No – Insulmax has no detrimental effect on wiring or other existing building elements. However we recommend replacing older rubber coated wires before the installation of any wall insulation. TPS is the newer form of wiring and has been used for many years and is the wiring with the white/cream plastic insulating outer sheath. Rubberised wiring is becoming rarer since it’s generally required to be ungraded to TPS for insurance purposes, as the age of the wiring and it’s nature can lead to problems of degradation of the outer rubberised sheath. Polystyrene insulation has been shown to degrade the outer sheath of TPS cables (the polystyrene effects the plasticisers in the plastic sheath causing it to become more brittle) and should not come into contact with standard TPS wiring. Insulmax is not polystyrene.