Screw depth gauge device

Abstract

The present disclosure relates to a device 100 for gauging the depth of a screw in a socket e.g. in a socket of a smart meter. The device comprises a mount 104 for mounting at the socket and a sliding

Description

Field of the Invention The present disclosure relates to a device for gauging the depth of a screw in a socket and particularly, although not exclusively, to a device for gauging the depth of a screw in an electrical screw terminal of a smart meter. Background A smart meter is an electronic device for recording information about energy usage. The smart meter is installed at a premises to record the usage information directly and send it to an energy supplier, typically via a wireless network. Consumers may receive more accurate bills by having a smart meter to provide energy consumption data to the supplier more regularly. More than 29.5 million smart meters have already been fitted in homes and small businesses across Great Britain. Collectively, smart meters provide improved data to planners for predicting energy demand based on energy use in homes and businesses. Therefore, the continued installation of smart meters is beneficial to developing a more efficient energy network. It is important to check the installation of each smart meter for safety and to ensure its proper function. The process of installing a smart meter involves connecting different input / output wires to its electrical terminals. Smart meters normally have screw terminals to facilitate a reliable electrical and physical connection with the wires. Specifically, for each terminal, an exposed wire is inserted into the screw terminal whereupon a screw is inserted into a socket at a right-angle to the wire and tightened down onto the wire or electrical contact to clamp the wire against the electrical contact beneath the screw. Each screw must be tightened to ensure that a sufficient clamping force is established to secure the wire in its respective terminal. However, overtightening of the screws may cause damage to the wires and / or the electrical contacts. It may be time-consuming for an installation engineer to inspect the screw terminal connections in a smart meter using conventional tools. Even tools specifically designed for adjusting screws may not be suitable for examining an electrical screw terminal. The present invention has been devised in light of the above considerations. Summary of the Invention In the case of a wire connected to an electrical screw terminal by a screw inserted into a socket of the terminal, the present inventors have realised that the depth of the screw in the socket provides an accurate indication of how securely the wire is connected to the terminal. The present inventors have also identified issues with using conventional depth measuring devices. In particular, the process of obtaining and recording measurements may be subject to significant human error and the further requirement to interpret each measurement to determine whether or not the depth ofthe screw is sufficient can be time-consuming. Therefore, at its most general, the present invention relates to a device for gauging the depth of a screw in a socket, wherein the device is configured to provide positive feedback to a user when the depth is not less than a predetermined length, the predetermined length being the screw depth necessary for secure connection ofthe wire in the terminal. In a first aspect, there is provided a device for gauging the depth of a screw in a socket, the device comprising: a mount for mounting at the socket; a sliding member having a main body and a probe projecting from the main body and being slidably received in the mount; a feedback element for providing a first feedback to a user; a first switch electrically coupled to the feedback element; and actuator for reversibly actuating the first switch; wherein the sliding member is slidable from a non-actuating configuration in which the at least one probe is at least partially retracted into the mount and the first switch is unactuated by the actuator, to an actuating configuration in which the probe is extended from the mount by a predetermined length and the first switch is actuated by the actuator such that the feedback element provides the first feedback to the user. The predetermined length may be selected (e.g. by a smart meter provider) to be equal to a minimum depth ofthe screw which is deemed to be acceptable. Therefore, the first feedback provided to the user may indicate that the actual depth ofthe screw is acceptable. In this way, the user is not required to obtain a measurement ofthe depth ofthe screw nor manually interpret a measurement in order to determine whether or not the screw has been correctly inserted into the socket. Instead, the depth ofthe screw relative to the predetermined length determines whether or not the sliding member is slidable from its non-actuating configuration to its actuating configuration, i.e. whether or not the device provides the first feedback. If the depth of the screw is greater than or equal to the predetermined length, the at least one probe is extendable from the mount by the predetermined length without being obstructed by the screw. Therefore, the sliding member is slidable to its actuating configuration which causes the feedback element to provide the first feedback to the user. On the other hand, if the depth of the screw is less than the predetermined length, the extension of the at least one probe is limited by the screw to less than the predetermined length. Consequently, the sliding member is prevented by the screw from sliding to the actuating configuration and therefore the feedback element does not provide the first feedback. Hence, the lack of the first feedback may indicate to the user that the depth of the screw is not acceptable. When the screw is utilised in an electrical screw terminal, the first feedback may indicate to the user that the electrical screw terminal is suitably connected. This may be particularly useful for checking the installation of a smart meter. Specifically, by automatically providing the first feedback to the user, the device enables the user to check the installation of a smart meter more efficiently and reliably. The depth of the screw may be defined as a distance separating the screw from an opening of the socket. The mount will be mounted at the opening of the socket and the probe will be inserted into the socket via the socket opening. The probe may comprise a rod, e.g. a cylindrical rod. The probe may comprise a screw contact face at an axial end for forming an abutment with the screw within the socket. The screw contact face may be substantially planar. For example, the screw contact face may extend in a plane transverse to the elongation of the probe. The screw contact face may comprise a chamfered edge. When the screw contact face ofthe probe forms an abutment with the screw, the extension of the probe from the mount will be equal to the depth ofthe screw in the socket. The extension of the probe from the main body may be adjustable. For example, the probe may be connected to the main body (e.g. to a base plate of the main body) by mutual cooperation of threaded engagement portions on the probe and main body (e.g. base plate ofthe main body). For example, an axial end face opposing the screw contact face ofthe probe may comprise a threaded bore for receiving a threaded bolt depending from the main body (e.g. base plate ofthe main body). Adjustment ofthe length ofthe threaded bolt received within the threaded bore effects adjustment ofthe extension ofthe probe from the main body (e.g. from the base plate ofthe main body). The main body may define a chamber having an opening facing the mount. The opening may be provided in the base plate. The first switch may be mounted within the chamber. The mount may comprise a transverse plate and a guide portion depending (e.g. depending perpendicularly) from the transverse plate. The probe may slidably mounted in the guide portion through an opening in transverse plate. The guide portion may be a hollow, e.g. tubular guide portion. The guide portion may circumscribe the probe. The guide portion may comprise a socket contact face at an axial end (distal the transverse plate) for forming an abutment around the socket i.e. around the socket opening. The socket contact face may be substantially planar. For example, the socket contact face may extend in a plane transverse to the elongation of the guide portion. In these embodiments, as the sliding member moves from the non-actuating configuration to the actuating configuration, the screw contact face of the probe will move to extend beyond the socket contact face of the guide portion. In the actuating configuration, the screw contact face of the probe extends beyond the socket contact face of the guide portion by the predetermined length. The transverse plate of the mount may abut the main body of the sliding member in the actuating configuration thus acting as a mechanical stop. In the non-actuating configuration, the probe is at least partially retracted into the mount e.g. at least partially retracted into the guide portion. The probe may be fully retracted within the guide portion i.e. the screw contact face of the probe may be flush with the socket contact face of the guide portion or may be recessed away from the socket contact face within the guide portion. The actuator may be provided on the mount. It may be elongate and upstanding from the mount e.g. from the transverse plate in a direction opposing the elongation of the probe / guide portion. It may be a substantially cylindrical actuator upstanding from the mount e.g. from the transverse plate of the mount. The actuator may extend through the opening of the main body (e.g. the opening in the base plate of the main body) into the main body chamber. The actuator may be slidably received within the chamber of the main body (e.g. slidably received through the opening in the base plate of the main body). The main body may comprise an electrically insulative outer casing. By providing the electrically insulative outer casing, the user may be protected from electrical current, for example, when the screw is inserted into an electrical screw terminal. The sliding member may comprise a plurality of probes projecting in parallel from the main body. Each probe may be as described above. By providing the plurality of probes, the probes may be inserted into a corresponding plurality of sockets to gauge the depths of multiple screws at the same time. The plurality of probes may comprise one or more rows of probes. The rows of probes may be parallel. For example, the plurality of probes may be arranged in a square or rectangular array. The arrangement of probes may be selected based on a corresponding arrangement of sockets. For example, in some embodiments, there may be four probes. The four probes may be equally spaced i.e. arranged in a square configuration or may be arranged in a rectangular configuration. Where there is a plurality of probes, the guide portion may circumscribe some or all of the plurality of probes. For example, the guide portion may circumscribe a row of probes e.g. two probes aligned in a row. The mount may comprise a plurality of guide portions, each guide portion as described above. Where there are four probes, the mount may comprise two guide portions, each circumscribing two probes. In other embodiments, each probe may have a dedicated guide portion i.e. each probe is slidably received in its own guide portion. The actuator may be configured to actuate the first switch by physical contact (e.g. direct physical contact) with the first switch. In these embodiments, the actuator may be axially aligned with the first switch so that it can move in and out of contact with the first switch as the actuator slides within the chamber of the main body. Preferably, the first switch is a mechanical switch. The first switch may be a push-button switch that can be actuated by depression upon contact with the actuator in order to cause the feedback element to generate the first feedback. The first (e.g. push-button) switch may be movable between a non-depressed position and a depressed position. The first switch may comprise a biasing element configured to bias the push-button towards the non-depressed position. The non-depressed position and the depressed position may correspond to the first switch being open and closed, respectively. The actuator may close the first switch by forcing the push-button from its non-depressed position to its depressed position. The actuator may be adjustable to adjust the predetermined length by increasing or decreasing a sliding distance of the sliding member from the non-actuating to the actuating configuration. This may increase or decrease the distance that the sliding member can slide before the first switch and the actuator make contact. The actuator may be adjusted to increase or decrease the spacing between the first switch and the transverse plate of the mount in the actuating configuration of the sliding member. If the spacing is increased, the predetermined length is reduced; if the spacing is decreased, the predetermined length is increased. By allowing the predetermined length to be adjusted, the device is more adaptable to the requirements of the user. The actuator may be reversibly extendable i.e. the elongation / extension of the actuator from the mount e.g. from the transverse plate of the mount may be increasable / decreasable. The actuator may comprise an adjustment screw received in an axial bore of the actuator. The adjustment screw may have a first rotation direction that extends the actuator by advancing the adjustment screw from the axial bore of the actuator towards the first switch i.e. that increases the elongation of the actuator from the mount (e.g. from the transverse plate). The adjustment screw may have a second rotation direction that withdraws the adjustment screw into the bore of the actuator away from the first switch i.e. that reduces the elongation of the actuator from the mount (e.g. from the transverse plate). The mount, e.g. the transverse plate may comprise a threaded borehole forming a threaded engagement with the adjustment screw. The threaded borehole may fully extend through the transverse plate such that an axial end face of the adjustment screw is accessible from an exterior of the device thus allowing external adjustment of the elongation of the actuator. In some embodiments, rather than the first switch being a push-button switch actuated by depression by contact with the actuator, the first switch and actuator may both be electrically coupled to the feedback element, forming an electrical circuit. The actuator and first switch may both provide terminals which close the electrical circuit upon contact thus causing the feedback element to generate the first feedback. The main body of the sliding member may have a second switch. The mount or the actuator may have a actuation portion for actuating the second switch. The second switch may be electrically coupled to the feedback element or to a second feedback element. The feedback element or second feedback element may provide a second feedback to the user upon contact between the actuation portion and the second switch. The actuation portion may make contact with the second switch as the sliding member is sliding from the non-actuating to the actuating configuration. Preferably, the first feedback provided when the sliding member is in the actuating configuration is different to the second feedback provided when the sliding member is sliding from the non-actuating to actuating configuration. The second feedback may provide an indication to the user that the probe(s) is / are at least partially inserted into the socket(s), thus improving the reliability of the device. The actuation portion may be configured to actuate the second switch by physical contact (e.g. direct physical contact) with the second switch. Preferably, the second switch is a mechanical switch. The second switch may be a push-button switch that can be actuated by depression upon contact with the actuation portion in order to cause the feedback element or second feedback element to generate the second feedback. The second (e.g. push-button) switch may be movable between a non-depressed position and a depressed position. The second switch may comprise a biasing element configured to bias the pushbutton towards the non-depressed position. The non-depressed position and the depressed position may correspond to the second switch being open and closed, respectively. The actuation portion may close the second switch by forcing the push-button from its non-depressed position to its depressed position. The actuation of the second switch may be by depression in a direction transverse / perpendicular to the depression of the first switch. In some embodiments, rather than the second switch being a push-button switch actuated by depression by contact with the actuation portion, the second switch and actuation portion may both be electrically coupled to the feedback element or second feedback element, forming an electrical circuit. The actuation portion and second switch may both provide terminals which close the electrical circuit upon contact thus causing the feedback element or second feedback element to generate the second feedback. The actuation portion may be provided on the actuator so that it can move in and out of contact with the second switch as the actuator slides within the chamber of the main body. The actuation portion may be formed by a lateral surface of the actuator e.g. by a curved surface of the upstanding cylindrical actuator. The second switch may be slidably engageable with the actuation portion e.g. with the lateral surface of the actuator. The actuator e.g. the upstanding cylindrical actuator may have a shoulder in its lateral surface. The transverse cross section and / or diameter of the actuator (transverse to the elongation of the actuator) may increase from a reduced portion to an increased portion towards the mount (e.g. towards the transverse plate of the mount) at this shoulder. Preferably the shoulder provides a smooth, continuous transition from the reduced transverse cross section / diameter to the increased transverse cross section / diameter. The actuator may be considered to be “bottle-shaped”. In these embodiments, the axial end of the reduced transverse cross section / diameter portion will be configured the actuate the first switch whilst the lateral surface of the increased transverse cross section / diameter portion will be configured to actuate the second switch. In the non-actuating configuration of the sliding member, the second switch may sit adjacent the reduced transverse cross section / diameter portion of the actuator such that the second switch is not actuated / depressed. As the sliding member is moved towards the actuating configuration, the shoulder may guide the second (push-button) switch from its non-depressed position to its depressed position as the second switch slides along the lateral surface from the reduced transverse cross section / diameter portion to the increased transverse cross section / diameter portion. The second (push-button) switch may be retained in its depressed position by the lateral surface (actuation portion) when the second (push-button) switch is advanced beyond the shoulder towards the mount. The device may comprise a power supply (e.g. a battery) configured to supply power to the feedback element and the second feedback element (where present). The power supply may be mounted in the sliding member e.g. within the chamber of the main body. The first and / or second switch may be configured to interrupt and / or connect the power supply to the feedback element. The first feedback and / or the second feedback may correspond to switching ON / OFF the feedback element / second feedback element. The feedback element may be configured to provide one or more of visual feedback, audio feedback, or haptic feedback i.e. the first and / or second feedback may be any one of visual feedback, audio feedback, or haptic feedback. The feedback element may comprise at least one light source, e.g. one or more LEDs. The feedback element may comprise a plurality of light sources. The at least one light source may be configured to display a continuous light signal to the user. The first feedback and the second feedback may correspond to different colours emitted by different light sources. For example, the first feedback may be indicated using a green coloured light and / or the second feedback may be indicated using a red coloured light. The at least one light source may be illuminated in any coloured light (e.g. white, blue, etc.) and are not limited to the specific colours mentioned or illustrated herein. The second feedback element (where present) may be as described for the feedback element. In some embodiments, the feedback element and the second feedback element may comprise different coloured light sources. For example, the feedback element may comprise a green coloured light source and the second feedback element may comprise a red coloured light source. The light sources may be illuminated in any coloured light (e.g. white, blue, etc.) and are not limited to the specific colours mentioned or illustrated herein. The feedback element and optionally the second feedback element may be located on an external surface of the device, e.g. outer casing of the main body of the sliding member. Additionally, or alternatively, the feedback element may be housed within the main body. When the feedback element / second feedback element comprises at least one light source which is housed within the main body, the outer casing of the main body may comprise a window for transmitting light therethrough from within the main body. The feedback element may comprise a vibrating means in the form of a buzzer or alarm. The device may comprise a printed circuit board (PCB) housed in the main body. The PCB may be electrically coupled to the feedback element / second feedback element. The PCB may be electrically coupled to one or more of the first switch, and the second switch. The first switch may be electrically coupled to the feedback element via the PCB. The second switch may be electrically coupled to the feedback element or the second feedback element via the PCB. Additionally, or alternatively, the feedback element may be connectable to an external device and configured to transmit the first feedback to the external device. The external device may be a computer e.g. a mobile device, or a remote server. The feedback element may comprise a wireless interface configured to communicate wirelessly with the external device. According to a second aspect, there is provided a method of using the device according to the first aspect, the method including the steps: mounting the mount around a socket housing a screw; extending the probe into the socket by sliding the slidable member towards the mount; and determining that the depth of the screw is greater than or equal to the predetermined length in response to receiving the first feedback from the feedback element. In some embodiments, the method is for verifying terminal connections in a smart meter. When the feedback element is configured to provide visual feedback, the method may include recording the first feedback by taking a photograph of the device in situ. When the device is used to verifying terminal connections in a smart meter, the photograph may be used to document the correct installation of the smart meter. Additionally, or alternatively, where the feedback element is connected to an external device, the method may comprise transmitting the first feedback to the external device e.g. via wireless communication with the external device. The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided. Brief Summary of the Figures Embodiments of the invention will now be discussed with reference to the accompanying figures in which: Figure 1 shows a schematic front view of a device for gauging the depth of a screw in a socket. Figure 2 shows a schematic front view of the device of Figure 1 in a partially assembled state with its sliding member in a non-actuating configuration corresponding to a fully retracted configuration. Figure 3 shows a schematic front view of the device of Figure 1 in a different state of assembly omitting a base plate, with its sliding member still in the non-actuating configuration. Figure 4 shows a schematic front view of the partially assembled device of Figure 3 with its sliding member in a different non-actuating configuration corresponding to a probing configuration. Figure 5 shows a schematic front view of the partially assembled device of Figure 3 with its sliding member in an actuating configuration. Figure 6A shows a schematic drawing of a cross-section A-A through the device of Figure 1 with its sliding member in the probing configuration. Figure 6B shows an enlarged section of the device depicted in Figure 7A, illustrating a separation between an actuator and a first switch. Figure 6C shows an enlarged section of the device depicted in Figure 7A, illustrating a contact between the between a second switch and a contact portion on the actuator. Figure 7 shows a schematic side view of the device of Figure 1 with its sliding member in the probing configuration. Detailed Description of the Embodiments Aspects and embodiments will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. Figure 1 shows a schematic front view of device 100 for gauging the depth of a screw in a socket (not shown). The device 100 includes a sliding member 102 and a mount 104. The sliding member 102 comprises a set of four probes 106 (only two visible) which are rods extending from a main body 108 of the sliding member 102 in a probing direction D. The mount 104 includes a pair of guide portions 110, each guide portion circumscribing a respective pair of the probes 106. The guide portions 110 are configured to mount around four adjacent sockets (not shown). The sliding member 102 is movable relative to the mount 104 in the probing direction D. When located over the socket openings, the probes 106 may be inserted into the sockets by plunging the sliding member 102 in the probing direction D. Plunging the sliding member 102 causes the probes 106 to project beyond the guide portions 110 in the probing direction D while the guide portions 110 remain mounted. Since the guide portions 110 are mounted around the socket openings, a depth of insertion of the probes into the sockets is equal to an extension P of the probes 106 from the mount 104 (i.e. in the probing direction D). When at least one of the sockets houses a screw (not shown), the device 100 may be used to gauge a depth of the / each screw. Typically, all four sockets will have screws inserted therein. In an example, each socket is an electrical screw terminal for physically and electrically connecting a wire to an electrical contact. The strength of the connection may be determined based on the depth of the screw in the socket. The main body 108 comprises a plastic outer casing 112 which is electrically insulative to shield the user from any electrical current flowing through the terminal. Accordingly, the user may grip the main body 108 to operate the device 100 by hand. If one of the probes 106 forms an abutment with an inserted screw, the extension P of the probes 106 will be limited by the screw. Therefore, the device 100 can gauge whether or not the depth of the screw exceeds a predetermined length based on the extension P of the probes 106. This requires the user to plunge the sliding member 102 in the probing direction D until it is obstructed by a screw. Each probe 106 may comprise an axial end screw contact face 114 for forming the abutment with the screw. Each screw contact face 114 extends in a plane transverse to the projection of the probes 106 from the main body 108. The screw contact face 114 has a chamfered edge 116 to locate the probe 106 more easily into a socket. A feedback assembly 118 comprising first and second feedback elements is provided on the main body 108 of the sliding member 102. In this embodiment, the first feedback element is configured to provide visual (first) feedback to a user of the device 100. The first feedback element may comprise a green LED to provide a green light first feedback to the user. The second feedback element may comprise a red LED to provide a red light second feedback to the user. The device 100 includes a battery (not shown) in a battery mount 153 (see Figure 2) for supplying power to the feedback assembly 118. As discussed in detail below, the first feedback element of the feedback assembly 118 is actuated to generate the first feedback when the extension P of the probes 106 is equal to the predetermined length. This corresponds to an actuating configuration of the sliding member 102. Figure 2 shows the device 100 in a partially assembled state. Specifically, the outer casing 112 and the feedback assembly 118 have been omitted. Enclosed by the outer casing 112, the main body 108 further includes a base plate 122 to which each probe 106 is bolted. The main body 108 further comprises a top plate 124 spaced from the base plate 122 by a set of parallel support posts 126 and coupled to the base plate 122 by a set of screws 128 which extend through the respective support posts 126. The mount 104 comprises a transverse plate 130 which extends in a plane perpendicular to the projection of the probes 106 from the main body 108 which is parallel to the base plate 122. As such, the mount 104 and the base plate 122 are directly opposed to each other. The transverse plate 130 is integrally formed with the pair of guide portions 110 which extend from the transverse plate 130 in the probing direction D. Each guide portion 110 extends from an opening (not shown) in the transverse plate 130 to form a continuous passage therethrough for receiving a pair of probes 106. As shown in Figure 2, the sliding member 102 is in a non-actuating configuration, in which the probes 106 do not extend from the mount 104. Figure 3 shows the partially assembled device 100 omitting the base plate 122. Bolts 132 which secure each probe 106 to the base plate 122 are revealed in Figure 3, where they were previously obscured by the base plate 122 in Figure 2. An actuator 134 which is coupled to the transverse plate 130 is also shown. The actuator 134 is engageable with a first switch 136 and a second switch 138, which are coupled to the main body 108 of the sliding member 102. The first and second switches 136, 138 are mechanical pushbutton switches having respective push-buttons 136a, 138a facing the actuator 134. The switches 136, 138 are electrically coupled to the feedback assembly 118 and are housed in the main body 108 of the device 100. Figure 3 shows the actuator and first switch 134, 136 separated by a separation distance S. The actuator and first switch 134, 136 are oppositely arranged along the probing direction D, such that plunging the sliding member 102 causes the first switch 136 to travel along a linear path towards the actuator 134. The separation distance S is reduced by the insertion of the probes 106 into the sockets while their extension P is increased. The sliding member 102 is in a non-actuating configuration when the actuator and first switch 134, 136 are separated. The second switch 138 is adjacent to the actuator 134 in both the actuating and non-actuating configurations of the sliding member and is configured to engage with the actuator 134 in a transverse direction T which is perpendicular to the probing direction D. The actuator 134 comprises a bottle-shaped elongate member having a lateral surface 142. The sliding member 102 is movable to impart motion to the push-button 138a guided by the lateral surface 142. Hence, the push-button 138a acts as a follower which is movable in the transverse direction T between a non-depressed position and a depressed position. The push-button 138a is biased towards its non-depressed position, which is illustrated in Figure 3. The depressed position corresponds to the second switch 138 being closed. The second feedback element of the feedback assembly 118 is configured to provide auxiliary (second) feedback (i.e. a red light) to the user when the second switch 138 is closed. Figure 4 shows the partially assembled device 100 with its sliding member 102 in in transit from the nonactuating configuration (shown in Figure 3) to its actuating configuration (shown in Figure 5). During this sliding of the sliding member, the probes 106 are extended from the mount 104 by an extension P which is sufficient to close the second switch 138 by sliding the push-button 138a into contact with the lateral surface 142 of the actuator 134. Therefore, the second feedback element of the feedback assembly 118 provides the second feedback (i.e, a red light) to the user that the probes 106 are at least partially inserted into the sockets. The actuator 134 has a shoulder 144 in its lateral surface 142 which projects outwardly to guide the pushbutton 138a from its non-depressed position to its depressed position as the push-button 128a slides along the lateral surface 142 in the probing direction D. The shoulder 144 provide a smooth transition from a reduced diameter portion 134a of the actuator 134 to an increased diameter portion 134b. Accordingly, the increased diameter portion extends from the shoulder 144 to the mount 104 and as the second switch slides into contact with the increased diameter portion 134b, the second switch 138 is activated by depression of the push-button 138a by the lateral surface 142 of the increased diameter portion 134b of the actuator 134. As shown in Figure 4, the separation distance S between the actuator and first switch 134, 136 is reduced as the sliding member slides from the non-actuating configuration to the actuating configuration. Figure 5 shows the partially assembled device 100 with its sliding member 102 in an actuating configuration. In the actuating configuration, the probes 106 are extended from the mount 104 by an extension P which is sufficient to move the first switch 136 into contact with the actuator 134. In this embodiment, the contact of the actuator 134 presses the push-button 136a of the first switch 136 to close the first switch 136 to cause the first feedback element of the feedback assembly 118 to provide the first feedback. At this point, there is no separation between the actuator and first switch 134, 136 (i.e. the separation distance S is zero). The actuator 134 is a mechanical stop which forms an abutment with the first switch 136 to obstruct further movement of the sliding member 102 in the probing direction D. Hence, the probes 106 extend from the guide portions 110 at a maximum extension Pmax when the sliding member 102 reaches the actuating configuration. In this embodiment, the predetermined length is therefore equal to the maximum extension Pmax. If at least one of the sockets houses a screw having an insertion depth which is less than the predetermined length, the sliding member 102 will be obstructed by its abutment with the screw and the first switch 136 will not be closed by the actuator 134. Conversely, if all the screws are at the correct insertion depth, the probes 106 can be fully inserted to the maximum extension Pmax whereupon the first switch 136 is closed by the actuator 134 to cause the first feedback element of the feedback assembly 118 to provide the first feedback i.e. a green light. Therefore, the user is able to determine whether or not all of the screws are sufficiently inserted based on the provision of the first feedback from the first feedback element of the feedback assembly 118. As shown in Figure 5, the push-button 138a of the second switch 138 is held in its depressed position corresponding to the second switch 138 being closed. Accordingly, the first and second switches 136, 138 may be closed simultaneously. Figures 6A-C show a cross-section of the device 100 in the plane A-A, which is also labelled in Figure 7. The cross-section bisects the actuator 134 through its longitudinal axis. The actuator 134 has a bore along its longitudinal axis which receives an adjustment screw 146. The adjustment screw 146 threaded along its full length. The actuator 134 is coupled to the transverse plate 130 by the adjustment screw 146, which is received in a threaded borehole that extends fully through the transverse plate 130 in the probing direction D. As such, the adjustment screw 146 has a bottom axial end face 148 which is accessible through the transverse plate 130 from between the pair of guide portions 110. The bottom axial end face 148 includes a hexagonal recess for receiving an adjustment tool, such as an Allen key. Figure 6B shows an enlarged section of Figure 6A illustrating the separation between the actuator 134 and the first switch 136. The adjustment screw 146 has a top axial end face 150 which directly opposes the push-button 136a of the first switch 136. The top axial end face 150 of the adjustment screw 146 forms the abutment with the first switch 136. The adjustment screw 146 has a first rotation direction which advances the adjustment screw 134 towards the first switch 136 and a second rotation direction that withdraws the adjustment screw 134 away from the first switch 136. The movement directions of the adjustment screw 146 correspond to its threaded engagement with the transverse plate 130. Accordingly, the actuator 134 is adjustable to set the predetermined length by increasing or decreasing the separation distance S. This, in turn, increases or decreases the maximum extension Pmax. Therefore, the predetermined length can be selected to be any desired value within an adjustment range. Figure 6C shows an enlarged section of Figure 6A illustrating the engagement between the actuator 134 and the second switch 138. The push-button 138a of the second switch 138 is in its depressed position. Figure 7 shows the device 100 from a side view. In this embodiment, the feedback assembly 118 comprises two light sources connected to a printed circuit board (PCB) 152. A magnification lens 119 is provided over the feedback assembly 118. The PCB is coupled to the top plate 124 by a screw 154. The firstand second switches 136, 138 are electrically coupled to the PCB on an opposite side to the feedback assembly 118. The first and second switches 136, 138 are configured to switch the LED light source ON / OFF and change the colour of the LED light feedback. In the non-actuating configuration, the first and second switches 136, 138 are open and thus the LED light sources are switched OFF. As the sliding member moves from the non-actuating to the actuating configuration, only the second switch 138 is closed, the LED light source emits red coloured light representing second feedback. In the actuating configuration, both the first and second switches 136,138 are closed to actuate the feedback assembly 118, therefore the LED light source is driven to emit green coloured light (first feedback). When both switches are shut, a voltage is supplied to the gate pin of a MOSFET type transistor on the PCB which turns this MOSFET to an off state, breaking the circuit to the second feedback element. The closing of the first switch 136 also closes the circuit to the first feedback element (green LED). Therefore, the current is prevented from passing through the second feedback element (red LED) and allows it to pass through the first feedback element (green LED) so that the user is provided with the first feedback (green light) indicating that the probes 106 have reached the required predetermined depth. The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof. While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention. For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations. Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / -10%.

Claims

1. A device for gauging the depth of a screw in a socket, the device comprising:a mount for mounting at the socket;a sliding member having a main body and a probe projecting from the main body and being slidably received in the mount;a feedback element for providing a first feedback to a user;a first switch electrically coupled to the feedback element; andactuator for reversibly actuating the first switch;wherein the sliding member is slidable from a non-actuating configuration in which the at least one probe is at least partially retracted into the mount and the first switch is unactuated by the actuator, to an actuating configuration in which the probe is extended from the mount by a predetermined length and the first switch is actuated by the actuator such that the feedback element provides the first feedback to the user.

2. A device according to claim 1 wherein the extension of the probe from the main body is adjustable.

3. A device according to claim 1 or 2 wherein the main body defines a chamber having an opening facing the mount, wherein the first switch is mounted within the chamber and wherein the actuator is provided on the mount and is slidably received through the opening of the chamber.

4. A device according to any one of the preceding claims wherein the sliding member may comprises comprise a plurality of probes projecting in parallel from the main body.

5. A device according to any one of the preceding claims wherein the mount comprises a transverse plate and one or more hollow guide portions depending from the transverse plate, the probe(s) being slidably mounted in one or more guide portions.

6. A device according to any one of the preceding claims wherein the first switch is a push button switch and the actuator is configured to actuate the first switch by physical contact.

7. A device according to any one of the preceding claims wherein the actuator is adjustable to increase or decrease the spacing between the first switch and the mount in the actuating configuration of the sliding member.

8. A device according to claim 7 wherein the actuator is an elongate cylindrical actuator and comprises an adjustment screw received in an axial bore of the actuator, the adjustment screw being rotatable to extend and retract the adjustment crew within the axial bore.

9. A device according to claim 8 wherein the mount comprises a threaded borehole forming a threaded engagement with the adjustment screw such that an axial end face of the adjustment screw is accessible from an exterior of the device.

10. A device according to any one of the preceding claims wherein the main body of the sliding member comprises a second switch and therein the mount or the actuator has actuation portion for actuating the second switch to provide a second feedback to the user upon contact between the actuation portion and the second switch as the sliding member is sliding from the non-actuating to the actuating configuration.

11. A device according to claim 10 wherein the actuation portion is formed by a lateral surface of the actuator and the second switch is slidably engageable with the lateral surface of the actuator.

12. A device according to claim 10 wherein the actuator has a shoulder in its lateral surface and the transverse cross section and / or diameter of the actuator increases from a reduced portion to an increased portion towards the mount at the shoulder and wherein the lateral surface of the increased portion is configured to actuate the second switch.

13. A device according to any one of the preceding claims wherein the feedback element comprises at least one light source.

14. A device according to any one of the preceding claims wherein the feedback element is connectable to an external device and configured to transmit the first feedback to the external device wirelessly.

15. A method of using the device according to any one of the preceding claims, the method including the steps:mounting the mount around a socket housing a screw;extending the probe into the socket by sliding the slidable member towards the mount; anddetermining that the depth of the screw is greater than or equal to the predetermined length in response to receiving the first feedback from the feedback element.

16. A method according to claim 15 for verifying terminal connections in a smart meter by:mounting the mount around a socket in a smart meter housing a screw;extending the probe into the socket by sliding the slidable member towards the mount; anddetermining that the depth of the screw is greater than or equal to the predetermined length in response to receiving the first feedback from the feedback element.

17. A method according to claim 15 or 16 further comprising wirelessly transmitting the first feedback to an external device.

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