Choosing the right document
Getting this right is worth marks in the exam and saves arguments on site. There are three documents, and which one applies depends entirely on what the work was.
| Document | Regulation | When it applies |
|---|---|---|
| EIC — Electrical Installation Certificate | 644.1 | A new installation, or an addition or alteration that includes the replacement of a distribution board or consumer unit |
| MEIWC — Minor Electrical Installation Works Certificate | 644.4.201 | An addition or alteration to an existing circuit that does not include a new circuit or a board/CU replacement |
| EICR — Electrical Installation Condition Report | 653.1 | Periodic inspection of an existing installation |
The distinction that catches people out is between the EIC and the MEIWC. The test is not the size of the job or how long it took — it is whether a new circuit was created or a distribution board or consumer unit was replaced. Adding a socket-outlet to an existing ring is minor works, however much cable it took. Adding one new circuit at the board is an EIC, however quick it was.
An EICR is never the right document for new work. It reports on the condition of what already exists.
What accompanies a certificate
A certificate on its own is incomplete. Both the EIC and the EICR must be accompanied by:
- a Schedule of Inspections, recording what was inspected and the outcome
- a Schedule of Test Results, recording the measured values circuit by circuit
The Minor Works Certificate is self-contained — it has its own space for the limited test results the work requires — because it covers a single circuit alteration rather than an installation.
Supply characteristics and earthing arrangement
Every EIC and EICR records the characteristics of the supply, because they determine what the installation needs:
- Earthing arrangement — TN-S, TN-C-S, TT or IT
- Number and type of live conductors — for example, single-phase 2-wire, or three-phase 4-wire
- Nominal voltage (U₀) and frequency
- Ze at the origin — the external earth fault loop impedance
- PFC at the origin — the prospective fault current
- Main protective device — its type and rating
Ze and PFC are measured at the origin with the main earthing conductor disconnected from the earthing terminal, which means the installation must be isolated to take them safely. Recording a figure supplied by the distributor rather than measured is acceptable only where that is stated on the certificate.
The Schedule of Test Results
Circuit by circuit, the schedule records what the circuit is, how it is protected, and what it measured:
- circuit designation, reference method and conductor sizes
- protective device type, rating and short-circuit capacity
- RCD rating and operating time where fitted
- continuity results: r1, rn, r2 and R1+R2
- insulation resistance, line-line and line-earth
- polarity confirmed
- measured Zs
Blank cells on a test schedule are read as “not tested”. If a value genuinely could not be obtained, record why, rather than leaving a gap that implies an omission.
Who signs, and for what
An EIC carries three declarations:
- Design — that the design complies with BS 7671
- Construction — that the installation was built to that design
- Inspection and testing — that it was verified and found to comply
One person may sign all three, or three different people may sign one each. Signing a section means taking responsibility for it; you cannot sign for design work you did not do and did not see.
A Minor Works Certificate has a single signature. An EICR is signed by the person who carried out the inspection and testing, and, where different, by the person authorising the report.
Departures
Where the installation departs from BS 7671, the departure is recorded on the certificate along with the reasoning that makes it safe. A departure is not automatically a defect — the standard allows for designs that achieve the same degree of safety by other means — but it has to be declared, not quietly omitted.
The recommended interval
An EIC states a recommended date for the first periodic inspection. An EICR recommends the interval to the next one. That recommendation is a judgement based on the installation’s type, use, age, condition and the external influences acting on it, not a figure copied from a table.
Common exam mistakes
- Issuing a Minor Works Certificate for work that included a consumer unit replacement. That needs an EIC.
- Issuing an EICR for new work, or an EIC for a periodic inspection.
- Forgetting that the Schedule of Inspections and Schedule of Test Results are required parts of the certificate, not optional attachments.
- Recording Ze without noting whether it was measured or supplied by the distributor.
- Signing all three EIC declarations for a job where someone else did the design.