than the specified threshold than the permitted value of the contact resistance when instruments in the other sections e g apertures 24 26 are not isolated from or floating relative to the instruments in the housing main chamber 29 and the hand piece 30 by using a relatively high resistance contact rotatability of the hand piece 30 can be improved in some embodiments an outer layer of the hand piece is made from an insulating material in these embodiments the hand piece may be floated i e it may include two separate layers of insulation separating the outer exposed surface of the hand piece from any powered instruments and or powered components thereof that are disposed within the hand piece in addition instead of grounding the handpiece may be attached to the housing main chamber via an insulator contact that can withstand a specified voltage potential difference e g at a voltage potential difference of at least about 500 v 1 kv 1 5 kv 2 ky 5 kv 10 kv 20 kv etc with reference to fig2 a rotating optical knuckle 31 is coupled to a conduit 35 so that the two sections can rotate freely relative to each other while a laser.