The short answer
A full rewire replaces all the wiring, accessories and the consumer unit throughout the property; a partial rewire renews only part of the installation — often one floor, the kitchen, the bathroom, or specific damaged circuits. A full rewire is the right call when the cable insulation has degraded throughout or an old installation has accumulated many faults; a partial rewire suits a sound installation with localised problems or a single area being renovated. Full rewires cost more and take longer (roughly £4,450–£8,000 for a three-bed house), while a partial rewire is lower-cost but still needs making good. An EICR is the reliable way to decide, because it tests the whole installation and codes each fault.
The choice is rarely about preference — it follows from the condition of the wiring. The comparison below explains what each option covers and how the decision is usually made.
At a glance
- Full rewireWhole installation replaced
- Partial rewireOne area or circuits
- Decision toolAn EICR
- Full 3-bed cost~£4,450–£8,000
- Both needMaking good after
What each option covers
The two are different in scope, not just scale.
- Full rewire: all lighting and power circuits, sockets, switches and light fittings are replaced, along with a new consumer unit. The whole installation is renewed and certified as new work.
- Partial rewire: only part of the installation is renewed — for example, rewiring the kitchen during a kitchen renovation, replacing one floor's circuits, or repairing specific circuits flagged as faulty. The rest of the existing wiring stays in place.
A partial rewire is often combined with a consumer unit upgrade and added RCD protection, which improves safety across the whole installation even where older cable remains.
It is worth being clear that a partial rewire is not simply a smaller version of a full one — it is a different decision about what to keep. In a full rewire the assumption is that none of the existing fixed wiring is worth retaining, so everything is stripped back and replaced. In a partial rewire the assumption is the opposite: most of the installation is sound enough to keep, and only the failing or renovated part is renewed. That distinction matters because it changes how the work is certified. A full rewire is certified as a wholly new installation; a partial rewire is certified for the part that was done, with the electrician confirming that the new work has not impaired the safety of the existing installation it connects to.
| Full rewire | Partial rewire | |
|---|---|---|
| Scope | Whole property | One area or circuits |
| Consumer unit | Usually replaced | Sometimes |
| Typical 3-bed cost | ~£4,450–£8,000 | Lower, varies by scope |
| Disruption | High, whole house | Localised |
| Certificate | EIC for all new work | EIC / MWC for the work done |
Indicative comparison for guidance. MWC = Minor Works Certificate. Sources: Checkatrade and NICEIC guidance.
How to tell which you need
The deciding factor is the condition of the existing wiring, established by an Electrical Installation Condition Report (EICR). The report tests insulation resistance, earthing and the consumer unit, and records faults as C1, C2, C3 or FI codes. From that, an electrician advises on scope:
- Full rewire tends to be recommended when the cable itself has degraded (for example perished rubber insulation), when there is no satisfactory earthing, or when an old installation carries numerous C1 and C2 codes across many circuits, so repairing them one by one is no longer sensible.
- Partial rewire suits a fundamentally sound installation with localised faults, or where only one area is being renovated. There is no point replacing wiring that tests well.
This is why a rewire should not be assumed from symptoms alone. Plenty of EICR faults are fixed by a new consumer unit or individual circuit repairs, without disturbing the whole house.
It also matters who is doing the assessing. The most reliable picture comes from an electrician with no stake in the outcome — for example one carrying out a periodic EICR you have commissioned independently, rather than a quote for the rewire itself. Their job in that report is simply to test and code the installation, and the codes either justify replacing everything or they do not. If a recommendation for a full rewire rests on a handful of C3 improvement items, or on age alone with the wiring testing soundly, it is reasonable to ask for the specific findings that drive it. A full rewire that genuinely follows from degraded cable, missing earthing or a run of C1 and C2 faults across many circuits will be easy to explain in those terms; one that cannot be tied back to the report deserves a second opinion before you commit to the cost and disruption.
Cost, disruption and certification
A full rewire costs more and is far more disruptive: every room is affected, floors come up, walls are chased, and making good follows across the property. A partial rewire is lower-cost and contained to one area, though it still needs plastering and decorating where cable has been run.
Both produce paperwork. New work is signed off with an Electrical Installation Certificate (EIC), or a Minor Works Certificate for smaller alterations. Where the work is notifiable under Part P of the Building Regulations — which includes a new consumer unit and most circuit additions in special locations — it is registered with Building Control, usually automatically through the electrician's competent person scheme. Keep these certificates; they matter when you sell.
One point that catches people out is that a partial rewire still involves real disruption to the area it touches, even though it spares the rest of the house. Running new cable to a kitchen or one floor still means lifting boards, chasing walls and replastering in that zone, so the saving over a full rewire is in the untouched parts of the property, not in avoiding mess altogether. The other consideration is future-proofing: if an installation is borderline and likely to need further work within a few years, doing a contained partial rewire now and a second one later can cost more in combined disruption and making good than a single full rewire would have. Weighing the condition of the whole installation, not just the area in front of you, is what stops a sensible partial job becoming the first of several.
Common situations and which option fits
The right choice usually becomes clear once you look at the specific circumstances rather than the labels. Some typical scenarios:
- Renovating one room: a kitchen or bathroom refit is a natural moment for a partial rewire of that area, since the walls are open anyway. The rest of a sound installation is left in place.
- An old fuse board with no RCD, but sound wiring: often this needs a consumer unit upgrade rather than any rewire — the board is replaced and RCD protection added, while the existing cable that tests well stays.
- A few faulty circuits flagged on an EICR: targeted circuit repairs or a partial rewire of the affected runs, not a whole-house job.
- Perished cable throughout an old house: where the insulation itself has degraded across the installation, a full rewire is the sensible answer, because patching individual circuits leaves the underlying problem in place.
- Buying a period property with original wiring: commission an EICR first; the result tells you whether you are looking at a full rewire, targeted work, or simply a board upgrade.
The thread running through all of these is that scope follows condition. A full rewire is not inherently safer than a partial one if the partial work addresses everything the EICR flagged — and it is more expensive and disruptive. The report is what turns the question from guesswork into an evidence-based decision.
Frequently asked questions
Can I just rewire one room?
Yes. A partial rewire of a single room or area is common, especially during a kitchen or bathroom renovation. The rest of the installation stays in place, and the new work is certified with an EIC or Minor Works Certificate. Making good the affected walls is still needed.
Is a partial rewire a false economy?
Not if the rest of the wiring is sound. There is no benefit in replacing cable that tests well. A partial rewire becomes a false economy only when the wider installation is already degraded, in which case repeated localised repairs add up — an EICR settles the question.
Does a partial rewire need Building Control notification?
It can. Work in special locations like a kitchen or bathroom, and most consumer unit changes, are notifiable under Part P. A registered electrician handles the notification through their competent person scheme, so you usually do not need to contact Building Control yourself.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property. They are guidance, not a quotation. Legal duties are summarised for guidance — confirm the current position on GOV.UK.