The present invention relates to a duct access system, and in particular to an underground duct access system to allow user access to underground ducts for data cables.

In underground data cable networks, the data cables tend to be carried in ducts for protection. The network includes two types of ducts: “spine” ducts, and “lead-in” ducts. Lead-in ducts are typically smaller in diameter than the spine ducts, and lead-in ducts extend over the final section of the network between the customer’s house and the adjacent spine duct.

The network may be connected to a customer’s house at the same time as the network is originally laid. However, there are often times when it is desired to connect a data cable into an existing network, for example when a customer wishes to connect to the data cable network for the first time. Another example is where a customer wishes to change to a different supplier and that supplier is allowed to install its own cables in the existing network.

It may also be desired to gain access to a duct of the existing network to clear a blockage in the duct, for example.

Hitherto, when it has been desired to connect a data cable into an existing network or to gain access to a duct of the existing network, first of all a hole is excavated to expose the underground duct. If there are several ducts side by side, the hole is excavated to expose all the ducts. The hole creates a chamber over the ducts. The ducts are then cut at their entry and exit points to the chamber, and the sections of duct between the entry and exit points are removed to expose the data cables inside. If it is desired to connect a data cable into the existing network, a separate duct for the data cable may be laid into the chamber and the data cable is run through the duct into the chamber and into one of the ducts which was cut. In some cases, a so-called swept tee can be connected to the cut ends of the duct and the separate duct may be connected to the swept tee. However, it is preferred not to use a swept tee unless necessary because it does not allow access to the data cable inside after it has been installed. This conventional approach has several drawbacks. For example, a large hole must be excavated to allow the ducts to be cut and the cut sections removed. In addition, because sections of duct are removed, there is a risk that the data cables inside will be damaged during the removal.

The present invention aims to mitigate at least one of the problems associated with conventional approaches.

A first aspect of the present invention provides a duct access system comprising a duct access device and a duct, the duct access device comprising a first part and a second part, one of the first and second parts received in and coupled to the other of the first and second parts to define a chamber inside the first and second parts, the first part comprising a duct mating portion which is shaped to mate with the radially outer surface of the duct, the duct mating portion being capable of being brought into mating contact with the radially outer surface of the duct by moving the duct mating portion only in a radial direction with respect to the duct, into a mating position in which the duct extends axially into, through and out of the first part, the second part having an opening that is large enough for a user’s hand to pass through to gain access to the chamber, and the second part being for supporting a lid for closing the chamber, wherein the duct is received in the duct mating portion in the mating position in which the duct extends axially into, through and out of the first part, wherein the portion of the duct extending through the first part has a hole in it, and the chamber allows access to the inside of the duct through the hole in the duct, and wherein one of the first and second parts is received in and coupled to the other of the first and second parts in such a way that the position of the second part can be adjusted with respect to the first part without separating the two parts to open the chamber.

When the duct access system of the first aspect of the present invention is used in order to gain access to the duct, it is only necessary to make a small hole in the duct by removing a small section of the wall of the duct. Accordingly, there is less risk of damage to the data cables inside the duct than in the conventional approach where whole lengths of duct are removed between the entry and exit points into the excavated chamber. Since only a small hole needs to be cut in the duct, the device can be rodded through unlike in the conventional approach. Moreover, a smaller hole needs to be excavated in the ground than in the conventional approach, which is less labour- intensive and also reduces the amount of material that needs to be excavated and disposed of. “Axially” refers to the longitudinal axis of the duct.

Since the position of the first and second parts can be adjusted without separating the two parts to open the chamber, the backfilling material is less likely to pass into the chamber when the device is being buried. The fact that the first and second parts are coupled together also assists in keeping backfilling material out of the chamber.

The opening is large enough for the user’s hand to pass through to gain access to the chamber. For example, the opening may have a width of at least 100mm, more preferably at least 120mm, more preferably at least 140mm. The opening may have a width in a direction perpendicular to that direction of at least 60mm, more preferably at least 70mm, more preferably at least 80mm.

Preferably, the duct is a straight duct.

Preferably, the duct mating portion is shaped to mate with a curved radially outer surface of the duct. Preferably, the outer surface of the duct curves in a direction about the longitudinal axis of the duct. Preferably, the duct mating portion is curved to mate with the curved radially outer surface of the duct. Preferably, the duct mating portion forms a section of a cylinder to mate with the radially outer surface of the duct. Preferably, the duct mating portion has a constant curvature. Preferably, the duct is circular in cross-section. Preferably, the outer diameter of the duct is at least: 20mm, 30mm, 40mm or 50mm, for example 54mm or 96mm. Preferably, the outer diameter of the duct is at most: 200mm, 150mm or 100mm.

The duct mating portion may extend outwards from one side of the first part along the longitudinal direction of the duct. The duct mating portion may extend outwards from opposite sides of the first part in opposite directions along the longitudinal direction of the duct. Thus, during installation of the duct access system, cable ties may be fastened around these portions of the duct mating portion, for example in respective slots in these portions, and around the back of the duct in order to prevent movement of the first part with respect to the duct.

As well as the duct mating portion maintaining the device in position with respect to the duct, the duct mating portion also prevents earth and other debris from passing between the device and the duct and into the hole in the duct, for example during backfilling of the hole in which the device is to be buried.

The position of the second part can be adjusted with respect to the first part without separating the two parts to open the chamber. This prevents external debris and the like from entering the chamber.

The chamber may allow access to the inside of the duct when the device is positioned over a hole in the duct so that the user can both reach and/or see into the duct.

Preferably, the duct mating portion faces away from the chamber, more preferably in the direction in which the first and second parts are arranged with respect to each other.

In the duct access system of the present invention, the first part may be a lower part, and the second part may be an upper part.

Preferably, the device is provided with means for maintaining the adjusted position of the second part with respect to the first part.

Preferably, the means for maintaining the adjusted position of the second part comprises a protrusion or flange of the second part which protrudes outward from the second part to grip in the ground when the device is buried.

Preferably, the protrusion or flange protrudes outward from the second part to restrict movement of the second part towards the first part. Preferably, the protrusion or flange protrudes outward from the second part at an angle to the direction in which the first and second parts are arranged with respect to each other. Preferably, the protrusion or flange protrudes in a direction which is normal to the direction in which the first and second parts are arranged with respect to each other. Preferably, the protrusion or flange protrudes substantially horizontally in use.

Preferably, when viewed along the direction in which the first and second parts are arranged with respect to each other, the protrusion or flange extends along the periphery of the second part. In this way, the protrusion or flange can present a large surface area to grip in the ground when viewed along the direction in which the first and second parts are arranged with respect to each other.

Preferably, the device comprises a casing defined by the first and second parts.

In one preferred form, the position of the second part can be adjusted by tilting the second part with respect to the first part. Preferably, the second part can be tilted by at least: 5°, 10°, 15°, 20° or 30°. Preferably, the second part can be tilted by up to 40°.

In one preferred form, the position of the second part can be adjusted by moving the second part away from or towards the first part.

Typically, for lead-in ducts, the standard cover depth, which is the distance from the top of the lid to the top of the lead-in duct, is 250mm. However, the duct may sometimes be installed shallower or deeper than this. The device allows the position of the second part to be adjusted with respect to the first part so that the device can be mated with a duct installed shallower or deeper than the standard cover depth. The second part may be adjusted by moving the second part away from or towards the first part by at least 10mm, more preferably by at least 20mm, more preferably by at least 30mm. The second part may be moved by up to 40mm. The minimum cover depth (when the second part has been moved towards the first part as far as possible) may be about 210mm. The maximum cover depth (when the second part has been moved away from the first part as far as possible) may be about 250mm, i.e. about standard cover depth.

For spine ducts, on the other hand, the typical standard cover depth is 300mm. The second part may be adjusted by moving the second part away from or towards the first part by at least 10mm. The second part may be moved by up to 20mm. The minimum cover depth (when the second part has been moved towards the first part as far as possible) may be about 300mm i.e. about standard cover depth. The maximum cover depth (when the second part has been moved away from the first part as far as possible) may be about 320mm.

In addition, one of the first and second parts may be cut shorter to suit shallower cover depths. The part may be cut shorter by up to 40mm.

Preferably, there is at least one hole, knock-out for a hole, or marking for a hole to be cut, in the first part or the second part through which a cable can pass from outside the device into the chamber and into the duct through the hole in the duct. Therefore, device can easily be used to connect a data cable into the existing network.

The hole, knock-out or marking may be provided with a collar protruding outwards and shaped to receive another duct for carrying the cable to hold the other duct in position.

Preferably, there is at least one of the holes, knock-outs or markings located in the second part.

Preferably, there is at least one of the holes, knock-outs or markings located in a lateral surface of the first part with respect to the longitudinal axis of the duct. This means that the cable can pass into the chamber from one side of the duct in use, which may provide a convenient way for the cable to pass into the hole in the duct. “Longitudinal axis” of the duct refers to the portion of the duct in mating contact with the duct mating portion. “Lateral surface” refers to a lateral surface when the device is in use.

Preferably, the hole, knock-out or marking allows the cable to pass into the chamber in a lateral direction with respect to the longitudinal axis of the duct.

Preferably, there is at least one of the holes, knock-outs or markings located in an end surface of the first part or the second part with respect to the longitudinal axis of the duct. This means that the cable can pass into the chamber in the same direction as the duct extends in use.

Preferably, the hole, knock-out or marking allows the cable to pass into the chamber in a longitudinal direction with respect to the longitudinal axis of the duct. Preferably, there is at least one of the holes, knock-outs or markings located in an end surface of the first part with respect to the longitudinal axis of the duct.

Preferably, the hole, knock-out or marking is laterally offset from the centre of the first part. Preferably, the hole, knock-out or marking is located on the first part between the duct mating portion and the second part. Preferably, the entire hole, knock-out or marking is located above the middle of the duct in the direction in which the first and second parts are arranged, in use. Preferably, at least part of the hole, knock-out or marking is located below the top of the duct in the direction in which the first and second parts are arranged, in use. Preferably, the hole, knock-out or marking is spaced from the duct mating portion.

Preferably, the second part (the inner part) is configured to be received in the first part (the outer part).

Preferably, one of the first and second parts (preferably, the outer part) has a surface (preferably, an inner or outer surface) which faces a portion of the other of the first and second parts (preferably, the inner part), and the surface has at least one deformable seal protruding from the surface into contact with the other of the first and second parts (preferably, the inner part) to couple the first and second parts together.

The seal acts to prevent ingress of debris during backfilling of the excavation.

The seal is deformable so it can deform when one part is tilted with respect to the other part thereby allowing the one part to tilt. In addition, when the portion of the inner part that is received in the outer part is tapered, the seal can deform to allow the vertical position of the inner part to be adjusted to a greater extent without the inner part becoming wedged in position.

The seal may take the form of a strip.

The seal may be compressible and/or flexible.

The at least one seal may be made of a foam material, and may be elongate in the direction in which it protrudes. Preferably, the first part has the duct mating portion at one of its ends, and has a side wall which extends away from the duct mating portion towards the other end of the first part, and preferably the at least one seal is attached to and protrudes from the side wall of the first part. Preferably, the second part has one (upper) end for supporting the lid, and has a side wall which extends away from that (upper) end towards the other (lower) end of the second part, and in one form the at least one seal is attached to and protrudes from the side wall of the second part. The at least one seal may protrude from the side wall of the first part towards the side wall of the second part, or vice versa.

The at least one seal may be split along its length so that the two parts can move substantially independently. There may be a gap between the parts, or the parts may contact each other.

Preferably, there are at least two seals spaced apart in the direction in which the first and second parts are arranged with respect to each other. Preferably, when viewed along the direction in which the first and second parts are arranged with respect to each other, the seal or each seal extends along the periphery of the first or second part to which it is attached. Preferably, the seal or each seal extends at a right angle to the direction in which the first and second parts are arranged with respect to each other.

Preferably, the seal is retained in position by and between a pair of ribs attached to one of the first and second parts. Preferably, the ribs are attached to and protrude from the surface of the first or second part that has the seal towards the other of the first and second parts. Preferably, when viewed along the direction in which the first and second parts are arranged with respect to each other, the each rib extends along the periphery of the first or second part to which it is attached. Preferably, the rib extends at a right angle to the direction in which the first and second parts are arranged with respect to each other.

Alternatively, the seal may be attached to one of the first and second parts, for example by an adhesive. In its non-deformed state (before insertion of the inner part into the outer part), the seal may protrude at least twice as far as the ribs, and preferably at least 3 or 4 times as far. In its deformed state however, the foam strip seal may protrude less than twice as far.

In one preferred form, the duct mating portion has: an opening, a recess, and a mating surface which defines the recess and faces the opening and which is shaped to mate with a radially outer surface of the duct, wherein, when the duct mating portion is brought into mating contact with the duct only in a radial direction with respect to the duct, the radially outer surface of the duct passes through the opening and into the recess and mating contact with the mating surface.

Preferably, the width (i.e. in a lateral direction with respect to the longitudinal axis of the duct) of the portion of the first part where the portion of the duct passes through the first part is less than twice the width of the portion of the duct, more preferably less than 1.5 times, more preferably less than 1.25 times, more preferably less than 1.2 times, more preferably less 1.1 times. In some instances, ducts may run very close alongside each other. By limiting the width of the first part in this way, the device can be used on a duct which is very close to other ducts without the device touching the other ducts.

Preferably, the chamber allows access to the inside of the duct through a gap or hole in the duct mating portion.

Preferably, when viewed along the longitudinal axis of the duct, the gap or hole in the duct mating portion is laterally offset from the centre of the first part.

Preferably, the gap or hole in the duct mating portion has guiding means at its periphery to guide duct rodding equipment travelling along the duct away from the gap or hole. This reduces the risk of the duct rodding equipment travelling upwards into the gap or hole and becoming caught. The guiding means may include an inclined surface to guide the rodding equipment away from the duct mating portion. The guiding means may be provided on the leading edge and/or trailing edge of the gap or hole with respect to the longitudinal direction of the duct. Preferably, the device further comprises a foam filter positioned to prevent debris from passing from the second part into the first part.

Preferably, when the duct mating portion is in mating contact with the radially outer surface of the duct, the opposite radially outer surface of the duct protrudes beyond the first part in the direction in which the first and second parts are arranged with respect to each other. This means the user does not need to dig such a deep hole to accommodate the duct mating portion, and therefore there is less disturbance and risk of damage to the duct.

Preferably, the device further comprises an intermediate part or frame coupled to the second part for supporting the lid, wherein the intermediate part or frame is rotatable with respect to the first part so that the lid is rotatable with respect to the first part.

The device may further comprise the lid.

Typically, the outer diameter of the lead-in duct is 54mm, and the outer diameter of the spine duct is 96mm.

A typical lid may have dimensions of 125mm by 140mm, or 150mm by 150mm, in plan view.

Preferably, when the chamber is viewed along the direction in which the first and second parts are arranged, the chamber has an internal dimension which is at least 100mm, more preferably at least 120mm, more preferably at least 140mm. That is, the dimension is in a direction normal to the direction in which the first and second parts are arranged. In this way, the chamber may be large enough to receive the hand of the user.

Preferably, when viewed in the same direction, the chamber may have an internal dimension which is at least 100mm, more preferably at least 120mm, more preferably at least 140mm, and an internal dimension perpendicular to that dimension which is at least 60mm, more preferably at least 70mm, more preferably at least 80mm. In this way, the chamber may be large enough to receive the hand of the user. Preferably, the first and/or second part includes coupling means to couple the first and second parts together.

Preferably, the second part comprises a flange for supporting the lid or another part for supporting the lid. Preferably, one end of the second part is configured to be received in the first part, and preferably the flange is provided at the other end of the second part.

Preferably, the second part comprises a tubular portion configured to be received in a tubular portion of the first part. Alternatively, the first part may comprise a tubular portion configured to be received in a tubular portion of the second part. The tubular portions may be rectangular in cross-section, or square, circular or oval in cross- section.

Preferably, the tubular portion of the second part narrows towards its end which is received first, so that its end is smaller than the opening. In this way, two of the parts can be stacked on top of each other.

Preferably, an opening is formed at one end of the tubular portion of the second part, and allows access into the tubular portion and chamber.

Preferably, the chamber extends from the opening through the tubular portion of the second part and the tubular portion of the first part to where the duct passes through the device.

A second aspect of the present invention provides a method of installing a duct access system according to any preceding claim, comprising the step of bringing the duct mating portion into mating contact with the radially outer surface of the duct by moving the duct mating portion only in a radial direction with respect to the duct, into a mating position in which the duct extends axially into, through and out of the first part.

The method of the second aspect may comprise the step of inserting one of the first and second parts into the other of the first and second parts. The method of the second aspect may comprise the step of adjusting the position of the first part with respect to the second part.

The method of the second aspect may comprise the step of removing, for example by cutting, a portion of the first or second part so that more of it can be received in the other of the first or second part. Preferably, in this step, a portion of the tubular portion may be removed.

The method of the second aspect may comprise the step of stacking two or more of the second parts on top of each other. The step may comprise inserting the tubular portion of one second part into the opening of another second part.

The method may comprise the step of cutting a hole in the duct. The method may comprise the steps of removing a portion of the duct which is less than the whole circumference or periphery of the duct. The removal of such a portion does not completely split the duct in two.

A third aspect of the present invention provides a duct access device holding tool for holding a duct access device in the ground, the holding tool comprising: a first foot and a second foot for supporting the holding tool on the ground, each foot having a ground contacting surface; a bridge section extending from the first foot to the second foot; and a pair of manually adjustable jaws, which are lockable or biased together, between the first foot and the second foot and connected to the bridge section; wherein, when the ground contacting surfaces of the first and second feet are in a first plane, the jaws are configured to grip the duct access device when positioned between the first and second feet further from the bridge section than the first plane.

As the jaws are manually adjustable, there is no need for an electrical power source. This provides a simple and robust solution. Since the jaws are configured to grip the duct access device further from the bridge section than the first plane, the jaws can grip the duct access device below the level of the ground, in use. The top of the lid of the duct access device is typically desired to be level with the ground when installed. The tool therefore needs to grip the duct access device below the level of the ground. The tool is preferably portable. If the tool can be carried by a user, it may be easier to manoeuvre than if the tool needs to be wheeled into position.

Preferably, the jaws are adjustable without changing their relative orientation. For example, a substantially parallel orientation of jaws can be maintained during adjustment.

Preferably, the length of bridge section is adjustable so that the distance between the first and second feet can be adjusted. This means different widths of excavations can be accommodated. Preferably, the length of bridge section is adjustable so that the distance between the first foot and the jaws can be adjusted. More preferably, the length of bridge section is adjustable so that the distance between the first foot and the jaws and between the second foot and the jaws can be adjusted.

Preferably, the length of the bridge section is adjustable by sliding one portion of the bridge section along another. Preferably, the length of the bridge section is adjustably by way of a telescopic arrangement.

Preferably, the length of the bridge section is adjustable between the first foot and the jaws. Preferably, the length of the bridge section is adjustable between the first foot and the jaws on one side of the jaws, and is adjustable between the second foot and the jaws on the other side of the jaws.

Preferably, the length of bridge section is adjustable and lockable in its adjusted length.

Preferably, the bridge section is lockable in its adjusted length by means of a locking pin or screw in a first part of the bridge section being removably received in a hole in a second part of the bridge section. Preferably, the second part of the bridge section has at least two holes so that the first part is lockable in at least two different positions with respect to the second part.

Preferably, the jaws are lockable by means of a rod connected to a first of the jaws slidable in a groove formed in, or in a part fixed to, a second of the jaws, the position of the rod in the groove being lockable. Preferably, the rod is threaded, with a handle in threaded engagement with the rod, and the handle can be rotated to grip the second jaw, or a part fixed to the second jaw, between the handle and the first jaw, or a part fixed to the first jaw.

Preferably, the jaws are connected to the bridge section between the first and second feet.

Preferably, the jaws are configured to grip the duct access device so as to prevent movement of the duct access device in a direction parallel with the first plane. Hence the jaws prevent horizontal movement of the duct access device, in use of the tool.

Preferably, wherein the jaws are connected to the bridge section so as to prevent rotation or swinging of the jaws with respect to the bridge section. In this way, the jaws may prevent horizontal movement of the duct access device, in use of the tool.

Preferably, the jaws are configured to grip outer sides, preferably a pair of opposite outer sides, more preferably two pairs of opposite outer sides, of the duct access device, which are normal to the first plane, further from the bridge section than the first plane.

Preferably, each jaw extends (from its fixed end to its free end) towards the first plane. Therefore, the jaws extend vertically downwards in use of the tool.

Preferably, the jaws a positioned approximately halfway between the first and second feet.

A fourth aspect of the present invention provides a duct cutting or marking guide, comprising: a duct mating portion having a curved inner surface which is shaped to mate with a curved radially outer surface of a duct, the duct mating portion having a guiding hole which, when the duct mating portion is in a mating position on the duct, is able to guide a cutting tool or marker to cut or mark a hole in the radially outer surface of the duct, and a spirit level. A pen may be used as the marker. A depth-stopped vibrating multi-cutter may be used as the cutting tool.

Preferably, the duct is a straight duct.

Preferably, the duct cutting or marking guide further comprises a handle for moving the guide into an out of a mating position on the duct.

Preferably, the spirit level measures the level in two mutually perpendicular directions.

Preferably, when the duct mating portion is in a mating position on the duct, the spirit level is configured to measure the level in a duct lateral direction.

Preferably, when the duct mating portion is in a mating position on the duct, the spirit level is configured to measure the level in the duct longitudinal direction.

Preferably, the duct mating portion comprises two parts hinged together so that the duct mating portion can be opened to receive the duct.

Preferably, the duct mating portion is in a mating position on the duct, the two parts are hinged together by a hinge whose axis is substantially parallel to the longitudinal axis of the duct. This allows parts to open in a duct lateral direction. Preferably, the two parts are hinged together by two such hinges.

Preferably, the two parts of the duct mating portion are joined to a respective flange, and the two parts are hinged together by a hinge joined to the respective flanges.

Preferably, the two parts are hinged together by two such hinges.

The duct cutting or marking guide may further comprise a locking mechanism to lock the two parts of the duct mating portion in a closed position on the duct.

Preferably, the locking mechanism comprises a rod received in respective recesses in the flanges. Preferably, when the duct mating portion is in a mating position on the duct, the rod extends in a direction substantially parallel to a tangent of the duct.

Preferably, the recesses are located between the two hinges.

Preferably, the locking mechanism comprises a handle in threaded engagement with a threaded rod to allow the tightness of the locking mechanism to be adjusted. The rod may be the rod of the locking mechanism previously described.

The locking mechanism may comprise an over-centre mechanism to lock the locking mechanism.

The over-centre mechanism may comprise a cam lever.

Preferably, a straight edge of the guiding hole extends along the longitudinal axis of the duct when the duct mating portion is in a mating position on the duct.

Preferably, the straight edge is the longest edge of the guiding hole.

Preferably, the guiding hole is rectangular or square in the duct radial direction.

Preferably, the duct mating portion is made of a rigid material.

Preferably, the duct mating portion is capable of being brought into mating contact with the radially outer surface of the duct by moving the duct mating portion only in a radial direction with respect to the duct, into a mating position in which the duct extends axially into, through and out of the duct mating portion.

A duct cutting system may comprise the duct cutting or marking guide and the duct.

A fifth aspect of the present invention provides a duct access device comprising a first part and a second part, one of the first and second parts configured to be received in and coupled to the other of the first and second parts to define a chamber inside the first and second parts, the first part comprising a duct mating portion having a curved inner surface which is shaped to mate with a curved radially outer surface of a straight duct, the duct mating portion being capable of being brought into mating contact with the radially outer surface of the duct by moving the duct mating portion only in a radial direction with respect to the duct, into a mating position in which the duct extends axially into, through and out of the first part, the second part having an opening that is large enough for a user’s hand to pass through to gain access to the chamber, and the second part being for supporting a lid for closing the chamber, wherein, when the portion of the duct extends through the first part has a hole in it, the chamber allows access to the inside of the duct through the hole in the duct, and wherein one of the first and second parts is configured to be received in and coupled to the other of the first and second parts in such a way that the position of the second part can be adjusted with respect to the first part without separating the two parts to open the chamber.

The optional features of the duct access system of the first aspect are equally applicable to the duct access device of the fifth aspect.

A sixth aspect of the present invention provides a kit of parts comprising a duct access device holding tool according to the third aspect, a duct cutting or marking guide according to the fourth aspect; and a duct access device according to the fifth aspect.

Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of a duct access system according to a first embodiment;

Fig. 2 is a perspective view of the duct access system of Fig. 1 but with the duct hidden;

Fig. 3 is a plan view of the duct access system of Fig. 1;

Fig. 4 is a cross-sectional view of the duct access system of Fig. 2; Fig. 5 is another cross-sectional view of the duct access system of Fig. 2;

Fig. 6 is a perspective view of a duct access system according to a second embodiment;

Fig. 7 is a perspective view of the duct access system of Fig. 6 but with the duct, frame and lid hidden;

Fig. 8 is a plan view of the duct access system of Fig. 7;

Fig. 9 is a plan view of the duct access system of Fig. 6 but with the duct and lid hidden;

Fig. 10 is a cross-sectional view of the duct access system of Fig. 6 but with the duct hidden;

Fig. 11 is another cross-sectional view of the duct access system of Fig. 6 but with the duct hidden;

Fig. 12 is another cross-sectional view of the duct access system of Fig. 6;

Fig. 13 is a perspective view of a duct access device holding tool according to a third embodiment;

Fig. 14 is a perspective view of the holding tool of Fig. 13 but with the duct access device hidden;

Fig. 15 is a front elevation view of the holding tool of Fig. 14;

Fig. 16 is a perspective view from below of the holding tool of Fig. 14;

Fig. 17 is a perspective view of a duct cutting system according to a fourth embodiment; and

Fig. 18 is a perspective view of a duct cutting system according to a fifth embodiment. Fig. 1 shows a lead-in duct access system 1 of a first embodiment of the present invention comprising a duct access device 2 and a straight lead-in duct 20 of 54mm outer diameter.

Referring to Fig. 1, the duct access device 2 is shown comprising a casing 9 defined by a first, lower part 5 and a second, upper part 6. In the present embodiment, the upper part 6 is received in and coupled to the lower part 5 to define a chamber 10 inside the lower part 5 and the upper part 6.

The upper part 6 comprises a tubular portion 4 which is received in a corresponding tubular portion 3 of the lower part 5 to define the chamber 10. In the present embodiment, the tubular portions 3, 4 are rectangular in cross-section, but this is not essential and they could, for example, be square, circular or oval in cross-section.

The first, lower part 5 may be referred to as a duct mating collar, and the second, upper part 6 may be referred to as a frame mounting collar.

The first, lower part 5 comprises a duct mating portion 15 which is shaped to mate with the radially outer surface of the duct 20. In the present embodiment, the duct 20 has a 54mm outer diameter. In other embodiments, the duct mating portion 15 may be shaped to mate with the radially outer surface of a larger or smaller duct.

The duct mating portion 15 extends from opposite sides of the first, lower part 5 in opposite directions along the longitudinal direction of the duct 20.

The second, upper part 6 allows access to the chamber 10 through an opening 22. The opening 22 is large enough for the user’s hand to pass through. The second, upper part 6 is for supporting a lid for closing the chamber 10. In the present embodiment, the upper part 6 does not connect directly to the lid, but an intermediate part (not shown) is interposed between the upper part 6 and the lid. However, this is not essential, and in other embodiments the upper part 6 may connect directly to the lid. In the present embodiment, the intermediate part and lid are the same as the intermediate part or frame 107 and lid 108 of the second embodiment described below. Fig. 2 is the same view as Fig. 1 except that the duct 20 is not shown. Fig. 2 shows how the duct mating portion 15 is capable of being brought into mating contact with the radially outer surface of the duct 20 by moving the duct mating portion 15 only in a radial direction with respect to the duct 20, into a mating position in which the duct 20 extends axially into, through and out of the lower part 5. Therefore, the device can be mated with a duct 20 between its ends, rather than requiring the duct 20 to have a free end, and so the device can be used with in-situ ducts which are already connected to the network. The ducting mating portion 15 has an opening 16, a recess 21 and a mating surface 23 which defines the recess 21 and faces the opening 16 and is shaped to mate with the radially outer surface of the duct 20. In the present embodiment, the opening 16 of the duct mating portion is narrower than the outer dimension of the duct 20. However, the duct mating portion 15 is flexible enough for the opening 16 to flex open so that it can receive and mate with the duct 20. In this regard, the duct mating portion 15 may be formed of polypropylene, and the duct 20 may be made of polyethylene, and the duct mating portion 15 may be able to flex over the duct 20. Alternatively, in this embodiment, the lower part 5 is formed of two parts 5a, 5b which can be separated in a direction perpendicular to the longitudinal direction of the duct 20. The two parts 5a, 5b are held together by clips 17 which can be opened when the parts 5a, 5b need to be separated. The separated parts 5a, 5b can be brought together around the duct 20 only in a radial direction with respect to the duct 20.

Referring to Fig. 1, the duct 20 is received in the duct mating portion 15 in the mating position in which the duct 20 extends axially into, through and out of the lower part 5.

Fig. 3 is a plan view of the duct access system 1 shown in Fig. 1. Fig. 3 shows the device 2 positioned over a hole 25 in the duct 20. The portion of the duct 20 extending through the lower part 5 has the hole 25 in it. The chamber 10 allows access to the inside of the duct 20 through the hole 25 in the duct 20 so that the user can reach into the duct 1.

Referring to Fig. 1 again, the second, upper part 6 is received in and coupled to the lower part 5 in such a way that the position of the second, upper part 6 can be adjusted with respect to the first, lower part 5 without separating the two parts to open the chamber 10 or the casing 9. The duct access device 2 is provided with means in the form of a flange 28 for maintaining the adjusted position of the second, upper part 6 with respect to the first, lower part 5 when the device 2 is buried. The flange 28 protrudes outward from the upper part 6 to grip in the earth when the device 2 is buried. In this embodiment, the flange 28 also supports another part (an intermediate part, not shown) for supporting the lid. The other part is stacked on the flange 28, and the lid is stacked on the other part. The other part may be referred to as a frame.

In the present embodiment, the upper part 6 is received in the lower part 5. In this way, the upper part 6 can be considered the inner part, and the lower part 5 can be considered the outer part. In particular, one end of the upper part 6 (the lower end of the upper part 6) acts as a spigot and is received in one end of the lower part 5 (the upper end of the lower part 5) which acts as a socket.

In the present embodiment, the flange 28 protrudes outward from opposite end of the upper part 6 from the end which is received in the lower part 5.

The lower part 5 has four knock-outs 11-14 for holes in its lateral surfaces. Once one of the knock-outs has been knocked out to form a hole, the user can pass a cable from the duct 20 into the bottom of chamber 10, through the newly-formed hole, and out of the device 2. Each knock-out 11-14 has a collar 1 T-14’ protruding outwards and shaped to receive another duct for carrying the cable, to hold the other duct in position.

The upper part 6 has markings 18, 19 for holes to be cut on its longitudinal end surfaces. The holes can receive cables, and ducts for the cables, when it is desired to connect them into the duct 20.

Fig. 4 shows a vertical cross-section of the device 2 shown in Fig. 2. The opening 22 is formed at one end of the tubular portion 4 of the upper part 6, and allows access into the tubular portion 4 and chamber 10. The chamber 10 extends from the opening 22 through the tubular portion 4 of the upper part 6 and the tubular portion 3 of the lower part 5 to where the duct 20 passes through the device 2. In the present embodiment, this is the lower portion of the lower part 5 which is adjacent to the tubular portion 3.

The mating surface 23 is shaped to mate with the radially outer surface of the duct 20. In this embodiment, the mating surface 23 forms part of a circle in cross-section along the longitudinal axis of the duct 20. Referring to Fig. 4, as mentioned above, the second, upper part 6 is received in and coupled to the lower part 5 in such a way that the position of the second, upper part 6 can be adjusted with respect to the first, lower part 5 without separating the two parts to open the chamber 10 or the casing 9. In particular, the upper part 6 (the inner part) is received in the lower part 5 (the outer part); the outer part 5 has an inner surface 30 which faces a portion of the inner part 6 that is received in the outer part 5; and the outer part 5 has two ribs 31, 32 attached to and protruding from the inner surface 30 towards the inner part 6. The ribs 31 , 32 are provided to define a space 35 between them for a seal in the form of a foam strip. The ribs 31, 32 retain the foam strip seal in position. The foam strip seal is not shown in the drawings. The foam strip seal couples the inner and outer parts 6, 5 together. Thus, the position of the inner part 6 can be adjusted by moving it towards or away from the outer part 5, or by tilting it with respect to the outer part 5, and that movement or tilting will not open the chamber 10 or casing 9. The foam strip seal also acts to prevent ingress of debris during backfilling of the excavation.

In the present embodiment, in its non-deformed state (before insertion of the inner part 6 into the outer part 5) the foam strip seal protrudes about four times as far as the ribs 31, 32. The foam strip seal is also positioned midway between the ribs 31, 32 and is wider than the distance it protrudes.

In the present embodiment, the inner part 6 can be tilted by up to 40°. That is, the inner part 6 can be tilted between positions which are 40° apart.

The tubular portion 3 of the lower part 5 has the inner surface 30 with the ribs 31, 32. The ribs 31, 32 protrude from the inner surface 30 towards an outer surface 34 of the tubular portion 4 of the upper part 6.

In the present embodiment, the ribs 31, 32 are not each formed in one piece around the periphery of the lower part 5, but are separated into parts by gaps. The gaps are formed at the corners of the tubular portion 3 of the lower part 5. In the present embodiment, each rib is also split at a position along its length but without a gap.

Fig. 4 shows an internal dimension A of the chamber 10. This dimension A is in a direction normal to the direction in which the first and second parts 5, 6 are arranged. (The first and second parts 5, 6 are arranged in the Y direction shown in Fig. 4). In this embodiment, the dimension A is about 75mm.

Referring to Figs. 4 and 5, compression dampers or stops 40 are located in the tubular portion 3 of the lower part 5 to stop the tubular portion 4 of the upper part 6 above the duct 20. This prevents the tubular portion 4 from coming into contact with the duct 20 and prevents any direct vertical load on the duct 20.

Fig. 5 shows another vertical cross-section of the device 2 shown in Fig. 2. Fig. 5 also shows an internal dimension B of the chamber 10. This dimension is in a direction perpendicular to the direction in which dimension A is measured, and also perpendicular to direction Y. In this embodiment, the dimension A is about 150mm. In this way, the chamber is intended to be large enough to receive the hand of the user.

Next, a method of installing the duct access system 1 of the first embodiment will now be described. First of all, a hole is excavated to expose the duct 20. If it is desired to connect a new cable or duct into the duct access device 2 and existing duct 20, additional excavation will be required in which to lay the new cable or duct. In that case, holes in the duct access device 2 are cut or knocked out as desired at knock-outs 11-14 or markings 18, 19. It is also possible to cut a hole in the intermediate part or frame if it is desired to lay a new cable or duct nearer the surface.

Next, the user positions cable ties under and around the duct 20 ready to fix the duct mating portion 15 to the duct 20. Then the user cuts a hole in the duct 20 being careful not to damage any cables within the duct 20. The hole is cut above the horizontal, typically so that the middle of the hole is about 30-40° above the horizontal. This means that new cabling descends down to the existing cabling in the duct, rather than crossing the existing cabling from the side as would be the case with a swept tee providing a horizontal entry point. A swept tee cannot be used in this way in cases where there are three ducts side by side and the two outer ducts are blocking the horizontal entry points to the inner duct. If a hole were cut so that the new cabling descends down from directly above the duct (top dead centre), the new cabling can create a ramp up which duct rodding equipment can climb. The rodding equipment can then easily snag on the cabling which can block passage of the duct rodding equipment. However, entry of the new cabling at about 30-40° above the horizontal allows the new cabling to be shed from the duct rodding equipment more easily thereby reducing the likelihood of snagging, blockage of the duct and damage to the new cabling.

For this, a template tool or duct marking guide which mates with the duct 20 may be used to mark the position of the hole, for example with a pen. The tool has an opening of the same size as the hole desired to be cut into the duct 20. When cutting the hole, a depth-stopped vibrating multi-cutter may conveniently be used, with which the user follows the marks to cut the hole. The cut-out section of duct is then removed. After that, the user uses the hole in the duct 20 as desired, for example for clearing a blockage in the duct 20, for rodding the duct 20, or to install a cable in the duct 20. When a new cable is installed, the user passes the cable along the existing duct 20 to the position of the hole, out of the hole in the duct 20, through the chamber 10 of the device 2 and out of the hole knocked out at knock-outs 11-14. Alternatively, the cable may be passed out of holes cut at markings 18, 19 in the upper part 6.

The lower part 5 is then fitted to the duct 20 by the duct mating portion 15 being brought into mating contact with the duct 20 so that the device 2 is positioned over the hole in the duct 20.

The cable ties are brought up around the duct 20 and duct mating portion 15 at each side of the lower part 5 to fix the device 2 in position on the duct 20. One of the cable ties passes around the duct 20 and sits over clip 17 on duct mating portion 15 shown in Fig. 2.

When a new cable is being installed, an exit duct may next be attached to one of the collars 11-14’.

Next, the upper part 6 is fitted to the lower part 5 by the user pushing the upper part into the lower part 5. The user pushes the upper part 6 into the lower part until the desired height and tilt is achieved. When the device 2 is being used for less than standard cover depths, the upper part 6 (specifically, the tubular portion 4 of the upper part) can be cut shorter. On the other hand, when the device is being used for unusually deep excavations, an additional upper part 6 or parts 6 can be stacked on top of the first upper part 6. This is possible because the upper part 6 tapers (narrows) slightly from the end with the opening 22 to its other end.

When a new cable is being installed, an exit duct may next be attached to one of the holes cut at markings 18, 19 in the upper part 6.

After that, the intermediate part or frame and lid is fitted to the top of the upper part 6 and is rotated in order to align it with street features.

Backfilling of the hole then begins using sand around the duct 20 and duct mating portion 15. The sand is then compacted. At this point, an alignment tool or jig may be used once the level of the top of the device 2 has been matched with the ground, to hold the device 2 in position during curing of the concrete. Then the concrete is poured up to the level of the underside of the flange 28 of the upper part 6, and is left to cure. The concrete holds the flange 28 in position in the ground. Finally, the surface is reinstated using the desired surface material.

The installed system 1 provides a user access point allowing the user to revisit and inspect the duct 120 and any newly connected ductwork.

The duct access system 101 of a second embodiment of the present invention will now be described. Fig. 6 shows a spine duct access system 101 of a second embodiment of the present invention comprising a duct access device 102 and a straight spine duct 120 of 96mm outer diameter.

Referring to Fig. 6, the duct access device 102 is shown comprising a casing 109 defined by a first, lower part 105 and a second, upper part 106. The upper part 106 is the same as the upper part 6 of the first embodiment. In the present embodiment, the upper part 106 is received in and coupled to the lower part 105 to define a chamber 110 (not shown in Fig. 6) inside the lower part 105 and the upper part 106.

The upper part 106 comprises a tubular portion 104 which is received in a corresponding tubular portion 103 of the lower part 105 to define the chamber 110. In the present embodiment, the tubular portions 103, 104 are rectangular in cross-section, but this is not essential and they could, for example, be square, circular or oval in cross-section.

The first, lower part 105 may be referred to as a duct mating collar, and the second, upper part 106 may be referred to as a frame mounting collar.

The first, lower part 105 comprises a duct mating portion 115 which is shaped to mate with the radially outer surface of the duct 120. In the present embodiment, the duct 120 has a 96mm outer diameter. In other embodiments, the duct mating portion 115 may be shaped to mate with the radially outer surface of a larger or smaller duct.

As in the first embodiment, in the second embodiment the duct mating portion 115 extends from opposite sides of the first, lower part 105 in opposite directions along the longitudinal direction of the duct 120.

In the present embodiment, the duct access device 102 further comprises an intermediate part or frame 107 and a lid 108. The frame 107 is stacked on the upper part 106, and the lid 108 is stacked on the frame 107. In the present embodiment, the frame 107 is received in the upper part 106, and the lid 108 is received in the frame 107. However, the frame 107 is not essential, and in other embodiments the upper part 106 may connect directly to the lid 108.

Fig. 7 is the same as Fig. 6 except that the duct 120, frame 107 and lid 108 are not shown. The second, upper part 106 allows access to the chamber 110 through an opening 122. The opening 122 is large enough for the user’s hand to pass through. Fig. 7 shows how the duct mating portion 115 is capable of being brought into mating contact with the radially outer surface of the duct 120 by moving the duct mating portion 115 only in a radial direction with respect to the duct 120, into a mating position in which the duct 120 extends axially into, through and out of the lower part 105. Therefore, the device can be mated with a duct 120 between its ends, rather than requiring the duct 120 to have a free end, and so the device can be used with in-situ ducts which are already connected to the network. In this embodiment, the lower part 105 is formed of two parts 105a, 105b. In the second embodiment, unlike the first embodiment, the two parts 105a, 105b can be separated in a direction along the longitudinal direction of the duct 120. The two parts 105a, 105b are held together by clips 117 which can be opened when the parts 105a, 105b need to be separated.

Referring to Fig. 6, the duct 120 is received in the duct mating portion 115 in the mating position in which the duct 120 extends axially into, through and out of the lower part

105.

Fig. 8 is a plan view of the duct access system 101 shown in Fig. 7. In the present embodiment, unlike in the first embodiment, the duct mating portion 115 also extends from one side of the first, lower part 105 to the other side of the first, lower part 105 along the longitudinal direction of the duct 20, thereby forming a floor 111 of the chamber 110. As shown in Fig. 12, the device 102 is positioned over two holes 125, 126 in the duct 120. The portion of the duct 120 extending through the lower part 105 has the two holes 125, 126 in it. The duct mating portion 115 (floor 111) has holes 135, 136 which coincide with holes 125, 126 in the duct 120. The chamber 110 allows access to the inside of the duct 120 through the holes 125, 126 in the duct 120 so that the user can reach into the duct 101.

In Fig. 9, dimension C is a dimension along the Z direction of the opening in the frame 107 below the lid 108 which has been removed in Fig. 9. Dimension D is a dimension along the X direction of the opening in the frame 107 below the lid 108. Dimension C is about 130mm. Dimension D is about 100mm.

Referring to Figs. 7 and 9, the upper part 106 has a recess 142 in which the frame 107 is received. The frame 107 has a flange 145 to contact the flange 128 of the upper part

106. The recess 142 of the upper part 106 for receiving the frame 107 is generally circular in plan view. The flange 145 of the frame 107 is also generally circular in plan view, which allows the frame 107 to be rotated in the recess 142 about a vertical axis (the Y axis).

Teeth 140 (two in the present embodiment) protrude inwards from the inner cylindrical side walls 141 of the recess 142 of the upper part 106 in which the frame 107 is received. The teeth 140 are diametrically opposed. The flange 145 of the frame 107 has flattened portions 148 diametrically opposed so that the flange 145 can fit between the teeth 140 during insertion into the recess 142. Once inserted, the frame 107 and flange 145 are rotated so that the teeth 140 overlie the flange 145 and prevent it being removed from the recess 142. The frame 107 can be rotated to a desired position so as to line up with features of the street in which the system 101 is being installed (for example, the side of the pavement).

Fig. 10 shows a vertical cross-section of the device shown in Fig. 6 but with the duct not shown. The opening 122 is formed at one end of the tubular portion 104 of the upper part 106, and allows access into the tubular portion 104 and chamber 110. The chamber 110 extends from the opening 122 through the tubular portion 104 of the upper part 106 and the tubular portion 103 of the lower part 105 to where the duct 120 passes through the device 102. In the present embodiment, this is the duct mating portion 115.

The ducting mating portion 115 has an opening 116, a recess 121 and a mating surface 123 which defines the recess 121 and faces the opening 116 and is shaped to mate with the radially outer surface of the duct 120. In this embodiment, the mating surface forms 123 part of a circle in cross-section along the longitudinal axis of the duct 120.

Referring to Fig. 10, as mentioned above, the second, upper part 106 is received in and coupled to the lower part 105 in such a way that the position of the second, upper part 106 can be adjusted with respect to the first, lower part 105 without separating the two parts to open the chamber 110 or the casing 109. In particular, the upper part 106 (the inner part) is received in the lower part 105 (the outer part); the outer part 105 has an inner surface 130 which faces a portion of the inner part 106 that is received in the outer part 105; and the outer part 105 has three flexible rib 131, 132, 133 attached to and protruding from the inner surface 130 towards the inner part 106. Ribs 131, 133 are provided to define a space 138 between them for a seal in the form of a foam strip. The ribs 131, 133 retain the foam strip seal in position. The foam strip seal is not shown in the drawings. The foam strip seal couples the inner and outer parts 106, 105 together. (The rib 132 is only provided on longitudinal end surfaces of the lower part 105.) Thus, the position of the inner part 106 can be adjusted by moving it towards or away from the outer part 105, or by tilting it with respect to the outer part 105, and that movement or tilting will not open the chamber 110 or casing 109. The foam strip seal also acts to prevent ingress of debris during backfilling of the excavation. The foam strip seal is the same as that of the first embodiment.

The tubular portion 103 of the lower part 105 has the inner surface 130 with the ribs 131, 132, 133. The ribs 131, 132, 133 protrude from the inner surface 130 towards an outer surface 134 of the tubular portion 104 of the upper part 106.

In the present embodiment, the ribs 131, 132, 133 are not each formed in one piece around the periphery of the lower part 105, but are separated into parts by gaps.

Referring to Figs. 10 to 12, each hole 135, 136 in the duct mating portion 115 (floor 111) has guiding means 150 at its periphery in the form of inclined surfaces 155 to guide rodding equipment travelling along the duct 120 away from the duct mating portion 115 and to stop the equipment riding up through the holes 135, 136 in the duct mating portion 115. In the present embodiment, plural inclined surfaces are arranged along each longitudinal edge of the holes 135, 136, but this is not essential. For example, a single inclined surface may be provided along each edge. Also, the inclined surface or surfaces may only be provided at the outer longitudinal edges of the holes 135, 136. In addition, a single hole may be provided instead of two holes 135, 136.

Next, a method of installing the duct access system 101 of the second embodiment will now be described. The method of installing the duct access system 101 of the second embodiment corresponds to the method of method of installing the duct access system 1 of the first embodiment except for the following points. Firstly, as in the first embodiment, a template tool or duct cutting guide which mates with the duct may be used, but in the second embodiment the tool is clamped to the duct and left in situ while the hole in the duct is cut. Secondly, after installing the upper part 106 and before installing the intermediate part or frame 107, a foam filter in the form of a silt filter block is inserted into the tubular portion 104 of the upper part 106. The silt filter block may be sized so that it becomes wedged in position in the slightly tapering tubular portion 104, or it may be fixed by an interference fit. When the lid is being removed, for example, the silt filter block catches silt to prevent it from falling into the lower part 5, but allows water to pass. The duct access device holding tool 201 of a third embodiment of the present invention will now be described.

Fig. 13 shows a duct access device holding tool 200 of a third embodiment of the present invention holding a duct access device 202. In Fig. 13, only the top of the duct access device 202 is shown, in particular, the frame 207 and lid 208 (which correspond to the frame 107 and lid 108 of the second embodiment).

The duct access device holding tool 200 is for holding the duct access device 202 in the ground. The holding tool 200 comprises a first foot 203, a second foot 204, a third foot 205 and a fourth foot 206 for supporting the holding tool 200 on the ground. Each foot 203-206 has a ground contacting surface.

The holding tool 200 comprises a bridge section 210 extending from the first foot 203 to the second foot 204, and from the third foot 205 to the fourth foot 206. In the present embodiment, the bridge section includes legs 213, 214, 215, 216, one for each foot 203-206, which extend vertically upwards from each foot 203-206.

Referring to Fig. 14, the holding tool 220 comprises a pair of manually adjustable jaws 211, 212 between the first foot 203 and the second foot 204, and between the third foot 205 and the fourth foot 206, and connected to the bridge section 210.

Fig. 15 shows the ground contacting surface 203’ of the first foot 203, and the ground contacting surface 204’ of the second foot 204. Referring to Figs. 13 and 15, when the ground contacting surfaces 203’, 204’ of the first and second feet 203, 204 are in a first plane, the jaws 211, 212 are configured to grip the duct access device 202 when positioned between the first and second feet 203, 204 further from the bridge section 210 than the first plane. Fig. 13 shows the duct access device 202 positioned between the first and second feet 203, 204, and between the third and fourth feet 205, 206.

In the present embodiment, the jaws 211, 212 face each other and are substantially parallel to each other, and this orientation can be maintained during adjustment of the jaws 211, 212.

Jaw 211 is fixed perpendicularly to a plate 218 forming part of the bridge section 210. Plate 218 extends in a horizontal plane. Jaw 211 has a pair of spaced apart, parallel side members 211a, 211b which lie in the same plane. One end (the upper end) of each of the side members 211a, 211b is fixed to the plate 218. Jaw 211 also has a crossing member 211c which crosses between, and is fixed to, respective lower ends of the side members 211a, 211b.

In the present embodiment, the side members 211a, 211b are inside the crossing member 211c in the direction in which the jaws 211, 212 face each other. Therefore, when the holding tool 200 is used with the duct access device 202 shown in Fig. 13, the side members 211a, 211b contact the outer side surface of the duct access device 202 when the jaws 211, 212 close. The side members 211a, 211b are dimensioned and positioned so that they do not come into contact with the triangular ribs formed on the outer side surface of the duct access device 202.

Where the crossing member 211c is fixed to the respective lower ends of the side members 211a, 211b, the crossing member 211c lies in the same plane. At each of its ends the crossing member 211c bends at right angles to form a preferably short guiding section. The guiding section guides the jaw 211 onto the duct access device. In particular, the guiding sections contact opposing outer side surfaces of the duct access device 202 (which are adjacent to the outer side surface of the duct access device 202 that the side members 211a, 211b contact).

In this embodiment, the crossing member 211c has a recessed section 211 d between where it is fixed to the side members 211a, 211b. The recessed section is recessed outwards in the direction in which the jaws 211, 212 face each other. The purpose of the recessed section is twofold: firstly, to avoid the crossing member 211c coming into contact with the triangular ribs formed on the outer side surface of the duct access device 202; and secondly, so that the holding tool 200 can be used with a narrower duct access device (not shown in the drawings) and so that the recessed section 211 d provides guiding sections to guide opposing outer side surfaces of the narrower duct access device.

Jaw 212 has the same structure as jaw 211 described above but faces in the opposite direction so that the jaws 211, 212 oppose each other. Jaw 211 is fixed perpendicularly to the plate 218 forming part of the bridge section 210. The plate 218 has a pair of parallel grooves 219, 220, extending in the direction that the jaws 211, 212 are opposed, but alternatively a single groove may be provided. Jaw 212 is fixed perpendicularly to a different plate 222 to which rods 224, 225 are fixed. Rod 224 is located in groove 219, and rod 225 is located in groove 220. Plate 222 extends in a horizontal plane in a direction perpendicular to the direction in which the jaws 211, 212 face each other.

In the present embodiment, each rod 224, 225 is threaded and a respective handle 226, 227 is threadedly engaged with each rod 224, 225. Each handle 226, 227 can be rotated by the user to grip the plate 218 between the handle 226, 227 and the plate 222.

When the handles 226, 227 are released, the rods 224, 225 can slide in the grooves 219, 220 when the user pulls or pushes the jaws 211, 212 apart or together to adjust the jaws. The handles 226, 227 can then be tightened to lock the laws 211, 212 in the new position.

Referring to Fig. 16, legs 213, 215 are fixed perpendicularly to a first outer plate 230, and legs 214, 216 are fixed to a second outer plate 231. The first and second outer plates 230, 231 extend in the same horizontal plane. The first and second outer plates 230, 231 can slide with respect to plate 222.

At one end of plate 222 it has guides 240, 242 fixed to two of its sides. The guides 240, 242 guide plate 230 as it slides with respect to plate 222 thereby increasing or decreasing the distance between, on the one hand, feet 213, 215 and, on the other hand, feet 214, 216. A second set of guides 241 , 243, which correspond to the first set 240, 242, is provided at the other end of plate 222 to guide plate 231.

The outer plates 230, 231 have, in this embodiment (though not essential) four locking screws in threaded engagement with the outer plates 230, 231. The plate 222 has several holes for each locking screw. The locking screws are removably received in the holes in different positions. In this way, the length of bridge section 210 is adjustable so that the distance between the first and second feet 203, 204, and between the third and fourth feet 205, 206 can be adjusted, to accommodate different widths of excavations. The duct cutting system of a fourth embodiment of the present invention will now be described.

Fig. 17 shows a duct cutting system 301 of a fourth embodiment of the present invention comprising a duct cutting or marking guide 302 and a straight spine duct 320 of 96mm outer diameter.

Referring to Fig. 17, a duct cutting or marking guide 302 is shown comprising a duct mating portion 315 having a curved inner surface which is shaped to mate with a curved radially outer surface of the duct 320.

The duct mating portion 315 has a guiding hole 303 which, when the duct mating portion 315 is in a mating position on the duct 320, is able to guide a cutting tool to cut a hole in the radially outer surface of the duct 320.

The duct cutting or marking guide 302 further comprises a spirit level 304. In the present embodiment, the spirit level 304 measures the level in two mutually perpendicular directions. More specifically, a first vial is provided to measure the level in a duct lateral direction, and a second vial is provided, which extends perpendicularly to the first vial, to measure the level in the duct longitudinal direction.

The guiding hole 303 is rectangular when viewed in the duct radial direction, and a straight edge 308 of the guiding hole 303, which is its longest edge, extends along the longitudinal axis of the duct 320.

It is preferable, as in the present embodiment, for one or more grips 310 to be provided on the curved inner surface of the duct mating portion 315 to grip the duct 320. The grips 310 may be made of rubber or another elastomeric material, for example.

The duct mating portion 315 has two parts 315a, 315b which are hinged together by two hinges 325, 326 whose axes are substantially parallel to the longitudinal axis of the duct 320. In particular, the two parts 315a, 315b of the duct mating portion 315 are joined to a respective flange 316, 317, and the two parts 315a, 315b are hinged together by the hinges 325, 326 joined to the respective flanges 316, 317. The hinges 325, 326 are bolted to the flanges. The spirit level 304 is screwed to a bracket which is bolted one of the flanges by the same bolts as one of the hinges.

A locking mechanism 330 is provided to lock the two parts 315a, 315b of the duct mating portion 315 in a closed position on the duct 320. The locking mechanism 330 comprises a threaded rod 318 received in respective recesses in the flanges 316, 317.

The locking mechanism 330 comprises a handle 335 in threaded engagement with the threaded rod 318 to allow the tightness of the locking mechanism 330 to be adjusted.

The locking mechanism 330 comprises an over-centre mechanism including a cam lever 340 to lock the locking mechanism 330. The cam lever 340 is provided at one end of the threaded rod 318, and the handle 335 is provided at the other end. The flanges are gripped between the cam lever 340 and handle 335 during locking.

The duct cutting system of a fifth embodiment of the present invention will now be described.

Fig. 18 shows a duct cutting system 401 of a fourth embodiment of the present invention comprising a duct cutting or marking guide 402 and a straight lead-in duct 420 of 54mm outer diameter.

Referring to Fig. 18, a duct cutting or marking guide 402 is shown comprising a duct mating portion 415 having a curved inner surface which is shaped to mate with a curved radially outer surface of the duct 420.

The duct mating portion 415 has four guiding holes 403 (only three of which are shown in Fig. 18). Each guiding hole 403, when the duct mating portion 415 is in a mating position on the duct 420, is able to guide a cutting tool to cut a hole in the radially outer surface of the duct 420.

The duct cutting or marking guide 402 further comprises a spirit level 404 which is of the same type as the spirit level 304 of the fourth embodiment. A handle 450 is provided for moving the guide 402 into and out of a mating position on the duct 420.

In each guiding hole 403, a straight edge 408 of the guiding hole 403, which is its longest edge, extends along the longitudinal axis of the duct 420. Each hole 403 extends for most of its length along the longitudinal axis of the duct 420, but at each longitudinal end the hole 403 turns and extends in a circumferential or tangential direction. This change of direction allows the cutting tool to cut in the circumferential or tangential direction.

Typically, two guiding holes 403, the lowest on one side and the second lowest on one side, will be used to cut top and bottom longitudinal edges of the hole in the duct while the duct cutting or marking guide 402 is in position on the duct 420. Then, the guide 402 will be removed and the edges along the circumferential direction will be cut to complete the hole.

The present invention has been described above purely by way of example. Modifications in detail may be made to the present invention within the scope of the appended claims. Furthermore, it will be understood that the invention is not necessarily limited to the combination of features shown in the examples described within the scope of the appended claims and their equivalents.