At worst, faulty electrics can be a serious fire hazard and can lead to electrocution and a potentially fatal accident. This is why electrics were brought in to the building regulations under Part P. Existing wiring installations are not covered, but if you make significant alterations or new additions to the wiring in your home, the regulations come into force.
If you are thinking of buying a property more than 25 years old, it is important to check that the wiring is up to date before you buy. Ideally, you will get an idea of what work is required and an estimate of the likely cost so that you can take this into account when assessing the feasibility of the project and how much to offer.
Even if you already own the property you are renovating, it is important to know early on if any rewiring work will be necessary, as it can be very disruptive to the fabric and decor of the building, and so is best completed early on, before any re-plastering or redecorating work takes place.
When is Rewiring Necessary?
If a property has not already been rewired within the last 25-30 years, the chances are it will need upgrading at least in part in order to bring it up to current standards.
If you plan major remodelling work that constitutes a material alteration as defined by the Building Regulations, it is likely that you will need to rewire part, if not all, of the property, including upgrading the consumer unit (fuse box).
If you are extending your home, or converting an attic or garage, this will constitute new work and therefore all of the new wiring will have to conform to Part P: Electrical Safety, and all existing wiring will have to be improved to ensure that it is able to carry the additional loads safely, it is earthed to current requirements and that cross bonding is satisfactory.
Where you are extending or remodelling, the rest of the existing wiring does not have to be upgraded, except where upgrading is required by the energy efficiency requirements of the Building Regulations, i.e. central heating controls.
How to tell if Your Property has Been Rewired
You should be able to tell if a house has been rewired recently by inspecting exposed parts of the wiring and by the electricity meter and fuse box (now known as the consumer unit). You can ask to do this when being shown around a property you are thinking of buying, or by inspecting your home. If there is an old-fashioned-style fuse box, with big white ceramic-style fuses, then the chances are that the property needs completely rewiring.
With two or more sets of circuits, it can be very difficult to know if all of them have been disconnected when undertaking work and this is unsafe. Another tell-tale sign that a rewire may be necessary is a mix of different socket and switch styles. This could indicate that a partial rewire has taken place, especially if there is evidence of surface-mounted wiring running along skirting boards and up walls.
In some rare cases of properties that have not been renovated in decades, you may still find examples of old round pin sockets or original dolly switches, both of which are a sure sign that a rewire is necessary.
Another clue is the colour and style of the cabling, which you should be able to see at light fittings, around the fuse box. Modern electrical installations are wired in PVCu insulated cable coloured grey or white.
What if it has not Been Rewired?
Unless the wiring is the modern PVCu coated type, then a rewire is likely to be necessary. If you see any old rubber insulated cabling, fabric insulated cabling (used until the 1960s), or lead insulated cabling (used until 1955) then it needs replacing as the insulation can rot and/or break down, leading to short circuiting: a fire hazard and potential electrocution.
Even older PVCu cable may need replacing if it is not twin earthed cabling (with a second earth cable running within the outer sleeve), but this may only be evident if you are able to remove a switch or socket faceplate and look closely.
If you are in any doubt, assume that a total rewire is required and budget accordingly. It may be that the system can be improved for less money by upgrading earthing and cross bonding.
If you proceed with the project, then before exchanging contracts you can arrange for me to do a survey and find out exactly what work is required.
How Much Will Rewiring Cost?
A full rewire will cost around £2-2,500 for a small property and considerably more for a larger property, not including the cost of making good the decoration.
Very often, a full rewire can be avoided, however; providing the existing cabling is sound and able to carry any additional loads, it also may be possible to upgrade it by adding a modern consumer unit, proper earthing arrangements and cross bonding.
What is Involved When Rewiring?
If rewiring work is required, it should be undertaken at first fix stage (before plastering), at the same time as any central heating and plumbing work. New cabling cannot be surface mounted and so the installation will involve lifting the floor coverings and floorboards and possibly the skirting boards too, routing out channels in the walls and possibly in some ceilings that are inaccessible from above. All of this work will cause major disruption and so it is best not to try and live around the work if possible.
As well as installing new cabling, first fix stage will involve fitting new back boxes for all sockets and switches. In addition to rewiring for all power and lighting circuits, it is a good opportunity to rewire for modern central heating controls, alarms, smoke detectors and doorbells, to add outdoor lighting and sockets, and to rewire the telephones and television aerial sockets. It is also worth redesigning the wiring plan for sockets and switches to make sure it meets your needs and those of modern house buyers.
Think about specifying two-way or even three-way switching for hallways and landings and other rooms with more than one main access. For a high-value property, consider adding a separate 2 amp circuit with separate switching for table and standard lamps in the main living rooms and principal bedrooms. It may also be worth considering adding automated lighting, home network cablings, speaker cabling and other modern technology.
If the mains connection and meter needs moving, this will have to be undertaken by the local electricity utility company. There will be a charge and several weeks notice will be needed.
Once the first fix stage has been completed, the property can be re-plastered or the walls and ceilings filled and made good, and the flooring replaced. The second fix work can then proceed fitting sockets and switch plates, light fittings, the consumer unit and wiring any electric fans, cookers, extractor hoods, electric showers and the immersion heater, if there is a hot water storage cylinder.