A great many London houses are still running on wiring that was installed several decades ago, sometimes added to by every owner since. Old wiring does not always mean dangerous wiring, and a full rewire is not always the answer. This guide sets out the warning signs, which ones are urgent, how to find out what you actually have, and the difference between a full rewire, a partial rewire and a new consumer unit.
Which signs are urgent
Some signs mean you should stop using the circuit and call an electrician now. Others mean the installation is dated and should be tested soon. Burning smells, scorch marks, sockets that are hot to the touch, sparking, and tingles or shocks from switches or appliances are all urgent. Switch off the affected circuit at the consumer unit if you can do so safely.
Signs your house needs rewiring
1. An old fuse box with rewireable fuses
A wooden-backed board, a cast iron switch or a fuse carrier with fuse wire usually means the installation has no modern protection. It does not automatically mean a rewire, but it does mean the wiring behind it needs testing.
2. Rubber, lead or fabric-covered cable
Cable insulated in rubber or sheathed in lead or fabric dates from before modern PVC cable became standard. Rubber insulation becomes brittle and crumbles with age, and that is one of the clearest reasons for a full rewire. You may see it where cables enter the consumer unit, in the loft or under floorboards.
3. Round-pin sockets and old switches
Round-pin sockets, brown bakelite switches and surface-mounted sockets on skirting boards are signs of wiring that has not been renewed for a very long time.
4. Circuits that keep tripping
A breaker or RCD that trips repeatedly is telling you something: a fault on a circuit, damp in a fitting or an appliance, or an overloaded circuit. It should be investigated rather than reset again and again.
5. Flickering or dimming lights
Lights that flicker when something else is switched on can point to loose connections or overloaded circuits.
6. Warm, discoloured or loose sockets and switches
Brown marks around a socket, a faceplate that is warm, or a plug that falls out are signs of heat at the connection, which is a fire risk.
7. Not enough sockets
Extension leads in every room and adaptors stacked on sockets mean the wiring was designed for a different way of living and is being asked to carry loads it was never sized for.
8. No earth on the lighting
Older lighting circuits were often installed without an earth conductor. That makes metal light fittings unsafe to fit and is a common finding on an EICR.
9. Years of DIY additions
Spurs from spurs, junction boxes under floors, cables run in the wrong zones in walls and kitchens extended without new circuits all build up over time. An electrician will find them during testing.
How to find out for certain
The only reliable way to know the condition of your wiring is an Electrical Installation Condition Report. A registered electrician inspects and tests every circuit and codes anything dangerous or below standard. The report tells you whether you need a few repairs, a new consumer unit, a partial rewire or a full rewire, and gives you something concrete to price against. See our EICR page, and EICR cost in London for what affects the price.
Full rewire, partial rewire or consumer unit?
Consumer unit replacement
If the cables test well but the board is old, replacing the consumer unit with one that has RCD protection may be all that is needed, along with any earthing and bonding corrections.
Partial rewire
Where one part of the house was rewired more recently, for example a kitchen extension, only the older circuits may need replacing.
Full rewire
Where the cable itself is at the end of its life, as with rubber insulation, the sensible answer is new wiring throughout. Our full house rewire and rewiring and consumer unit pages explain each option.
What a rewire involves
A rewire is done in two stages. First fix runs the new cables and back boxes, which means lifting floorboards and cutting channels in plaster. Then walls are made good and plastered. Second fix connects the sockets, switches, lights and the new consumer unit, and everything is tested and certified. In England, rewiring is notifiable work under Part P of the Building Regulations, so it must be done by a registered electrician who can self-certify or be approved through Building Control. You receive an Electrical Installation Certificate at the end.
The house is dusty and disrupted during first fix, so a rewire is best done empty or alongside other work. If you are planning a refurbishment, rewire before the plastering and decorating, not after.
Rewiring period homes
Victorian and Edwardian houses need care during a rewire. Lath and plaster ceilings, cornices, original floorboards and panelled doors can all be damaged by careless chasing and lifting. Routes can often be planned under floors and through voids to keep chasing to a minimum, and boards lifted and relaid rather than cut.
Rewiring rented properties
For landlords, an unsatisfactory EICR with C2 items on old wiring often makes a rewire the better long-term choice than repeated remedials. It is easiest done between tenancies, and the new installation certificate restarts the five-year inspection cycle. Our guide on when a landlord needs an EICR explains the rules.
What affects the cost of a rewire
- The size of the property and the number of circuits.
- How many sockets, lights and switches you want, and where.
- Whether the house is occupied or empty.
- Floor and wall construction, and how much plastering and making good follows.
- Extras such as outside lighting, an electric vehicle charger supply or data cabling.
We price every rewire in writing after seeing the property, with making good either included or listed separately.
How GMAS handles a rewire
- Test first. An EICR or a survey of the installation to confirm what is needed.
- Written quote. Circuits, accessories, making good and certification itemised.
- First fix and making good. Cables run, walls repaired and plastered.
- Second fix and certificate. Accessories fitted, tested and certified.
Frequently asked questions
How do I know if my house needs rewiring?
Warning signs include an old fuse box, rubber or fabric-covered cable, round-pin sockets, repeated tripping, warm or scorched sockets and no earth on the lighting. An EICR tells you for certain.
Does every old house need a full rewire?
No. If the cable tests well, replacing the consumer unit or rewiring only the oldest circuits may be enough.
How long does a rewire take?
It depends on the size of the house and whether it is occupied. Allow for first fix, plastering and second fix as separate stages.
Can I live in the house during a rewire?
Often yes, but it is disruptive and dusty during first fix. An empty house is quicker to rewire.
Do I need a certificate after a rewire?
Yes. You should receive an Electrical Installation Certificate and confirmation that the work has been notified under Part P.