A shutter for insulating electrical contacts includes a first panel having a first opening and a second panel having a second opening. The first opening is offset from the second opening when the shutter is in a closed position. The second panel includes a first guide configured to react to a pressure of a phase barrier of an insertable withdrawable unit thereon to move the second panel in a first sliding direction relative to the first panel such that the first and second openings align so as to allow an electrical contact to extend therethrough. A spring housing having a spring disposed therein between at least two support legs is slidably disposable in the first panel and extends through the second panel.