An isolating switch for isolating a component of a circuit, the switch comprising: a switching mechanism movable between an open position in which the circuit is open and a closed position in which the circuit is closed; and a housing comprising: a first housing component coupled to and enclosing the switching mechanism, a second housing component coupled to the switching mechanism and movable with respect to the first housing component to move the switching mechanism between the open position and the closed position, at least one aperture arranged in one of the first or second housing components, and at least one test point which is configured to be electrically connected to the component of the circuit the closed position and arranged in the other of the first or second housing components; wherein the second housing component is movable with respect to the first housing component between at least: a first relative position in which the switching mechanism is in the closed position and the at least one test point is not exposed through the at least one aperture, a second relative position in which the switching mechanism is in the open position and the at least one test point is not exposed through the at least one aperture, and a third relative position in which the switching mechanism is in either the closed or the open position and the at least one test point is exposed through the at least one aperture, characterized in that the at least one test point is configured to be electrically connected to the component of the circuit in both the open and the close positions. a switching mechanism movable between an open position in which the circuit is open and a closed position in which the circuit is closed; and a housing comprising: a first housing component coupled to and enclosing the switching mechanism, a second housing component coupled to the switching mechanism and movable with respect to the first housing component to move the switching mechanism between the open position and the closed position, at least one aperture arranged in one of the first or second housing components, and at least one test point which is configured to be electrically connected to the component of the circuit the closed position and arranged in the other of the first or second housing components; a first housing component coupled to and enclosing the switching mechanism, a second housing component coupled to the switching mechanism and movable with respect to the first housing component to move the switching mechanism between the open position and the closed position, at least one aperture arranged in one of the first or second housing components, and at least one test point which is configured to be electrically connected to the component of the circuit the closed position and arranged in the other of the first or second housing components; wherein the second housing component is movable with respect to the first housing component between at least: a first relative position in which the switching mechanism is in the closed position and the at least one test point is not exposed through the at least one aperture, a second relative position in which the switching mechanism is in the open position and the at least one test point is not exposed through the at least one aperture, and a third relative position in which the switching mechanism is in either the closed or the open position and the at least one test point is exposed through the at least one aperture, characterized in that the at least one test point is configured to be electrically connected to the component of the circuit in both the open and the close positions. a first relative position in which the switching mechanism is in the closed position and the at least one test point is not exposed through the at least one aperture, a second relative position in which the switching mechanism is in the open position and the at least one test point is not exposed through the at least one aperture, and a third relative position in which the switching mechanism is in either the closed or the open position and the at least one test point is exposed through the at least one aperture, characterized in that the at least one test point is configured to be electrically connected to the component of the circuit in both the open and the close positions.