WO2013030587A2

WO2013030587A2 - Improved lighting system

Info

Publication number: WO2013030587A2
Application number: PCT/GB2012/052139
Authority: WO
Inventors: Michael Mcneill; Jonathan SOMMERSETT; Paul Brown
Original assignee: LOW CARBON LIGHTING Ltd
Current assignee: LOW CARBON LIGHTING Ltd
Priority date: 2011-09-01
Filing date: 2012-08-31
Publication date: 2013-03-07
Anticipated expiration: 2014-03-01
Also published as: WO2013030587A3; GB2494171A; GB201115121D0; GB2494302A; GB201215643D0

Abstract

A lighting device mountable to a column fixed to the ground comprises a first portion including engagement means for engaging the column, said first portion being movable between a first condition in which the engagement means engages a horizontally extending portion of a said column, and a second condition in which the engagement means engages a vertically extending portion of a said column.

Description

Improved Lighting System

The present invention relates to an improved lighting system, in particular an improved system for providing street lighting.

Typically, street lighting is provided by means of a plurality of street lights, each comprising a lighting portion comprising one or more light emitters, often referred to as a luminaire, mounted on an elongate and generally vertically disposed column fixed to the pavement towards the side of a road.

There are numerous different types and sizes of street lights in use but at the time of writing, the most popular type of street light involves the mounting of the luminaire on the column such that the column enters the luminaire either vertically from below the luminaire, or horizontally from the side of the luminaire. These two types of street light are illustrated in Figures l a and lb respectively.

Known luminaires incorporate two different means of attaching the luminaire to the column, so that they are adaptable to both of the types of columns shown in Figures la and lb respectively. In this way, personnel installing the street lights can select the most appropriate means of attaching the luminaire according to the type of column they are dealing with.

To facilitate this adaptability, these known luminaires feature a changeable orientation portion, which must be accessed by personnel, removed from the luminaire and replaced with the correct type of orientation portion to match the design of the column to which it is to be attached (that is, either a column as shown in Figure l a requiring vertical entry of the column from below the luminaire, or a column as shown in Figure lb requiring horizontal entry of the column from the side).

Alternatively, there are other types of luminaire which are only able to be attached either to the type of column as shown in Figure 1 a or the type of column as shown in Figure 1 b, but not both. It is also to be noted that, when the luminaire is mounted on the column, it must be electrically connected to the power supply in order to provide power to the light emitters of the luminaire. This is normally achieved by means of isolating the mains electricity supply at ground level and then supporting the luminaire whilst accessing the electrical connections of the luminaire in order to electrically connect the light emitters to the power supply cable which is connected to the electricity supply and disposed within the column.

Furthermore, known street lights often comprise some form of beam angle adjustment means whereby the angle of the light beam leaving the luminaire can be adjusted as required once the luminaire has been mounted on the column, in order that the correct area at ground level is adequately illuminated.

The beam angle adjustment means is normally located within the luminaire, and so in order to carry out the beam angle adjustment, the seal on the luminaire, which prevents the ingress of water into the luminaire, must be breached. In order to adjust the angle of the light beam leaving the luminaire, the bolts fixing the luminaire to the changeable orientation portion are first released whilst supporting the luminaire (which can sometimes weigh up to 12kg). The angle of the luminaire is then adjusted relative to the column by various means including the selective meshing together of gears. Finally, the bolts are tightened once again whilst resealing the luminaire against the ingress of water.

Normally, the angle of the light beam leaving the luminaire is approximately adjusted first as described above to provide an approximately correct light beam path. For fine adjustment of the light beam, two personnel are required to return to the street light once the available daylight level is low enough to identify the illuminated area on the street below and finely adjust the beam path. The street light must first be switched on in order to identify the illuminated area, and then electrically isolated to allow fine adjustment of the light beam. The electricity supply is then reconnected and the luminaire is then switched on to verify the illuminated area and this process is repeated until the illuminated area is correct. It is to be noted that each time the angle of the light beam is to be adjusted, the luminaire must again be opened to access the beam angle adjustment means. This beam angle adjustment process requires skilled labour both in terms of the manipulation of the beam angle adjustment means, which can be complicated, and the repeated electrical isolation at ground level during the adjustment process.

The aim of the present invention is to overcome, or at least alleviate, at least the above mentioned disadvantages of the prior art.

In accordance with a first aspect of the present invention there is provided a lighting device mountable to a column fixed to the ground, wherein said lighting device comprises: - a lighting portion comprising at least one light emitter; and a mounting portion selectively attachable to said lighting portion and adapted to be attached to said column.

This provides the advantage that the lighting portion can easily be replaced when required, for example in the event that the lighting portion is to be upgraded or repaired. In having a separate mounting portion and lighting portion, when it is required to upgrade or repair the lighting portion, it is only necessary for personnel to have to deal with the lighting portion when carrying out this type of maintenance and not the mounting portion in addition.

Moreover, in the event that the lighting portion is to be connected to the column, it is only the mounting portion which is firstly required to be manipulated in order to attach it to the column and not the lighting portion (which is separately attached to the mounting portion once the mounting portion has been attached to the column) in addition. This is a huge relief for personnel carrying out the repair or the upgrade, with the result that the work can be carried out much quicker than with known street lights and by one person as opposed to two.

Further, in having a separate mounting portion and lighting portion, costs are reduced in the event that it becomes necessary to replace the lighting portion, for example in the event of failure or upgrade of light emitters, since only the lighting portion is required to be replaced in this instance and not the mounting portion in addition. In accordance with a second aspect of the present invention there is provided a lighting device mountable to a column fixed to the ground, wherein said lighting device comprises a first portion including engagement means for engaging the column, said first portion being movable between a first condition in which the engagement means engages a horizontally extending portion of a said column, and a second condition in which the engagement means engages a vertically extending portion of a said column.

This provides the advantage that various types of column (i.e. those shown in both Figure la and Figure lb) can be easily accommodated by the lighting device.

Preferably, the lighting device comprises a lighting portion comprising at least one light emitter; and a mounting portion attachable to the lighting portion, whereby the first portion is movably mounted on the mounting portion.

Preferably, the first portion is additionally movable to and from at least one further condition in which the engagement means is disposed so that the column is mountable to the lighting device by means of engagement of the engagement means with the column in a direction intermediate between the first and second conditions.

This provides the advantage that the lighting device can be conveniently located on ground which is on an incline, for example the side of a hill.

Preferably, the engagement means comprises an elongate recess in the first portion.

Preferably, the elongate recess is shaped so that a portion of the column can be disposed and retained therein.

Preferably, the first portion is rotatable between the first and second conditions.

Preferably, the mounting portion comprises a locking means adapted to lock the first portion in its first and second conditions respectively.

Preferably, the locking means comprises a spring biased means disposed on the mounting portion, which selectively engages with either one of two corresponding portions on the first portion in order to selectively retain the first portion in its first and second conditions respectively.

Preferably, the spring biased means comprises a first spring biased peg disposed on the mounting portion, which is selectively locatable inside either of two first holes formed in the first portion.

Alternatively, the locking means comprises a screw disposed on the mounting portion, which selectively engages with either one of two corresponding portions on the first portion in order to selectively secure the first portion in its first and second conditions respectively.

This provides the advantage that the orientation of the lighting device relative to the column can be carried out quickly and easily and without the requirement for tools, thereby enabling quick and easy accommodation of the different types of column currently in use. Moreover, there is no requirement to remove and replace different versions of components from the lighting device in order to carry out this orientation of the lighting device relative to different types of column, thereby saving time and effectively de-skilling the process. Moreover, there is no requirement to breach the waterproof seal which prevents the ingress of water into the lighting portion in order to carry out this orientation.

Preferably, the first portion is adapted so that it rotates through approximately 180 degrees as it rotates between its first and second conditions.

Preferably, the first portion is rotatably mounted on a rotationally symmetric bearing.

Preferably, the first portion is rotatably mounted on a conical shaft mounted to the mounting portion.

In this way, as the first portion rotates between its first and second conditions, it follows a conical path. Preferably, the axis of rotation of the first portion is disposed at an angle of approximately 45 degrees relative to the longitudinal axis of the lighting portion.

Alternatively, the first portion is rotatably mounted on a cylindrical shaft mounted to the mounting portion.

Preferably, the lighting portion comprises a first electrically safe connector electrically connectable at one end to the light emitters and electrically connectable at the other end to a second electrical connector providing electricity to the lighting device.

This provides the advantage that in the event that maintenance is required, it is not necessary to completely isolate the electricity supply from the lighting device; instead, the personnel carrying out the maintenance can safely connect and disconnect the electricity supply to and from the lighting portion without isolating the electricity supply at ground level.

Preferably, the second electrical connector comprises an elongate electrical conductor electrically connectable at one end to a power supply and electrically connectable at the other end to the first electrical connector, said elongate electrical connector having a length at least the length of the column.

This provides the advantage that the electrical wiring required to be carried out by skilled personnel at first installation and also during any subsequent maintenance of the lighting device, can be carried out at ground level.

Preferably, the lighting portion further comprises a third electrically safe connector electrically connectable at one end to the first electrical connector, and a fourth electrically safe connector electrically connected at one end to at least one said light emitter and electrically connectable at its other end to the third electrical connector.

This provides the advantage that electrical components forming a part of the lighting device (in particular, those disposed between the first electrical connector and the third electrical connector) can be easily replaced when necessary, without the requirement to isolate the electricity supply at ground level.

Preferably, the interface defined by the mounting portion and the lighting portion is provided with a seal to prevent the ingress of water between the lighting portion and the mounting portion.

In accordance with a third aspect of the present invention there is provided a lighting device mountable to a column fixed to the ground, wherein the lighting device comprises: - a lighting portion comprising at least one light emitter; and a mounting portion pivotally attached to said lighting portion and adapted to be attached to said column, wherein one of the mounting portion and the lighting portion comprises a locking element and the other of the mounting portion and the lighting portion comprises a plurality of corresponding engagement means, such that the angle of the lighting portion relative to the mounting portion is adjustable by means of selective engagement of the locking element with any one of the plurality of engagement means.

This provides the advantage that the beam angle can be quickly and easily adjusted by personnel, without the requirement for any tools, in order to ensure that the correct area of ground is illuminated by the lighting device. Moreover, the adjustment of the beam angle can be carried out without breaching the seal that prevents the ingress of water into the lighting portion.

This provides the further advantage that it is not necessary to isolate the electricity supply when adjusting the angle of the beam, thereby speeding the process up, since access to the lighting portion itself is not required.

In accordance with a fourth aspect of the present invention there is provided a lighting device mountable to a column fixed to the ground, wherein the lighting device comprises a lighting portion comprising at least one light emitter mounted in a case, wherein the or each light emitter is mounted so that it is in direct thermal contact with the case and the case is made from a thermally conductive material. In accordance with a fifth aspect of the present invention there is provided a lighting device mountable to a column fixed to the ground, wherein the lighting device comprises a first portion comprising an engagement means for engagement with the column, said first portion being movable between a first condition in which the engagement means is disposed so that the column is mountable to the lighting device by means of sideways engagement of the column with the engagement means, and a second condition in which the engagement means is disposed so that the column is mountable to the lighting device by means of upwards engagement of the column with the engagement means.

Preferred embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which: -

Figure 1 a shows an example of a prior art street light in which the column enters the lighting device vertically from below;

Figure lb shows an example of a prior art street light in which the column enters the lighting device horizontally from the side;

Figure 2 shows a sectional view of a portion of a lighting device in a first condition, in accordance with an embodiment of the present invention;

Figure 2a shows a sectional view of a lighting device in a first condition, in accordance with an embodiment of the present invention;

Figure 3 shows the lighting device of Figure 2 in a second condition;

Figure 3a shows the lighting device of Figure 2 in a second condition, illustrating further detail;

Figure 3b shows the lighting device of Figure 2 in a second condition, illustrating further detail; Figure 3c shows the lighting device of Figure 2 in a second condition, illustrating further detail;

Figure 4 shows a perspective view of a lighting device in accordance with an embodiment of the present invention, in situ on a column and illustrating the range of movement of the lighting portion;

Figure 5 shows a side view of the lighting device of Figure 4, in situ on a column and illustrating the range of movement of the lighting portion;

Figure 6 shows a sectional view of the luminaire illustrating in particular the LEDs in situ i the case of the luminaire; and

Figure 7 .shows an exploded view of a lighting device in accordance with an embodiment of the present invention, in situ on a column.

With reference to the Figures, a lighting device mountable to an elongate generally vertical column fixed to the ground is represented generally by reference numeral 1.

The lighting device 1 comprises a lighting portion in the form of a luminaire 3, comprising a plurality of light emitters in the form of LEDs 5 mounted within a case 6. The luminaire 3 is attached to a mounting portion 7, which is itself adapted to be attached to the elongate generally vertical column 9 fixed to the ground.

In having a separate mounting portion 7 and luminaire 3, whereby the luminaire 3 is attachable to the mounting portion 7, this provides the advantage that the luminaire 3 can easily be replaced when required, for example in the event that the luminaire 3 is to be upgraded or repaired. In particular, when it is required to upgrade or repair the luminaire 3, it is only necessary for personnel to have to remove and replace the luminaire 3 when carrying out this type of maintenance and not the mounting portion 7 in addition. Moreover, costs are reduced, since it is only the luminaire 3 which is required to be replaced and not the mounting portion 7 in addition. Moreover, in the event that the luminaire 3 is to be connected to the column 9, it is only the mounting portion 7 which is required to be manipulated by personnel in order to attach it to the column 9, and not the luminaire 3 (which is separately attached to the mounting portion 7 once the mounting portion 7 is attached to the column 9) in addition.

As a result, the work can be carried out much quicker than with known street lights and by one person as opposed to two.

The lighting device 1 further comprises a first portion 1 1 comprising an engagement means for engagement with the column 9. The engagement means comprises an elongate recess 15.

The first portion 1 1 is rotatably mounted on the mounting portion 7 and is rotatable between a first condition (shown in Figure 2) in which the elongate recess 15 is disposed substantially horizontally so that the column 9 is mountable to the mounting portion 7 by means of sideways engagement of the column 9 with the elongate recess 15, and a second condition (shown in Figure 3 and Figure 3a) in which the elongate recess 15 is disposed substantially vertically so that the column 9 is mountable to the mounting portion 7 by means of upwards engagement of the column 9 with the elongate recess 15.

In this way, the lighting device 1 is inherently adaptable to both columns 9 in which that portion which attaches to the lighting device 1 extends horizontally (shown in Figure lb) and also columns 9 in which that portion which attaches to the lighting device 1 extends vertically (shown in Figure l a).

It is to be appreciated that the first portion 1 1 is additionally movable to and from at least one further condition (not shown) in which the elongate recess 15 is disposed in a position intermediate between the first and second conditions, which is particularly suitable for the situation whereby the lighting device 1 is to be attached to a column 9 located on an incline such as the side of a hill for example. The mounting portion 7 comprises a locking means adapted to lock the first portion 1 1 in its first and second conditions respectively. As can be seen from Figure 2, Figure 3 and Figure 3a in particular, the locking means comprises a spring biased peg 19 which selectively engages with one of two corresponding portions in the form of holes 21 a and 21b formed on the first portion 1 1 in order to selectively secure the first portion 1 1 in its first and second conditions respectively. The holes 21a and 21b are shaped and sized so as to correspond to the spring biased peg 19.

In this way, the orientation of the lighting device 1 relative to the column 9 can be carried out quickly and easily and without the requirement for tools. In particular, in order to move the first portion 1 1 from its first condition to its second condition, the personnel carrying out the installation simply pulls the spring biased peg 19 against the action of the spring in order to dislodge the peg 19 from the hole 21a and then rotates the first portion 1 1 through 180 degrees. Once the first portion 1 1 is in its second condition, then the peg 19 is released with the result that it locates in the hole 21 b in order to retain the first portion 1 1 in its second condition.

Moreover, in using the lighting device 1 , there is no requirement to use tools or remove and replace components from the lighting device 1 in order to carry out the orientation of the lighting device 1 relative to the column 9, thereby saving time and effectively de-skilling the process.

Further, it is not necessary to isolate the electricity supply to the lighting device 1 in order to carry out this orientation process.

In an alternative embodiment (not shown), the locking means could comprise a screw as opposed to the spring biased peg 19, which can be selectively engaged with one of the two holes 21a and 21 b on the first portion 1 1 , in order to selectively secure the first portion 1 1 in its first and second conditions respectively.

As can be seen from Figure 2, Figure 3 and Figure 3a, the first portion 1 1 is adapted so that it rotates through approximately 180 degrees as it rotates between its first and second conditions on a rotationally symmetric bearing 13, in particular a conical shaft. As can be seen from Figure 4 and Figure 5 in particular, in this way, as the first portion 1 1 rotates between its first and second conditions, it follows a conical path. However, it is to be appreciated that the first portion 1 1 could alternatively be mounted on a cylindrical shaft (not shown) mounted to the mounting portion 7.

With particular reference to Figure 7, the mounting portion 7 further comprises an electric cable 14 for providing power to the luminaire 3. The cable 14 is electrically connected at one end to the LEDs 5 of the luminaire 3 and electrically connectable at the other end to the electricity supply by means of a first electrically safe connector 23 . The column 9 includes an elongate cable 24 which connects the lighting device 1 to the electricity supply at ground level. The cable 24 has a length at least as long as the column 9 but preferably slightly longer. The cable 24 is connected at its lower end to the electricity supply and is connected at its upper end to a second electrically safe connector 26, which itself is electrically connectable to the first connector 23.

This provides the advantage that in the event that maintenance is required, it is not necessary to completely disconnect the electricity supply at ground level; instead, the personnel carrying out the maintenance can safely connect and disconnect the electricity supply to and from the lighting device 1 simply by means of unplugging the first electrically safe connector 23 from the second electrically safe connector 26. This also obviates the requirement for re-wiring the lighting device 1 each time the luminaire 3 is replaced or maintained, which reduces costs on account of less requirement for skilled personnel.

The lighting device 1 further comprises a third electrically safe connector 32 which is electrically connectable at one end to the first electrical connector 23, and a fourth electrically safe connector 34. The fourth electrically safe connector 34 is electrically connected at one end to the LEDs 5 and electrically connectable at its other end to the third electrical connector 32.

This provides the advantage that electrical components forming a part of the lighting portion (in particular, those disposed between the first electrical connector and the third electrical connector) can be easily replaced when necessary, without the requirement to isolate the electricity supply at ground level. The lighting device 1 also benefits from the advantage of comprising a beam angle adjustment means 25 for facilitating the quick and easy adjustment of the angle of the light beam leaving the luminaire 3. In this way, personnel can ensure that the correct area is adequately illuminated by the lighting device 1.

In order to facilitate this adjustment, the luminaire 3 is pivotally mounted on the mounting portion 7 about an axis A. In this way, the luminaire 3 can be pivoted about the axis A, in effect moving the path of the light beam leaving the lighting device 1. The beam angle adjustment means 25 comprises a locking element in the form of a spring biased peg 27 disposed on the luminaire 3 and a plurality of engagement means in the form of a plurality of holes 29 disposed on the mounting portion 7. In this way, the angle of the luminaire 3 relative to the mounting portion 7 can be quickly and easily adjusted by means of selective engagement of the locking element 27 with any one of the plurality of holes 29, without the requirement for tools and without the requirement to isolate the lighting device 1 from the electricity supply at ground level. In particular, in order to adjust the angle of the light beam leaving the lighting device 1 , the personnel carrying out the adjustment simply pulls the spring biased peg 27 against the action of the spring in order to dislodge the peg 27 from the hole 29 and then pivots the luminaire 3 relative to the mounting portion 7 until the light beam is at an angle such that the correct area of ground is illuminated. Once the luminaire 3 is in the correct position then the peg 27 is released with the result that it locates in the appropriate hole 29 in order to retain the luminaire in position.

The lighting device 1 further comprises a means (not shown) for adjusting the lateral position of the light beam once the beam angle adjustment means 25 has been used to adjust the angle of the light beam. This enables the luminaire 3 to be moved in a direction parallel to the axis A, as required.

Further, the lighting device 1 comprises a means (not shown) for adjusting the distance between the luminaire 3 and the mounting portion 7, thereby enabling the lighting portion to be moved in a direction towards and away from the axis A, as required. As can be seen from Figure 6 in particular, the LEDs 5 are mounted such that they are each in direct thermal contact with the case 6 of the luminaire 3, whereby the case 6 is made from a thermally conductive material. This obviates the requirement for a separate heat sink between the case 6 and the LEDs 5 for conducting the heat away from the LEDs. In particular, there is no requirement to first of all fix the LEDs 5 to a heat sink, which itself must then be fixed to the case 6. Instead, the case 6 acts as the heat sink, whereby heat is conducted away from the LEDs by means of the case 6 itself. This provides the advantage that the cooling effect is improved, and the lighting device 1 is easier to manufacture, having fewer component parts.

Moreover, the case 6 has a smooth profile to reduce the likelihood of insects nesting within the luminaire 3 and to reduce the likelihood of dirt accumulating on the luminaire 3. In having a smooth profile, this additionally provides a self-cleaning effect whereby rain is able to wash away any dirt which accumulates on the luminaire 3.

The present invention, one embodiment of which is described above, facilitates the quick and easy attachment of the luminaire to the column by means of orientation of the mounting portion with respect to the column and then the subsequent mounting of the luminaire to the mounting portion. Once the luminaire has been mounted to the column in this way, the angle of the light beam leaving the lighting device can be quickly and easily adjusted in order to ensure that the correct ground area is illuminated by the lighting device. Finally, the lateral position of the light beam can be fine tuned as required.

The present invention, one embodiment of which is described above, facilitates the orientation of the lighting device (both in respect of the movement of the first portion 1 1 between its first and second conditions and in respect of the movement of the luminaire 3 with respect to the mounting portion 7 in order to adjust the light beam) without personnel being required to expose any areas containing optical or electronic components to the atmosphere.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departing from the scope of the invention as defined by the appended claims.

Claims

1. A lighting device mountable to a column fixed to the ground, wherein said lighting device comprises a first portion including engagement means for engaging the column, said first portion being movable between a first condition in which the engagement means engages a horizontally extending portion of a said column, and a second condition in which the engagement means engages a vertically extending portion of a said column.

2. A lighting device as claimed in claim 1, comprising a lighting portion

comprising at least one light emitter; and a mounting portion attachable to the lighting portion, whereby the first portion is movably mounted on the mounting portion.

3. A lighting device as claimed in any one of the previous claims, wherein the first portion is additionally movable to and from at least one further condition in which the engagement means is disposed so that the column is mountable to the lighting device by means of engagement of the engagement means with the column in a direction intermediate between the first and second conditions.

4. A lighting device as claimed in any one of the previous claims, wherein the engagement means comprises an elongate recess in the first portion.

5. A lighting device as claimed in claim 4, wherein the elongate recess is shaped so that a portion of the column can be disposed and retained therein.

6. A lighting device as claimed in any one of the previous claims, wherein the first portion is rotatable between the first and second conditions.

7. A lighting device as claimed in any one of the previous claims, wherein the mounting portion comprises a locking means adapted to lock the first portion in its first and second conditions respectively.

8. A lighting device as claimed in claim 7, wherein the locking means comprises a spring biased means disposed on the mounting portion, which selectively engages with either one of two corresponding portions on the first portion in order to selectively retain the first portion in its first and second conditions respectively.

9. A lighting device as claimed in claim 8, wherein the spring biased means comprises a first spring biased peg disposed on the mounting portion, which is selectively locatable inside either of two first holes formed in the first portion.

10. A lighting device as claimed in claim 7, wherein the locking means comprises a screw disposed on the mounting portion, which selectively engages with either one of two corresponding portions on the first portion in order to selectively secure the first portion in its first and second conditions respectively.

1 1. A lighting device as claimed in any one of the previous claims, wherein the first portion is adapted so that it rotates through approximately 180 degrees as it rotates between its first and second conditions.

12. A lighting device as claimed in any one of the previous claims, wherein the first portion is rotatably mounted on a rotationally symmetric bearing.

13. A lighting device as claimed in any one of the previous claims, wherein the first portion is rotatably mounted on a conical shaft mounted to the mounting portion.

14. A lighting device as claimed in any one of the previous claims, wherein the axis of rotation of the first portion is disposed at an angle of approximately 45 degrees relative to the longitudinal axis of the lighting portion.

15. A lighting device as claimed in any one of claims 1 to 12, wherein the first portion is rotatably mounted on a cylindrical shaft mounted to the mounting portion.

16. A lighting device as claimed in any one of the previous claims, further

comprising a first electrical connector electrically connectable at one end to the light emitters and electrically connectable at the other end to a second electrical connector providing electricity to the lighting device.

17. A lighting device as claimed in claim 16, wherein the second electrical

connector comprises an elongate electrical conductor electrically connectable at one end to a power supply and electrically connectable at the other end to the first electrical connector, said elongate electrical connector having a length at least the length of the column.

18. A lighting device as claimed in any one of claims 16 or 17, further comprising a third electrical connector electrically connectable at one end to the first electrical connector, and a fourth electrical connector electrically connected at one end to at least one said light emitter and electrically connectable at its other end to the third electrical connector.

19. A lighting device as claimed in any one of claims 2 to 18, wherein the interface defined by the mounting portion and the lighting portion is provided with a seal to prevent the ingress of water between the lighting portion and the mounting portion.

20. A lighting device mountable to a column fixed to the ground, wherein said lighting device comprises: - a lighting portion comprising at least one light emitter; and a mounting portion selectively attachable to said lighting portion and adapted to be attached to said column.

21. A lighting device mountable to a column fixed to the ground, wherein the lighting device comprises: - a lighting portion comprising at least one light emitter; and a mounting portion movably attached to said lighting portion and adapted to be attached to said column, wherein one of the mounting portion and the lighting portion comprises a locking element and the other of the mounting portion and the lighting portion comprises a plurality of

corresponding engagement means, such that the angle of the lighting portion relative to the mounting portion is adjustable by means of selective engagement of the locking element with any one of the plurality of engagement means.

22. A lighting device mountable to a column fixed to the ground, wherein the lighting device comprises a lighting portion comprising at least one light emitter mounted in a case, wherein the or each light emitter is mounted so that it is in direct thermal contact with the case and the case is made from a thermally conductive material.

23. A lighting device mountable to a column fixed to the ground, wherein said lighting device comprises a first portion comprising an engagement means for engagement with the column, said first portion being movable between a first condition in which the engagement means is disposed so that the column is mountable to the lighting device by means of sideways engagement of the column with the engagement means, and a second condition in which the engagement means is disposed so that the column is mountable to the lighting device by means of upwards engagement of the column with the engagement means. A lighting device mountable to a column fixed to the ground substantially hereinbefore described with reference to the accompanying drawings.