Cloth-insulated wiring

Before plastic coatings became standard, wire was often insulated with rubber and wrapped in woven cloth. It still shows up in some older homes. Over many years the covering can dry out, crack and flake. Damaged insulation can lead to arcing or a short circuit.

The Electrical Safety Foundation International (ESFI) notes that many older homes were built with electrical systems and components that are no longer safe and may be considered fire hazards. Only a licensed electrician should judge wiring inside walls and boxes. See also knob and tube wiring and the residential electrician service.