GB2386316A - Cabinet or enclosure for an electrical transformer or switchgear - Google Patents

Abstract

A device for rendering the interior of a transformer enclosure safe comprises a structure adapted to fit over live electrical equipment such as transformers, switchgear or fuses that is mounted on the interior wall (20 figure 1a), where the structure comprises two end panels 36 and 37 mounted perpendicularly to the wall, upper and lower elongate members 46 and 47 extending horizontally between the top and bottom of the end panels, at least one removable front panel 24 between the end panels, where the front panels 24, 26 and 27 have a locking means 48, 49 and 50 to secure it to the upper and lower rails. The panels and upper and lower elongate members may be plastic, where the front panels are a honeycomb structure (figure 1c) and have laterally extending flanges (3f) as a continuation of their front face to overlie the front edge of an end panel on one side and adjoining the front face of the central panel on the other side. The structure may also include a top panel 38 and have cut outs 40 and 42 for ventilation. Also included is a method of construction.

Description

Title: Improvements in and relating to transformer enclosures Field of the

invention

This invention concerns transformer enclosures of the type comprising a small building containing a transformer for serving a local neighbourhood with ac electric power, and related switchgear.

Background to the invention

Transformer enclosures as above will typically be located at a convenient location relative to a small estate of houses or offices which require single phase ac power (nominally at 230 volts) or three phase ac power (nominally at 440v). In conventional manner three-

phase power is supplied from the National Grid at a very much higher voltage (often 16Kv or higher), and the purpose of the transformer is to provide power at the lower voltages.

For safety and general protection against damage and the elements, transformers of this type are housed in small buildings which are locked to prevent unauthorised entry. The buildings also serve to protect switchgear and fuses which are associated with the primary and secondary windings of the transformer and typically are mounted on one of the internal walls of the building. The switchgear is usually arranged to automatically disconnect the transformer from the National Grid if a fault develops in secondary or in the domestic/business supply circuits connected to the transformer. Likewise, the transformer can be isolated by manual operation of the switchgear.

The need for access to the interior of the building can arise for two reasons. Firstly to deal with any fault that has developed. Secondly, however, there is a regular need for other personnel (often employees of an outside contractor) to gain access for servicing and routine maintenance of the transformer and for maintenance of the interior of the building.

Whilst only qualified and authorised personnel would be involved in the first instance, the problem arises that a suitably qualified and authorised person is needed to be in attendance during other visits, to isolate the switchgear and render the area safe for the maintenance or servicing or cleaning operations to be performed, and then to recommission the unit afterwards. It is an object of the present invention to provide a device for rendering the interior of a transformer enclosure safe for use.

Summary of the invention

A device for rendering the interior of a transformer enclosure safe comprises a structure adapted to be fitted over live electrical equipment such as switchgear, fuses and the like mounted on an interior wall of the enclosure, comprising: (a) two end panels for mounting upright and generally perpendicular to the interior wall and adapted by brackets to be secured to the wall, as by screws; (b) upper and lower elongate members forming rails which extend horizontally between tops and bottoms of the end panels; (c) at least one removable front panel for mounting upright and generally parallel to the interior wall between the end panels and adapted at its top and bottom by locking means for securing to the upper and lower rails, so as to form with the end panels a housing which encloses the live electrical equipment and will prevent someone from accidentally touching live terminals and being electrocuted while working within the enclosure. The height of the panels is preferably such that when mounted upright they extend from the floor to substantially above the live equipment.

Preferably the top of the housing is closed by a roof panel which when fitted extends in a generally horizontal manner across the housing between the two end panels.

Preferably the front edge of the top panel constitutes the upper elongate member to which the upper end of the front panel(s) is secured.

Preferably the front of the housing is formed from at least two panels, each of which is removable independently of the other and each of which is fixed in place between the upper and lower elongate members.

In a preferred arrangement there are three front panels, one central and two outer panels, and the latter each includes laterally extending flanges as a continuation of its front face, to overlie the front edge of an end panel on one side and the adjoining front face of the central panel on the other side, so that when both outer panels are in position the central panel is held in place and cannot be removed due to the presence of the two flanges protruding over it from each of the outer panels.

Typically bolts are provided at the top of each of the outer panels by which each can be bolted to the upper member, and locking means is provided to retain at least some of the bolts in their closed position.

Conveniently the lower elongate member is an L-shaped rigid profile and may be formed from GRP.

Typically the upper elongate member comprises a rigid plastics profile, and may be fitted to the front edge of the roof panel.

Preferably a pin and socket is provided at the foot of the central panel so that the panel can be lowered into position with the pin engaging the socket, to centre and position the panel.

Preferably an apertured plate is secured to or extends from the upper edge of the central panel to protrude upwardly therebeyond, the aperture being adapted to receive a pin which protrudes forwardly from the front of the upper rail, as the central panel is pivoted backwards into a generally upright position.

The engagement of the lower pin and socket allows the central panel to be lowered so that the pin and socket become engaged, whilst the upper end of the central panel is tilted forwardly by 10 -15 from the vertical, after which the panel can be pushed backwards, pivoting on the pin and socket joint, until the pin and plate at its upper end engage.

The upper pin preferably has a transverse hole through which a locking closure can be threaded, after the plate has been pushed fully onto the pin and the central panel is upright, to prevent the upper end of the central panel from pivoting forward. The locking closure is a split pin.

The lower edge (foot) of each of the panels making up the front wall of the housing is preferably adapted to fit to the rear of the lower rail, and the pin and socket joint between the lower edge (foot) of the central panel and the lower rail permits the lower edge (foot) of the panel to slide behind the rail, the pin and socket being associated with the front face of the panel and the rear of the lower rail.

The lower edge of each of the side panels may be cut away (and where a top panel is provided, its rear edge may be similarly cut away), to allow air to circulate, to provide ventilation for the live equipment in the housing, when assembled.

Additionally the lower edge of some or all of the front panels may be cut away, to provide at least one ventilation opening at a lower region of each front panel.

Where there are three front panels, the height of each of the outer front panels may be less than the central panel, so that a gap for ventilation is provided between the upper edge of each outer panel and the underside of the front rail, when the outer panels are in place.

Each panel preferably comprises front and back sheets joined by a honeycomb structure sandwiched between the sheets which serves to separate the sheets and introduce rigidity and structural strength.

Conveniently each panel is formed at least in part from plastics, or GRP, or at least in part from UV stabilised polypropylene (HDPE).

The side edges of the panels are preferably joined using profiles, and typically brackets and/or other fixings and/or profiles are formed from stainless steel.

The lower elongate member is preferably an L-section bar formed by moulding, or extruding plastics material which may be internally reinforced with rods or bars of metal, or by moulding or pultruding GRP.

The panels may include handles to facilitate lifting and carrying.

The live electrical equipment is mounted on a free-standing panel within the enclosure, and in that event the protective housing is secured to the free-standing panel, which comprises the said interior enclosure wall. In this arrangement the housing preferably includes an additional wall to completely encase the free standing panel and the equipment mounted thereon, and the additional wall may be formed from a single panel or from a plurality of panels, and corner profiles may be provided on rear edges of at least the side wall panels, and a similar profile may be provided at floor level, so that one or more panels can be fitted to the rear of the free-standing panel.

The invention also lies in a transformer enclosure comprising: (a) a building comprised of walls, a roof and a lockable access door;

(b) a transformer mourited within the building and spaced from the inside walls of the building to give access for servicing and maintenance work thereon; (c) switchgear and fuses comprising live electrical equipment mounted on a wall inside the building, and (d) a housing around the live electrical equipment to prevent accidental contact therewith by engineers or other persons working on the transformer, wherein the housing is comprised of separate panels forming at least a front wall and two end walls, which panels are joined together to encase the live electrical equipment, with the end wall panels secured to the wall carrying the live electrical equipment.

Typically the enclosure also comprises a roof panel.

Preferably each panel is dimensioned so that individually they can be carried into the building when the access door is opened.

The end wall panels may be joined to upper and lower elongate members which constitute upper and lower rails, to form a sub-assembly, and the or each front wall panel is secured to the rails.

The panels may be formed from UV stabilised polypropylene (HDPE) and corners of the panels are joined using profiles of similar material.

The front edge of the roof panel can serve as the upper rail, and may be reinforced by means of a profile of similar material.

The wall containing the live equipment may be a wall of the building or a free standing wall within the building.

The invention also lies in a kit of parts for constructing a protective housing to encase live electrical equipment on a wall in a transformer enclosure comprising: (a) two rectilinear end panels having front and rear parallel edges, (b) at least one rectilinear front panel, (c) a top panel adapted to be joined at its ends at least to the upper ends of the end panels to extend horizontally therebetween when the end panels are upright and suitably spaced apart, to form a roof to the housing, (d) upper and lower rails also adapted to be joined to the end panels, to extend horizontally therebetween, (e) the or each front panel being adapted to be joined to the upper and lower rails, to form a front wall of the housing, extending between the front edges of the end panels, and fixings extending from the end panels near the rear edges thereof, by which the end panels can be secured to the said wall, on either side of live electrical equipment thereon. In a kit of parts as aforesaid the front edge of the top panel may reinforced by an elongate profile which constitutes the upper rail, and the panels and at least the upper rail may be formed from UV stabilised polypropylene (HDPE).

The panels may be comprised of two sheets of HDPE separated by a honeycomb spacer.

Where the kit of parts is to form the protective casing to enclose a freestanding equipment containing panel, the kit of parts may further comprise at least one further panel adapted to be fitted at least to the rear edges of the end wall panels, to close off the rear of the housing behind the free-standing panel, together with at least an additional lower rail for

fitting at floor level across the rear of the housing to retain the lower edge of the or each further panel making up the rear wall of the casing.

The invention also lies in a method of constructing within an existing enclosure containing a transformer mounted centrally thereof, a device or housing as aforesaid, wherein the panels are carried in one at a time with the end panels and upper and lower rails first, and the end panels are secured to a wall within the enclosure containing live equipment so that the panels extend generally perpendicularly from the wall on either side of the equipment, and after securing the upper and lower rails to the end panels so as to extend therebetween, the or the central front panel is carried in and assembled between the upper and lower rails, after which front panels are carried in, and secured in position.

Where there are three front panels, their assembly may be achieved by first positioning the central panel in an upright position with its foot to the rear of the lower rail, and thereafter positioning each of the outer panels on either side of the central panel so that its foot is also located to the rear of the lower rail, and tilting each outer panel into an upright position so that a bolt at its upper end can be pushed upwardly to secure it to the upper rail and so that side flanges extending from the edges of the outer panels overlie the left- and right- hand upright edges of the central panel and thereby prevent it from being removed.

Where a top panel is to be secured to the upper edges of at least the end panels, so as to provide a roof to the device or housing, the top panel and/or upper rail is located in position before the front panels are put in place.

The invention also lies in a method of constructing within an existing enclosure a device or housing as aforesaid wherein the end panels and upper and lower elongate members are assembled externally of the enclosure to form a sub-assembly, and the latter is carried into the enclosure and fitted as a single unit to a wall within the enclosure carrying live equipment.

To facilitate the lifting and carrying of the pre-assembled unit, and/or to keep it structurally rigid in transit and while being secured to the wall, the end panels may include sockets adapted to receive carrying bars which when in place extend across the opening between the end panels. After securing the unit in place, the carrying bars can be removed before any front panel is introduced.

The carrying bars may be formed from GRP, or plastics which may be reinforced, or from HDPE. The invention will now be described by way of example with reference to the accompanying drawings in which: Fig 1A illustrates diagrammatically a typical transformer enclosure, Fig 1B is a perspective view of the end wall of the building with a housing embodying the invention fitted over the live electrical equipment carried on that wall, and Fig 1C is a cut away scrap section of a panel; ,. Figs 2a to 2G are elevations and top plan views of the various panels that make up a protective housing embodying the invention, for fitting into an enclosure such as shown in Fig 1 to encase live electrical equipment on one side wall thereof; Figs 3A to 3G are scrap sections of the similarly labelled regions A-G in Figs 2A-2G, to an enlarged scale; and Fig 4 is a perspective view of the pin and socket joint 3E.

In Fig 1A of the drawings, a transformer lO is shown located in a building 12. The latter includes a front wall 14 having a lockable access door 16, which when opened gives access to the inside of the building. To the rear of the transformer is a panel 18 mounted on the

inside wall 20 at the rear of the building, which panel carries switchgear, fuses, meters and the like, which when connected to the grid are electrically live.

The invention provides a demountable portable structure which can be mounted within the building so as to protect engineers and the like working on the transformer, from accidentally making contact with the live electrical equipment, so that authorised electricians do not have to attend when maintenance engineers or similar personnel need to have access to the transformer for servicing or maintenance purposes.

The structure is shown as hidden detail in Fig 1A and more clearly in Fig 1B, and is made up from panels and elongate struts so that it can be carried piece by piece, or in partly assembled form, through the opening normally closed by the door 16, for assembly at the rear of the building, so as to encase the panel 18 and the equipment mounted thereon, as shown in dotted outline at 22.

Referring to Fig 1B and Figs 2A-2G, the front of the housing 22 is made up of a central panel 24 and two outer panels 26, 27, one of which is shown at 26 in Fig 2C. Each has a pair of handles 2S, 30 and 31 and each outer panel has a profile fitted over its longer edges at 32, 24 and 33, 35. Detail of the profile cross sections 32, 24 can be seen in Fig 2D, and in Fig OF. The cross section of 33, and 35 is similar.

The handles are not shown in the top plan views of the panels, in Figs 2B and 2D.

The laterally extending flanges of the profiles 32, 34 and 33, 35 serve to overly the abutting edges of the central panel 24 and the front edges of two side panels, one of which is visible at 36 in Fig 1B, and the other of which is shown at 37 in Fig 2G.

Both side panels 36, 37 are visible in Fig 2E.

The housing is closed by a roof panel 38 visible in Fig 1B and shown in more detail in Fig 2F. The roof panel 38 is cut away at 40 to provide for ventilation as are the side panels at 42, 44.

The edges of the panels are joined using proprietary profiles as shown in the detailed enlargement of Fig 3C. The front edge of the top panel 38 (see Fig 2E) is reinforced by a channel section profile 46.

At floor level, along the lower front edge of the front panels 24, 26, 27 runs an L-section profile 47 typically of GRP, best shown in Fig 2G, Fig 3D, and in Fig 4, but also visible in Figs 2E and 2F.

The upright limb of 47 serves as a stop for the lower edges of panels 24, 26, 27 and the central panel 26 is secured in place by the pin and socket joint 39 of Fig 1B and Fig 4.

Due to the overlap of the flanges 33 and 34 with the side panels and the overlap of flanges 32, 35 with the central panel 26, by locking the latter in place as shown in Fig 4, so the two outer panels 26, 27 are prevented from being disengaged from 47.

i - Bolts 48, 50 (see Figs 1B, 2C and 3A) serve to secure the upper ends of the panels 26, 27 to the roof panel 38 and padlocks (one of which is shown at 52) serve to retain the bolts in their locking condition.

The panels are typically formed from parallel spaced apart sheets of IJV stabilised polypropylene (HDPE) separated by a honeycomb structure, such as shown in Fig 1C.

Such panels and edge joining profiles can be obtained under the trade name Panel-plus, made from HDPE.

The side panels 36, 37 are secured to the wall 20 by means of L shaped brackets 54, 56 and 58, 60 as shown in Figs 2E, 2G and 3G.

The pin and socket is simply formed by providing a hole 41 in the horizontal part of the profile 47 and a pin 43 welded to a plate 45, itself screwed to the front face of panel 24.

The thickness of the plate 45 is slightly greater than the thickness of the upright limb of the profile 47.

A gap of some 30rnm is preferably provided between the upper edges of the panels 24, 26, 27 and the roof panel 38 to further assist ventilation.

If the side walls 36, 37, top panel 38 and lower rail 47 are joined together to form a sub-

assembly, two carrying rails 62, 64 may be temporarily secured between the side panels 36, 37 as shown in Fig 2E to assist in carrying the subassembly and positioning it relative to the panel 18 in the building 12.

The rails 62, 64 can be removed after locating the sub-assembly in place to enable front panels 24, 26 27 to be fitted.

Fig 3B shows an apertured plate 49 secured to and extending above the upper edge of the central panel 24. The aperture in the plate 49 receives a pin 51 (shown in Figs lB and 2E) protruding forwardly from the front of the upper rail 46, as the central panel is pivoted backwards into a generally upright position.

Claims (52)

1. A device for rendering the interior of a transformer enclosure safe comprising a structure adapted to be fitted over live electrical equipment such as switchgear, fuses and the like mounted on an interior wall of the enclosure, comprising: (a) two end panels for mounting upright and generally perpendicular to the interior wall and adapted by brackets to be secured to the wall, as by screws; (b) upper and lower elongate members forming rails which extend horizontally between tops and bottoms of the end panels; (c) at least one removable front panel for mounting upright and generally parallel to the interior wall between the end panels and adapted at its top and bottom by locking means for securing to the upper and lower rails, so as to form with the end panels a housing which encloses the live electrical equipment and will prevent someone from accidentally touching live terminals and being electrocuted while working within the enclosure.

2. A device as claimed in claim 1 wherein the height of the panels is such that when mounted upright they extend from the floor to substantially above the live equipment.

3. A device as claimed in claim 1 or 2 wherein the top of the housing is closed by a roof panel which when fitted extends in a generally horizontal manner across the housing between the two end panels.

4. A device as claimed in claim 1, 2 or 3 wherein the front edge of the top panel constitutes the upper elongate member to which the upper end of the front panel(s) is secured.

5. A device as claimed in any of claims 1 to 4 wherein the front of the housing is formed from at least two panels, each of which is removable independently of the other and each of which is fixed in place between the upper and lower elongate members.

6. A device as claimed in claim 5 wherein there are three front panels, one central and two outer panels, and the latter each includes laterally extending flanges as a continuation of its front face, to overlie the front edge of an end panel on one side and the adjoining front face of the central panel on the other side, so that when both outer panels are in position the central panel is held in place and cannot be removed due to the presence of the two flanges protruding over it from each of the outer panels.

7. A device as claimed in any of claims 1 to 6 wherein bolts are provided at the top of each of the outer panels by which each can be bolted to the upper member, and locking means is provided to retain at least some of the bolts in their closed position.

8. A device as claimed in any of claims 1 to 7 wherein the lower elongate member is an L-shaped rigid profile.

9. A device as claimed in claim 8 wherein the lower elongate member is formed from GElP.

10. A device as claimed in any of claims 3 to 9 wherein the upper elongate member comprises a rigid plastics profile.

11. A device as claimed in claim 10 wherein the upper elongate member is fitted to the front edge of the roof panel.

12. A device as claimed in any of claims 6 to 11 wherein a pin and socket is provided at the foot of the central panel so that the panel can be lowered into position with the pin engaging the socket, to centre and position the panel.

13. A device as claimed in claim 12 wherein an apertured plate is secured to or extends from the upper edge of the central panel to protrude upwardly therebeyond, the aperture being adapted to receive a pin which protrudes forwardly from the front of the upper rail, as the central panel is pivoted backwards into a generally upright position.

14. A device a claimed in claim 13 wherein the engagement of the lower pin and socket allows the central panel to be lowered so that the pin and socket become engaged, whilst the upper end of the central panel is tilted forwardly by 10 -15 from the vertical, after which the panel can be pushed backwards, pivoting on the pin and socket joint, until the pin and plate at its upper end engage.

15. A device as claimed in claim 14 wherein the upper pin has a transverse hole through which a locking closure can be threaded, after the plate has been pushed fully onto the pin and the central panel is upright, to prevent the upper end of the central panel from pivoting forward.

16. A device as claimed in claim 15 wherein the locking closure is a split pin.

17. A device as claimed in any of claims 12 to 16 wherein the lower edge (foot) of each of the panels making up the front wall of the housing, is adapted to fit to the rear of the lower rail, and the pin and socket joint between the lower edge (foot) of the central panel and the lower rail permits the lower edge (foot) of the panel to slide behind the rail, the pin and socket being associated with the front face of the panel and the rear of the lower rail.

18. A device as claimed in any of claims 1 to 17 wherein the lower edge of each of the side panels is cut away and where a top panel is provided, its rear edge is similarly cut away, to allow air to circulate, to provide ventilation for the live equipment in the housing, when assembled.

19. A device as claimed in claim 18 wherein the lower edge of some or all of the front panels is cut away, to provide at least one ventilation opening at a lower region of each front panel.

20. A device as claimed in claim 19 wherein there are three front panels and the height of each of the outer front panels is less than the central panel, so that a gap for ventilation is provided between the upper edge of each outer panel and the underside of the front rail, when the outer panels are in place.

21. A device as claimed in any of claims 1 to 20 wherein each panel comprises front and back sheets joined by a honeycomb structure sandwiched between the sheets which serves to separate the sheets and introduce rigidity and structural strength.

22. A device as claimed in any of claims 1 to 21 wherein each panel is formed at least in part from plastics, or GRP.

23. A device as claimed in any of claims 1- to 21 wherein each panel is formed at least in part from UV stabilised polypropylene (HDPE).

24. A device as claimed in any of claims 1 to 23 wherein the side edges of the panels are joined using profiles.

25. A device as claimed in any of claims l to 24 wherein the brackets and/or other fixings and/or profiles are formed from stainless steel.

26. A device as claimed in any of claims l to 25 wherein the lower elongate member is an L-section bar formed by moulding, or extruding plastics material which may be internally reinforced with rods or bars of metal, or by moulding or pultruding GRP.

27. A device as claimed in any of claims 1 to 26 wherein at least one of the panels includes at least one handle to facilitate lifting and carrying.

28. A device as claimed in any of claims 1 to 27 wherein the live electrical equipment is mounted on a free-standing panel within the enclosure.

29. A device as claimed in claim 28 wherein the protective housing is secured to the free-

standing panel, said panel comprising the said interior enclosure wall.

30. A device as claimed in claim 28 wherein the housing includes an additional wall to completely encase the free standing panel and the equipment mounted thereon.

31. A device as claimed in claim 30 wherein the additional wall is formed from a single panel or from a plurality of panels, and corner profiles are provided on rear edges of at least the side wall panels, and a similar profile is provided at floor level, so that one or more panels can be fitted to the rear of the free-standing panel.

32. A transformer enclosure comprising: (a) a building comprised of walls, a roof and a lockable access door; (b) a transformer mounted within the building and spaced from the inside walls of the building to give access for servicing and maintenance work thereon; (c) switchgear and fuses comprising live electrical equipment mounted on a wall inside the building, and (d) a housing around the live electrical equipment to prevent accidental contact therewith by engineers or other persons working on the transformer, wherein the housing is comprised of separate panels forming at least a front wall and two end walls, which panels are joined together to encase the live electrical equipment, with the end wall panels secured to the wall carrying the live electrical equipment.

33. An enclosure as claimed in claim 32 further comprising a roof panel to the housing.

34. An enclosure as claimed in claim 32 or 33 wherein each panel is dimensioned so that individually they can be carried into the building when the access door is opened.

35. An enclosure as claimed in any of claims 32 to 34 wherein the end wall panels are joined to upper and lower elongate members which constitute upper and lower rails, to form a sub-assembly, and the or each front wall panel is secured to the rails.

36. An enclosure as claimed in any of claims 32 to 35 wherein the panels are formed from UV stabilised polypropylene (HDPE) and corners of the panels are joined using profiles of similar material.

37. An enclosure as claimed in claim 36 wherein the front edge of the roof panel serves as the upper rail.

38. An enclosure as claimed in any of claims 32 to 37 wherein the front edge of the roof panel is reinforced by means of a profile of similar material.

39. An enclosure as claimed in any of claims 32 to 38 wherein the wall containing the live equipment is a wall of the building or is a free standing wall within the building.

40. A kit of parts for constructing a protective housing to encase live electrical equipment on a wall in a transformer enclosure comprising: (a) two rectilinear end panels having front and rear parallel edges' (b) at least one rectilinear front panel,

(c) a top panel adapted to be joined at its ends at least to the upper ends of the end panels to extend horizontally therebetween when the end panels are upright and suitably spaced apart, to form a roof to the housing, (d) upper and lower rails also adapted to be joined to the end panels, to extend horizontally therebetween, (e) the or each front panel being adapted to be joined to the upper and lower rails, to form a front wall of the housing, extending between the front edges of the end panels, and fixings extending from the end panels near the rear edges thereof, by which the end panels can be secured to the said wall, on either side of live electrical equipment thereon.

41. A kit of parts as claimed in claim 40 wherein the front edge of the top panel is reinforced by an elongate profile which constitutes the upper rail.

42. A kit of parts as claimed in claim 40 or 41 wherein the panels and at least the upper rail are formed from UV stabilised polypropylene (HDPE).

43. A kit of parts as claimed in any of claims 40 to 42 wherein at least one of the panels are comprised of two sheets of HDPE separated by a honeycomb spacer.

44. A kit of parts as claimed in any of claims 40 to 43 wherein the protective casing is to enclose a free-standing equipment containing panel, and the kit of parts further comprises at least one further panel adapted to be fitted at least to the rear edges of the end wall panels, to close off the rear of the housing behind the free-standing panel, together with at least an additional lower rail for fitting at floor level across the rear of the housing to retain the lower edge of the or each further panel making up the rear wall of the casing.

45. A method of constructing within an existing enclosure containing a transformer mounted centrally thereof, a device or housing as claimed in any of claims 1 to 39, wherein the panels are carried in one at a time with the end panels and upper and lower rails first, and the end panels are secured to a wall within the enclosure containing live equipment so that the panels extend generally perpendicularly from the wall on either side of the equipment, and after securing the upper and lower rails to the end panels so as to extend therebetween, the or the central front panel is carried in and assembled between the upper and lower rails, after which front panels are carried in, and secured in position.

46. A method as claimed in claim 45 wherein there are three front panels and assembly of the three panels is achieved by first positioning the central panel in an upright position with its foot to the rear of the lower rail, and thereafter positioning each of the outer panels on either side of the central panel so that its foot is also located to the rear of the lower rail, and tilting each outer panel into an upright position so that a bolt at its upper end can be pushed upwardly to secure it to the upper rail and so that side flanges extending from the edges of the outer panels overlie the left- and right-hand upright edges of the central panel and thereby prevent it from being removed.

47. A method as claimed in claims 45 or 46 wherein a top panel is secured to the upper edges of at least the end panels, so as to provide a roof to the device or housing, and to provide the upper rail (or be attached thereto), before the front panels are put in place.

48. A method of constructing within an existing enclosure a device or housing as claimed in any of claims 1 to 39 wherein the end panels and upper and lower elongate members are assembled externally of the enclosure to form a sub-assembly, and the latter is carried into the enclosure and fitted as a single unit to a wall within the enclosure carrying live equipment.

49. A method as claimed in claim 48 wherein the end panels include sockets adapted to receive carrying bars across the opening between the end panels, to facilitate the lifting and

carrying of the pre-assembled unit, to keep it structurally rigid in transit and while being secured to the wall.

50. A method as claimed in claim 49 wherein after securing the unit in place, the carrying bars are removed before any front panel is introduced.

51. A method as claimed in claim 49 or 50 wherein the carrying bars are formed from GRP, or plastics which may be reinforced, or from HOPE.

52. A device as claimed in claim l constructed and arranged substantially as herein described with reference to and as illustrated in the accompanying drawings.