Consumer Unit Upgrade Checklist | C-Lec Electrical
Consumer unit guide • Milton Keynes

Consumer Unit
Upgrade Checklist

The full UK consumer unit upgrade checklist for 2026. Before, during plus after the install: what to check, what to verify, what paperwork must arrive plus what to ask your electrician.

Get a Free Quote Call Now
Updated: April 2026
Written by: Curtis Williams, Director, C-Lec Electrical
For: Milton Keynes & Bedfordshire homeowners
The short answer

A UK consumer unit upgrade lands in three stages. Before: establish whether you need an upgrade, scope the work plus pick a Part P registered installer. During: the unit is replaced in a single working day with safe isolation through the supply head. After: you receive an Electrical Installation Certificate, a Building Control notification through Part P plus an updated wiring drawing for your tenancy or property file. Each stage has its own checklist of items to confirm.

The numbers behind it

Three figures
worth knowing

1day

Typical Duration

A standard UK domestic consumer unit upgrade is a single working-day job. Power off for 4 to 6 hours during the install.

30days

Building Control Window

Your installer must notify Building Control through their Part P scheme within 30 days of completing the work.

25+yrs

Service Life

A correctly installed modern consumer unit normally lasts 25 to 30 years. The next upgrade trigger is normally a regulatory change rather than a fault.

The full process

Three stages of the
consumer unit upgrade

Each stage has its own checklist. Work through them in order. Skip nothing.

01

Before the Install

Research, scope plus installer choice

Before any spanner comes out, six items need to be confirmed. Each one shapes the scope plus the price plus the timeline of the work.

✓ Establish why you need the upgrade Failed EICR, planned EV charger install, property sale, plastic enclosure replacement, addition of new circuits or simple end of service life.
✓ Take a clear photo of the existing board Cover off, all devices visible, plus the meter cabinet showing the supply tails. This is enough for most installers to produce an initial quote.
✓ Confirm Part P registration of any installer Check NICEIC, NAPIT, Stroma or ELECSA registration online before booking. Cheap installs without registration cannot legally produce the EIC plus Building Control notice.
✓ Get at least two written quotes Each quote should specify the board manufacturer, the layout (full RCBO, high-integrity, dual RCD), inclusion of SPD plus AFDD where relevant, plus the price for any earthing or bonding upgrades discovered on survey.
✓ Confirm the install date plus duration Most upgrades are a single working day. Confirm the start time, expected finish time plus the windows when the supply will be off.
✓ Plan around the power-off window Move freezer contents if needed. Power down servers, NAS, alarms or anything sensitive to abrupt mains loss. Notify household members.
02

During the Install

What good practice looks like on site

A competent install follows a predictable sequence. You do not need to be an electrician to spot whether the work is being done properly. Six things should happen.

✓ Safe isolation through the supply head The DNO supply head fuse is removed (or the cut-out tag is broken under the installer's accreditation) before the existing tails are touched. Power confirmed dead with a voltage tester.
✓ Earthing plus bonding inspected first Main earthing conductor sized correctly (16mm sq minimum on TN-C-S). Main bonding to gas plus water inspected. Any undersized cables flagged plus quoted before the new board goes in.
✓ Existing wiring tested for insulation resistance Each existing circuit tested before reconnection to the new board. Faults found in the existing wiring flagged plus addressed separately rather than buried under a new unit.
✓ New unit fitted to BS 7671 layout Steel enclosure, 100A double-pole main switch, full RCBO or high-integrity layout, SPD where required, AFDD where required, all circuits identified plus labelled.
✓ Live testing on completion Earth fault loop impedance measured at every circuit. RCD trip times verified. AFDD self-test buttons confirmed. Polarity confirmed at every accessible point.
✓ Front cover labelled clearly Each MCB or RCBO labelled with the circuit it protects. Main switch identified. Test button locations marked. The label set should still make sense to the next electrician 10 years on.
03

After the Install

Paperwork, registration plus property file

The install is not complete when the lights come back on. Six items of paperwork plus follow-up close out the job properly. Without these the work fails Part P scrutiny on a future EICR or property sale.

✓ Electrical Installation Certificate (EIC) Issued by your installer on completion. Lists every circuit, the protective device fitted, the test results plus the engineer's signature. Keep with property documents.
✓ Building Control notification Your installer notifies Building Control through their Part P scheme within 30 days. You should receive a separate confirmation certificate from the scheme by post or email.
✓ Updated circuit chart on the cover The interior or back of the cover should hold a printed list of circuits matching the labels on the front. Update this if any circuits were renamed or rerouted during the install.
✓ Test the RCDs at six month intervals Press the T (test) button on every RCD or RCBO every six months. Each must trip cleanly. Reset plus continue. Note the date in your property records.
✓ Notify your insurer plus update tenancy file Some home insurers ask for confirmation of recent electrical work. Landlords should also add the EIC plus Building Control notice to the tenancy file within 28 days.
✓ Diary the next EICR date 10 years for an owner-occupied home. 5 years for a rental property. Set a calendar reminder. The new install certificate effectively resets the clock.
The detailed answer

Why the paperwork matters as much as the install itself

A consumer unit upgrade is partly a physical job (a new steel enclosure, new protective devices, properly torqued terminations) plus partly a documentation job. Both halves matter. The physical install protects the household from electrical faults today. The documentation protects the household from disputes in 10 years' time.

What the EIC actually does

The Electrical Installation Certificate is the formal record that the installation meets BS 7671 at the moment it was tested. It records:

  • The earthing system type (TN-S, TN-C-S, TT) plus the measured supply earth fault loop impedance.
  • Each circuit, its protective device rating, the cable size, the cable type plus the route.
  • The measured insulation resistance, continuity plus disconnection times for every circuit.
  • The signature, qualifications plus scheme registration number of the engineer.

An EICR carried out 5 or 10 years later starts by checking the position the EIC documented. If the EIC is missing or incomplete the EICR engineer has to test from scratch which takes longer plus can produce different conclusions. Without the original EIC there is no baseline.

What Part P notification actually does

The Building Control notification registers your consumer unit replacement with the local authority through the installer's Part P competent person scheme. The scheme issues a separate certificate confirming notification. This certificate is what conveyancing solicitors plus insurers ask for when proving the work was done legally. Without it, future property sales can encounter problems even if the EIC is in order.

The 30-day notification window is set in the Building Regulations 2010. An installer who does not notify within 30 days has technically committed an offence under the regulations even if the work itself is fine. Always confirm receipt of the certificate plus chase if it does not arrive within 6 weeks.

What good labelling actually does

The hardest part of a future fault diagnosis is normally identifying which circuit feeds which load. A board labelled "MCB 1 = sockets" is useless to the homeowner who needs to isolate the fridge socket at 11pm. A board labelled "MCB 1 = kitchen sockets ring (north wall plus island)" takes the same number of letters plus saves real time during a fault. Insist on circuit labels that match the actual loads, not just generic descriptions. The next electrician (or you) will thank you.

UK regulatory source check. The standards referenced here come from BS 7671:2018+A2:2022, Part P of the Building Regulations 2010 plus the Part P competent person scheme rules of NICEIC, NAPIT, Stroma plus ELECSA published by BSI plus the IET. C-Lec Electrical is a registered installer covering Milton Keynes, Bedford plus the surrounding Bedfordshire area.
Questions to ask

Six questions to ask
your installer before booking

Use these to compare quotes plus to confirm the installer knows what good practice looks like. Honest answers to these six questions tell you more than any glossy website.

Question 01

What is your Part P scheme registration number?

A direct ask. Should be answered immediately with the scheme name plus number. Verify the registration online at the scheme website before booking. No registration means no legal Part P notification.

Question 02

What board layout are you proposing plus why?

You want to hear "full RCBO with SPD" or "high-integrity" with a clear reason tied to your property. Avoid installers who default to dual RCD without explaining the trade-off.

Question 03

Will you survey the earthing plus bonding before quoting?

The right answer is yes. Undersized main earthing or bonding is the single most common surprise discovered during a board upgrade. An installer who does not check is one whose price will rise on the day.

Question 04

How long will the supply be off?

Honest answer is normally 4 to 6 hours. If you hear "an hour at most" the installer is either skipping testing or skipping safe isolation. Both are bad.

Question 05

When will the EIC plus Part P notification arrive?

The EIC should be on the day of completion. Part P notification within 30 days, certificate by post within 6 weeks. An installer who is vague on either is one to avoid.

Question 06

What does your warranty cover plus for how long?

Reputable installers cover their workmanship for 1 to 2 years plus carry public liability insurance plus professional indemnity. Get the warranty in writing before signing.

Practical takeaways

Four things every homeowner
should know

Part P registration is non-negotiable

Verify scheme registration before booking. Without it the legal Part P notification cannot be issued.

Earthing plus bonding drives price

The single most common scope addition is undersized main earthing or bonding. Insist on a survey before quoting.

Paperwork closes the job

EIC on completion. Building Control notification within 30 days. Without these the work is incomplete from a property records point of view.

Test the RCDs every six months

Press the test button. Each RCD or RCBO must trip cleanly. Reset. Diary the next test. Simple, free, important.

Ready to upgrade?

Consumer Unit Upgrades in Milton Keynes

C-Lec Electrical handles the full upgrade process plus paperwork across Milton Keynes, Bedford plus the surrounding Bedfordshire area. Same-day quotes from photos. EIC plus Part P notification handled in full.

Get a Free Quote Call Now

For the wider context on consumer units, RCBOs, AFDDs plus the regulations behind UK distribution boards, head back to our full guide to consumer units where every common question is answered in one place.

Part of the hub

Back to the Consumer Units Guide

This article sits inside our complete Consumer Units knowledge base. The hub covers everything from board types plus RCBOs through to landlord requirements plus BS 7671 wiring regulations.

Visit the Hub Call Now
Keep reading

More on planning
your upgrade

To work out whether you actually need an upgrade in the first place, start with do I need to upgrade my consumer unit. To plan the cost, see how much to change a consumer unit for typical UK pricing in 2026. To understand the regulations behind the work, see consumer unit wiring regulations. If you need a new consumer unit fitted in Milton Keynes or Bedford, our consumer unit upgrades service page is the fastest route to a quote.

Consumer Units

Do I need to upgrade my consumer unit?

Read article → Consumer Units

How much to change a consumer unit?

Read article → Consumer Units

Consumer unit wiring regulations

Read article →
Frequently asked

Upgrade checklist questions

How long is the supply off during a consumer unit upgrade?
Typically 4 to 6 hours. The exact window depends on the size of the board, the condition of the existing wiring plus whether earthing or bonding upgrades are also being completed. Smaller properties (1 to 2 bed flats) can sometimes be done in 3 to 4 hours. Larger properties or those needing additional remedial work can stretch to 7 or 8 hours. An honest installer will give you a realistic estimate at the point of quoting.
What happens if my freezer thaws during the upgrade?
A typical freezer holds its temperature for 4 to 6 hours unopened. The supply-off window normally falls within that range. To be safe move highly perishable items into a cooler for the day or arrange the install for a day when the freezer is least full. Some installers can fit a temporary supply lead from the meter direct to the fridge or freezer for the duration of the work. Ask at quote stage if this is needed.
Can I stay in the property during the upgrade?
Yes. Most occupants are home during the work. The supply is off in safe isolation but the rest of the property is normally accessible. Bring a battery torch for moving around in dim hallways. Wifi will be off so plan for any deadlines that need internet. Lift access in flats may also be off so plan for that if relevant.
What if my installer disappears without sending the Part P certificate?
First contact the installer directly. The certificate sometimes simply gets stuck in the scheme post-out queue plus a chase email resolves it. If no response within 4 weeks of completion, contact the Part P scheme directly (NICEIC, NAPIT, Stroma or ELECSA) with the EIC reference number plus the engineer's registration number. The scheme can investigate plus issue the certificate or pursue the registration. Avoid installers who refuse to confirm scheme registration in writing.
Should I get an EICR before or after the upgrade?
Both are valid approaches. An EICR before the upgrade gives you a clear scope of what defects exist plus what the new unit needs to fix. This is normally the better approach if you suspect the existing installation has issues beyond the consumer unit itself. An EICR after the upgrade can wait 5 to 10 years because the new install is itself a tested baseline. For landlords the 5-year EICR cycle continues regardless of the install date plus the new EIC effectively counts as the latest test.