GB2566447A

GB2566447A - Methods and apparatus for electrical installations

Info

Publication number: GB2566447A
Application number: GB1714366.0A
Authority: GB
Inventors: Barker James; Sneddon Darren
Original assignee: ELECTRICAL TESTING Ltd
Current assignee: ELECTRICAL TESTING Ltd
Priority date: 2017-09-07
Filing date: 2017-09-07
Publication date: 2019-03-20
Also published as: GB201714366D0

Abstract

Highway electrical furniture (HEF) or street furniture installation and method of electrical testing and removing the same. Method of forming a spur from said HEF and an electrical apparatus for use in said HEF. The HEF installation comprises an item of HEF and power supply cable 5A, wherein said cable 5A is terminated with an electrical socket 23 and said HEF is provided with a plug 24. The HEF may be provided with an electrical socket 27 in operative connection with said plug 24 to enable power to be passed through the HEF to a further power supply cable 5B terminated with a plug 28. The cable 5A and /or further cable 5B is / are metal-wire-armored cable. The HEF may be a street light, lamp post, traffic lights or illuminated sign or bollard, wherein said installation allows for simple connection and disconnection of the power cables 5A, 5B.

Description

Field of the Invention

The invention relates to installations of highway electrical furniture (HEF), methods for installing, testing, removing and extending such installations, and highway electrical furniture suitable for use in such installations.

Background and Prior Art

Modern highways, such as roads and pavements (also known as footways, or sidewalks), and other areas of the public realm such as parks, public squares and the like, are commonly home to items of street furniture that require electrical power. These items are referred to as “highway electrical furniture”, or HEF. The items are also often referred to by the broader term “street furniture”, but the term HEF will be used herein, limiting the scope to street furniture that requires a power connection. Such items are intended to be permanent (or at least semi-permanent) in the public realm. Typical such items of HEF include street lighting, traffic signals, illuminated bollards and signs and ticket machines (e.g. for parking or transport systems). More recently, items such as electric vehicle charging points, telecommunications masts and public WiFi transceivers have joined the list of such HEF.

A typical such installation is illustrated in Figure 1 which illustrates a column 1 to support an item of street lighting (also referred to as a “street lighting column” or, colloquially, a “lamp post”). The column 1 is secured in place on the pavement 2 by an extending flange 3 that is bolted into a concrete foundation 4. Electrical power is supplied to the column via a metalarmoured cable (typically a steel-wire-armoured cable, often referred to in the UK as SWA) 5 that is laid underground, and passes through a conduit 6 in the foundation 4. The power cable 5 is wired into electrical apparatus 7 such as a cut-out (which cuts the power to the lamp should an electrical fault be detected). Other such apparatus 7 might include e.g. an isolator, an overcurrent protector or fault-current protector, a fuse, a voltage conditioning unit to remove noise from the power supply or a voltage transformer if a lower voltage is require to drive low-voltage light such as LED units.

If multiple such units are installed on a road, or elsewhere, they are typically connected in looped in and out fashion (i.e. “daisy-chained”): A second cable 8 is also wired into the apparatus 7 to take power back out of the column 1, through a conduit 9, and underground to the next installation. Because of the need to provide electrical safety for the public, the apparatus 7, and its electrical connections are typically housed behind a lockable door 10. Inside the column 1, a flex 11 is wired into the apparatus 7 to take power up to a luminaire (not illustrated), or to a junction box 12 to which a luminaire may be connected.

Figure 2 illustrates, for reference, a cross-section though metal-wire-armoured cable 5 of the type typically used to install HEF. An outer plastics sheath 13 provides protection against water ingress, and covers a layer of metal armouring 14 in the form of stranded wire, often made from galvanised steel, that provide mechanical protection to the cable. An inner bedding layer 15, often also of plastics, surrounds multiple electrical conductors 16, each provided with its own insulation 17.

In order to make the electrical connection to the HEF, the qualified electrical technician needs to prepare the end of the cable to expose the various elements. This is shown in Figure 3, which illustrates a typical electrical connection between an item of HEF and its power cable 5. The prepared cable is passed through an aperture in the enclosure 18 that houses the electrical apparatus to be connected. A cable gland (not illustrated), typically made of a metal such as brass for HEF installation, is used to grip the armouring 14 and to secure the cable in place as it passes through the enclosure. Individual connections are then made between the enclosed conductors 16 and corresponding screw terminals 19 within the apparatus. This work is skilled, and crucial to the safety and performance of the HEF.

As a result, the installation, removal, and repair of such HEF items requires not only personnel who are able to carry out the mechanical installation, but also suitable staff who are skilled and qualified to make (or disconnect) the required electrical connections to the equipment. This causes a number of difficulties and inefficiencies.

During installation, separate mechanical and electrical installation teams are required to commission a new item of HEF. This requires careful scheduling of the work to minimise delays.

If an item of HEF is damaged, and needs to be replaced, two different teams are typically required. Taking as an example the case where a column-mounted street lamp has been knocked over or misaligned by a road traffic accident, an electrically-qualified operative needs to attend the scene to disconnect the power from the column. If, as is typical, the column is in an array of series-connected columns, this results in loss of power (and thus lighting) to all the columns “downstream” of the damaged column. Then, and only then, the mechanical team need to visit the scene to remove the damaged column, and replace it. Once the new column is in position, the electrical team need to attend once more, to reconnect the power to the column, and thereby restore the functioning of the lamp, and all of the downstream units. This will require the re-fitting of a cable gland, and re-termination of the cables. This clearly leads to delay and added costs in effecting such a repair or replacement.

Another issue concerns testing: throughout the lifetime of an item of HEF, regular electrical inspection and testing of the HEF is required to ensure the continuing safety of the items. This requires the attendance of qualified electrical personnel who can disconnect the type of wiring illustrated in Figure 3, after power has been removed, in order to connect the required testing modules used for the safety check. These might be modules that check the operation of circuit breakers or voltage regulators, or check the integrity of earthing systems used in the installation. Once the checks have been completed, and any repairs made, the cables need to be reconnected once more to allow continuing operation. For street lighting in the UK, such electrical testing is typically carried out every six years. Not only is this work timeconsuming, but the requirement to disconnect and reconnect the screw terminal connections leads to a risk that faults might be introduced by the process, perhaps weakening the connection of the conductor in the screw terminal or reducing the watertightness (i.e. the IP [ingress protection] rating) of the installation.

A further issue that can occur when an item of HEF is disconnected, and then subsequently reconnected is the risk of misidentification of the incoming and outgoing cables. If this occurs, the HEF will still function, but it poses a risk when a subsequent electrical team need to isolate the HEF from its adjacent units - if the wrong cable is disconnected, then “downstream” HEFs might still be powered even though what appears to be the outgoing cable has been disconnected.

Among the objects of the inventions is to attempt a solution to these and other problems.

Summary of the Invention

Accordingly, the invention provides a highway electrical furniture (HEF) installation comprising: an item of highway electrical furniture (HEF); and a power supply cable; wherein said power supply cable is terminated with an electrical socket and said HEF is provided with a cooperating plug thereby allowing a reversible electrical connection to be made between said cable and item of HEF to supply power thereto.

Preferably, said HEF is further provided with an electrical socket in operative connection with said plug, to enable power to be passed through the HEF to a further power supply cable terminated with a cooperating plug.

In either case, it is further preferred that said HEF comprises electrical apparatus, and said HEF-associated plugs and/or sockets form part of said electrical apparatus.

More preferably, said electrical apparatus is selected from the group consisting of: safety cutout; isolator switch; voltage conditioner; voltage transformer; fuse; overload protection device; fault protection device; functional switch.

In any aspect of the invention, it is also preferred that said power supply cable and /or further power supply cable is/are metal-wire-armoured cable.

In any aspect of the invention, it is also preferred that said HEF is selected from the group consisting of: street light; traffic signal; illuminated bollard; ticket machine; electric vehicle charging point; illuminated sign; telecommunications mast; telephone box; advertising panel; public transport shelter; internet distribution cabinet; telephone distribution cabinet; vending machine.

Also provided is a method of electrical testing a highway electrical furniture installation as described herein, comprising the steps of: (a) disconnecting a power supply cable from said HEF; (b) providing an electrical testing test module having a connector cooperating with a socket or plug on said HEF; (c) connecting said test module to said HEF; and (d) performing an electrical test on said HEF.

Also provided is a method of electrical testing a highway electrical furniture installation as described herein, comprising the steps of: (a) disconnecting a power supply cable from said HEF; (b) providing an electrical tee, said tee comprising: (i) a socket to connect to a corresponding plug on a cable or HEF; (ii) a plug to connect to a corresponding socket on a cable or HEF; (iii) a signal take-off in electrical communication with said socket and plug, said signal take-off being connected or connectable to a test module; (c) connecting said power supply cable to said tee; (d) connecting said tee to said HEF; (e) connecting said signal take-off to a test module if not already connected; (e) performing an electrical test on said HEF.

Also provided is a method of removing a highway electrical furniture installation as described herein, and which has power passed through an HEF to a further power supply cable, comprising the steps of: (a) disconnecting said power supply cable from said HEF; (b) disconnecting said further power supply cable from said HEF; (c) providing an electrical jumper, said jumper comprising: (i) a plug to connect to a corresponding socket on said power supply cable; (ii) a socket to connect to a corresponding plug on said further power supply cable; said jumper plug and socket being in electrical communication with each other to allow power to pass through said jumper; (d) connecting said power supply cable to the plug of the jumper; (e) connecting said further power supply cable to the socket of the jumper; (f) removing said disconnected HEF.

Also provided is a method of forming a spur from a highway electrical furniture installation as described herein comprising the steps of: (a) disconnecting said power supply cable from said HEF; (b) providing a spur electrical tee, said spur tee comprising: (i) a socket to connect to a corresponding plug on a cable or HEF; (ii) a plug to connect to a corresponding socket on a cable or HEF; (iii) a socket to connect to a corresponding plug on a cable; the pins of said plug being in electrical connection with the corresponding contacts of said sockets; (c) connecting the plug of the power supply cable to a socket of the spur tee; (d) connecting the plug of the spur tee to a socket of said HEF; (e) connecting the remaining socket of the spur tee to a spur cable having a corresponding plug. Preferably, said spur cable comprises metalwire-armoured cable.

Also within the scope of the invention is an item of HEF for use in an installation described herein comprising a plug for receiving a power cable having a corresponding socket. Preferably said item of HEF further comprises a socket in operative connection with said plug to enable power to be passed through the HEF to a further power supply cable terminated with a cooperating plug. More preferably, said HEF comprises electrical apparatus, and said plug and socket (if provided) form part of said electrical apparatus. Also within the scope of the invention is electrical apparatus suitable for use in such an item of HEF.

Brief Description of the Figures

The invention is described with reference to the accompanying drawings in which:

Figure 1 illustrates a typical street lighting column installation;

Figure 2 illustrates the inner structure of steel wire armoured cable;

Figure 3 illustrates a known method of connection of a cable to an HEF;

Figures 4 to 6 illustrate HEF insallations of the invention;

Figures 7 and 8 illustrate electrical jumpers for use in embodiments of the invention;

Figure 9 illustrates an arrangement of plugs and sockets forming part of an embodiment of the invention;

Figures 10 and 11 illustrate a method of testing an HEF installation of the invention; and Figures 12 to 15 illustrate electrical tees for use in a method of the invention.

Description of Preferred Embodiments

Figure 4 illustrates an embodiment of a highway electrical furniture installation of the present invention, generally indicated by 20. In this embodiment the installation is of two illuminated bollards 21 supplied with power by means of a loop in/out connection using underground metal-wire-armoured cabling 5. The expanded view 22 of the internal contents of the bollard show the arrangement of the electrical connections. An incoming power cable 5A is terminated with a socket 23 that is connectable to a cooperating plug 24 mounted within the HEF. In this case, the electrical apparatus 25, comprising equipment such as a safety cut-out, a voltage transformer and timer or light sensor to control operation of the illumination, houses the plug. A flex 11 is used to provide conditioned power to an LED array 26 to provide the illumination. An electrical socket 27 is also provided on the housing of the apparatus to allow power to be passed through the unit to a further power supply cable 5B via a cooperating plug 28.

In the context of this specification, by “plug” we mean an accessory having pins designed to engage with the contacts of a corresponding socket and incorporating means for electrical connection. By “socket”, we mean an electrical connector having electrical contacts on an inner surface for making electric engagement with the outer surface of pins on a corresponding plug. “Plugs” and “sockets” of the invention may be connected without the use of tools to form the electrical contacts. So, for the avoidance of doubt, a bare wire does not fall within this definition of a plug, nor does an electrical screw terminal fall within the definition of a socket, as a tool is required to make the electrical connection.

Figure 5 illustrates a further embodiment of a highway electrical furniture installation of the present invention, generally indicated by 29. In this case, the HEF comprises a ticketing machine 30. The expanded view 31 shows the internal contents of the HEF, usually hidden by a lockable door, 32. Power is supplied by a metal-wire-armoured cable 5, located below street level 18, and terminating in a socket 23 that can be detachably connected to a corresponding plug 24 mounted on electrical apparatus 25 forming part of the HEF. Again, such apparatus might comprise equipment such as a safety cut-out, a voltage transformer and voltage conditioner. An electrical connection, e.g. a flex 11, is used to carry power to the ticketing apparatus 33.

Figure 6 illustrates an electrical apparatus 25 forming part of an embodiment of the invention. The apparatus could be e.g. a safety cut-out, voltage conditioner, electrical isolator, voltage transformer or the like. The apparatus 25 is provided with a plug 24 to receive power from a power supply cable 5A (preferably a metal-wire-armoured cable) that is terminated with a corresponding cooperating socket 23. The apparatus 25 is also provided with a socket in operative connection with the plug 24 to enable power to be passed through the apparatus 25 to a further power cable 5B, terminated with a plug 36.

The apparatus 25 is also provided with a second socket 34 that can provide conditioned and/or protected power to further elements within the HEF.

It will be evident that in all embodiments described, live power connectors are terminated with sockets, and “power receiving” connectors are terminated as plugs. This arrangement (known in the art generally) increases the safety of the arrangement in that no live parts are accessible to installation, maintenance or repair personnel. It is, of course, technically feasible to use either plugs or sockets on each end of the connections, but this removes this safety feature.

Figure 7 illustrates an embodiment of an electrical jumper for use in an embodiment of the invention, generally indicated by 35. The jumper 35 comprises a plug 36 and a socket 23, electrically connected by a flexible cable 37. As this cable 37 is not always intended to be used underground, it is not necessarily metal-wire-armoured, but can be so protected if the situation requires it. For underground cables, an IP rating of at least IP66 would normally be employed. The jumper 35 can be used to connect the socket/plug terminated ends of two power cables 5.

Figure 8 illustrates an alternative embodiment of an electrical jumper for use in an embodiment of the invention, generally indicated by 35. In this embodiment, the jumper is configured such that the joining cable 37 conforms to a generally U-shaped configuration, to make it easier to connect to connector-terminated power cables lying in a parallel configuration as illustrated.

Figure 9, illustrates an arrangement of a plug 24 and socket 27 mounted on an electrical apparatus 25, and a corresponding socket 23 and plug 36 terminating respective cables 5. Each of the sockets 27, 23 is provided with recessed electrical contacts 38, whilst the plugs 24, 36 are provided with corresponding extending pin contacts 39. Each plug and socket pair may be provided with cooperating means to secure the parts together once electrical contact has been made. In this embodiment, this is achieved by providing cooperating internal 40 and external 41 threads in an arrangement that will be known to the skilled addressee. Other such arrangements are envisaged, such as a locking tab arrangement.

Figure 10 illustrates a method of testing electrical apparatus 25 within an item of HEF. A test module 42 is provided having an electrical lead 43 terminating in a socket 23 that can be connected to the corresponding plug 24 mounted on the apparatus 25. The normally-installed power cable 5 is unplugged from the apparatus 25, and the test module 42 is plugged in in its place. As no exposed live contacts are present, this means that the apparatus 25 can be tested without having to unscrew cables from a screw connector which requires specially trained personnel and is more likely to lead to errors or the introduction of new faults, as discussed above.

Figure 11 illustrates the use of an electrical tee, generally indicated by 44, to enable testing of is electrical apparatus 25 while it is still in use. The tee 44 comprises a corresponding plug 45 and socket 46 enabling it to be connected in-line with a power cable 5 and the apparatus 25. The tee 44 can be configured to allow access to electrical signals from the apparatus, transmitted along the lead 43 to the test module 42. Various configurations of such tees are shown in Figures 12-14.

Figure 12 illustrates, in schematic cross-sectional view, an embodiment of an electrical tee 44 for use in an embodiment of the invention. In this embodiment, an electrical connection is provided with each of the conductors 16 and these are carried to the test module 42 by means of the lead 43. In this way, measurements such as voltage across any of the conductors may be made, or electrical test signals may be injected into the conductors 16.

Figure 13 similarly illustrates an embodiment of an electrical tee 44 in which one of the conductors 16' is routed through the lead 43, rather being a direct connection. In this way, the electrical current flowing through that connector 16' may be measured. Only one such routing is illustrated, but such routing may be applied to any or all of the conductors 16.

Figure 14 similarly illustrates a yet further embodiment of an electrical tee 44 in which an inductive coupling has been made to one of the conductors 16' by means of a coil 47 wrapped around the conductor. In this way, information about the current flow through the conductor may be gathered and sent to a test module 42 via the lead 43 whilst isolating a test module 42 5 from the live electrics.

Figure 15 illustrates in schematic cross-sectional view a spur electrical tee 48 for use in an embodiment of the invention. In this embodiment, each of the conductors 16 extending between a socket 46A and a plug 45 A also extends to a further socket 46B. This allows a io spur to be formed from the circuit via a further power cable 5 provided with a corresponding plug 45B.

Whilst the embodiments described herein have illustrated the presence of three conductors, for clarity, it will be apparent that the invention can extend to more or fewer such conductors.

Claims

1. A highway electrical furniture (HEF) installation comprising:

an item of highway electrical furniture (HEF); and a power supply cable;

wherein said power supply cable is terminated with an electrical socket and said HEF is provided with a cooperating plug thereby allowing a reversible electrical connection to be made between said cable and item of HEF to supply power thereto.

2. An installation according to Claim 1 wherein said HEF is further provided with an electrical socket in operative connection with said plug, to enable power to be passed through the HEF to a further power supply cable terminated with a cooperating plug.

3. An installation according to either one of Claim 1 or Claim 2 wherein said HEF comprises electrical apparatus, and said HEF-associated plugs and/or sockets form part of said electrical apparatus.

4. An installation according to Claim 3 wherein said electrical apparatus is selected from the group consisting of:

safety cut-out;

isolator switch;

voltage conditioner;

voltage transformer;

fuse;

overload protection device;

fault protection device;

functional switch.

5. An installation according to any preceding claim wherein said power supply cable and /or further power supply cable is/are metal-wire-armoured cable.

6. An installation according to any preceding claim wherein said HEF is selected from the group consisting of:

street light;

traffic signal;

illuminated bollard;

ticket machine;

electric vehicle charging point;

illuminated sign;

telecommunications mast;

telephone box;

advertising panel;

public transport shelter;

internet distribution cabinet;

telephone distribution cabinet;

vending machine.

7. A method of electrical testing a highway electrical furniture installation according to any preceding claim comprising the steps of:

(a) disconnecting a power supply cable from said HEF;

(b) providing an electrical testing test module having a connector cooperating with a socket or plug on said HEF;

(c) connecting said test module to said HEF; and (d) performing an electrical test on said HEF.

8. A method of electrical testing a highway electrical furniture (HEF) installation according to any of Claims 1 to 6 comprising the steps of:

(a) disconnecting a power supply cable from said HEF;

(b) providing an electrical tee, said tee comprising:

(i) a socket to connect to a corresponding plug on a cable or HEF;

(ii) a plug to connect to a corresponding socket on a cable or HEF;

(iii) a signal take-off in electrical communication with said socket and plug, said signal take-off being connected or connectable to a test module;

(c) connecting said power supply cable to said tee;

(d) connecting said tee to said HEF;

(e) connecting said signal take-off to a test module if not already connected;

(e) performing an electrical test on said HEF.

9. A method of removing a highway electrical furniture (HEF) installation according to any of

Claims 2 to 6 comprising the steps of:

(a) disconnecting said power supply cable from said HEF;

(b) disconnecting said further power supply cable from said HEF;

(c) providing an electrical jumper, said jumper comprising:

(i) a plug to connect to a corresponding socket on said power supply cable;

(ii) a socket to connect to a corresponding plug on said further power supply cable;

said jumper plug and socket being in electrical communication with each other to allow power to pass through said jumper;

(d) connecting said power supply cable to the plug of the jumper;

(e) connecting said further power supply cable to the socket of the jumper;

(f) removing said disconnected HEF.

10. A method of forming a spur from a highway electrical furniture (HEF) installation according to any of Claims 1 to 6 comprising the steps of:

(a) disconnecting said power supply cable from said HEF;

(b) providing a spur electrical tee, said spur tee comprising:

(i) a socket to connect to a corresponding plug on a cable or HEF;

(ii) a plug to connect to a corresponding socket on a cable or HEF;

(iii) a socket to connect to a corresponding plug on a cable;

the pins of said plug being in electrical connection with the corresponding contacts of said sockets;

(c) connecting the plug of the power supply cable to a socket of the spur tee;

(d) connecting the plug of the spur tee to a socket of said HEF;

(e) connecting the remaining socket of the spur tee to a spur cable having a corresponding plug.

11. A method according to Claim 10 wherein said spur cable comprises metal-wire-armoured cable.

12. An item of HEF for use in an installation according to any of Claims 1 to 6 comprising a plug for receiving a power cable having a corresponding socket.

13. An item of HEF according to Claim 12, further comprising a socket in operative connection with said plug to enable power to be passed through the HEF to a further power supply cable terminated with a cooperating plug.

14. An item of HEF according to either of Claims 12 or 13 wherein said HEF comprises electrical apparatus, and said plug and socket (if provided) form part of said electrical apparatus.

15. Electrical apparatus suitable for use in an item of HEF according to Claim 14.