GB2477964A

GB2477964A - Making an electrical connection with an insulated electricity cable

Info

Publication number: GB2477964A
Application number: GB201002896A
Authority: GB
Inventors: James Donaldson; Christopher Shelley; Paul Rowe; Christopher Lemondine-Martin; Christopher Saunders; Michael Beadman; Richard Hunt; Carol Lo
Original assignee: Intelligent Sustainable Energy Ltd
Current assignee: Intelligent Sustainable Energy Ltd
Priority date: 2010-02-19
Filing date: 2010-02-19
Publication date: 2011-08-24
Anticipated expiration: 2030-02-19
Also published as: GB2477964B; GB201002896D0

Abstract

A device 10 is operable to enable a user to make an electrical connection with the conducting core of an insulated electricity cable 12 by piercing the insulation and doing so without disconnecting the electricity supply and without compromising the safety of the user. The device may comprise a base portion 30 and cover portion 32 arranged to engage with each other and retain the cable between them. An actuator 18 in the form of a push button may engage with the cover portion and may include a conducting pin (16, Fig 2) or member arranged to pierce the cable insulation when pressure is applied to surface 80. The configuration ensures that the user remains electrically insulated from the internal conductor once the electrical connection has been made. There is also described a kit for monitoring electricity, such as may be applied to Non-Intrusive Load Monitoring (NILM) applications to assess electricity usage.

Description

MAKING AN ELECTRICAL CONNECTION WITH AN INSULATED

ELECTRICiTY CABLE

FIELD OF THE INVENTION

The present invention relates to a method of and a device for making an electrical connection with an insulated electricity cable. The invention further relates to a kit for monitoring electricity.

BACKGROUND OF THE INVENTION

There is an increasing concern to reduce the consumption of electricity, both at a domestic level in residential buildings, and at a commercial level in offices, shops, factories and so forth. The reasons for this are both to save costs and also because of concerns for the environment, such as the conservation of finite resources such as coal, gas and oil.

Conventionally1 consumers receive electricity bills that may indicate the quantity of electricity used since the last bill, for example monthly or quarterly, based on periodic meter readings or even based on estimates of consumption since the last meter reading. The information is presented to the consumer in terms of the number of kilowatt hours of electrical energy that has been used, which is meaningless to many people, and gives very little idea about how they are actually using the energy and where they can cut back. Studies have shown that the effect of providing consumers with real-time detailed information about the energy they are using is that their consumption reduces by up to 20%. In order to provide this information, it is necessary to be able to provide real-time measurements of the current and voltage of the electricity supply. Such measurements have applications in Non-Intrusive Load Monitoring (NILM) in which the voltage and current of the electricity supply to a residence may be monitored in order to determine which appliances are running at any particular time and to determine the energy consumed by each. Such information enables consumers to better understand their electricity usage and thereby to reduce their overall electricity consumption.

Devices are known which may monitor the current supplied to a residence by an electricity cable. For example, a current clamp is an electrical device having two jaws which open to allow clamping around an electrical cable. This allows the electrical current in the cable conductor to be measured, without having to make physical contact with it, or to disconnect it for insertion through the device.

However, there is no such equivalent device available for safely and easily measuring the voltage supplied by an electricity cable. The present invention seeks to provide a method and device for making an electrical connection with an insulated electricity cable. Such a device enables measurement of the voltage supplied by the electricity cable. In particular, it is desired to provide such a device which may be safely and easily fitted to an electricity cable by a consumer without disconnecting the supply and without requiring the services of an electrician.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a device for making an electrical connection with an insulated electricity cable. The device comprises an arrangement for piercing an insulation layer of a length of electricity cable to thereby make an electrical connection with an internal conductor of the length of electricity cable. In addition, the device comprises an actuator coupled to the arrangement, wherein the actuator is äctuable by a user to cause the arrangement to pierce an insulation layer of a length of electricity cable so as to make an electrical connection with an internal conductor of the length of electricity cable. The device is configured to ensure that the user remains electrically insulated from the internal conductor of a retained length of electricity cable once the electrical connection has been made with the internal conductor of the length of electricity cable.

Thus, the device of the present invention allows a consumer to safely and easily make an electrical connection with the conducting core of an insulated electricity cable without disconnecting the supply and without requiring the services of an electrician. In this way, the electricity supply to which the device is being connected may remain live throughout the connection process. This is particularly beneficial for electricity monitoring applications andfor Non-Intrusive Load Monitoring (NILM) applications where it is desirable to measure the instantaneous voltage supplied by an incoming electricity cable for a particular residence or property. In the UK, such an electricity cable is usually part of an unprotected circuit carrying a 100A supply. Hence, safety is key and the present device ensures that the user is insulated from the electricity supply once the electrical connection has been made.

Advantageously, the device is configured to ensure that the user remains electrically insulated from the internal conductor of a length of electricity cable during the piercing of the insulation layer of the length of electricity cable.

Advantageously, the device is configured to prevent the user from directly contacting the internal conductor of a length of electricity cable once the electrical connection has been made with the internal conductor of the length of electricity cable.

Advantageously, the device is configured to ensure that the user remains electrically insulated from the electrical connection by means of two or more separate layers of electrical insulation. One layer of the two or more separate layers of electrical insulation may comprise an air gap.

In one embodiment, the arrangement comprises a conducting pin arranged to pierce the insulation layer of a length of electricity cable to thereby make the electrical connection with the internal conductor of the length of electricity cable. Thus, in this embodiment, the piercing and electrical connection functions are performed by a single device -the conducting pin.

In another embodiment, the arrangement comprises a piercing member for piercing the insulation layer of a length of electricity cable, and a conducting member for forming an electrical connection with the internal conductor of a length of electricity cable. Thus, in this embodiment, the piercing and electrical connection functions are performed by separate components. Nonetheless, the components may be coupled together.

Advantageously, the device further comprises an insulating member arranged to retain a length of electricity cable for piercing. The this embodiment, the insulating member and the actuator are together configured to ensure that the user remains electrically insulated from the internal conductor of a retained length of electricity cable once the electrical connection has been made.

Advantageously, the device is arranged to substantially enclose a length of electricity cable.

Advantageously, the device is arranged to fully enclose a length of electricity cable. This enhances the safety of the device.

Advantageously, the device has an initial open configuration which enables insertion of a length of electricity cable into the device, the device being moveable to a closed configuration in which an inserted length of electricity cable may be retained by the device.

Advantageously, the device comprises a cable locking member arranged to permanently couple a length of electricity cable to the device in a fixed position. This ensures that the device may not be removed from a length of cable once it has been secured thereto. Again, this enhances the safety of the device since a user may not accidentally or purposefully remove the device from a cable and potentially expose a mains electrical connection. More advantageously, the cable locking member is arranged to permanently lock the device in the closed configuration after the device has been moved from the open configuration to the closed configuration. Still more advantageously, the cable locking member comprises a permanent snap-fit connector arranged to connect two portions of the device. This is a cheap and effective method of ensuring permanent engagement.

Advantageously, the device further comprises a biasing member arranged to maintain the electrical connection with the internal conductor of the length of electricity cable once the electrical connection has been made. For example, the biasing member could be arranged such that the electrical connection is sprung.

This biasing ensures that the electrical connection is maintained, even over long time periods during which the conducting member might otherwise work its way out of the electricity cable. More advantageously, the biasing member comprises a spring. In one embodiment, the biasing member is arranged to bias the conducting pin (or the conducting member) of the device towards the length of electricity cable once the electrical connection has been made.

Advantageously, the device further comprises a stop member having an initial configuration which prevents actuation of the actuator, the stop member being moveable to a secondary configuration by inserting a length of electricity cable into the device for retention therein, wherein the secondary configuration of the stop member enables actuation of the actuator. This ensures that the actuator cannot be actuated until the device has been closed around a length of electricity cable. Again, this enhances the safety of the device. Alternatively, the stop member may be moveable to the secondary configuration by moving the device from the open configuration to the closed configuration.

Advantageously, the actuator is manually actuable by a user without the need for tools. This provides ease of use of the device. More advantageously, the actuator comprises a push button. The push button is moveable relative to a length of electricity cable to be pierced. This provides a simple and effective method of actuation.

Advantageously, the actuator comprises an actuator locking member arranged to permanently lock the actuator in an actuated configuration once the electrical connection has been made. The "actuated configuration" is the configuration of the actuator relative to the device once the actuator has been actuated to pierce the insulation layer. This enhances the safety of the device.

In particular, this ensures that a user may not subsequently expose a mains electrical connection once the electricity cable has been pierced during actuation.

More advantageously, the actuator locking member comprises a permanent snap-fit connector arranged to engage with the device. This is again a cheap and effective method of permanent engagement.

Advantageously, the device further comprises a connector arranged to be coupled to the internal conductor of a length of electricity cable once the electrical connection has been made with the internal conductor of the length of electricity cable. This enables a user to utilise the electrical connection which the device has made with the electricity cable. For example, the electrical connection may be used to take voltage measure measurements from the electricity cable, or may be used to provide a small amount of power to the device. More advantageously, the device further comprises at least one resistor arranged to couple the connector in series to the internal conductor of a length of electricity cable once the electrical connection has been made with the internal conductor of the length of electricity cable, thereby limiting the current able to flow through the connector.

This ensures that the connector is safe for a user since only a limited current may flow through the device. Furthermore, the current limitation prevents a user from abusing the device to illegally draw a large current from the electricity cable. The connector may comprise a connector cable, a connector socket or a connector plug.

Advantageously, the device further comprises circuitry to measure the current passing through a retained length of electricity cable. This enhances the functionality of the device by providing the means to obtain current measurements as well as voltage measurements.

According to a second aspect of the present invention, there is provided a kit for monitoring electricity. The kit comprises two or more devices in accordance with the first aspect of the present invention, an apparatus for measuring the electrical current passing through an insulated electricity cable coupled thereto, and a processor arranged to be connected with each of the two devices and with the apparatus so as to enable the receiving of voltage and current measurements therefrom.

Such a kit may be used to easily and safely obtain measurements of the current and voltage of a mains electricity supply to a residence or building.

Advantageously, the kit further comprises a display device operable to display information based on voltage and current measurements received from the processor. This allows the current and voltage measurements to be displayed, e.g. to a user of the electricity, so as to potentially alter the energy usage by that user.

Advantageously, the apparatus for measuring the electrical current passing through an insulated electricity cable coupled thereto is a current clamp (or current probe). Such devices are known in the art.

According to a third aspect of the present invention, there is provided a method of making an electrical connection with an insulated electricity cable. The method comprising the steps of: (1) providing a device comprising: an arrangement for piercing an insulation layer of a length of electricity cable to thereby make an electrical connection with an internal conductor of the length of electricity cable; and an actuator coupled to the arrangement; and (2) actuating the actuator to cause the arrangement to pierce the insulation layer of the length of electricity cable so as to make an electrical connection with the internal conductor of the length of electricity cable. The device is configured to ensure that a user remains insulated from the conducting member and from the internal conductor of the retained length of electricity cable once the electrical connection has been made.

This method corresponds to the device of the first aspect of the present invention.

Advantageously, the method further comprises a step of retaining the length of electricity cable in the device prior to the step of actuating the actuator.

In one embodiment, the step of retaining the length of electricity cable comprises using an insulating member of the device to substantially enclosing the length of electricity cable. more advantageously, the step of retaining the length of electricity cable comprises closing the device around the length of electricity cable by moving the device from an initial open configuration to a closed configuration, the initial open configuration enabling insertion of the length of electricity cable into the device, and the closed configuration enabling the inserted length of electricity cable to be retained by the device. Advantageously, the step of retaining the length of electricity cable further comprises moving a stop member from an initial configuration to a secondary configuration, the initial configuration preventing actuation of the actuator, and the secondary configuration enabling actuation of the actuator. Again, this enhances safety and ease of use by ensuring that the actuator may not be accidently actuated until a length of electricity cable has been retained within by device.

Advantageously, the method further comprises a step of using a cable locking member to permanently lock the retained length of electricity cable in place relative to the insulating member. Again, this enhances safety.

Advantageously, the method further comprises a step of biasing a conducting member of the arrangement towards the retained length of electricity cable once the electrical connection has been made so as to maintain the electrical connection. The conducting member of the device is the part of the arrangement which forms the electrical connection with the internal conductor of the length of electricity cable. This boasing ensures long-term maintenance of the electrical connection.

Advantageously, the method further comprises a step of using an actuator locking member to permanently lock the actuator in place relative to the insulating member once the electrical connection has been made. Again, this enhances safety by ensuring that the device may not be removed from an electricity cable once the cable insulation has been pierced.

According to a fourth aspect of the present invention, there is provided a device operable to enable a user to make an electrical connection with the conducting core of an insulated electricity cable without disconnecting the electricity supply and without compromising the safety of the user.

Other preferred features of the present invention are set out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a device for making an electrical connection with an insulated electricity cable in accordance with an embodiment of the present invention. Figures la-d are perspective views showing progressive stages of the device as it goes from a "disengaged" configuration (as shown in Figure la) to a "fitted" configuration (as shown in Figure id).

Figure 2 is a vertical cross-sectional view through the centre of the fitted device of Figure id along the length of the electricity cable.

Figure 3 is a vertical cross-sectional view through the centre of the fitted device of Figure Id from one end of the electricity cable.

Figure 4 is a perspective view of an actuator of the device of Figures 1 -3.

Figure 5 is a vertical cross-sectional view through the device of Figure 1 showing partial engagement of the actuator with the remainder of the device.

Unlike the cross-sectional view of Figure 3, the cross-section of Figure 5 does not pass through the centre of the device. Part of the cross-section is also shown enlarged.

Figure 6 is a vertical cross-sectional view through the device of Figure 1 showing full engagement of the actuator with the remainder of the device. The cross-sectional view of Figure 6 is taken in the same plane as the cross-sectional view of Figure 5. As for Figure 5, part of the cross-section is also shown enlarged.

Figure 7 schematically illustrates an electricity monitoring system incorporating devices of the type shown in Figures 1-6.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Figure 1 shows a device 10 for making an electrical connection with an insulated electricity cable 12 (or electric cable or electrical cable or power cable) in accordance with an embodiment of the present invention. The insulated electricity cable 12 comprises two tubular layers of cable insulation 50 (namely an external layer 50a and an internal layer 50b) with a number of copper conducting cores 51 received concentrically therethrough. The device is intended to be fitted to electricity cables 12 having diameters of 3-16mm, or preferably electricity cables having diameters of 4-12.6mm (i.e. up to 35mm2 sized cables). However, it will be appreciated that the device could be used in conjunction with somewhat smaller or larger cables if desired. The device 10 comprises an electrically insulating member 14, an electrically conducting pin or needle 16 (not seen in Figure 1), an actuator 18 and a connector cable 20. The insulating member 14 comprises two portions: a base portion 30 and a cover portion 32.

-10 -In Figure 1, the device 10 is shown in various stages of engagement with the electricity cable 12. In the "disengaged" configuration of the device 10 as shown in Figure la, the base portion 30 and the cover portion 32 of the insulating member 14 are disengaged from one another and from the actuator 18. The electricity cable 12 is also disengaged from all components of the device 10 in Figure Ia. In Figure Ib, the only change is that the actuator 18 is partially engaged with the cover portion 32 of the insulating member 14. This is the so-called delivery" configuration of the device in which it is intended that the device be delivered to a user. In Figure Ic, the only change is that the base portion 30 and the cover portion 32 of the insulating member 14 are engaged with one another so as to retain a length/section of the electricity cable 12 therebetween; this is the so-called "primed" configuration of the device 10. In Figure id, the device is shown in the "fitted" configuration in which the actuator is fully engaged with the cover portion 32 of the insulating member 14.

Orthogonal axes are shown in Figures la-d. The electricity cable 12 extends along the y-axis. The base portion 30 and the cover portion 32 of the insulating member 14 engage with one another in a vertical direction by movement towards one another along the z-axis. Similarly, the actuator 18 and the cover portion 32 of the insulating member 14 engage with one another in a vertical direction by movement towards one another along the z-axis.

A vertical cross-sectional view through the device 10 along the length of the electricity cable 12 (i.e. in the y-z plane) is shown in Figure 2. A vertical cross-sectional view through the device 10 from one end of the electricity cable 12 (i.e. in the x-z plane) is shown in Figure 3.

The various components of the device 10, and the interactions between each of the components is described in greater detail below with reference to the figures.

The insulating member 14 is arranged to retain a length of insulated electricity cable 12. In the embodiment of Figure 1, this retaining ability is accomplished by means of the insulating member 14 comprising two separate portions: the base portion 30 and the cover portion 32. The base portion 30 and -11 -the cover portion 32 are moveable relative to each other from an initial open configuration of the insulating member 14 (as in Figures la and Ib) to a secondary closed configuration of the insulating member 14 (as in Figure ic and id). In the closed configuration of the insulating member 14, an engagement end 40 of the base portion 30 abuts an engagement end 42 of the cover portion 32.

In the closed configuration of the insulating member 14, the insulating member 14 is substantially box-shaped with a recess 34 for receiving the actuator 18. The recess 34 is disposed at an actuator end 43 of the cover portion 32, opposite the engagement end 42 of the cover portion 32.

The base portion 30 has a base cable recess 44 extending all the way across the engagement end 40 of the base portion 30. The cover portion 32 has a cover cable recess 46 extending all the way across the engagement end 42 of the cover portion 32. Both the base cable recess 44 and the cover cable recess 46 are substantially formed as half-cylinders (i.e. each recess has a semi-circular cross-section). In the closed configuration of the insulating member 14, the base cable recess 44 aligns with the cover cable recess 46 so as to form a substantially cylindrical bore through the insulating member 14. The substantially cylindrical bore is sized to tightly receive a length of the insulated electricity cable 12. The base cable recess 44 comprises four substantially semi-circular ribs 48 which, in the closed configuration, protrude into the substantially cylindrical bore through the insulating member 14 for tight gripping or shallow penetration of the cable insulation 50 of the retained insulated electricity cable 12. Similarly, the cover cable recess 46 comprises four substantially semi-circular ribs 49 which, in the closed configuration, protrude into the substantially cylindrical bore through the insulating member 14 for tight gripping or shallow penetration of the cable insulation 50 of the retained insulated electricity cable 12. Thus, the ribs 48 and 49 act as cable engagement members. In particular, the ribs 48 and 49 engage with the external layer 50a of the cable insulation 50, but do not penetrate as far as the internal layer 50b of the cable insulation 50.

The base portion 30 of the insulating member 14 has two snap-fit connectors 60 disposed at the engagement end 40 of the base portion 30. The cover portion 32 of the insulating member 14 has two corresponding recesses 61 -12 -disposed near the engagement end 42 of the cover portion 32. As most clearly seen in the cross-sectional view of Figure 3, the snap-fit connectors 60 are configured to mate with the recesses 61 in the closed configuration of the insulating member 14 such that the base portion 30 and the cover portion 32 may not thereafter be disassembled without breaking the components. Such snap-fit connections are known as "permanent" snap-fit connections which are used in single-use applications only.

Each snap-fit connector 60 comprises a resilient projecting member 62 which is substantially planar and projects away from the engagement end 40 of the base portion 30. At the free end 64 of the resilient projecting member 62 is a wedge portion 66 comprising an angled surface 67 and a 90° hook 68. The angled surface 67 is angled such that the width of the wedge portion 66 increases with distance away from the free end 64. The angled surface 67 terminates at the hook 68 at a distance L from the free end 64 of the resilient projecting member 62.

As the insulating member 14 is moved from the open configuration (see Figure Ib) to the closed configuration (see Figure ic), the snap-fit connectors 60 enter corresponding openings in the engagement end 42 of the cover portion 32.

The openings are partially bounded by surfaces 63 which abut against the angled surfaces 67 of the resilient projecting members 62 as the insulating member 14 is closed (i.e. as the base portion 30 and the cover portion 32 are brought together).

The angled surfaces 67 are angled such that the resilient projecting members 62 deform away from their natural (i.e. unstressed) orientation during the closing of the insulating member 14 due to the interaction between the angled surfaces 67 and the surfaces 63. When the insulating member 14 reaches the closed configuration, the wedge portions 66 of the snap-fit connectors 60 are received in the corresponding recesses 61 in the surfaces 63 and the resilient projecting members 62 return to their natural orientations. The hooks 68 engage around corresponding corners 65 of the recesses 61 in the cover portion 32 to ensure that the snap-fit connectors 60 cannot be disengaged from the corresponding recesses 61 after closure of the insulating member 14. Thus, the hooks 68 act as -13 -locking members which act to retain the insulating member 14 in the closed configuration.

The actuator 18 is arranged to engage with the insulating member 14. In particular, the actuator 18 is arranged to engage with the cover portion 32 of the insulating member 14 in the recess 34 at the actuator end 43 of the cover portion 32. The actuator end 43 of the cover portion 32 is substantially opposite the engagement end 42 of the cover portion 32. There are two distinct engagement configurations of the actuator 18 with the cover portion 32, namely a partially engaged configuration and a fully engaged (i.e. "actuated") configuration, as described further below.

As best seen in Figures 1 a and 4, the actuator 18 is in the form of a push button comprising a push button surface 80, a printed circuit board (PCB) 81, two lateral snap-fit connectors 82, an end snap-fit connector 84 and a central connection section 86.

If we define that the push button surface 80 faces upwards (in direction +z), then the snap-fit connectors 82 and 84 and the central connection section 86 can be said to extend downwardly away from the upwardly-facing push button surface 80 (in direction -z). In other words, the snap-fit connectors 82 and 84 and the central connection section 86 extend away from the push button surface in a direction opposite to the facing direction of the push button surface 80.

The central connection section 86 of the actuator 18 is substantially cylindrical with a slightly larger diameter disc or washer 88 at its free end. In the partially and fully engaged configurations of the actuator 18, the central connection section 86 is received (to varying degrees) within a substantially cylindrical bore 73 in the cover portion 32. One end of the cylindrical bore 73 is formed by a substantially circular central opening 57 in the recess 34 at the actuator end 43 of the cover portion 32. Within the cylindrical bore 73 are disposed a number of protruding members (not shown) in the form of break-away ribs. In particular, the protruding members are fixed to an internal surface of the cylindrical bore 73 and are formed from relatively soft plastic compared to the central connection section 86 of the actuator 18. The conducting pin 16 of the -14 -device 10 is coupled to the central connection section 86 of the actuator 18. In particular, the conducting pin 16 is concentrically received within the central connection section 86 and protrudes from the disc 88 at the end of the central connection section 86 in a direction away from the upwardly-facing push button surface 80 of the actuator 18 (i.e. along the -z direction). The central connection section 86 of the actuator 18 is moveable in the z-direction to a limited extent with respect to the push button surface 80 of the actuator 18. This movement is effected by means of a coil spring 70 disposed around the central connection section 86 of the actuator 18.

In the partially engaged configuration of the actuator 18 and the cover portion 32, the protruding members within the cylindrical bore 73 engage with the central connection section 86 of the actuator 18 so as to central ise the conducting pin 16 within the cylindrical bore 73 and so as to retain the end 17 of the conducting pin 16 within the cylindrical bore 73. Thus, in the partially engaged configuration of the actuator 18 and the cover portion 32, the end 17 of the conducting pin 16 does not protrude from the cylindrical bore 73 in the cover portion 32. In the partially engaged configuration, the spring 70 is in its natural (i.e. uncompressed) configuration and does not act to move any of the components of the actuator 18 relative to one another. Thus, in the partially engaged configuration, the sharp end 17 of the conducting pin 16 is held safely within the cylindrical bore 73 such that it may not penetrate an electricity cable 12 or a user's finger, for example.

As the actuator 18 is moved from the partially engaged configuration to the fully engaged configuration by depressing the push button surface 80 of the actuator 18, the central connection section 86 of the actuator 18 is moved downwards (in direction -z) and breaks off the soft protruding members within the cylindrical bore 73 such that the end 17 of the conducting pin 16 may extend out of the cylindrical bore 73 so as to penetrate an electricity cable 12.

In the fully engaged configuration of the actuator 18 and the cover portion 32, the end 17 of the conducting pin 16 is forced to penetrate through the insulation layer 50 of the electricity cable 12 into electrical contact with the conducting core 51. The electricity cable 12 provides some resistance against -15 -penetration by the conducting pin 16 which tends to compress the spring 70.

Nonetheless, the depression of the actuator "button" provides sufficient force and extent of movement for the conducting pin to fully penetrate the cable insulation so as to form an electrical connection with the conducting core 51.

Since the device 10 only draws a small current (see below), it is sufficient that the end 17 of the conducting pin 16 remains gently in contact with the conducting core 51. In other words, it is not necessary for the conducting pin 16 to penetrate into the copper conducting core 51; in any case, such penetration may damage the copper conducting core 51. Therefore, the device 10 does not apply a large downward force (in the -z direction) on the conducting pin 16.

However, the cable insulation 50 is plastically deformed when pierced, and copper yields. Thus, it has been found that, over time, the conducting pin 16 has a tendency to work its way back out of the electricity cable 12 such that the electrical connection between the conducting pin 16 and the conducting core 51 would be lost. Hence, the contact between the conducting pin 16 and the conducting core 51 is sprung to overcome this tendency. In particular, the compressed spring 70 acts against this bias in the system in the fully engaged configuration of the actuator 18. The spring 70 pushes on the top side of the disc 88 so as to move the central connection section 86 and the conducting pin 16 down away from the push button surface 80 in the -z direction. Thus, the spring ensures that the eIectrical connection between the conducting pin 16 and the conducting core 51 is maintained after the actuator 18 has been fully actuated.

The connector cable 20 of the device 10 is coupled to the actuator 18 at an end adjacent the end snap-fit connector 84. The connector cable 20 extends away from the actuator 18 parallel to the electricity cable 12 (i.e. parallel to they-direction). The connector cable 20 is coupled to the conducting pin 16 by means of circuitry including the PCB 81. In a preferred embodiment, the connector cable includes two wires (not shown): a first wire for transmitting voltage measurements, and a second wire which draws a small power supply for the device 12 from the electricity cable 12. The PCB 81 supports four metal film resistors 83, as best seen in Figures 2 and 4. The PCB 81 connects two of the resistors 83 in series between the conducting pin 16 and the first wire in the -16 -connector cable 20. The PCB 81 connects the other two resistors 83 in series between the conducting pin 16 and the second wire in the connector cable 20.

Each resistor 83 has a relatively high resistance so as to restrict the current through the wires of the connector cable to low enough values to be completely safe for the user.

In one example, each current-limiting resistor 83 is an 8k) resistor (other values are also envisaged within the scope of the invention). In this example, the total resistance provided by the resistors 83 on each wire is I 6k0 which restricts the current through the wires to the connector cable 20 to 1 5mA each (i.e. I = V/R = 240 / 16000 = l5mA). Each resistor 83 is individually rated at greater than mains voltage. Thus, if one resistor 83 fails thereby causing a short circuit (which would be very unusual for a metal film resistor), the other resistor on that wire will still be operational and would restrict the current to 3OmA in the above example, thereby keeping the current at a safe level even in the event of an unlikely resistor failure. Of course, if a resistor 83 were to fail thereby causing an open circuit, then the system would be inherently safe regardless. Apart from enhancing the safety of the device 10, the resistors 83 also prevent the device 10 from being misused to tap into an electricity supply illegally. In particular, the resistors 83 restrict the current through the connector cable 20 to such a low level that it could not be used as a normal mains electricity supply.

In an alternative embodiment, the resistors 83 are not included. Instead, both the first and second wires in the connecting cable are high resistance wires.

In a further alternative embodiment, a fuse is provided in the device 10. In yet another alternative embodiment, it would be possible to combine the functions of the first and second wires into a single wire within the connector cable 20.

However, the use of two separate wires for the two separate functions is advantageous so that the electricity supply to the device does not impact on the voltage measurements.

Returning to engagement of the actuator 18 with the insulating member, the lateral snap-fit connectors 82 enable the actuator 18 to partially engage with the actuator end 43 of the cover portion 32 by means of partial insertion of the -17 -two lateral snap-fit connectors 82 into two corresponding apertures 56 in the recess 34 at the actuator end 43 of the cover portion 32. Similarly, the two lateral snap-fit connectors 82 enable the actuator 18 to fully engage with the actuator end 43 of the cover portion 32 by means of full insertion of the two lateral snap-fit connectors 82 into the two corresponding apertures 56 in the actuator end 43 of the cover portion 32.

As seen most clearly in the cross-sectional view of Figure 2, the end snap-fit connector 84 has a 900 hook 85 that is configured to mate with a corresponding 90° hook 58 near the actuator end 43 of the cover portion 32 when the actuator 18 is fully engaged with the cover portion 32. The end snap-fit connector 84 has a similar form to the two snap-fit connectors 60 of the base portion, and similarly enables a permanent connection such that the actuator 18 and the cover portion 32 may not thereafter be disassembled without breaking the components. Thus, the end snap-fit connector 84 is a form of locking member which acts to retain the actuator 18 in full engagement with the cover portion 32 (i.e. the end snap-fit connector 84 acts to retain the actuator 18 in the "actuated" configuration and the device in the "fitted" configuration) once the actuator 18 has been actuated.

Each lateral snap-fit connector 82 comprises a resilient projecting member 90 which is substantially planar and projects away from the push button surface of the actuator 18. At the free end 91 of the resilient projecting member 90 is a first wedge portion 92 comprising a first angled surface 93 and a first 90° hook 94. The first angled surface 93 is angled such that the width of the first wedge portion 92 increases with distance away from the free end 91. The first angled surface 93 terminates at the first hook 94 at a distance Li from the free end 91 of the resilient projecting member 90. After the distance Li from the free end 91 of the resilient projecting member 90, there is a second wedge portion 96 comprising a second angled surface 97 and a second 90° hook 98. The second angled surface 97 is angled such that the width of the second wedge portion 96 increases with distance away from the free end 91. The second angled surface 97 terminates at the second hook 98 at a distance L2 from the free end 91 of the resilient projecting member 90, where L2> L1.

-18 -As the actuator 18 is moved from a disengaged configuration to the partially engaged configuration, the lateral snap-fit connectors 82 enter the corresponding apertures 56 in the actuator end 43 of the cover portion 32. The apertures 56 are partially bounded by surfaces 59 which abut against the first angled surfaces 93 of the first wedge portions 92 as the actuator 18 is partially engaged (i.e. as the actuator 18 and the cover portion 32 are brought together).

The first angled surfaces 93 are angled such that the resilient projecting members 90 deform away from their natural (i.e. unstressed) orientation during the engagement of the actuator 18 due to the interaction between the first angled surfaces 93 and the surfaces 59. When the actuator 18 reaches the partially engaged configuration, the first hooks 94 hook over the end of the surfaces 59 and the resilient projecting members 90 return to their natural orientations. The first hooks 94 ensure that the lateral snap-fit connectors 82 cannot thereafter be disengaged from the apertures 56 in the cover portion 32. Thus, the first hooks 94 act as locking members which act to retain the actuator 18 in partial engagement with the cover portion 32. The actuator 28 and the cover portion 32 are shown in the partially engaged configuration in Figures Ib, Ic and 5.

As the actuator 18 is moved from the partially engaged configuration to the fully engaged configuration, the lateral snap-fit connectors 82 move further into the corresponding apertures 56 in the actuator end 43 of the cover portion 32.

The surfaces 59 partially bounding the apertures 56 start to abut against the second angled surfaces 97 of the second wedge portions 96 as the actuator 18.

When the actuator 18 reaches the fully engaged configuration, the second hooks 98 hook over the end of the surfaces 59 and the resilient projecting members 90 return to their natural orientations. The second hooks 98 ensure that the lateral snap-fit connectors 82 cannot thereafter be disengaged from the apertures 56 in the cover portion 32. Thus, like the end snap-fit connector 84, the second hooks 94 act as locking members which act to retain the actuator 18 in full engagement with the cover portion 32, i.e. the second hooks 94 act to retain the actuator 18 in the "actuated" configuration once the actuator 18 has been actuated. The actuator 28 and the cover portion 32 are shown in the fully engaged (i.e. -19 -actuated) configuration in Figures id, 2, 3 and 6. This corresponds to the "fitted" configuration of the device 10.

As shown in Figures 5 and 6, the cover portion 32 includes stops 72 which prevent the actuator from becoming fully engaged with the cover portion 32 until the cover portion 32 has been engaged with the base portion 30. In particular, there are two respective stops 72 for each lateral snap-fit connector 82.

As shown in Figure 5, each stop 72 comprises an elongate resilient portion 74 which has a natural (i.e. unstressed) orientation in which it extends downwardly (i.e. in direction -z) from the bottom of the recess 34 in the actuator end 43 of the cover portion 32. At the end of the elongate resilient portion 74 is a 90° hook portion 76 which projects in the y-direction (out of the page in Figure 5) and is arranged to engage with the free end 91 of one of the lateral snap-fit connectors 82 as the actuator 18 engages with the cover portion 32. The length of the elongate resilient portion 74 is such that the end 91 of the lateral snap-fit connector 82 engages with the hook portion 76 of the stop 72 just after the actuator 18 has been inserted to its "partial engagement" configuration within the cover portion 32. In its natural orientation, the hook portion 76 of the stop 72 prevents the actuator 18 from being engaged any further with the cover portion 32.

As shown in Figure 6, the stops 72 may be moved aside by engagement of the base portion 30 with the cover portion 32. In particular, the base portion 30 includes four upwardly-projecting fins 78, there being a respective fin 78 for each stop 72. Each fin has a sloping surface 79 at the engagement end 40 of the base portion 30. As the base portion 30 engages with the cover portion 32, the sloping surface 79 of each fin 78 abuts against the side of a respective stop 72. As the base portion 30 is further engaged with the cover portion 32, the sloping surfaces 79 of each fin 78 force the respective stops 72 to bend aside such that the hook portions 76 no longer inhibit the progress of the end 91 of the lateral snap-fit connectors 82. Thus, the actuator 18 may be moved from the partially engaged configuration to the fully engaged configuration with the cover portion 32 once the

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base portion 30 has been engaged with the cover portion 32 so as to deflect the stops 72.

In an alternative embodiment, the stops 72 need not be resiliently deformable. Instead, the stops 72 could be broken off by interaction with the fins 78.

In use, the various components of the device 10 are initially separate from one another, as shown in Figure Ia. In order to use the device 10 to make an electrical connection with an insulated electricity cable 12, the actuator 18 is first partially engaged with the cover portion 32 by insertion of the actuator 18 into the recess 34, as described above. This leads to the "delivery" configuration of the device 10 as shown in Figure lb. In the delivery configuration of the device 10, the lateral snap-fit connectors 82 have been partially received within the apertures 56 in the recess 34 at the actuator end 43 of the cover portion 32. In particular, the first wedge portions 92 have been received within the apertures 56, but the second wedge portions 96 remain substantially outside (i.e. above) the apertures 56. A user is thereafter prevented from disengaging the actuator 18 from the cover portion 32 by virtue of the resilient projecting members 90 returning to their natural orientations such that the first wedge portions 92 are no longer aligned with the apertures 56. In this configuration, the first hooks 94 prevent removal of the first wedge portions 92 from the apertures 56. Furthermore, at this stage, the user is prevented from fully engaging the actuator 18 with the cover portion 32 by means of the stops 72, as described above.

Once the actuator 18 has been partially engaged, the central connection section 86 of the actuator 18 is held steady within the cylindrical bore 73 by the protruding members as described above. In this configuration, the end 17 of the conducting pin 16 is received within the cylindrical bore 73 in the cover portion 32 and does not protrude therefrom. This is a safety feature which reduces the risk of the user themselves contacting the sharp end 17 of the conducting pin 16. It is intended that the device 10 be provided to a user in this safe, "delivery" -21 -configuration. This ensures a safe, known position of the conducting pin 16 during transit to the user.

Once the user has received the device 10 in the "delivery" configuration of Figure 1 b, the user then selects a length of the electricity cable 12 along which the electrical connection is to be made. The user encloses the length of electricity cable 12 between the base portion 30 and the cover portion 32 of the insulating member 14 such that the length of electricity cable is retained in the substantially cylindrical bore formed between the base cable recess 44 and the cover cable recess 46 as shown in Figure ic. At this stage, the snap-fit connectors 60 of the base portion 30 mate with the corresponding recesses 61 in the cover portion 32 and the hooks 68 engage around corresponding corners 65 of the recesses 61 such that the base portion 30 may not thereafter be disengaged from the cover portion 32. Furthermore, the ribs 48 and 49 engage with the cable insulation 50 of the retained insulated electricity cable 12 as shown in Figure 2 so as to prevent longitudinal movement of the electricity cable 12 within the substantially cylindrical bore through the insulating member 14. In addition, the stops 72 are moved out of the way of the actuator 18 by virtue of the action of the fins 78 during engagement of the base portion 30 and the cover portion 32. In this configuration, the end 17 of the conducting pin 16 is received within the cylindrical bore 73 in the cover portion 32 and does not contact the electricity cable 12.

In an alternative methodology, the actuator 18 may be partially engaged with the cover portion 32 after the insulating portion has been closed around the length of electricity cable 12. However, this is less preferable since the end 17 of the conducting pin 16 would be accessible to the user during use of the device 10, as compared to the device 10 being delivered to the user in the safe "delivery" configuration of Figure lb. The next step is for the user to make the electrical connection between the conducting pin 16 of the device 10 and a conducting core. This is done by moving the actuator 18 from the partially engaged configuration to the fully engaged configuration with the cover portion 32. In order to effect this change, the user pushes down upon the push button surface 80 such that the actuator 18 -22 -is moved further into the recess 34 in the actuator end 43 of the cover portion 32.

This movement enables penetration of the cable insulation 50 by the end 17 of the conducting pin 16 such that an electrical connection is made. During this step, the lateral snap-fit connectors 82 are received further within the apertures 56 in the recess 34 at the actuator end 43 of the cover portion 32. In particular, the second wedge portions 96 are received within the apertures 56. In addition, this step causes the hook 85 of the end snap-fit connector 84 to mate with the corresponding hook 58 of the cover portion 32. The user is thereafter prevented from moving the actuator 18 back to partial engagement with the cover portion 32 by virtue of both the lateral snap-fit connectors 82 and the end snap-fit connector 84. In particular, in the fully engaged configuration of the actuator 18, the resilient projecting members 90 of the lateral snap-fit connectors 82 return to their natural orientations such that the second wedge portions 96 are no longer aligned with the apertures 56 such that the second hooks 98 prevent removal of the second wedge portions 96 from the apertures 56. Similarly, in the fully engaged configuration of the actuator 18, the end snap-fit connector 84 returns to its natural orientation such that the mating of the hooks 85 and 58 prevents removal of the end snap-fit connector 84 from the cover portion 32. Once the actuator 18 has been fully engaged, the situation is as shown in Figures Id, 2, 3 and 6.

In the fitted configuration of the device 10 (as shown in Figures id, 2, 3 and 6), the insulating member 14 and the actuator 18 together form an insulating housing which protects a user from the electricity supply through the electricity cable 12 and the conducting pin 16. In the fitted configuration, the conducting pin 16 and the punctured portion of the electricity cable 12 are disposed entirely within the housing. Furthermore, the housing formed by the insulating member 14 and the actuator 18 also insulates the user from the electricity supply in the "primed" configuration of the device as shown in Figure ic in which the insulating member 14 retains a length of electricity cable 12 and the actuator 18 is partially engaged with the cover portion 32 of the insulating member 14. Since the actuator 18 is operable from outside the insulating housing (by means of pushing -23 -on the push button surface 80), the user is never in danger of coming into contact with the electricity supply.

In addition, the housing formed by the insulating member 14 and the actuator 18 is splash-proof, like an electricity meter, such that the device 10 may be used in an outdoors environment.

Importantly, it should be noted that the device "double-insulates" a user from the electrical connection that is made. In other words, there are at least two separate layers of electrical insulation between the conducting pin 16 or conducting core 51 and the outside of the device. This is a safety requirement of such devices, It should be noted that the electrical insulation may be in the form of a solid insulating material (such as plastic), or may be in the form of an air gap.

Referring to the cross-sectional view of Figure 2, there are three layers of insulation in the z-direction between the electrical connection (i.e. the conducting core 51) and the base of the device 10, namely the two layers of cable insulation 50a and 5Db, and the base portion 30 of the insulating member 14. There are two layers of insulation in the z-direction between the electrical connection (i.e. the conducting pin 16) and the top of the device 10, namely the push button of the actuator 18, and a portion 71 of the central connection section 86 of the actuator 18 which holds the conducting pin 16. There are four layers of insulation in the y-direction between the electrical connection (i.e. the conducting pin 16) and the left hand side of the device (i.e. the side from which the connector cable extends), namely an outer insulating layer which forms part of the cover portion 32, a first air gap, and inner insulating layer which forms part of the cover portion 32, and a second air gap. There are two layers of insulation in they-direction between the electrical connection (i.e. the conducting pin 16) and the right hand side of the device (i.e. the side opposite the connector cable 20), namely an inner air gap and an outer insulating layer which forms part of the cover portion 32. Similarly, "double-insulation" may be seen in any diagonal direction in Figure 2, or in any direction in the cross-sectional view of Figure 3.

-24 -Thus, the device 10 enables a user to make an electrical connection with an insulated mains electricity cable 12 without danger to the user. This allows the device 10 to be operated by a home owner themselves without the need for the services of a qualified electrician.

The present device 10 has many applications, particularly in monitoring electricity usage. For example, the device 10 may be connected to an incoming mains electricity cable for a residence (e.g. near the electricity meter). This part of the electrical circuit is usually unprotected by fuses and/or circuit breakers, for example, but there is no danger to the user fitting the device 10 since the user remains insulated from the electricity supply at all times by the cable insulation 50 and/or the device 10. Once fitted, the device 10 may then be used to obtain real time measurements of the instantaneous electrical voltage supplied by the electricity cable 12. Furthermore, since the fitted device 10 has a direct connection to the conducting core 51 of the mains electricity cable 12, there is no need for the device to be battery-powered since it may draw power from the electricity supply along the electricity cable 12.

Figure 7 depicts a monitoring system 100 incorporating devices of the type described above. The system 100 is applied to the incoming electricity supply of a residence on the output (i.e. consumer) side of the electricity meter 102. This is an unprotected portion of the supply (i.e. there is only a I OOA fuse present at this point in the circuit, so large currents of up to 100A may flow freely). The electricity meter 102 is a meter for a single-phase AC electricity supply. The outputs comprise a single live electricity cable 12a and a single neutral electricity cable 12b. The electricity meter 102 clearly also has live and neutral input cab'es, but these are not shown in Figure 8.

The system 100 comprises a first device I Oa, a second device 1 Ob, a current clamp 104, a processor 106, and a display system 110.

The first device lOa is fitted to the live electricity cable 12a such that an electrical connection is made between the conducting pin 16a of the first device 1 Oa and the conducting core 51 a of the live electricity cable 1 2a. The first device -25 -lOa is connected to the processor 106 by means of the connecting cable 12a of the first device 1 Oa.

The second device 1 Ob is fitted to the neutral electricity cable 1 2b such that an electrical connection is made between the conducting pin 16b of the second device lOb and the conducting core 51b of the neutral electricity cable 12b. The second device lOb is connected to the processor 106 by means of the connecting cable 12b of the second device lOb.

The current clamp or current probe 104 is an electrical device having two jaws which open to allow clamping around the live electricity cable 12a. This allows the electrical current in the conducting core 51a of the live electricity cable 12a to be measured (e.g. by induction or using the Hall effect), without having to make a physical connection with the conducting core 51a, and without having to disconnect the live electricity cable 12a for insertion through the current clamp 104. Thus, the current clamp 104 is fitted to the live electricity cable 12aso as to monitor the current passing along the live electricity cable 12a. The current clamp 104 is connected to the processor 106 by means of the connecting cable 114 of the current clamp 104.

Together, the first device I Oa and the second device 1 Ob provide the processor 106 with measurements of the instantaneous voltage supplied to the residence. The current clamp 104 provides the processor with measurements of the instantaneous current supplied to the residence. These measurements may be processed by the processor 106. The processor is powered by means of the power supply wires within the connection cables 120a and 120b of the devices 1 Oa and lob. Following the optional processing, the measurements of current and voltage may be transmitted wirelessly to the display device 110 for display to a user. In a preferred embodiment, the measurements may be transmitted wirelessly by a transmitter 108 of the processor 106 to be received by a receiver 112 of the display device 110. Alternatively, there may be a hard-wired connection between the processor 106 and the display device 110. The display device 110 may display the current and/or voltage measurements received from the processor 106. Further optional processing may be performed by a processor within the display device 110 before displaying data to the user.

-26 -Thus, the system 100 is able to provide consumers with real-time detailed information about the energy they are using. As mentioned previously, studies have shown that the effect of providing consumers with real-time detailed information about the energy they are using is that their consumption reduces by up to 20%. Thus, the system 100 can aid the reduction of energy consumption.

Advantageously, the system 100 is operable to process the current and voltage measurements to provide a user with detailed information regarding which electrical appliances are in use at particular times, and how much energy they are consuming. Such a system 100 would then be referred to as a Non-Intrusive Load Monitoring (NILM) system.

In an alternative embodiment, the current clamp 104 could be fitted to the neutral electricity cable 12b rather than to the live electricity cable 12a. In this embodiment, the sign of the measured current would be different and the combined current and voltage measurements would indicate negative measurements of power. However, the processor 106 could easily be arranged to compensate for this possibility by reversing the sign. Thus, the system 100 would work equally well with the current clamp 104 on either the live electricity cable 12a or the neutral electricity cable 12b.

Although preferred embodiments of the invention have been described, it is to be understood that these are by way of example only and that various modifications may be contemplated.

For example, it will be appreciated that the permanent snap-fit connections described above are one of many ways of connecting components together.

Other connection types (permanent or not) are also considered to fall within the scope of the invention.

In an alternative embodiment, the use of a hinged insulating member is envisaged. In particular, the insulating member could be arranged to close around a length of electricity cable 12 by means of a hinged movement, rather than using a "push-fit" closure of the base member 30 and the cover member 32 parallel to the z-axis as shown in Figures lb to I c.

-27 -In the embodiment described above, the insulating member 14 fully encloses the length of electricity cable 12 when it is in the closed configuration.

In alternative embodiments, substantial enclosure of the length of electricity cable 12 would be adequate. For example, the base portion 30 of the insulating member 14 could include one or more apertures through to the cable insulation 50. Thus, in the fitted configuration of the device 10, the user would be insulated from the electricity supply by means of the insulating member 14 and/or the actuator 18 and/or the cable insulation 51 on the lower half of the electricity cable 12 (i.e. the half of the electricity cable 12 resting in the base cable recess 44).

A further alternative embodiment provides a connector cable which couples to the insulating member 14 (e.g. the cover portion 32) rather than the connector cable 20 coupling to the actuator 18. As yet another alternative, it would also be possible to provide a connector plug or socket as part of the device 10, rather than providing the connector cable 20.

Finally1 in an alternative embodiment it is envisaged that the cable insulation 50 could be pierced by a component other than the conducting pin 16.

Such a component may be conducting or non-conducting. In this embodiment, there may be a two-step piercing process in which the piercing component pierces the cable insulation 50 in a first step, and in which the conductor pin 16 (or conductor element) is inserted via the pierced hole to make electrical contact with the conducting core 51 of the electricity cable 12 in a second step.

Alternatively, there could be a single-step piercing process in which the conducting pin 16 is rigidly coupled to the piercing member such that the conducting pin 16 forms an electrical connection with the conducting core 51 of the electrical cable 12 as the piercing member pierces the cable insulation 50.

Claims

-28 -CLAIMS: 1. A device for making an electrical connection with an insulated electricity cable, the device comprising: an arrangement for piercing an insulation layer of a length of electricity cable to thereby make an electrical connection with an internal conductor of the length of electricity cable; and an actuator coupled to the arrangement, wherein the actuator is actuable by a user to cause the arrangement to pierce an insulation layer of a length of electricity cable so as to make an electrical connection with an internal conductor of the length of electricity cable; wherein the device is configured to ensure that the user remains electrically insulated from the internal conductor of a length of electricity cable once the electrical connection has been made with the internal conductor of the length of electricity cable.
2. The device of claim 1 wherein the device is configured to ensure that the user remains electrically insulated from the internal conductor of a length of electricity cable during the piercing of the insulation layer of the length of electricity cable.
3. The device of claim 1 or claim 2 wherein the device is configured to ensure that the user is electrically insulated from the electrical connection by means of two or more separate layers of electrical insulation.
4. The device of claim 3 wherein one layer of the two or more separate layers of electrical insulation comprises an air gap.
5. The device of any of claims 1 to 4 wherein the arrangement comprises a conducting pin arranged to pierce the insulation layer of a length of electricity cable.

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6. The device of any of claims 1 to 4 wherein the arrangement comprises: a piercing member for piercing the insulation layer of a length of electricity cable; and a conducting member for forming an electrical connection with the internal conductor of a length of electricity cable.
7. The device of any preceding claim further comprising an insulating member arranged to retain a length of electricity cable for piercing, wherein the insulating member and the actuator are together configuied to ensure that the user remains electrically insulated from the internal conductor of a retained length of electricity cable once the electrical connection has been made.
8. The device of any preceding claim wherein the device is arranged to substantially enclose a length of electricity cable.
9. The device of any preceding claim wherein the device is arranged to fully enclose a length of electricity cable.
10. The device of any preceding claim wherein the device has an initial open configuration which enables insertion of a length of electricity cable into the device, the device being moveable to a closed configuration in which an inserted length of electricity cable may be retained by the device.
11. The device of any preceding claim wherein the device comprises a cable locking member arranged to permanently couple a length of electricity cable to the device in a fixed position.
12. The device of claim 11 when dependent upon claim 10 wherein the cable locking member is arranged to permanently lock the device in the closed configuration after the device has been moved from the open configuration to the closed configuration.-
13. The device of any preceding claim further comprising a biasing member arranged to maintain the electrical connection with the internal conductor of the length of electricity cable once the electrical connection has been made.
14. The device of claim 13 wherein the biasing member comprises a spring.
15. The device of any preceding claim further comprising a stop member having an initial configuration which prevents actuation of the actuator, the stop member being moveable to a secondary configuration by inserting a length of electricity cable into the device for retention therein, wherein the secondary configuration of the stop member enables actuation of the actuator.
16. The device of any preceding claim wherein the actuator is manually actuable by a user without the need for tools.
17. The device of claim 16 wherein the actuator comprises a push button moveable relative to a length of electricity cable to be pierced.
18. The device of any preceding claim wherein the actuator comprises an actuator locking member arranged to permanently lock the actuator in an actuated configuration once the electrical connection has been made.
19. The device of any preceding claim further comprising a connector arranged to be coupled to the internal conductor of a length of electricity cable once the electrical connection has been made with the internal conductor of the length of electricity cable.
20. The device of claim 19 further comprising at least one resistor arranged to couple the connector in series to the internal conductor of a length of eectricity cable once the electrical connection has been made with the internal conductor of the length of electricity cable, thereby limiting the current able to flow through the connector.

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21. The device of claim 19 or claim 20 wherein the connector comprises one of a connector cable, a connector socket and a connector plug.
22. The device of any preceding claim further comprising circuitry to measure the current passing through a retained length of electricity cable.
23. A kit for monitoring electricity, the kit comprising: two or more devices in accordance with any one of the preceding claims; io an apparatus for measuring the electrical current passing through an insulated electricity cable coupled thereto; and a processor arranged to be connected with each of the two devices and with the apparatus so as to enable the receiving of voltage and current measurements therefrom.
24. The kit of claim 23 further comprising a display device operable to display information based on voltage and current measurements received from the processor.
25. The kit of claim 23 or claim 24 wherein the apparatus is a current clamp.
26. A method of making an electrical connection with an insulated electricity cable, the method comprising the steps of: providing a device comprising: an arrangement for piercing an insulation layer of the length of electricity cable to thereby make an electrical connection with an internal conductor of a length of electricity cable; and an actuator coupled to the arrangement; and actuating the actuator to cause the arrangement to pierce the insulation layer of the length of electricity cable so as to make an electrical connection with the internal conductor of the length of electricity cable; -32 -wherein the device is configured to ensure that a user remains insulated from the internal conductor of the length of electricity cable once the electrical connection has been made.
27. The method of claim 26 further comprising a step of retaining the length of electricity cable in the device prior to the step of actuating the actuator.
28. The method of claim 27 wherein the step of retaining a length of electricity cable comprises closing the device around the length of electricity cable by moving the device from an initial open configuration to a closed configuration, the initial open configuration enabling insertion of the length of electricity cable into the device, and the closed configuration enabling the inserted length of electricity cable to be retained by the device.
29. The method of claim 27 or claim 28 wherein the step of retaining the length of electricity cable further comprises moving a stop member from an initial configuration to a secondary configuration, the initial configuration preventing actuation of the actuator, and the secondary configuration enabling actuation of the actuator.
30. The method of any of claims 26 to 29 further comprising a step of permanently coupling the length of electricity cable to the device prior to the step of actuating the actuator.
31. The method of any of claims 26 to 30 further comprising a step of biasing a conducting member of the arrangement towards the internal conductor of the length of electricity cable once the electrical connection has been made.
32. The method of any of claims 26 to 31 further comprising a step of permanently locking the actuator in an actuated configuration once the electrical connection has been made.

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33 - 33. A device operable to enable a user to make an electrical connection with the conducting core of an insulated electricity cable without disconnecting the electricity supply and without compromising the safety of the user.
34. A device for making an electrical connection with an insulated electricity cable, the device being substantially as herein described with reference to Figures Ito 6 of the accompanying drawings.
35. A system substantially as herein described with reference to Figure 7 of the accompanying drawings.
36. A method of making an electrical connection with an insulated electricity cable, the method being substantially as herein described with reference to Figures Ito 6 of the accompanying drawings.