Why is my electrical cable insulation becoming brittle and crumbly to touch – Advice from Electriman, North London Electricians

If you have noticed that the plastic or rubber coating around your electrical cables is cracking, flaking, or turning powdery when touched, this is not something to ignore. That outer layer is called the insulation, and its entire job is to keep the live electrical conductors safely contained. When it fails, those conductors can become exposed, which creates a real risk of electric shock, short circuits, and house fires.

The most common reason this happens is simply age. Older properties built before the 1970s often still have rubber-insulated wiring, sometimes called VIR (vulcanised india rubber) or lead-sheathed cable. Rubber insulation naturally degrades over decades, especially when exposed to heat. You may also find that PVC-insulated cables, which became common from the 1960s onwards, have gone brittle if they have been installed too close to boilers, hot water pipes, or old-style incandescent light fittings in enclosed ceiling roses.

Other causes include:

1. Cables routed through loft spaces that experience extreme temperature swings between summer and winter.

2. Cables in contact with certain types of expanded polystyrene insulation, which can attack PVC over time.

3. Rodent damage combined with heat exposure, which accelerates breakdown.

4. Cables that were overloaded for long periods, causing the conductor to run hot and cook the insulation from the inside out.

What you should do right now:

Do not prod, bend, or

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Electriman covers Mill Hill, Barnet, Finchley, Edgware, Enfield, Watford and surrounding areas. All work is Part P certified and fully insured.