( Electrical ( Wiring ( Insulation . ) ) )
(ROOT (NP (NNP Electrical) (NNP Wiring) (NNP Insulation) (. .)))
Electrical Wiring Insulation .
(ROOT (S (NP (JJ Electrical) (NNS wires)) (VP (VBP are) (ADVP (RB usually)) (VP (VBN covered) (PP (IN with) (NP (NN plastic) (CC or) (NN rubber))) (S (VP (TO to) (VP (VB insulate) (NP (DT the) (JJ electrical) (NN wire))))))) (. .)))
Electrical wires are usually covered with plastic or rubber to insulate the electrical wire.