( ( Once ( ( the track ) ( is ( in place ) ) ) ) ( , ( you ( ( will ( conceal ( ( the ( wires ( and ( electrical box ) ) ) ) ( with ( a ( plastic cover ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Once) (S (NP (DT the) (NN track)) (VP (VBZ is) (PP (IN in) (NP (NN place)))))) (, ,) (NP (PRP you)) (VP (MD will) (VP (VB conceal) (NP (NP (DT the) (NNS wires) (CC and) (JJ electrical) (NN box)) (PP (IN with) (NP (DT a) (JJ plastic) (NN cover)))))) (. .)))
Once the track is in place, you will conceal the wires and electrical box with a plastic cover.
(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.