RAMS for a Consumer Unit Replacement — Method Statement & Risk Assessment

A generic electrical RAMS doesn't cover a consumer unit replacement properly. The hazards stack up at the origin of the installation: you are working a few millimetres from the un-isolated supply tails, the customer is losing all power for the day, the cabling is often old and brittle, and you have a hard deadline — the board must be back on and tested before you leave.

Under the CDM 2015 framework and the Electricity at Work Regulations 1989 (EAWR), the duty holder is required to plan the work, assess the foreseeable risks and document the control measures before work begins. The Elec-Mate RAMS Generator builds a CU-specific RAMS pack in two minutes — but whether you generate it or write it yourself, the document must reflect what you will actually do on the day, not a copy-pasted template.

A risk assessment is only useful when it identifies the real hazards in front of you. For a consumer unit change in a UK property the principal hazards are:

For each identified hazard the RAMS must record the control measure, who is responsible, and how it will be verified on the day. The non-negotiable controls for a consumer unit replacement are:

The biggest single control measure for a consumer unit change is the isolation step. This is where almost every serious incident on a board change comes from — and it is the area where DIYers and inexperienced installers make the most dangerous decision: cutting the distributor's seal without authority.

Once the distributor has isolated upstream (or you have isolated at the main switch of the existing CU where the new board is being swapped without disturbing the tails), follow the standard safe-isolation sequence:

1. Identify the point of isolation — main switch on the existing CU, or upstream isolator fitted by the DNO.
2. Switch off, withdraw any plug-in fuses, and apply a personal lock-off device and a "Danger — Do Not Switch" caution notice. The key stays in your pocket. If a customer has access to the area, brief them and barrier off.
3. Prove your approved voltage indicator (GS38) on a known live source — a proving unit or a separate live point.
4. Test for absence of voltage at the actual point of work — between phase and neutral, phase and earth, and neutral and earth, on every conductor you are about to disconnect.
5. Re-prove the voltage indicator on the same known live source to confirm it is still functioning.
6. Record the isolation in the RAMS / permit-to-work, sign and time-stamp.

A formal permit-to-work for electrical isolation is overkill for a single-electrician domestic CU change, but in any commercial or HMO setting it is the right paperwork — and the RAMS should reference it. For more detail on the working-near-live-mains element, see our guide on hazard control near live mains.

PPE is the last line of defence after every other control — but a CU change has specific PPE requirements that a generic site PPE list doesn't cover:

BS 7671:2018+A4:2026 came into force during 2026 and a consumer unit replacement is the one job where you have full design control over the new installation. The RAMS should reference these compliance points so the customer is aware the new board will exceed the bare minimum:

A consumer unit replacement is an alteration to the distribution circuit at the origin of the installation. Under BS 7671 Part 6 it requires full initial verification — not a Minor Works Certificate. The output document is an Electrical Installation Certificate (EIC) signed by the designer, constructor and inspector (often all the same competent person on a domestic job).

The test sequence on a CU change follows BS 7671 Reg 643 and IET GN3 Section 2. Dead tests first, then live tests after energisation:

1. Continuity of protective conductors (R1+R2 on every final circuit, plus continuity of main protective bonding).
2. Continuity of ring final circuit conductors (line, neutral and CPC end-to-end and cross-connected).
3. Insulation resistance — between line conductors and earth, and between line and neutral, at 500 V DC, with electronic equipment disconnected or tested at 250 V where damage is a concern.
4. Polarity dead — confirm correct connection of every line conductor at every accessory.
5. Earth electrode resistance where the earthing arrangement is TT (not common on a CU replacement unless the supply earth has been refused).
6. Energise the installation (this is the live-working step — controlled, brief, with no terminations being touched while live).
7. Earth fault loop impedance (Zs) at every final circuit, recorded on the schedule of test results, with the measured value plus the calculated maximum from Table 41.x.
8. Prospective fault current at the origin (Ipf).
9. RCD operating-time tests at the rated 1× and 5× residual operating currents, including the supplementary 6 mA DC test for Type A/B RCDs as required.
10. Functional testing of every protective device (RCD test button, AFDD self-test, main switch operation).
11. Phase sequence on three-phase installations.

Every result lands on the schedule of test results, which is appended to the EIC. The customer receives the EIC and a copy is retained for six years for liability cover. Generate the EIC digitally with the Elec-Mate EIC Certificate tool — it auto-populates the schedule columns updated under A4:2026 and exports a Building Regulations Part P compliant PDF.