London is a historic city, with many buildings dating back hundreds of years. These not only include churches and monuments -- many residents of the city live in houses which are 100 years old or more, and a surprising number of these retain electrical wiring which was installed as far back as the mid-19th century. This wiring presents a threat not just to the building, but to its occupants too -- yet many owners are quite unaware of the problem. However, the fact is that faulty wiring is one of the most common causes of fire in historic buildings.
Although the Electrical Regulations state that a historic building that has been rewired should be inspected every two-and-a-half years, this seldom happens. One reason for this is that the inspection is a disruptive and expensive process. However, the result is that the scale of the risk to historic buildings has never been properly assessed.
Really Old Wiring
If a building has really old wiring, with vulcanised rubber -- or VIR -- cables, electrical testing is not really advisable. By now, the rubber is likely to be perished, so that the testing itself could actively damage the installation, and make it even more dangerous than it was in the first place. In order to update installations where the VIR cables are run in steel conduits, it is possible to run new single PVC cables within the conduits to the points that already exist. As the steel conduit may not be continuous, it is necessary to take care to check that every circuit has its own earth, neutral and live conductor. To render the system complete, the steel conduit needs to be earth bonded.
Tips For Rewiring An Old Building
If you have an old building that needs rewiring, your best plan is to start by doing an inventory, listing all the appliances you will be using, and where you will be using them. If your house is a period or listed building, you need to be aware that rewiring to modern requirements may well do structural damage, as the old system will be nowhere near adequate for all the appliances used nowadays. You therefore need to decide how important it is to you, for your internal structure and decor to be preserved. However, it may not be necessary to replace the entire system -- parts of the old system may well work perfectly well, so only replace what is necessary.
The job of wiring historic buildings is complex and demanding. In order to ensure the work is done properly, you need to find an electrician who understands old buildings and knows exactly what they require. By finding the right electrician, you can be confident both that the wiring will be safe, and that the beauty of the building will be preserved.