Minor Works Certificate: When and How
A Minor Works Certificate covers an addition or alteration to an existing circuit that doesn't create a new one — add a socket to a ring, move a light, swap an accessory — but the moment the job becomes a new circuit, you need an EIC instead.
The Minor Electrical Installation Works Certificate (MEIWC) is the everyday certificate for small jobs: the socket added to a ring, the light moved along a lighting circuit, the accessory replaced. It's shorter than an EIC for a reason — it covers work that changes an existing circuit without creating a new one — but the boundary of what it can cover is precise, and crossing it means you need a full EIC.
This guide sets out exactly when a Minor Works Certificate is the right document, when it isn't, what testing still has to be done, and how to complete it properly.
Key takeaways
- A MEIWC covers an addition or alteration to an existing circuit that does NOT include a new circuit.
- One certificate covers one circuit — minor works to a single existing final circuit.
- The moment the work creates a new circuit, you need an EIC, not a Minor Works Certificate.
- You still have to test: verify the existing circuit's earthing and polarity, and test the work you did (continuity, insulation resistance, Zs, RCD).
- It confirms the minor work complies with BS 7671 and hasn't impaired the safety of the existing installation.
What a Minor Works Certificate is for
A Minor Electrical Installation Works Certificate certifies an addition or alteration to an existing circuit that does not extend to a new circuit. The typical jobs are adding a socket-outlet or a fused connection unit to an existing ring or radial, extending or moving a point on a lighting circuit, adding a spur, or replacing an accessory such as a socket or switch on an existing circuit.
The point of the MEIWC is proportionality: it would be excessive to complete a full EIC with all its schedules for the sake of one added socket, but the work still has to be certified and tested. The Minor Works Certificate is the right-sized document — it records the work, confirms it complies with BS 7671, and confirms it hasn't made the existing installation less safe.
The line you can't cross: a new circuit
The single defining limit is this: a Minor Works Certificate cannot be used where the work involves a new circuit. A new circuit — a new way run from the distribution board, a new protective device populated at the board — is new installation work, and new installation work requires an Electrical Installation Certificate with its full schedules of inspections and test results.
So adding a socket to an existing ring is minor works; running a brand-new radial from the board for that socket is an EIC. Extending a lighting circuit is minor works; adding a new lighting circuit on its own breaker is an EIC. When you're unsure, ask whether you've created a new circuit at the board — if you have, it's an EIC, no matter how small the rest of the job felt.
One certificate, one circuit, no new circuit
A MEIWC covers minor work on one existing circuit. Touch the board to add a new circuit and it's an EIC — the Minor Works Certificate can't cover that.
What you still have to test
Minor works being minor doesn't excuse testing — it just narrows the scope. Before you work, you verify the existing circuit is sound enough to add to: confirm the earthing and bonding arrangements, and the polarity, of the circuit you're altering. If the circuit you're extending has no CPC or a broken earth, you need to know before you add to it.
After the work, you test what you did: continuity of the protective conductor to the new point, insulation resistance of the altered circuit, polarity, and the earth fault loop impedance (Zs) at the new point to confirm disconnection times are still met. Where the circuit is RCD-protected, verify RCD operation. The results go on the certificate — the MEIWC has space for the essential test results even though it's shorter than an EIC's full schedule.
Completing the certificate
A properly completed MEIWC describes the minor works carried out, identifies the circuit altered and its protective device, and records the test results for the work: the protective conductor continuity, insulation resistance, polarity, measured Zs and RCD operating time where applicable. It's signed by the competent person who did and tested the work.
Crucially, the certificate includes a declaration that the minor works comply with BS 7671 and that the work has not impaired the safety of the existing installation. That second part matters: even a small alteration can expose an existing defect or overload a circuit, and by signing you're confirming you checked that what you added is safe in the context of what was already there.
"Not impaired" isn't a formality
Signing a MEIWC declares the existing installation is no less safe for your work. Spot the existing broken CPC before you add a socket to it — the declaration is yours.
Minor works, EIC or EICR?
Line the three up and the choice is clear. Minor Works Certificate: an addition or alteration to an existing circuit, no new circuit — a socket on a ring, a moved light, a replaced accessory. EIC: a new circuit, a new installation, or a rewire — new work you designed and built. EICR: a report on the condition of an existing installation you're assessing rather than adding to.
The confusion almost always sits between minor works and an EIC, and the test is always the new circuit. It's never about how big the job feels or how long it took — a quick job that happens to run a new circuit from the board is an EIC, and a fiddly afternoon spent extending one existing circuit is minor works. Certify by what the work is, not by how it went.
Frequently asked questions
When do I use a Minor Works Certificate?
For an addition or alteration to an existing circuit that doesn't create a new circuit — adding a socket to a ring, extending or moving a light, adding a spur, or replacing an accessory. One certificate covers minor work to one existing final circuit.
Can a Minor Works Certificate cover a new circuit?
No. The moment the work involves a new circuit run from the board, it's new installation work and needs an Electrical Installation Certificate (EIC) with full schedules. That new-circuit line is the defining limit of a Minor Works Certificate.
Do I still have to test for minor works?
Yes. You verify the existing circuit's earthing, bonding and polarity before adding to it, then test your work: protective conductor continuity, insulation resistance, polarity, Zs at the new point, and RCD operation where the circuit is RCD-protected. The results go on the certificate.
Does a consumer unit change need a Minor Works Certificate?
No — replacing a consumer unit is significant work affecting every circuit, and it's certified with an EIC, not a Minor Works Certificate. A MEIWC is for a single addition or alteration to one existing circuit.
From guidance to action
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Initial Verification: The BS 7671 Testing Sequence
The correct dead-then-live testing sequence for initial verification, step by step.
