Tests and Records. A limitation must never be used to hide something that looks dangerous. If you could not confirm a thing that matters to safety, that is an FI observation, not a line in the limitations box.
How are observations coded on a commercial report?
The codes are the ones used everywhere: C1 danger present, C2 potentially dangerous, C3 improvement recommended, FI further investigation. What changed in 2026 is the outcome rule.
| Model form | What makes the report unsatisfactory | Status |
|---|---|---|
| BS 7671:2018+A2:2022 | Any C1, C2 or FI | Withdrawn 15 October 2026 |
| BS 7671:2018+A4:2026 | Any C1 or C2. C3 and FI are listed separately as advisory | Published 15 April 2026 |
The IET's explanation, in Wiring Matters in July 2026, is that C3 and FI were decoupled from C1 and C2 to make clear they do not produce an unsatisfactory outcome. That does not make FI a soft option on a commercial site. A duty holder who has been told in writing that something needs investigating, and does nothing, has a weak answer under Regulation 4(2). Write the FI so it says what to investigate and why, as shown in How to Write EICR Observations That Stand Up.
One caution on sources. Electrical Safety First's Best Practice Guide 4 is written for domestic and similar installations. It is a sound starting point for a small shop or office, but in a factory or a plant room the classification rests on your engineering judgement of who has access and what a fault would do. The codes themselves are explained in EICR Observation Codes Explained: C1, C2, C3 and FI.
What defects are found most often in commercial installations?
| Observation | Regulation | Typical code | Notes |
|---|---|---|---|
| No circuit chart, or one that no longer matches the board | 514.9.1 | C3 | Where circuits cannot be identified for safe isolation, say so and treat tracing as part of the remedial work |
| Borrowed neutral between circuits on different devices | 314.4 | C2 | Usually lighting after alterations; shows up when insulation resistance only passes with the next circuit off |
| Socket-outlets up to 32 A without 30 mA RCD protection | 411.3.3 | C3, or C2 where they could supply equipment outdoors or in wet areas | Ask for the risk assessment before accepting an exemption |
| No main bonding to structural steel or incoming services | 411.3.1.2 | C2 where the part is extraneous | Test before coding; FI if it cannot be established |
| Main bonding undersized for the supply neutral | Table 54.8 | C3, or C2 if grossly undersized or damaged | Common where a supply has been upgraded and the bonding left |
| Missing blanks, broken covers, exposed live parts | 416.2 | C1 if touchable, otherwise C2 | Make safe or isolate with the client's agreement before leaving |
| Device breaking capacity below the measured fault current | 434.5.1 | C2 | Check the manufacturer's back-up data before coding |
| Overheated terminals, discoloured busbars | 526.1 | C2 | Look at loading and loose connections; thermal images help the client see it |
| Connections outside an enclosure above ceilings | 526.5 | C2 | Typical of luminaire changes during fit-outs |
| Inadequate IP rating in kitchens, wash-down or external areas | 512.2 | C2 | Water tracking into live parts |
| Cables supported only by plastic clips or trunking | 521.10.202 | C3 | Premature collapse in fire; the rule covers the whole installation, not only escape routes |
| Fire-stopping missing where containment passes through compartment walls | 527.2 | C2 or C3 on judgement | Tell the responsible person so it reaches the fire risk assessment |
| Unidentified or abandoned cables still connected | n/a | FI | Common after tenant changes |
Sockets and the 411.3.3 risk assessment
Regulation 411.3.3 requires 30 mA RCD protection for (i) socket-outlets up to 32 A in locations where they are liable to be used by ordinary persons, disabled people or children, (ii) socket-outlets up to 32 A in other locations, and (iii) mobile equipment up to 32 A for use outdoors. Since Amendment 2 in 2022 the exception for a documented risk assessment, in premises other than dwellings, applies to item (ii) only. The IET's guidance adds that the assessment is made by a skilled person (electrically), is attached to the certificate, and that giving staff instructions does not turn ordinary persons into instructed ones. In practice an open-plan office or a shop floor cannot rely on the exception for new work; a locked plant room or a workshop staffed only by skilled people might. On an existing installation, record what you find and code on risk.
Borrowed neutrals
Where two lighting circuits share a neutral, the neutral of the circuit you have isolated still carries return current from the one left on. Regulation 314.4 requires each final circuit to be electrically separate, and the hazard is to the next person who works on it. Finding and coding them is covered in Borrowed Neutrals: How to Find, Test and Code Them.
Structural steel
Portal-frame warehouses and steel-framed offices have exposed steel that may or may not be an extraneous-conductive-part. Measure between the steel and the main earthing terminal. A very low reading with no visible bond suggests it is connected somewhere through fixings or containment. A reading above about 22 kΩ suggests it cannot introduce a dangerous potential and needs no bond. Anything in between needs judgement and a note of the reading on the report. The reasoning is in What is main protective bonding? Explained.
What do insurers, landlords and facilities managers need from the report?
Insurers usually require inspection by a competent person at a stated interval, commonly 5 years and sometimes 3 for higher-risk trades, with defects rectified. Some ask for the report at renewal; most ask after a fire. An unsatisfactory report that has sat in a drawer for two years is worse than no report, because it shows the duty holder knew.
In leased premises the lease decides who commissions the work. Under a full repairing and insuring lease the tenant maintains the installation within the demise and the landlord the common parts and incoming supply, and both are duty holders for what they control. Blocks with shared landlord's supplies are covered in EICR for Flats and Communal Areas: Who Is Responsible?.
A facilities manager wants four things: a clear overall assessment, observations they can price from, a recommended date for the next inspection, and paperwork for the remedials. Issue an Electrical Installation Certificate or Minor Works certificate for the remedial work so the file closes the loop (/guides/minor-works-certificate-when-to-use-it and Unsatisfactory EICR: What Happens Next (Landlords & Electricians)). Keep your own copy as well; retention periods are in Electrical Certificate Retention and GDPR for Electricians.
How should a commercial EICR be scoped and priced?
Price from the number of boards and circuits, the sampling percentage and the shutdown hours, never from floor area. Walk the site or ask for board photographs and the last report before quoting, because a 12-way board in a ceiling void above a trading shop floor takes longer than a 24-way board in a plant room. Allow for out-of-hours work, a second person for live measurement, and the write-up, which on a 20-board site can take as long as a day on the tools. Worked figures are in How to Price an EICR: A Method for Electricians and How Long Does an EICR Take? Typical Times by Property Type.
How Certio helps
Certio produces the EICR, EIC, Minor Works certificate and PAT records on the BS 7671 model forms and turns them into branded PDFs. Photograph the consumer unit and the circuit schedule drafts itself; point the phone camera at a Megger MFT-X1 and the reading goes straight into the schedule of test results, or dictate it while your hands stay on the probes. Suggested observation wording with the regulation reference is there for you to check and confirm. The judgement stays yours; the typing goes. Starter is free for 7 days, then £4.99 a month.