IE20170226A1 - A trunking system - Google Patents

Abstract

A trunking system (1) is installed in clean rooms (2, 3, 4 and 5) with floors (10, 11 and 12) and ceilings (13, 14). Power cables and fluid hoses are routed between the rooms by the trunking system (1). The trunking system (1) comprises conduit branches (20) with hollow conduits (21) interconnected by various couplers. The cables are connected into control cabinets (22) and/or devices/ appliances/ instruments as required within the clean rooms. Also, they are connected into a junction box (25) in-between rooms. The system includes a, bridging conduit (30) which extends through a ceiling to provide continuity to other clean rooms without risk of contamination across the rooms or between ceiling spaces and rooms or conduits. Couplers and end caps have radial surfaces (391, 392, and 393) which are tapered to narrow in the direction in which the conduit is pushed. Such surfaces extend in some cases from 0-ring grooves so that any adhesive which migrates from the 0-ring grooves does not affect the electrical inter-connection. A bridging conduit (30) has external threads (63) at one end with 0-rings (62) in grooves between the threads, allowing directing push-fitting of conduit if desired. <Figure 1>

Description

Field of the Invention The invention relates to a trunking system for distribution of power cables and/or hoses to locations within a room such as a clean room in a manufacturing facility, or to transfer low pressure fluid or gas.

Prior Art Discussion US5290073 describes an expansion seal for pipes for multiple electrical cables.

US4647074 describes a conduit system with flexible conduits.

US4374596 describes conduits with couplers which fit within conduit section ends, and branches off to distribute cabling.

US4377291 describes a sealing assembly for establishing a water-tight and rodent/insect-proof seal.

GB2351333 describes conduits which have an enlarged end portion terminating in an end plate with multiple exit holes for cable-embracing connectors.

An object of the invention is to provide a trunking system for improved and more versatile sealing across different rooms and also within rooms.

SUMMARY OF THE INVENTION 30 We describe a trunking system comprising: a plurality of conduits having a longitudinal axis, -2a plurality of conduit couplers having a tubular body with longitudinal axis and being for interconnecting at least some of said conduits, at least some of said conduit couplers comprising a male or female end comprising radial surfaces including: a tapered radial surface configured to: if the end is female, narrow in an axially internal direction, or if the end is male, widening in an axial internal direction, and a a contact surface axially internally of said tapered surface, said contact surface being adapted to contact a conduit radial surface when the coupler is connected to said conduit; end caps for one or more of the conduits, each said end caps having a longitudinal axis; at least one bridging conduit comprising: a pipe-shaped main body having a longitudinal axis, a pair of opposed annular axial seals around the main body for pressing against a ceiling or wall opposed surfaces through which said bridging conduit extends, at least one of the annular seals being axially movable on external threads on the conduit main body, and a coupler or an end of the main body at each end of the main body adapted to engage a conduit on either side of a wall or ceiling; at least one box for distribution of cables, the box having a housing panel; a panel joint having a longitudinal axis and comprising a tubular body configured to extend through a panel of a box. and an annular· axial seal arranged to press axially against panel opposed surfaces to seal against the panel.

At least one bridging conduit may comprise external threads at one or both ends, said threads having an outside diameter matching a conduit internal diameter, whereby the conduit can be pushed over the threads for engagement with the bridging conduit.

Preferably, the outside diameter of the threads matches internal diameter of the main body of said bridging conduit.

Preferably, the system further comprises at least one O-ring in a groove between said threads.

There may be at least two axially spaced-apart O-rings between said threads.

Preferably, at least one bridging conduit comprises a shoulder around the main body and at least one axial seal is threaded to external threads on said shoulder, and the internal diameter of the -3main body is substantially equal to the internal diameter of the a conduit which fits said bridging conduit.

Preferably, the system comprises an external junction box adapted to be connected to the bridging conduit by a panel joint, for termination or routing of cables which run through the bridging conduit from a room and for distribution to other rooms.

Preferably, at least one panel joint comprises at a first end a sleeve for male or female engagement with a conduit end, said sleeve having a shoulder with an axially-facing surface for engaging a panel external surface, and at a second end comprises external threads engaged by said axial seal for engaging a panel internal surface.

Preferably, a conduit coupler tubular body comprises an end with external or internal O-rings for male or female engagement with a conduit, and radial contact surfaces are adjacent said resilient seals. A conduit coupler may comprise an annular shoulder either external or internal, having an axial contact surface with an undercut.

At least one conduit coupler may have an internal surface with tapered ends, narrowing in the axially internal direction.

Preferably, at least one end cap is configured to seal an end of a conduit or allow a cable or pipe to pass through, wherein an end cap comprises a male sleeve with an external seal for insertion in a conduit. Preferably, an end cap includes external threads for engagement in a versatile manner with an end plate for cable glands.

Preferably, at least one end cap comprises a tapered radial surface configured to: if the end is female, narrow in an axially internal direction, or if the end is male, widening in an axial internal direction, and a contact surface axially internally of said tapered surface, said contact surface being adapted to contact a conduit radial surface when the end cap is connected to said conduit.

We also describe a bridging conduit comprising: a pipe-shaped metal main body having a longitudinal axis, a pair of opposed annular axial seals around the main body for pressing against a ceiling or wall opposed surfaces through which said bridging conduit extends, at _ 4 least one of the annular seals being axially movable on external threads on the conduit main body, and a coupler or an end of the main body at each end of the main body adapted to engage conduit on either side of a wall or ceiling, external threads at one or both ends, said threads having an outside diameter matching a conduit internal diameter, whereby the conduit can be pushed over the threads for engagement with the bridging conduit, and at least one O-ring in a groove between said threads.

Preferably, the bridging conduit further comprises a panel joint comprising a tubular body configured to extend through a panel of a box, and an annular axial seal arranged to press axially against panel opposed surfaces to seal against the panel. Preferably, said threads have an outside diameter matching internal diameter of the bridging conduit main body.

We also describe a conduit coupler comprising a metal tubular body with a longitudinal axis and being for interconnecting conduits, said main body comprising radial surfaces including: a tapered radial surface configured to: if the end is female, narrow in an axially internal direction, or if the end is male, widening in an axial internal direction, and a contact surface axially internally of said tapered surface, said contact surface being adapted to provide metal-to metal contact with a conduit radial surface for electrical earthing continuity when the coupler is connected to said conduit Preferably, the main body comprises an annular shoulder either external or internal, having an axial contact surface with an undercut. Preferably, the shoulder has an annular recess with a gasket.

Additional Statements According to the invention, there is provided a trunking system comprising: a plurality of conduits arranged to be mounted in a room and interconnected by conduit couplers; end caps for one or more of the conduits; a bridging conduit comprising a pipe-shaped main body and a main body annular seal for pressing against a ceiling or wall surface through which said bridging conduit extends. -5In one embodiment, the bridging conduit comprises a panel coupler with an annular seal for sealing to a panel through which the bridging conduit passes.

In one embodiment, the panel coupler comprises a plurality of annular seals, one for each opposed side of a panel, said seals being arranged to press axially against the panel and to radially seal against the bridging conduit.

In one embodiment, the panel coupler annular seal is axially movable, such as by a nut on external threads on the conduit.

In one embodiment, the panel coupler comprises a sleeve which is in male or female engagement with the conduit end.

In one embodiment, the system comprises an external junction box adapted to be connected to the bridging conduit, for termination or routing of cables which run through the bridging conduit from a room.

In one embodiment, the bridging conduit is arranged to be connected to the external junction box by the panel coupler.

In one embodiment, the bridging conduit main body annular seal comprises a washer and an annular gasket around a conduit.

In one embodiment, the bridging conduit main body annular seal is movable axially on the conduit.

In one embodiment, the bridging conduit main body annular seal comprises a pair of axially separated seal parts for engaging opposed surfaces of a wall or ceiling.

In one embodiment, the bridging conduit main body annular seal comprises a component such as a nut engaged with external threads on the conduit for controlled axial movement.

In one embodiment, the bridging conduit main body annular seal comprises a fixed annular seal part and a movable annular seal part. -6In one embodiment, a conduit coupler comprises a conduit end with external or internal resilient seals such as O-rings for male or female engagement with another conduit or other component bodies.

In one embodiment, at least one conduit coupler comprises a threaded body comprising a sleeve with external threads and configured to surround an end of a conduit and support an annular seal, to convert a conduit into a bridging conduit.

In one embodiment, the threaded body includes at least one internal resilient seal such as an 0ring.

In one embodiment, a conduit coupler includes a sleeve having an internal seal at each end, arranged to receive conduit ends inserted into the sleeve.

In one embodiment, a conduit coupler includes a sleeve having an external seal at each end, arranged to receive conduit ends around the sleeve. in one embodiment, a conduit coupler comprises a shoulder around the periphery of the sleeve, said shoulder separating two male sleeve ends, and the conduits are configured to receive the male ends and abut axially the shoulder.

In one embodiment, the sleeve has an internal surface with tapered ends, narrowing from outer edges of the sleeve.

In one embodiment, the system further comprises at least one end cap configured to seal an end of a conduit or allow a cable or pipe to pass through.

In one embodiment, an end cap comprises a male sleeve with an external seal for insertion in a conduit.

In one embodiment, an end cap includes external threads for engagement in a versatile manner with an end plate.

In one embodiment, a conduit coupler comprises a sleeve-shaped body with internal threads at one end and either a male plug or a female socket at the other end. -7In one embodiment, there is an internal annular stop around the periphery of the body between the ends.

In one embodiment, the system comprises at least one end cap having threads for engaging threads of a conduit end, and an end face.

In another aspect, the invention provides a bridging conduit comprising a pipe-shaped main body and a main body annular seal around the conduit for pressing against a ceiling or wall surface through which said bridging conduit extends.

In one embodiment, the bridging conduit comprises a panel coupler with an annular seal for sealing to a panel at an end of the bridging conduit. In one embodiment, the panel coupler comprises a plurality of annular seals, one for each side of a panel, said seals being arranged to press axially against the panel and to radially seal against the bridging conduit. In one embodiment, the bridging conduit is arranged to be connected to an external junction box by a conduit end being inserted into the junction box and the panel coupler annular seal surrounding the conduit end inside the box and pressing against inside and outside surfaces of a junction box wall with resilient seals.

In one embodiment, the panel coupler annular seal is axially movable, such as by a nut on external threads on the conduit.

In one embodiment, the bridging main body annular seal comprises a washer and an annular gasket around a conduit, and wherein the bridging main body annular seal is movable axially on the conduit.

In another aspect, the invention provides a conduit coupler comprising a sleeve body and a movable annular seal and being arranged to be welded over a conduit.

In another aspect, the invention provides a conduit coupler comprising a tapered body with a narrowing surface towards one end and external threads at the other end, and an annular seal movable on the external threads for connection to a panel, junction box, cabinet, or end plate.

In another aspect, the invention provides a conduit coupler comprising a double-ended male coupler sleeve and a shoulder or annular stop around the sleeve and annular seals such as O-rings -8οη either side of the shoulder, and in which the internal surface of the sleeve is ramped or tapered to allow ease of feed of cable/ hose through the system.

In another aspect, the invention provides a conduit coupler comprising a sleeve having a male end and an opposed externally threaded end engaging a pair of axially movable seals for engaging opposed sides of a panel through which the threaded end extends.

In another aspect, the invention provides a conduit coupler comprising a sleeve-shaped body forming an internal shoulder for axial abutment with a conduit end and optionally an annular recess in the shoulder.

Preferably, the shoulder has an annular recess with a gasket.

In another aspect, the invention provides a conduit end cap comprising a cup-shaped body with a tubular side wall with internal or external threads which have an internal/ external socket end gasket/ seal for engaging a conduit end.

In another aspect, the invention provides a conduit end cap comprising a cub-shaped body with a tubular side wall forming a male plug or a female socket to engage with a conduit end.

DETAILED DESCRIPTION OF THE INVENTION Brief Description of the Drawings The invention will be more clearly understood from the following description, of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:Fig. 1 is a diagram showing a trunking system for multiple rooms; Fig. 2 is a diagram showing on a larger scale a pail of the system of Fig. 1 within, and immediately above, one room; and Fig. 3 is an enlarged front view of a junction box and its connections of Fig, 2, particularly above a room and linking into a cable rail; -9Fig. 4(a) is a sectional view of a bridging conduit and linked conduits in use passing through a ceiling, and Fig. 4(b) shows the bridging conduit in more detail as a set of side, sectional, cut-away perspective and end views in clockwise order from top right; Fig. 5(a) is a sectional view of an alternative bridging conduit and linked conduits in use passing through a ceiling, and Fig. 5(b) shows the bridging conduit in more detail as side (top) and sectional (bottom) views; Figs, 6 and 7 each show a part of the system of Fig. 1 where cables exit conduit within a room; Fig. 8 is a set of side, sectional, perspective cut-away and end views of an alternative bridging conduit; Fig. 9 shows a conduit joint having a sleeve body with a female joint part on one side and threads at the opposite end on which is engaged a movable annular clamping axial seal, for engaging a panel of a junction box; Fig. 10 shows a conduit joint having a sleeve body with a movable clamping axial seal, the whole length of the body having threads; Fig. 11 shows a female double ended conduit coupler having two pairs of internal O-rings in a body, on pair on each side of an annular stop providing axial contact faces, with sloped or tapered internal radial surfaces for direct contact with a conduit; Fig. 12 shows a female blank or end cap having a sleeve body, internal O-rings, and an end face, with sloped or tapered internal radial surfaces for direct contact with a conduit; Fig. 13 is a set of views showing a conduit joint having a tapered body narrowing externally towards one end and external threads at the other end which has a fastening nut and two gaskets, again for connection into a junction box across a panel or wall of the box; - 10Fig. 14 shows a double-ended male conduit coupler having a central annular stop around the body of the coupler at its axially central position, and external O-rings between whih there are external radial contact surfaces for electrical earthing continuity, and Fig. 15 shown an alternative male double-ended male conduit coupler, having a similar configuration in general terms but with exaggerated slopes leading into the radial contact surfaces; Fig. 16 is a series of side, sectional, perspective, and end views showing a male conduit blank having a sleeve body with external O-rings and an end face, again with external radial contact surfaces adjacent the O-rings; Fig. 17 is a set of views showing a conduit joint having a male end and an opposed externally threaded end which has a fastening nut and a gasket for engaging opposed faces of a panel of a junction box; and Figs. 18, 19, and 20 are each a set of side, sectional, perspective cut-away, and end views of a coupler which can be used with bridging conduits or couplers for connection to a conduit.

Description of the Embodiments Referring to Figs. 1 and 2 a trunking system 1 is shown installed in clean rooms 2, 3, 4 and 5 with floors 10, 11 and 12 and ceilings (which may be walk-on ceilings) 13 and 14. Power cables and fluid hoses are routed between the rooms by the trunking system 1. An inter-room conduit 15 is mounted on brackets 16 between ceilings and floors.

The trunking system 1 comprises conduit branches 20 with hollow conduits 21 interconnected by various conduit couplers, as described in more detail below. The cables are connected into control cabinets 22 and/or devices appliances and instruments as required within the clean rooms. These connections are most often made with conduit joints. Also, they are connected into a junction box 25 in-between rooms, again by a conduit joint.

Within and above the clean room 4 there are stages as follows, as shown in Fig. 2: - 11 25, junction for distribution of cables to other rooms; , bridging conduit through ceiling; 32, spurs to gauges and to branch off individual cables; and 34, termination of cables into a terminal or junction box 23.

In summary, the trunking system 1 primarily comprises conduits which are inter-connected by couplers, and are connected to junction boxes or instruments by conduit joints. Conduit which passes through a wall or ceiling is referred to as a bridging conduit. All of these are described in more detail below. These components fit together to provide a sealed environment for the cables which they house, and there is excellent structural rigidity at component inter-connections, and also excellent metal-to-metal contact for electrical earthing.

Fig. 3 shows the stage 25, with a junction box 40 from which cables 41 extend via sealed glands 42. A panel joint 45 has a longitudinal axis and it seals a conduit 61 to the box 40 so that cables (not shown) can be routed from within the box 40 down into the room 4. The panel joint 45 comprises a male sleeve 65 with external O-rings 66 extending into the conduit 61 end, and a threaded portion 68 extending into the box. This end is sealed by a nut 67 clamping a side wall of the box 40 against a shoulder 69 of the sleeve 65 with a gasket (or “seal”) on each side of the box wall or panel.

As can be seen in this view, there is a complete seal between the rooms, due to sealing between the panel joint and the junction box, without possibility of contamination along the conduits and via the junction box.

Referring to Figs. 4(a) and (b) a bridging conduit 30 comprises a tubular body 46 with a longitudinal axis and being joined to a conduit 47 below by a double-ended male coupler 48 which has a sleeve body extending into the opposing conduit ends. The coupler 48 has external O-rings 49 engaging the inside surfaces of the conduit ends. As can be seen in this view there is extensive metal-to-metal contact between the O-rings 49, providing excellent ground continuity. This contact is between external radial surfaces of the coupler 48 and internal radial surfaces of the conduits.

The lower surface of the ceiling is engaged by a resilient gasket 56 backed by a washer 55 which extend around, and are fixed to, the bridging conduit tubular body 46. - 12Outside of the room 4, the bridging conduit 30 seals against the top ceiling surface by a movable axial seal part comprising a resilient gasket 57 backed by a washer 58 and pressed by a nut 59 on threads 60. The upper end of the bridging conduit 30 engages within the conduit 61 by insertion of the threaded end 63 into the end of the conduit 61. the seal being completed by O-rings 62. In this case the threaded end 63 has an OD matching the ID of the conduit 61. This allows multiple uses of the threaded end 63, to engage a conduit with matching internal threads or by simply sliding over with O-ring sealing.

It will thus be appreciated that the trunking system can extend through the ceiling without allowing ingress of any contamination into the room or into a conduit. This may be installed in a versatile manner due to the fact that the external, top part of the seal is axially movable on the threads 60. Thus, a range of ceiling thicknesses can be easily accommodated. Advantageously the threaded end 63 acts both to support the axially-movable seal 57-59 and to also engage a conduit.

An alternative bridging conduit, 70, is shown in Figs. 5(a) and (b). In this case a conduit 71 has a longitudinal axis and has a lower male fitting 73 with external O-rings inserted into a conduit 72. At the upper end there is a threaded body 77 in the form of a shoulder with external threads supporting a movable seal part comprising a gasket 78, a washer 79, and a nut 80. These provide an axially-movable top seal engaging the ceiling top surface. The upper end terminates in a male fitting 81 with Ο-rings inserted into a conduit 82.

Fig. 6 shows the stage 32 of the trunking system 1, with T-conduits 100 having spurs closed off by an end cap 1.10 having a single aperture 112 for a cable C or hose. The blank 110 is sealed by O-rings 111. The main branches of the conduits 100 are joined by double-ended male couplers 48, Any or all of the branches may have end plates which have multiple apertures and associated cable glands, allowing multiple cables or pipes to be routed through the branch to an item in the clean room.

Fig. 7 shows in more detail the stage 34 of the trunking system 1. This has a conduit 35 with a primary branch coupled at its top end by a coupler 48, and blanked off at the bottom by an end cap 120 with a male sleeve and external O-rings 121. A spur is linked into the body 23(a) of the -13box 23, by a panel joint 65. This provides a seal equivalent to the seal of the box 40. The box 23 also has a sealed lid 23(b) on the side opposed to the conduit.

Fig. 8 shows an alternative bridging conduit, 150, having: - a conduit 151 with open ends; - a fixed annular axial seal having a washer 152 and a resilient gasket 153; - an axially movable annular axial seal having a gasket 155, a washer 156, and a nut 157 threaded onto external threads 154.

The external threads 154 are on a raised shoulder 160 around a part of the conduit 151. This provides an increased diameter for the threads for improved axial clamping strength, but more importantly it allows the conduit 151 to have a continuous uniform internal profile 161. This assists with running of cables or the like through the conduit 150.

The bridging conduit ends may be joined by a male or female coupler, or by welding for example.

Fig. 9 shows a panel joint 180 which is a variation of the panel joint 65. It comprises a sleeve body with a female joint part 181 with a narrowing tapered end 182, and threads 185 at the opposite end. There is an axially movable seal comprising a gasket 195, a washer 196, and a nut 197. There is also an opposed axial seal part comprising a washer 192 and a gasket 193. This panel joint has internal radial surfaces 185, 186, and 187 in order from the left end axially inwardly. Each of these radial surfaces has a tapered part which narrows n the axially internal direction and terminates in a contact surface part. This provides excellent metal-to-metal contact with conduit inserted into the end, with the wider end of the tapered parts accommodating any excess adhesive which migrates axially internally as the conduit Is pushed in.

Fig. 10 shows a panel joint 200 having a sleeve body with a similar movable axial seal 155/156/157 and 152/153. The whole length of the body has threads 201. This can be welded over the pipe on the outer diameter of the pipe at any point necessary to engage with a wall, ceiling or bridging conduit.

Fig. 11 shows a female double ended female coupler 250 having two pairs (can be single or more than two) of internal O-rings 253 in a body 251. This coupler 250 does not reduce the internal -14diameter of the pipe when engaged. It has multiple direct contact surfaces, both radial and axial, which engage directly with the conduit. This facilitates rigidity of the joint and continuity of the earthing of the system across couplers throughout even if bonding agents are used. At each end a. radial surface 254 is tapered to narrow in diameter in the axially internal direction for tighter engagement as the conduit is pushed in. There is a second radial surface 255 on each side, extending from an O-ring groove 256. The radial surface 255 is also tapered to narrow inwardly from the O-ring groove 256. There is a third radial surface, 257, on each side tapering inwardly from a second O-ring groove 258. The tapered configuration allows easy conduit insertion, and the innermost ends (where narrowest) provide good metal-to-metal contact with the inserted conduits with avoidance of excessive travel of any adhesive that might be drawn from the O-ring grooves. Finally, there is an axial contact surface 260 on each side of an internal annular stop at a central location along the length of the coupler.

Fig. 12 shows a female blank or end cap 300 having a sleeve body 301, internal O-rings 303, and an end face 302. This end cap can have a plurality of holes and also does not require need for a reduced internal diameter of the connecting conduit. It has multiple metal-to-metal contacting surfaces, both radial and axial, which engage directly with the conduit. This facilitates rigidity to the system and continuity of the earthing of the system throughout even if bonding agents are used. These radial contact surfaces are similar to those of the coupler 250: first, second, and third radial contact surfaces 310, 311, and 312 tapered to narrow in the direction of insertion of the conduit.

Fig. 13 shows a panel joint 350 having a tapered body 351 narrowing externally towards one end and external threads 352 at the other end which has a fastening nut 354 and two gaskets/ seals 353, only one of which is shown. It has a gasket/ seal to each side of the panel that it is connected to. This is for connection to a panel, junction box, cabinet, or end plate etc. Again, there are first, second, and third radial contact surfaces, 360, 361, and 362. There is also an axial contact surface 363 for contact with an end face of a conduit wall.

Fig. 14 shows the double-ended male conduit coupler 48 having a longitudinal axis. The coupler has a central shoulder or annular stop 48(a) around the body of the coupler at its axially central position. There are two (can be single or more than two) O-rings 48(b) on each side of the stop 48(a), providing excellent gripping and sealing against a conduit. The shoulder may in another embodiment have an under-cut detail to allow tight seamless termination of a pipe to the - 15 coupler. The internal surface of the conduit 48 body is ramped or tapered to allow ease of feed of cable/ hose through the system. Also, tt has multiple external radial contact surfaces 48(c), 48(d), and 48(e) which engage directly with the conduit. Again, these are tapered, outwardly in this case at a very small angle. This facilitates rigidity of the joint and continuity of the earthing of the system across couplers throughout even if bonding agents are used.

Referring to Fig. 15 a double-ended male coupler 380 is in general terms similar to the coupler 48 of Fig. 15. The coupler 380 is symmetrical about a central annular stop 381. It has external tapered radial surfaces 382 at each end for easier fitting into a conduit. As the coupler is male, the taper is outwards in the axially internal direction. There are two O-rings 383 on each side of the stop 381, in an outer (closest to end) groove 384 and an inner groove 385. The annular stop 381 provides an axial conduit-contacting surface 386 facing each end. These are multiple radial external surfaces some for direct metal-to-metal contact. In order from each end inwardly in the axial direction, these are: 382, tapered, for ease of insertion into conduit; 387, non-tapered, for direct metal-to-metal contact; 388, recessed immediately past first O-ring 383, can accommodate any spill-over adhesive from the O-ring groove; 389, tapered for lead-in to a contact surface; 390, contact surface; 391, recessed, like the surface 388; 392, tapered, like the surface 389; 393, contact, long, leading to axial surface 386.

The radial contact surfaces 387, 390, and 393 at both ends engage directly with the conduit. This facilitates rigidity of the joint and continuity of the earthing of the system across couplers throughout even if bonding agents are used. The lead-in tapered surfaces act to ensure that any adhesive inserted into the O-ring grooves does not travel sufficiently to damage the metal-tometal contact with the conduit.

Fig. 16 shows a male blank 400 having a sleeve body 401 with external O-rings 402 and an end face 403. This end cap can have a plurality of holes. It has multiple radial contact surfaces and one axial contact surface on the male end which engage directly with the conduit. In this the - 16taper of the radial contact surfaces is less. This facilitates rigidity of the joint and continuity of the earthing of the system across couplers throughout even if bonding agents are used.

Fig. 17 shows a panel joint 450 having a male end 451 and an opposed externally threaded end 452 which has a fastening nut 455 and a gasket 454. It has another gasket and nut for the opposed side of the panel that it is connected to. This is for connection to a panel, junction box, cabinet, or end plate, for example. It has multiple tapered radial contact surfaces 456, 457, and 458 on the male end which engage directly with the conduit. This facilitates rigidity of the joint and continuity of the earthing of the system across couplers throughout even if bonding agents are used.

Fig. 18 shows a female double-ended coupler 500 having a generally sleeve-shaped body 501 having external tapered surfaces 502 narrowing towards the ends. Internally, the coupler 500 comprises internal threads 503 at one end with an undercut annular recess 507 containing an end gasket. At the opposite end there is a female socket 508 with O-rings 505. These are multiple tapered radial contact surfaces 510, 511, and 512 on the female end which engage directly with the conduit. These also narrow in the axially internal direction. This facilitates rigidity of the joint and continuity of the earthing of the system across couplers throughout even if bonding agents are used. The ends are separated by a shoulder or annular stop 504 which forms the undercut 507 containing the end gasket/ seal. The threads 503 may be engaged with the external threads 60 of the bridging conduit 30 for example, or the other end of the bridging conduit may be inserted into the socket 505. Hence, one or two couplers 500 may be connected to the bridging conduit 30 or other conduit having similar end features.

Referring to Fig. 19 a coupler 550 has a sleeve-shaped body 551 with internal threads 552 at one end, and a male plug 553 at the other end, with external O-rings 554. The ends are separated by a shoulder or annular stop 556 which has an undercut recess containing an end gasket/ seal 560. Again, this may be connected to either end of the bridging conduit 30 or other conduit with similar features at the ends. The coupler 550 has external tapered radial contact surfaces 560, 561, and 562. The taper angle is very small in this case.

It has been found that the undercut recess is very effective at ensuring good quality joints, even with variances in finishing of the ends of the conduit engaging the coupler. - 17Referring to Fig. 20 an end cap 600 has internal threads 602 and an end face 603 which has a socket containing an end gasket/ seal. Hence, any of the conduits may be sealed at an end by an end cap engaging the end by a male plug, a female socket, or internal threads engaging conduit external threads for example.

It will be appreciated that the invention provides a trunking system which provides in a convenient and reliable manner continuity of sealing of cables across multiple rooms and also good rigidity and electrical earthing continuity. There is a bridging conduit to suit passages through ceilings and walls, joints for connection to junction boxes or the like, and couplers for inter-connecting conduits. These all provide the required properties mentioned above in a versatile and reliable manner.

The invention is not limited to the embodiments described but may be varied in construction and detail. All components and conduit/ pipes can be manufactured in multiple materials best suit to specific applications. Examples are stainless steel, carbon steel, aluminium, brass, bronze, copper and multiple plastics and composites. Where the material is an insulator the radial contact surfaces are not required for earthing continuity, but they do provide excellent structural rigidity.

Claims (20)

1. A trunking system comprising: a plurality of conduits having a longitudinal axis, a plurality of conduit couplers having a tubular body with longitudinal axis and being for interconnecting at least some of said conduits, at least some of said conduit couplers comprising a male or female end comprising radial surfaces including: a tapered radial surface configured to: if the end is female, narrow in an axially internal direction, or if the end is male, widening in an axial internal direction, and a a contact surface axially internally of said tapered surface, said contact surface being adapted to contact a conduit radial surface when the coupler is connected to said conduit; end caps for one or more of the conduits, each said end caps having a longitudinal axis; at least one bridging conduit comprising: a pipe-shaped main body having a longitudinal axis, a pair of opposed annular axial seals around the main body for pressing against a ceiling or wall opposed surfaces through which said bridging conduit extends, at least one of the annular seals being axially movable on external threads on the conduit main body, and a coupler or an end of the main body at each end of the main body adapted to engage a conduit on either side of a wall or ceiling; at least one box for distribution of cables, the box having a housing panel; a panel joint having a longitudinal axis and comprising a tubular body configured to extend through a panel of a box, and an annular axial seal arranged to press axially against panel opposed surfaces to seal against the panel.

2. A trunking system as claimed in claim 1, wherein at least one bridging conduit comprises external threads at one or both ends, said threads having an outside diameter matching a conduit internal diameter, whereby the conduit can be pushed over the threads for engagement with the bridging conduit.

3. A trunking system as claimed in claim 2, wherein the outside diameter of the threads matches internal diameter of the main body of said bridging conduit. -194. A trunking system as claimed in claim 2 or 3. further comprising at least one O-ring in a groove between said threads.

4. 5. A trunking system as claimed in claim 4, wherein, there are at least two axially spaced5 apart O-rings between said threads.

5. 6. A trunking system as claimed in any preceding claim, wherein at least one bridging conduit comprises a shoulder around the main body and at least one axial seal is threaded to external threads on said shoulder, and the internal diameter of the main body is 10 substantially equal to the internal diameter of the a conduit which fits said bridging conduit.

6. 7. A trunking system as claimed in any preceding claim, wherein the system comprises an external junction box adapted to be connected to the bridging conduit by a panel joint, for 15 termination or routing of cables which run through the bridging conduit from a room and for distribution to other rooms.

7. 8. A trunking system as claimed in any preceding claim, wherein at least one panel joint comprises at a first end a sleeve for male or female engagement with a conduit end, said 20 sleeve having a shoulder with an axially-facing surface for engaging a panel external surface, and at a second end comprises external threads engaged by said axial seal for engaging a panel internal surface.

8. 9. A trunking system as claimed in any preceding claim, wherein a conduit coupler tubular 25 body comprises an end with external or internal O-rings for male or female engagement with a conduit, and radial contact surfaces are adjacent said resilient seals.

9. 10. A trunking system as claimed in any preceding claim, wherein a conduit coupler comprises an annular shoulder either external or internal, having an axial contact surface 30 with an undercut.

10. 11. A trunking system as claimed in any preceding claim, wherein at least one conduit coupler has an internal surface with tapered ends, narrowing in the axially internal direction. -20

11. 12. A trunking system as claimed in any preceding claim, wherein at least one end cap is configured to seal an end of a conduit or allow a cable or pipe to pass through, wherein an end cap comprises a male sleeve with an external seal for insertion in a conduit.

12. 13. A trunking system as claimed in any preceding claim, wherein an end cap includes external threads for engagement in a versatile manner with an end plate for cable glands,

13. 14. A trunking system as claimed in any preceding claim wherein at least one end cap 10 comprises a tapered radial surface configured to: if the end is female, narrow in an axially internal direction, or if the end is male, widening in an axial internal direction, and a contact surface axially internally of said tapered surface, said contact surface being adapted to contact a conduit radial surface when the end cap is connected to said conduit.

14. 15. A bridging conduit comprising: a pipe-shaped metal main body having a longitudinal axis, a pair of opposed annular axial seals around the main body for pressing against a ceiling or wall opposed surfaces through which said bridging conduit extends, at 20 least one of the annular seals being axially movable on external threads on the conduit main body, and a coupler or an end of the main body at each end of the main body adapted to engage conduit on either side of a wall or ceiling, external threads at one or both ends, said threads having an outside diameter 25 matching a conduit internal diameter, whereby the conduit can be pushed over the threads for engagement with the bridging conduit, and at least one O-ring in a groove between said threads.

15. 16. A bridging conduit as claimed in claim 15, further comprising a panel joint comprising a 30 tubular body configured to extend through a panel of a box, and an annular axial seal arranged to press axially against panel opposed surfaces to seal against the panel.

16. 17. A bridging conduit as claimed in claims 15 or 16, wherein said threads hav an outside diameter matching internal diameter of the bridging conduit main body. -21

17. 18. A conduit coupler comprising a metal tubular body with a longitudinal axis and being for interconnecting conduits, said main body comprising radial surfaces including: a tapered radial surface configured to: 5 if the end is female, narrow in an axially internal direction, or if the end is male, widening in an axial internal direction, and a contact surface axially internally of said tapered surface, said contact surface being adapted to provide metal-to metal contact with a conduit radial surface for electrical earthing continuity when the coupler is connected to said conduit

18. 19. A conduit coupler as claimed in claim 18, wherein the main body comprises an annular shoulder either external or internal, having an axial contact surface with an undercut.

19.

20. A conduit coupler as claimed in claim 19, wherein the shoulder has an annular recess 15 with a gasket.