Why does my old cloth-covered electrical cable pose such a high fire risk?

Cloth-covered electrical cable, sometimes called vulcanised rubber cable or VRI wiring, was the standard installation method in UK homes up until roughly the late 1950s and into the 1960s. If your home was built or last rewired before that period and has never had a full rewire, there is a strong chance this type of cable is still hidden inside your walls, under your floors and in your loft. The core problem is age and material degradation. The cables use a rubber compound as their primary insulation, wrapped in a fabric braid, often cotton or jute. That rubber was never designed to last more than a few decades. After 50 to 70 years or more, it dries out completely, becomes brittle and begins to crack and crumble. Once the insulation breaks down, the copper conductors inside can touch each other or touch earthed metalwork, which causes short circuits. A short circuit produces intense heat in a fraction of a second, and that heat can ignite nearby timber joists, skirting boards and ceiling materials. The fabric braiding makes things worse, not better. It soaks up moisture over the years, and damp fabric sitting against a live conductor is a recipe for slow, smouldering ignition that can go undetected inside a wall cavity for a long time before breaking into open flame. There are some signs you can look for yourself without touching anything. Check the cables where they enter light fittings, plug sockets or your consumer unit. If you can see any wiring, look for a woven cloth outer covering rather than the smooth plastic sheathing you would see on modern cable. Look at the colour. Old rubber insulation often turns brown or black as it ages and oxidises. Check whether the rubber coating is flaking or has fallen away entirely in places. If you have a wooden consumer unit or fuse box rather than a modern plastic one with miniature circuit breakers, this is a strong indicator that the wiring throughout the property dates from the same era. Do not poke, pull or touch any wiring you find. If you recognise any of these signs, treat the situation as urgent. Call a registered electrician, ideally one registered with NICEIC, NAPIT or a similar competent person scheme, and ask for an Electrical Installation Condition Report. This is the formal inspection that will identify exactly how serious the risk is in your property.