Improper wiring and faulty electrics can cause a lot of damage. It could lead to electrocution and fire outbreak which can ultimately result into loss of life and property. Avoiding this unwanted situations is why the government included electrics under Part P in the building regulations. Although, the regulation does not cover existing wiring installations, when you carry out rewiring in your building or you make major changes to what you have beforehand, you must adhere to the regulation.
To do this, you must have some background information on the building you’re working on. If the building is older than 25 years, you must check to ensure that the wiring is up to date, and if not, to know the necessary corrections to be done and how much it will cost. On the other hand, if you are renovating a building, early information about the need for rewiring will make work faster and will avoid late wiring which affects the progress of work as it can deface already completed plastering and painting works.
When rewiring is necessary.
If your building’s wiring is older than 25 years, then there is a need for upgrading of the wiring system to bring it to the current standard. This is because the existing wiring system cannot meet the electrical demands of modern usage.
If you carry out significant alteration work especially one that includes change in material, there will be need to rewire most parts of the building. You will also need to change the consumer unit (fuse box). This is what the Building Regulations stipulate.
When you make an extension to your building, e.g. building an attic or garage, youo will have to make new wiring works which must be in line with Part P: Electrical Safety. Consequently, all existing wiring has to be upgraded to allow for additional loads.
When you are altering existing design or carrying out additional works, it is not compulsory to upgrade existing wiring except need be. You also need an upgrade when the efficiency requirement of the Building Regulation has to be met.
Tell-tale signs of a recently rewired building.
There are many ways through which you can know if a building has been rewired recently or not. One of such ways is by inspecting exposed parts of the wiring and by the electricity meter and fuse box (now known as the consumer unit).
In addition, when you’re being shown around the property you want to purchase, or the one you’ve purchased already, watch out for the cabling style, the socket types and the switches. Wall mounted or conduit PVC cabling are indicators of a recently rewired building. On the other hand, old-fashioned-style fuse box, with big white ceramic-style fuses, are signs that the property needs completely rewiring.
Another way to know if the building has been rewired recently is when you see a mixture of different socket and switch styles. When you see this, you know that partial rewire has recently been done. It takes a way all doubt when you notice a wiring style in which wires are mounted on the surface of the wall along skirting boards.
Another easy way to know is to notice the colour and style of the cabling. This you see around light fittings and around the fuse box. Plus a recent rewire will make use of white or grey coloured PVCu as coat for cables. It will also make use of circuit breakers and residual circuit devices.
Modern consumer unit will also have circuit breakers and residual circuit devices (RCDs). RCDs are installed to ensure safety of the whole system as they are designed to automatically shut down the building’s electricity when an electrical fault is detected.
What if it has not Been Rewired?
When you examine the wiring system of your property, be sure to check the cabling type. As mentioned earlier, anything other than the modern PVCu coated cable are old. Old rubber insulated cabling or fabric insulated cabling should be removed. They are old and out of style. Fabric insulated cabling has been outdated since the 1960s. Lead insulated cabling became outdated an earlier time, 1955. They have the tendency to rot and decompose, exposing cables and leading to short circuiting; an electrocution or a fire outbreak becomes imminent.
In order not the leave the matter to chance, if you are not certain whether the wiring system needs complete or partial rewiring; or not, it is better and safer to assume that the whole system needs rewiring. Better safe than sorry.
Cost Estimate for an initial electrical survey by an electrician?
It is highly recommended that before you begin rewiring works, contract the service of a cost expert in the area of electrical wiring; a quantity surveyor or a qualified electrical engineer. This is important as it will make you know the scope of work, and how much it will likely cost. It will cost you the range of £100-150 to get an electrician who will carry out the survey and will report to you orally alone. It will cost you more, about £250-350 to get an electrician who will carry the survey, make cost estimates and submit to you a report in written form.
What you must do before you begin rewiring works.
Carry out careful planning
Carrying out a rewiring work can be messy and stressful. It basically involves two stages: the first fix and the second fix. The first fix stage involves getting the overall layout of the wiring system. At this stage, boxes to hold sockets, switches and light fittings will be made on the walls. Chassis for electric conduit wiring will also be done. All work in this stage should be done before plastering. The second fix stage basically involves the installation of sockets, switches, lighting fittings, the consumer unit and RCD. At this stage, all necessary cable connections are also made.
This process can be long and time consuming, hence you need to have planned out the electrical layout of your building. You need to have made conclusion on where each light and bulb and other electrical equipment will be located. Once the installations has been made, it is difficult to make alterations. You can do this easily if you sketch your building plan on a paper sheet and you indicate in the drawing the positions of the appliances.
Make allowance for future installations
Advancement in technology might create new electrical needs in near future. You may want to consider the possibility of installing Ethernet cables, mood lighting, Wi-Fi, ultra-modern kitchen gadgets, bedside speakers, etc. You may also want to install CCTV surveillance system. All this must be put into consideration while wiring the building. This is to give allowance for them in the electric wiring design.
Vacate your home temporarily if possible
It can be very messy carrying out rewiring works. It requires electricians and workmen to constantly climb into the roof of the building, cut pieces of wire cables and their coating will litter the ground, and all the activities will generate a lot of dust. It is therefore advised that when you want to rewire your building, you move out for some time until all rewiring works are completed. If you feel you can’t move out of the house, the next best bet is to arrange for yourself a room in your house where you can stay temporarily. You could ask your electrician to install a temporary electrical wiring there to make it a little more habitable.
How Much Will Rewiring Cost?
The cost of rewiring a building will vary in relation to the location. In the UK, the average cost of rewiring a kitchen extension, including first and second fix with standard sockets and switches and not including light fittings, is estimated to be around £1,000-£1,500. The average estimated cost for carrying out rewiring works for a three-bed semi is £3,500. As mentioned earlier, the price will vary with different locations.
There are other factors that can also affect the cost of rewiring. They include: the size of the house, how accessible or empty the property is, and the complexity and standard of the finish.
Sometimes, you might not have to carry out rewiring works. This can be advised only when the cables used for existing wiring are good enough to receive additional electrical loads. You can upgrade the wiring system by adding a modern consumer unit, cross bonding and proper earthing.
How Long Will the Rewiring Take?
It takes about two days to rewire a kitchen. A three-bed semi takes longer, about four days – two days for each fix. Depending on the size of the property, it may take longer especially for larger properties.
What is Involved When Rewiring?
All rewiring works required for a building should only be carried out at the first fix stage, i.e. before plastering is done. It should be done simultaneously with central heating and plumbing works. As it would be poor work installing new wireworks on the surface of the wall, the work will require that floorboards be lifted, making chassis to walls, lifting skirting boards; it is usually dusty, messy and require a lot of movement. At this same stage (first fix), new back boxes will be fixed for all switches and sockets just as it would be in installing a new cabling system. Hence, it is best if you don’t live in the same house where rewiring activities are being carried out.
You can take the opportunity to rewire, not just for power and lighting devices. You can rewire to install modern central heating controls, alarms, smoke detectors and doorbells, to add outdoor lighting and sockets, and to rewire the telephones and television aerial sockets. In addition, you can carry out rewiring to have modern plan for switches and sockets in order to meet your needs and that of modern house buyers. Doing this will definitely increase the value of your building.
On completion of the first fix stage, re-plastering and making good of all opened up places can be done. Work can then proceed to the second fix stage; fitting sockets and switch plates, light fittings, the consumer unit and wiring any electric fans, cookers, extractor hoods, electric showers and the immersion heater, provided you have a hot water storage cylinder.
Checking Earth Bonding
Earth bonding is a safety measure to protect against electric shock in the building. It is also known as equipotential bonding and cross bonding. It should not be mixed up with earthing. Both are two different safety measures entirely.
For your electric installation to be safe, you need to carry out earth bonding. You might think that your renovation project does not require rewiring, however make sure that the kitchen and bathrooms are earth bonded. Earth bonding will protect your metallic appliances like metal plumbing, bath, taps, radiators or boiler casing, etc. from becoming live with electric current in case of electrical faults.
You can tell if your building is earth bonded by checking underneath the sink or bath for metal clamps around the copper pipes with green and yellow striped earth cable attached. You need to earth bond every metal pipe in and out of sinks, baths and heaters.
Installing electrics in wet areas
Concerning installing electrics in wet area like the bathroom and laundry, there are special rules that apply. And yes, there are restrictions. This is because there is the greatest tendency to be electrocuted in such areas of the house. Hence, the rules are more sever and rigorous than others. The Building Regulation stipulates that no power sockets are allowed in such regions, save for shaver sockets and they must be located away from showers splash zones. Furthermore, the regulation stipulates that only pull-cord operation switches or IR-type switches powered by battery or with just a very low voltage signal cable, such as Cat5e are allowed in the bathroom. Electrical appliances to be used in this area including electric showers, light fittings and ventilation fans, must have a certain level of moisture and mechanical protection. The only area excluded is the shaver point. This is known as the Ingress Protection number, IP. Every electrical appliances in this area should have IP rating. The IP rating has two the letters IP which is followed by two characters. The first character shows its level of protection against solid objects. The next shows its level of protection against liquids.
There are mandatory requirements by the I.E.E. wiring regulations (BS 7671: 2001 Section 601) for areas containing a bath or shower. These safety standards are measured in zones, each zone’s requirement is based on the level of perceived risk in the zone. There are four zone categories: 0, 1, 2 and 3.
Zone 0: Inside the bath or shower. Any fittings used here must be SELV (max 12V) and be rated IPX7 (protected against immersion in water).
Zone 1: Above the bath or shower to a height of 2.25m. A minimum rating of IPX4 is required.
Zone 2: The area stretching to 0.6m outside the bath or shower and above the bath or shower if over 2.25m. An IP rating of at least IPX4 is required.
Zone 3: Anywhere outside zones 0, 1 and 2. Where water jets are not to be used for cleaning purposes, the general rules of BS7671 apply. For detailed information, refer to the I.E.E. Wiring regulations (BS 7671: 2001 Section 601).
The Building Regulations Part P: Electrical Safety covers DIY, Do It Yourself electrical work, which includes rewiring work and alterations to electrical installations. If you know what to do, it is allowed that you undertake minor addition works or alteration works to existing electric circuits. Such work may include adding a new socket or light fitting. You do not need to make a Building Regulations application to do this. There is one exception: it must not be in a wet area, such as a kitchen or bathroom, outdoors, and must not be connected directly into the consumer unit.
If you feel your knowledge of electricity is sound enough for you to carry out some wiring works yourself, you can do that too. You can also do it in a wet area. However, to do this, you must make a Building Regulations application (current cost around £150 including inspection fee) and contact an electrician who is competent and registered to insect your work before and after you’re done. He’ll check to ensure work has been done properly and will sign off to attest to that if it has been. However, you can’t easily find electricians who are willing to offer this kind of service. Consequently, you might end up needing their service.
Do not forget that while making installations, you are to bury all cables in walls. Also, the cables are to run vertically or horizontally from sockets. This will help other tradesmen who are fixing appliances on the wall avoid breaking into these wiring.