Rewiring a House UK: Costs, Signs You Need It and Part P Explained

Outdated electrical systems are responsible for over 20,000 house fires in the UK every year, according to Electrical Safety First. The majority of properties that need rewiring are pre-1970s homes that have never had the electrical installation updated since the house was built. The wiring is not just old — it is actively degrading, and the insulation that separates live conductors from everything else is failing. This guide sets out how to identify whether your property needs rewiring, what it will cost, how Part P Building Regulations work, and what to expect during the work.

Signs Your House Needs Rewiring

Any of the following are indicators that the electrical installation needs professional assessment and likely a full rewire:

Rubber-insulated or lead-sheathed wiring (pre-1965): the rubber insulation becomes brittle over decades, cracking and crumbling to expose live conductors. This is a fire and shock hazard. If you see brown or black rubber cables in your loft or under floorboards, get an electrician in immediately.
Round-pin sockets (pre-1947 style): these two-pin ungrounded sockets are incompatible with modern appliances and have no earth connection. Their presence indicates the wiring has not been touched since the original installation.
Bakelite switches: the brown moulded plastic switches common in inter-war and post-war housing are 70–80 years old and inherently unreliable. Their presence usually means no rewiring has occurred.
Rewirable fuse box (ceramic fuses, no MCBs or RCDs): the old-style fuse board with individual wire fuses cannot trip fast enough to protect modern electrical loads and provides no residual current protection against electric shock. Replacing it with a modern consumer unit is a minimum requirement.
Single-core aluminium wiring (1960s–1970s): aluminium was used in branch circuit wiring during a period of copper shortage. It oxidises at connections, creating resistance and heat. UK wiring regulations no longer permit aluminium for branch circuits. Properties with aluminium wiring need full rewiring.
Persistent tripping under normal load: a circuit breaker that trips when you use an oven, kettle, and microwave simultaneously indicates the circuits are overloaded — designed for 1960s appliance loads, not modern kitchens.
EICR returning C1 or C2 codes: a Danger Present (C1) or Potential Danger (C2) classification on an Electrical Installation Condition Report requires remedial action. C1 is immediate; C2 should be addressed within 28 days.

These signs are especially common in Victorian and Edwardian properties — if you own a pre-1919 home, our Victorian and Edwardian house renovation guide covers the full priority sequence for updating the electrical, plumbing, and structural elements.

If any of these signs are present, do not attempt a DIY fix. The installation requires professional assessment — patching dangerous wiring is not a solution.

Rewiring Costs by Property Size

Property	Cost Range	Notes
1-bed flat	£3,000–£4,500	Includes consumer unit upgrade
2-bed house	£4,000–£6,000	5–6 circuits typical
3-bed semi	£5,000–£8,000	Most common UK rewire scenario
4-bed detached	£8,000–£12,000+	10–14 circuits, larger RCBO board

These figures are for the electrical work itself. Pre-war properties with lathe and plaster walls are harder to chase cables through and add £1,000–£3,000 for making good. Properties requiring a new incoming supply (where the DNO tails also need upgrading) add £500–£1,500 plus DNO coordination time.

In London and the South East, add 20–25% to labour costs.

What's Included in a Full Rewire

A complete house rewire should include:

New consumer unit (split-load RCBO board): each circuit gets its own MCB (miniature circuit breaker) and RCD (residual current device) combined in a single RCBO. This means a fault on one circuit cannot knock out half the house. Split-load boards with individual RCBOs are the current gold standard — avoid budget twin-RCD boards, which leave half your circuits unprotected if one RCD trips.
New cabling to all circuits: lighting, ring mains (sockets), cooker, shower, boiler, immersion heater if applicable
New sockets, switches, and ceiling roses throughout
Smoke and CO detector installation to BS 5839-6: at minimum, one smoke alarm per floor and a CO detector where there are combustion appliances
Testing to BS 7671:2018 (18th Edition IET Wiring Regulations)
Electrical Installation Certificate (EIC) issued on completion

NOT included (price separately): replastering after cable chasing (£500–£2,000), carpet relaying (£5–£10/m²), loft insulation reinstatement.

Consumer Unit Upgrade Only

If an EICR confirms the wiring itself is in serviceable condition (all C3 or better, no C1/C2 codes), a consumer unit replacement alone may be sufficient:

Cost: £500–£1,500 including Part P notification
This does NOT make old wiring safe if the wiring has deterioration issues — the board upgrade is not a substitute for rewiring
A split-load RCBO board is strongly preferable to a budget twin-RCD alternative
Consumer unit replacement is notifiable under Part P regardless of whether any new circuits are added

Part P Building Regulations — What It Means for You

Part P (Electrical Safety in Dwellings) is Schedule 1 of the Building Regulations 2010. It requires that electrical work in dwellings is designed, installed, inspected, and tested to protect persons from fire and injury. For a full overview of all notifiable works across all trades, see our building regulations approval guide.

Notifiable work (must comply with Part P and be notified to Building Control) includes:

Installation of a new circuit
Replacement or significant alteration of a consumer unit
Any work in a bathroom, shower room, or kitchen near a sink (Zone 0, 1, or 2)

Not notifiable: replacing like-for-like fittings outside special locations — swapping a socket faceplate, replacing a ceiling rose, changing a light fitting on an existing circuit in a bedroom or living room.

Two routes to compliance:

Use a Part P Registered Electrician (NICEIC, NAPIT, ELECSA, BRE, STROMA). They self-certify the work, notify Building Control automatically, and issue a BS 7671 test certificate. This is the standard route.
Use an unregistered electrician and notify Building Control yourself — add a £300–£500 inspection fee and allow 5–10 working days for the inspection to be arranged before work can begin.

Never use an unregistered electrician and skip Part P notification. This voids your buildings insurance policy, creates a compliance failure that will appear on a conveyancer's enquiries at sale, and is a criminal offence under the Building Act 1984.

EICR — Electrical Installation Condition Report

An EICR is a periodic inspection and test of an existing electrical installation, identifying deterioration, damage, defects, and non-compliance with current standards.

Cost: £150–£300 for a standard house (more for larger properties)
Condition codes: C1 (Danger Present — immediate action required), C2 (Potentially Dangerous — urgent remedial action), C3 (Improvement Recommended — not a fail, no immediate action required), FI (Further Investigation required)
Landlord legal requirement: EICR must be carried out at least every 5 years under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020. Copy must be provided to tenants.
Home buyers: always request a current EICR from the vendor before exchange. If none exists, commission one before exchange — it costs £150–£300 and tells you whether you're buying a property that needs a £500 consumer unit swap or a £7,000 full rewire. If you're buying a property and want to understand the full picture of what a survey will flag, see our home survey types guide.

An EICR does not certify new work. Work on new circuits requires an Electrical Installation Certificate (EIC), which only a registered electrician can issue.

Disruption — What to Expect

A full house rewire is one of the most disruptive domestic projects. Set expectations clearly:

Duration: 5–10 working days depending on property size and access conditions
Floorboards: upper floor floorboards are lifted to route cables beneath. Budget for re-securing loose boards and occasional replacement of damaged sections.
Carpets: must be lifted on upper floors — arrange this with the electrician in advance or remove carpets yourself beforehand
Wall chasing: cables are chased into wall surfaces throughout. Replastering is required after the work — budget £500–£2,000 depending on scale and your tolerance for DIY making-good
Living in the property: possible, but circuits are isolated room by room during the work. Expect periods without lighting or sockets in active work areas.

Critical sequence rule: rewire before you replaster, tile, or redecorate. An electrician chasing cables through a newly plastered or tiled wall will cost you double in making good. Always rewire first. This applies particularly when planning a bathroom renovation — always complete electrical first fix before tanking and tiling.