Why does polystyrene melt when in contact with plastic electrical cable insulation?

Answer 1

Oh, dude, it's like this - polystyrene melts when in contact with plastic electrical cable insulation because the insulation material can reach temperatures that are higher than the melting point of polystyrene. So, when they touch, it's like a hot mess waiting to happen. It's all about that heat transfer, man.

Answer 2

Answer

Isn't polystyrene commonly known as "styrofoam" ?

If so, why is it coming in contact with electrical wiring?

In any event, if the polystyrene is melting, the wiring may be overloaded or has a hotspot due to a failure. The wire may be getting hotter than it should be.

I am not aware of any chemical reaction that would occur if the two plastics touch each other at room temperature.

I am:-
Polystyrene is commonly used in loft and wall insulation, just the places that cables are run. The plasticisers used to make the PVC insulation on the cables flexible reacts with the polystyrene resulting in the polystyrene appearing to 'melt' and the plasticiser migrates out of the cable making it brittle and causing the insulating properties to break down. The cable will eventually fail, especially if disturbed and this is both a fire and electrocution risk.

There is the added problem that the cables will get hotter due to the thermal insulation properties of the polystyrene preventing the cable from losing heat. If this hasn't been allowed for in the design of the circuit it too could be a fire hazard.

The wiring regulations (BS7671 section 522.5.3) prohibits contact between PVC cables and polystyrene, but this is a common problem. An electrical engineer (or most electricians) can do a periodic inspection of your wiring system that includes insulation tests that will identify failed or failing cables. The only solution is to replace damaged cables and reroute them or provide conduit to protect them.

PS Styrofoam is, I believe, an American brand name for polystyrene often associated with disposable coffee cups and similar products.

Answer 3

Polystyrene melts when in contact with plastic electrical cable insulation because the insulation material contains chemicals that can react with and soften the polystyrene. The heat generated by the electrical current passing through the cable can further contribute to the melting of the polystyrene.