( ( conducts ( experiments ( to ( ( improve ( insulation compounds ) ) ( for ( electrical wiring ) ) ) ) ) ) . )
(ROOT (S (VP (VBZ conducts) (S (NP (NNS experiments)) (VP (TO to) (VP (VB improve) (NP (NN insulation) (NNS compounds)) (PP (IN for) (NP (JJ electrical) (NN wiring))))))) (. .)))
conducts experiments to improve insulation compounds for electrical wiring.
(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.