Answer / raghavendran

I am not sure but,this could be the reason, the Electrical
field intensity producing corona on contaminated areas,
water droplets, icicles, corona rings, ... This corona
activity then contributes nitric acid to form a chemical
soup to change the bonding cements and to create carbon
tracks, along with ozone and ultraviolet light to change the
properties of NCI insulator coverings. Other detrimental
effects include water on the surface or sub-surface freezing
and expanding when thawing, as a liquid penetrating into a
material and then a sudden temperature change causes change
of state to a gas and rapid expansion causing fracture or
rupture of the material.

Answer / aboli

I think impure water or ice being good conductor of
electricity,due to ice coating the insulator may get
directly short ckted.this could be called as puncturing of
insulator by ice coating.

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