Patent Application
20180286289
This invention relates to an identification tag for fitting on to an electrical cable to provide enhanced safety at a connection between the cable and another component and also cable identification. The invention further relates to a method of providing electrical shielding and identification for a cable at a connection between the cable and an electrical component.
This invention may be used in many electrical wiring situations, though it is primarily concerned with the safety and identification of electrical cables connected to single phase and three phase electricity meters. As such, the invention will be described hereinafter solely in relation to this situation though it is to be understood that the invention is not limited to this.
In many electrical wiring installations, it is essential that adequate safety be assigned to a connection between an electrical cable and a component to which the cable is connected. Further, it may be advantageous, or sometimes a requirement of the wiring regulations, to provide an identification of a cable carrying mains electricity, including easily visible and clear markings. A particular case in point is with supply cables connecting an incoming electrical supply to an electricity meter and feed cables connecting the electricity meter to an isolator switch, a consumer unit for distribution around a building or other electrical component.
The supply and feed cables to an electricity meter are usually referred to as “tails” and, for the domestic environment, normally have conductors of 25 mm2 cross-section or 16 mm2 cross-section. The electrical cables typically have a layer of insulation around the conductors and an outer sheath surrounding the insulation. Often, the insulation and sheath (if provided) are of a uniform grey colour and so do not serve to identify the whether the cable is a “live” or “neutral” cable. In some cases, however, one or both of the sheath and inner insulation may be coloured to denote the polarity of the electrical cable.
When a cable is to be connected to an electricity meter, the insulation and, if provided, the outer sheath must be cut away to expose the conductors which are then fitted into a connector within the meter and are clamped in place by means of screws provided as a part of the connector. It is important that there is no access to the conductors of the cable or the connector of the meter in the region of the connection. This is important for safety purposes, and also in order to prevent fraudulent tapping of electricity from the supply cables to the meter before the electricity has been metered.
In order to enhance the safety of the connections at an electricity meter and also to restrict access to the conductors of the cable or the connectors of the meter, it is known to provide the connectors within a meter housing at the inner end of a recess in the housing. Such a recess may be of uniform circular cross-section or may be generally conical. Further, it is known to provide an upstanding external rim on the housing around the recess leading to the connectors. With this arrangement the object is to ensure that the conductors of the cable cannot be accessed once fitted to the connector within the meter housing.
Following the preparation of an end portion of the cable by stripping away the insulation and the outer sheath to expose a pre-set length of the cable conductors, it is also known to fit a flanged collar to the cable. The flanged collar effectively enlarges the diameter of the cable at cut end of the insulation and aims to provide enhanced safety by reducing access to the conductors and the connectors within the meter. Most of the known collars have a protrusion which projects into a recess in the meter housing leading to the meter connector to assist safety, for example in the event that the insulation creeps back from where it was cut or that too great a length of the conductors was exposed. The known collars also have a radial flange at or adjacent an end of the collar intended to lie adjacent the exposed conductors such that the flange will seat against an outer end of the recess in the meter housing or against a surrounding rim, if provided. However, rather than enhancing safety and security, it is found that flexing of a cable carrying such a collar causes the flange of the collar to lever against a part of the meter housing. By pulling the cable to one side that leverage makes it relatively easy to gain access to the conductors of the cable between the collar or flange and the meter housing.
There is, therefore, a need to provide an improved collar which addresses the issues of both electrical shielding and safety of the conductors of a cable at a connection to an electrical component such as an electricity meter.
Current wiring regulations also require the supply cables to an electricity meter and the feed cables from a meter to a consumer unit, isolator switch or other electrical component to be appropriately identified both by colour and with symbols typically in the form of letters and/or numerals.
The colour may be provided by the colour of the outer sheath of the cable itself, by the use of coloured insulation tape wound around the cable, or by a collar fitted around the cable. In the case of an incoming supply cable to a meter, the live cable should carry a symbol in the form of a single letter L and the neutral cable a single letter N. In the case of a feed cable from a meter, the live cable should carry two letters L and the neutral cable two letters N. Further, in the case of a cable to certain specified items of electrical equipment, the live cable may be required to carry three letters L.
Appropriately coloured self-adhesive tape may be wound around the cables adjacent the connection thereof to an electricity meter. Brown tape may be used for the live cable and blue tape for the neutral cable, in accordance with the European regulations for a single phase supply. Further, the supply cables from the electricity supply to the meter may each carry one band of tape, and the feed cables from the meter to the consumer unit, isolator switch or other electrical component may carry two adjacent, but spaced apart, bands.
Symbols may be provided on the coloured tape, for example the letters L or N. Another possibility is for the symbols to be provided on separate components which are fitted to the cable either before or after the cable is connected to the meter. For example, it is known to use coloured cable ties having the letters marked on the tail of the tie. Once fitted, the cable ties are typically trimmed by cutting away the unwanted part of the tail. Each cable tie or coloured tape will include a band or series of repeated symbols along its length. To mark a cable with a single symbol, such as a single letter L, a single cable tie or strip of tape is wrapped around the electrical cable. To mark a cable with two symbols, such as a double letter L, two cable ties or strips of tape are wrapped around the electrical cable. As such, a single coloured cable tie may be used on an incoming supply cable to a meter and two coloured cable ties on the feed cable from the meter. It will thus be appreciated that six cable ties are required to mark the two incoming and two outgoing cables to an electricity meter, and in the case of a three phase meter twelve cable ties are required. The fitting of these is time-consuming and, of course, an electrician must carry a significant inventory of components in order to be able to adequately mark the cables associated with a meter.
The problem of adequate cable marking for an electricity meter is becoming more acute as there is a programme under way in the UK and elsewhere to replace all existing traditional electricity meters with smart meters. This requires a visit by an operative to each existing meter to check and identify the polarity and phase (in the case of a three-phase electricity supply) of the cables connected to the meter. Once identified, the cables are suitably marked before being disconnected from the meter. The existing meter is then removed and the replacement smart meter mounted in its place, whereafter the cables must be correctly connected to the smart meter. With a simple domestic supply there will be four cables connected to the traditional electricity meter, but with a three phase supply there will be eight such cables, and there may be further cables connected to the meter for example associated with other supply functionality such as a night time tariff. Depending upon when the original meter was installed those cables may carry no identification markings, or may be incompletely or inaccurately marked. As such, following disconnection of the cables from the existing meter, there could be a very high risk of confusion as to which cable is which when reconnecting the cables to the replacement meter unless steps are taken to identify the cables before disconnection from the existing meter and then marking the cables as appropriate.
In an attempt to ensure adequate cable identification for the future, current regulations specify that the cables connected to a new or replacement electricity meter must be appropriately identified, both by colour and symbols to show the function of the cable. These regulations must, therefore, be adhered to on replacing a meter, but the possible confusion of the cables connected to an existing meter must be addressed in order to ensure that, when an existing meter is replaced by a smart meter, the cables are appropriately identified before removal from the existing meter so that the cables are not confused when connected to the connectors of the replacement meter.
It is an aim of this invention to provide a device for attaching to an electrical cable that addresses one or more of the issues described above.
According to a first aspect of the present invention there is provided an identification tag for attachment to an end of an electrical cable, said cable end having a length of exposed inner conductor beyond an end of a surrounding layer, and the tag comprising:
In some embodiments at least a part of the outer surface of the collar portion has a tapered profile. A part of the outer surface of the collar portion may be dome-shaped. In preferred embodiments a part of the outer surface nearest the first end of the collar portion has a cylindrical shape. Typically the profile of the outer surface of the collar portion has three parts, a first part nearest the first end of the collar portion having a cylindrical shape, a second part extending from the first part having a tapered profile and a third part nearest the second end of the collar portion having a tapered profile, an angle of the taper of the third part being greater than an angle of the taper of the second part.
The bore preferably has a first section at the first end of the collar portion having a first diameter and a second section at the second end of the collar portion having a second diameter, the first diameter being larger than the second diameter. The abutment surface may be provided by a shoulder in the bore between the first and second sections. In other embodiments the abutment surface is provided at the first end of the collar portion.
The identification tag preferably comprises attachment means connected to the tab portion, the attachment means being configured to temporarily attach the tag to a cable. Typically the attachment means comprises a clip. The attachment means may comprise a pair of resilient arms extending from the tab portion, the arms being spaced apart to define a gap for receiving said cable. Preferably the resilient arms extend from opposite edges of the tag portion.
So that the identification means are clearly displayed when the tag is attached to a cable the identification means are preferably provided on a first face of the tag portion and the arms extend in a direction opposite to the first face. Each resilient arm may include a projection extending from a distal end region of the arm, each projection extending into said gap.
In some embodiments a distal end section of the tab portion extends beyond the attachment means in a direction away from the collar portion.
The identification means will typically comprise one or more symbols on a surface of the tag portion. The identification means may comprise one or more colours.
Preferably the tag comprises a hinge portion connecting the tab portion to the collar portion, the hinge portion being configured to permit movement of the tab portion relative to the collar portion between a first configuration in which the tab portion extends from the collar portion in a direction transverse to an axis of the collar portion and a second configuration in which the tab portion extends from the collar portion in a direction substantially parallel to the axis, the axis defined by the bore of the collar portion. The hinge portion may include a live hinge. Alternatively the hinge portion comprises a flexible member or element.
The identification tag is preferably made from a plastics material.
According to a second aspect of the present invention there is provided a method of shielding an end of an electrical cable using an identification tag according to the first aspect of the invention, said cable end having a length of exposed inner conductor beyond an end of a surrounding layer, and the method comprising inserting said cable end through the bore of the collar portion from the first end to the second end until the end of the surrounding layer contacts the abutment such that a distal end of the exposed conductor extends from the second end of the bore and a proximal end of the exposed conductor is located within the bore.
Typically, after inserting the cable end through the bore of the collar portion, the distal end of the exposed conductor will be connected to an electrical component. The electrical component may include an aperture in a housing of the component and a recess surface surrounding the aperture. The method therefore preferably comprises inserting the cable end into the aperture and seating the outer surface of the collar portion in contact with the recess surface.
According to a third aspect of the present invention there is provided an assembly comprising:
The electrical component may include an aperture in a housing of the component and a recess surface surrounding the aperture, and a part of the outer surface of the collar portion is preferably seated in contact with the recess surface. The electrical component may be an electricity meter.
In preferred embodiments the identification tag comprises attachment means connected to the tab portion, and the attachment means attach the tab portion to the cable such that the tab portion extends substantially parallel to the cable.
By way of example only, several specific embodiments of cable safety collar of this invention which also serve as a cable marker will now be described in detail, reference being made to the accompanying drawings, in which:—
The identification tags for electrical cables of the present invention are intended for use with insulated cables such as are used to make connections to an electricity meter. Such cables are usually referred to as meter tails and typically have conductors of 16 mm2 or 25 mm2 cross-section. The cables have a layer of insulation around the conductors and may also have an outer sheath around the insulation.
Wiring regulations require the cables (tails) connecting an electricity meter to the electricity supply and also the cables connecting the meter to an isolator switch, a consumer unit or another electrical component to be clearly marked for identification purposes. The identification tags described below are intended to be able to perform this function but could be used in other situations besides the wiring of an electricity meter. Furthermore, they may be formed for use with cable sizes other than those referred to in this application.
The socket 14 has a first part 20 of uniform outer diameter, a second part 22 of a generally conical form and a third part 24 also of a conical form but with a greater conical angle than that of the second part 22. As shown, the three parts 20, 22, 24 are distinct but could blend one into another with a smooth transition, or could be more rounded and so essentially of part-spherical form. Internally, the socket 14 has a bore 26 of two diameters with a step or shoulder therebetween. A first portion of the bore 26 having a larger diameter is within the cylindrical first part 20 of the socket 14, and a second portion of the bore 26 having a smaller diameter extends through the second and third parts 22, 24 of the socket 14.
The tab portion 16 is connected to the first part 20 of the socket 14 by a bridging portion 28 and is moulded so as to extend from the first part 20 of the socket 14 in a direction away from the second and third parts 22, 24 of the socket 14. The tab portion 16 is of a generally rectangular planar shape. The tab portion 16 is divided into three sections 30 by separation zones 32 configured such that it is possible to fully separate the sections 30. In particular, in this example, it may be possible manually to break away or snap off a free end section 30a furthest from the collar portion 12 from the other two sections 30b, 30c or the free end section 30a and the next adjacent section 30b leaving one section 30c connected to the collar portion 12. To assist this, the separation zone 32 may be weakened for example by including a transverse slot 34 therethrough such that the free end section 30a is connected to the next adjacent section 30b by two small, spaced apart ribs 36. In the alternative, the separation zones 32 may be cut or otherwise severed as required by using a suitable tool to remove one or more sections 30 from the identification tag 10—for example by using scissors or side cutters, which form a part of every electrician's kit, or by using another suitable tool.
Each section 30 of the tab portion 16 carries symbols 38 typically in the form of letters and/or numerals which act as identification means to identify the cable to which the identification tag 10 is fitted. In the case of the embodiment of
The example of an identification tag 110 shown in
Once the identification tags 10,110 have been attached to the ends of the cables 2, the cables 2 are connected to an electricity meter 90 such as that shown diagrammatically in
In the embodiment of
As with the previous embodiments, one or two sections 530 of the tab portion 516 may be divided, separated or removed prior to fitting the identification tag 510 to a cable 2, so that the identification tag 510 displays fewer symbols. Further, the identification tag 510 may be supplied with other symbols besides those shown in the drawings, or other numbers of sections 530 each carrying one or more symbols, besides those shown in
The collar portion 612 comprises a generally tubular socket 614 having a central bore 626. The bore 626 extends fully through the socket 614 between first and second ends 613, 615 of the socket 614, thereby defining an axis 618 of the collar portion 612.
In this embodiment the socket 614 has three parts 620, 622, 624 defined by the profile of an outer surface 644 of the collar portion 612. A first part 620 extending from the first end 613 of the socket 614 has a cylindrical outer surface so that an outer diameter of the first part 620 is constant. A second part 622 of the socket 614 extends from the first part 620 and has a tapered or conical outer surface. In this way an outer diameter of the second part 622 furthest from the first part 620 is smaller than the outer diameter of the first part 620. A third part 624 of the socket 614 extends from the second part 622 and has a tapered or conical outer surface. In this way an outer diameter of the third part 624 at the second end 615 of the socket 614 furthest from the second part 622 is smaller than the outer diameter of a section of the second part 622.
It will be appreciated that although the socket 614 of this embodiment has been described as having three distinct parts 620, 622, 624, in other embodiments the socket 614 may have a curved outer surface 644 such that there is a smooth transition between each of the first, second and third parts 620, 622, 624. Furthermore, in some embodiments the outer surface 644 of the socket 614 may be substantially dome-shaped. Importantly an outer diameter of the socket 614 is smaller at the second end 615 of the socket 614 than at the first end 613, and the outer diameter of the socket 614 increases gradually between the second and first ends 613, 615. In particular the outer surface 644 of the socket 614 does not include a distinct step or sharp change in diameter, but has a gradual and substantially continuous decrease in diameter from the first end 613 to the second end 615, thereby creating a generally tapered collar portion 612.
With reference to
In the embodiment of the identification tag 610 of
The separation portion 632 comprises a thinner region of material such that the tab portion 616 may be more easily broken in this region. This allows a user to easily separate the first section 630a from the second section 630b and the rest of the identification tag 610, as described above in relation to the earlier examples.
The hinge portion 642 is movable between a first configuration, shown in
In this embodiment the hinge portion 642 comprises a flexible member 654 that is connected to the socket 614 proximate the first end 613 of the socket 614. In particular the flexible member 654 extends from an outer surface 644 of the first part 620 of the socket 614. In the first configuration the flexible member 654 is substantially planar and in the second configuration the flexible member 654 is bent through about 90° proximate the socket 614.
The tab portion 616 of the identification tag 610 further comprises attachment means in the form of a pair of resilient arms 656. A first arm 656 extends from a first edge 658 of the tab portion 616 and a second arm 656 extends from an opposite, second edge 658 of the tab portion 616. The first and second arms 656 extend from the tab portion 616 in a direction substantially transverse to the tab portion 616. Furthermore, the first and second arms 656 extend in substantially the same direction from the tab portion 616 such that a gap 660 is defined between inner surfaces 662 of the first and second arms 656. A barb or hook portion 664 extends from a distal end 666 of each of the arms 656. Each of the barbs 664 extends into the gap 660, such that the barb 664 on the first arm 656 extends substantially towards the second arm 656 and the barb 664 on the second arm 656 extends substantially towards the first arm 656.
The gap 660 between the arms 656 is sized to receive an electrical cable 2 to which the identification tag 610 is to be attached. The arms 656 are configured to be releasably engaged with a cable 2 so that the identification tag 610 can be easily and quickly clipped onto and removed from a cable 2 during use. Once the identification tag 610 has been clipped onto the cable 2 the barbs 664 of the arms 656 resist withdrawal or removal of the identification tag 610 from the cable 2, thereby retaining the identification tag 610 on the cable 2; however, the resilience of the arms 656 allows a user to pull the identification tag 610 off the cable 2 by application of suitable force to cause the arms 656 to flex outwardly to disengage the barbs 664 from the cable 2.
The arms 656 extend from the second section 630b of the tab portion 616 in a direction opposite to the first surface 652 of the tab portion 616. In the first configuration of the identification tag 610 the first and second arms 656 extend from the tab portion 616 in an opposite direction to the socket 614. In the second configuration of the identification tag 610 the gap 660 between the first and second arms 656 is axially aligned with the bore 626 through the socket 614.
The identification tag 610 includes a single clip comprising the first and second arms 656, and this clip extends from the second section 630b of the tab portion 616. This enables a user to remove the first section 630a of the tab portion 616 if only one section and, therefore, one identification symbol is required.
The identification tag 610 will typically be manufactured in the first configuration and during use of the identification tag 610 a user will move the identification tag 610 into the second configuration. Use of the identification tag 610 will now be described with reference to
For relatively low power installations the conductors 4 of the tails will be of either 16 mm2 cross-sectional area or 25 mm2 cross-sectional area. Sometimes, 16 mm2 cross-sectional cables 2 have one layer of insulation 6 surrounding the conductors 4 whereas 25 mm2 cables have one layer of insulation 6 surrounding the conductors and an outer sheath 8 around the layer of insulation 6. The following description will primarily be concerned with cables 2 having both a layer of insulation 6 and an outer sheath 8, but is not limited to conductors 4 having a cross-sectional area of 25 mm2.
In a typical installation the cables 2 connected to the meter 91 may not be clearly identified, even if they were when the cables 2 were installed, perhaps several years previously. However, from the wiring diagrams usually provided with electricity meters it should be apparent to an electrical technician which cables are which. Even if the cables 2 or the meter 91 are not so marked, it is possible to use appropriate test equipment to determine which cables 2 are which—that is, which cable is the live feed from the supply to the meter, which is the live feed from the meter to an isolator switch or a consumer unit, and which are the corresponding neutral cables. With a three-phase meter 91, there will be six live cables 2 to be identified—three incoming and three outgoing—as well as the two neutral cables 2. When the meter 91 is to be changed the electricity supply to the meter 91 must be turned off and all of the cables 2 must be disconnected from the meter 91. In order to prevent confusion as to which cable is which, it is essential that the cables 2 are somehow identified before disconnection of those cables 2 from the existing meter 91 and the removal thereof.
In accordance with a method of this invention, all of the cables 2 connected to the meter 91 are identified as a first step and then are temporarily pre-marked with identification tags 610 before the disconnection of those cables 2 from the existing meter 91. As described above, each identification tag 610 has a collar portion 612 for fitting on to a cable end 2, once stripped to expose the conductors 4, and a tab portion 616 extending away from the collar portion 612. As manufactured, the identification tag 610 may carry two essentially identical symbols 638 arranged serially along the length of the tab portion 616 with a separation region or weakened zone 632 between the sections 630 carrying the symbols 638. On a face of the tab portion 616 opposed to the symbol 638 nearer the collar portion 612, there is a pair of arms 656 of a suitable configuration for clipping on to a cable 2 with which the identification tag 610 is to be used. In addition to the symbols 638 discussed above, the identification tags 610 are coloured—typically by being moulded from suitably coloured plastic material. In the UK, all markers for live cables are coloured brown, but within most other countries of the EU, different colours are used for the different phases of the live conductors and so the identification tags 610 should be correspondingly coloured.
In a first step in the method each of the cables 2 connected to the electricity meter 91 is identified. A user then selects the appropriate identification tag 610 for each cable 2. With the identification tag 610 in the first configuration the user clips the appropriate identification tag 610 onto the cable 2 at a distance from the end of the cable 2 and, therefore, at a distance from the meter 91, as shown in
The table below shows a selection of identification tags that may be used to pre-mark the cables connected to the electricity meter.
When clipped on to the cables 2 in this first configuration, each identification tag 610 has the axis 618 of the collar portion 612 extending in a generally radial direction with respect to the cable 2 and with the tab portion 616 lying in a plane substantially parallel to an axis of the cable 2. The attachment of the identification tag 610 is only temporary by virtue of the arms 656, but is sufficiently secure to allow disconnection of the cables 2 from the meter 91 without loss of the identification tags 610 identifying the cables 2 for subsequent reconnection to a replacement meter 91.
When all of the cables 2 have been disconnected from the meter, as shown in
Throughout this process, and while the cables 2 are removed from the meter 91, the identification tags 610 remain attached to each of the cables 2 allowing subsequent and continued identification of the cables 2.
Once the ends of the cables 2 have been satisfactorily prepared, the cables 2 may be connected to the replacement meter 91.
Taking each cable 2 in turn, the identification tag 610 clipped onto the cable 2 is released from the cable 2, either by pulling the identification tag 610 radially off the cable 2 or by sliding the identification tag 610 axially along the cable 2 and off the cable end. The end of the cable 2 is then inserted into the collar portion 612 of the identification tag 610, as shown in
The cable end 2 is preferably inserted through the bore 626 of the socket 614 until the layer of insulation 6 contacts the shoulder 650 of the bore 626. In this position the outer sheath 8 of the cable 2 (when present) preferably contacts the first end 613 of the socket 614, as illustrated in
As can be seen in
Once the collar portion 612 is engaged with the end of the cable 2, a user then moves the identification tag 610 into the second configuration. In this embodiment this is achieved by pressing on the tab portion 616 to bend the hinge portion 642 through approximately 90° in a direction towards the cable 2. Pressure is applied to the tab portion 616 to cause the first and second arms 656 to flex to engage the cable 2. In this way, the tab portion 616 of the identification tag 610 is once again clipped to the cable 2 such that the tab portion 616 extends along the length of the cable 2 with the identification symbols 638 visible, as shown in
It will be appreciated that either each cable 2 may be processed in sequence, i.e. the end of the cable 2 is prepared and the identification tag 610 repositioned on each cable 2 in turn, or the ends of all of the cables 2 may be prepared and then the identification tag 610 on each cable 2 is repositioned on the cable end one after the other.
Finally, a replacement meter 91 is secured to the mounting surface and all of the cables 2 marked with the identification tags 610 are connected to the appropriate connectors of the replacement meter 91, as illustrated in
Referring again to
In the embodiment of the identification tag 610 shown in
The first surface 870 of the hinge portion 842 is substantially coplanar with the first surface 852 of the tab portion 816. Furthermore, a second surface 872 of the hinge portion 842 is continuous with the second surface 868 of the tab portion 816 and, as shown most clearly in
At least a part of a distal edge of each of the resilient arms 856 is curved. This curved leading edge 874 of each arm 856 makes engagement of the resilient arms 856 with a cable 2 easier as the arms 856 are less likely to dig into the sheath 8 or insulation 6 of the cable 2 and will, instead, be flexed outwards as described above.
In this embodiment a tab portion 916 extends radially from a first end 913 of a collar portion 912 of the identification tag 910. The tab portion 916 is connected to the collar portion 912 by a hinge portion 942 including a live hinge. A first surface 952 of the tab portion 916 includes two identification symbols 938, which in this example are two letters.
A clip comprising first and second resilient arms 956 extends from the tab portion 916. The resilient arms 956 extend from a second surface 968 of the tab portion 916 opposite the first surface 952. The clip is positioned close to a proximal end of the tab portion 916 nearest the collar portion 912. In this way a distal end of the tab portion 916 extends from the clip in a direction away from the collar portion 912.
In the two embodiments of the identification tag 810, 910 shown in
An identification tag for fitting on to an electrical cable according to the present invention therefore provides electrical shielding and cable marking at a connection between the cable and an electrical component. As described above, the cable typically has an inner conductor and a surrounding insulation layer, and the connection comprises an end portion of the cable inner conductor connected to a connector within the electrical component. A collar portion of the identification tag comprising a socket configured for receiving the cable and having an abutment shoulder to engage an end of the insulation layer to limit movement of the cable into the socket but to allow a portion of the inner conductor to pass through the socket and into the component whereby in use an interface is formed between the identification tag and the electrical component at the connection. Advantageously the interface between the tag and the electrical component comprises profiles formed on the collar portion of the tag and a recess of the component and which fit closely together to provide electrical shielding at the connection. The identification tag includes a tab portion extending away from the socket and having at least one symbol for identifying the cable at or adjacent said connection.
The identification tag of this invention when in use on a cable connected to an electrical component such as an electricity meter provides enhanced safety at the connection of the cable to an electrical component, by ensuring there is no access to the conductors of the cable at that connection. The profile on the collar portion reduces the likelihood of the insulation layer surrounding the conductors being prised away from the connector on flexing of the cable. In addition, the symbols on the tab portion of the identification tag allows for clear marking and so identification of the cable and this too assists in improving safety for example by maintenance workers.
In some embodiments of the invention an additional advantage is that an electrician requires a smaller inventory of identification tags when effecting a meter-change, as one kind of identification has two uses by appropriate division of the tab portion of the tag.
It is advantageous for the profiles formed on the collar portion and component to fit one within the other when in use thereby to provide electrical shielding at the connection. The external profile of the socket of the collar portion may be of reducing size in the direction away from the tab portion. For example, the external profile of the socket may be of frusto-conical form, or of part-spherical form.
In order to allow use of the identification tag with a smaller diameter cable which might not have an outer sheath surrounding a single layer of insulation around the conductors, or with a larger diameter cable having a layer of insulation surrounding the conductors and most likely an outer sheath surrounding the insulation layer, the socket of the collar portion may have two internal diameters with the smaller diameter nearer the end of the socket having the profile, there being a step such as an annular shoulder between the two diameters.
A method of providing electrical shielding and cable marking at a connection between a cable and an electrical component according to the invention comprises
To give sufficient identification of the cable in such a way to meet the current UK and European single phase wiring regulations, at least the tab portion of the identification tag may be one of blue or brown, respectively for use with one of a live or neutral mains cable. These colours would also apply in the UK for a three phase installation, but in many countries of Europe, different colours are used for the three phases of the supply. Similarly, the symbols on the tab portion may consist of at least one letter L or at least one letter N, respectively for use with one of a live or neutral cable, but preferably two or three letters L and preferably two letters N. In the case of identification tags intended for use with the live cables of a three phase system, the symbols would typically be L1, L2 and L3. Again, preferably two such symbols are provided on each tab portion so that one symbol may be removed, depending upon the intended application. Alternatively three such symbols may be provided on each tab portion so that one symbol or two symbols may be removed, depending upon the intended application. Such symbols may be provided by one of printing, raised or depressed surfaces of the tab portion, providing a different surface texture or creating through-apertures in the tab portion, or combinations of these.
When there are at least two symbols on the tab portion, preferably a separation zone is provided between the two symbols. That zone may be a weakened line extending transversely across the tab portion to allow easy separation of a free end section of the tab portion, carrying one or two symbols.
The identification tag preferably comprises a tab portion of generally planar rectangular form and serving as a label, to lie along the outer surface of a cable being marked. Alternatively, the tab portion could extend in a generally radial direction away from the collar portion of the tag. Other shapes of tab portion could be employed for example to assist clarity of the symbols on the tab portion, when in use. The symbols may be arranged serially along the length of the tab portion, or transversely thereof. The identification tag may be provided with means to maintain the tab portion in contact with the cable, such as an integrally-moulded clip engageable with the cable. Another possibility would be for the tab portion to be generally tubular whereby the cable to be identified is passed through the tubular tab portion.
When performing the method of this invention with a cable having a layer of insulation overlying the conductors and a protective sheath overlying the insulation, the step of cutting away the sheath comprises removing back from the free end of the cable a length of the outer sheath and removing back from the free end of the cable a lesser length of the insulation to expose the conductors. Then, before fitting the identification tag to the cable and depending on the intended function of the cable, the tab portion may be shortened to display fewer symbols by breaking off an end section or by cutting or otherwise severing therethrough, between the symbols thereof.
In the above discussion of this invention, reference was made to the replacement of an electricity supply meter; however, it is to be understood that the invention is not to be regarded as limited to such replacement and is applicable to the changing of other kinds of electrical components as well.
For various reasons, it may be necessary to change one electrical component for another having essentially the same function—for example, if the original component has failed or if the replacement component has enhanced characteristics. A particular case in point is with electricity meters; the technology associated with these has evolved and the electricity supply companies are gradually replacing traditional electricity meters with so-called smart meters having additional functionality as compared to a traditional meter. Though both traditional and smart meters are able to measure the quantity of electricity used by a consumer, a smart meter has the additional ability to communicate directly with the electricity supply company and transmit thereto usage measurements, so obviating the need for personal meter reading either by a supply company employee or the consumer. Further, a smart meter may allow the instantaneous usage of electricity to be displayed to a consumer, so assisting the consumer in reducing electricity consumption, and also facilitate the remote control of appliances.
In view of the advantages of smart meters, there is a programme under way in the UK and elsewhere to replace all existing traditional electricity meters with smart meters. This requires a visit by an operative to each existing meter to check and identify the polarity and phase (in the case of a three-phase supply) of the cables connected to the meter before disconnecting the cables from that meter, remove the existing meter and mount the replacement smart meter, and then correctly reconnect the cables to the smart meter. With a simple domestic supply, there will be four cables connected to the traditional electricity meter but with a three phase supply, there will be eight such cables, and there may be further cables connected to the meter for example associated with other supply functionality, such as a night time tariff. Depending upon when the original meter was installed, those cables may carry no identification markings whatsoever, or may be incompletely or inaccurately marked. As such, following disconnection of the cables from the existing meter, there could be a very high risk of confusion as to which cable is which when reconnecting the cables to the replacement meter, unless steps are taken to identify the cables before disconnection from the existing meter.
In an attempt to ensure adequate cable identification for the future, current regulations specify that the cables connected to a new or replacement electricity meter must be appropriately identified, both by colour and symbols typically in the form of letters and/or numerals, to show the function of the cable. These regulations must therefore be adhered to on replacing a meter, but the possible confusion of the cables connected to an existing meter must be addressed in order to ensure that when an existing meter is replaced by a smart meter, the cables are appropriately identified before removal from the existing meter so that the cables are not confused when connected to the connectors of the replacement meter.
The present invention provides a pre-marking method for cables connected to an electrical component such as an electricity meter, to facilitate the replacement of that component by another similar component and ensure the cables are appropriately marked and safely connected to the replacement component.
In particular, the invention provides a method of changing an electrical component having at least two cables connected thereto and using for each cable a clip-on identification tag having a collar portion configured for fitting on to the cable and being provided with a tab portion having at least one symbol to identify the cable with which the tag is to be associated by temporarily clipping the identification tag on to the cable to which the symbol relates. The method is characterised by the steps of
The method of this invention, therefore, allows for quick and easy pre-marking of a cable attached to an electrical component such as an electricity meter using an identification tag which subsequently is re-used essentially permanently to mark the cable in accordance with the regulations. It will be appreciated that the term “permanently” as used herein in relation to the marking of cables means that the marker cannot be accidentally or inadvertently removed from the cable or otherwise be displaced from the cable; it can be removed only by disconnecting the cable from the electrical component or by deliberate cutting of and so destroying the tag to free it from the cable.
With this method, a technician needs make only one selection of an appropriate identification tag for each cable before starting the replacement procedure, and then temporarily clipping the selected tag to a cable. After removing the existing component and fitting the replacement, the technician may handle the cables one at a time, by moving the identification tag from its temporary attachment on one cable to the end of that cable to provide the permanent identification. Consequently, the method is both fast and easy to perform with a greatly reduced risk of connection errors. Further, in its preferred form the method may provide a safety collar for the cable, ensuring a safe connection of the cable to the electrical component
Preferably, the identification tag has an integral clip profiled for connection to the cable. Such a clip may be provided on the tag to allow the temporarily connection of the tag to the cable at some convenient point along the length of the cable but advantageously near to the existing component. In one embodiment, the clip has a pair of arms profiled to define a re-entrant slot and the tag is temporarily attached by springing the arms of the clip around the cable. In this case, after removal of the cable from the existing component and following the fitting of the collar portion to a cable end, and either before or after the connection of the cable to the replacement electrical component, the tab portion of the tag may be flexed or folded over to engage the clip with the cable, once more. To facilitate this, there may be a weakened zone to serve as a hinge between the collar portion and the tab portion, such that the folding over of the tab portion is performed about the hinge.
The method of this invention will usually be performed with a cable having conductors surrounded by a layer of insulation. A collar portion of the identification rag may have a bore through which the conductors of the cable are passed on fitting the tag to the cable, but the bore is of insufficient diameter to allow the outer layer to pass therethrough, such that the tag when fitted to the cable remains at the end region thereof. Preferably, the bore of the collar portion has a counter-bore at an end thereof adjacent the tab portion, so that on fitting the collar portion to the cable, the conductors of the cable are passed through the bore and the outer insulation layer is received in the counter-bore but cannot pass through the bore of the collar portion. In a case where a cable has conductors surrounded by a layer of insulation which is itself surrounded by an outer sheath, when fitting the collar to the cable, the conductors of the cable are passed through the bore, the layer of insulation is received in the counter-bore but cannot pass through the bore of the collar, and the outer sheath abuts an end of the collar adjacent the tab portion.
When performing the method, following removal of a cable from the electrical component it may be preferred for at least the exposed conductors of the cable to be cut off, and a fresh strip to be performed on the outer layer of the cable end portion to expose the conductors. If the cable has a layer of insulation and an outer sheath, following removal of a cable from the electrical component, preferably at least the exposed conductors of the cable are cut off and a fresh a two-level strip is performed on the cable such that the conductors are exposed at the end of the cable and a short length of the layer of insulation is exposed between the conductors and the outer sheath.
Preferably, the tab portion of an identification tag carries two cable-identifying symbols typically in the form of letters and/or numerals arranged serially along the tab portion, so that before the temporary clipping of the tag to a cable the symbol further from the collar portion may be selectively removed or not removed from the tag, to suit the function of the cable to which the tag is clipped. The tab portion may have a weakened zone between the symbols thereon, whereby the symbol further from the collar portion may be removed by cutting along the weakened zone or by breaking the tab portion along the weakened zone and leaving part of the tab portion having the symbol nearer the collar portion still attached thereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1506980.0 | Apr 2015 | GB | national |
| 1506982.6 | Apr 2015 | GB | national |
| 1506985.9 | Apr 2015 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2016/051134 | 4/22/2016 | WO | 00 |
