GB2584916A

GB2584916A - A fire resistant cable fastener

Info

Publication number: GB2584916A
Application number: GB1910273.0A
Authority: GB
Inventors: Blanks Steven; Doyle Anthony
Original assignee: HellermannTyton Ltd
Current assignee: HellermannTyton Ltd
Priority date: 2016-03-09
Filing date: 2016-03-09
Publication date: 2020-12-23
Anticipated expiration: 2036-03-09
Also published as: GB2584916B; GB201910273D0

Abstract

A cable clip or fastener 1 comprises a body 2 formed from a fire-resistant material, such as metal. The body 2 includes a clamp element 4 having an opening 8 at its base 10 for receiving an electrical cable. A lower fixing plate 14 is arranged at the base 10 of the clamp element 4 and includes a fixing aperture 16 for receiving a fixing member such as a nail or screw for fixing the cable clip 1 to a support surface. An upper fixing plate 26 is spaced vertically from the lower fixing plate 14 relative to the height of the clamp element 4. The upper fixing plate 26 includes a fixing aperture 28 that is aligned with the fixing aperture 16 of the lower fixing plate 14. A support member 21 is arranged to support the upper fixing plate 26 such that it is spaced apart from the lower fixing plate 14. One of the fixing plates includes a polymer coating in the region of the fixing aperture to enhance grip between the clip and a fixing member.

Description

A FIRE RESISTANT CABLE FASTENER

The present invention relates to cable fastener for fastening a cable to a support surface, and in particular a metal cable fastener that is able to securely retain a cable in a high temperature environment.

Electrical and data wiring and cabling within a building is commonly routed along walls, ceilings, and within ceiling voids. A common means for securing routed wiring and cabling comprises the use of plastic cable clips that are screwed or more typically nailed to the surface along which the cables are routed. Cable clips typically comprise a plastic body and a metal securing nail. The body includes a bridge section which extends over the cable in use and holds it in position when the body is secured to the support surface by the nail. The use of a moulded plastic body enables the low cost manufacture of such clips, which is important given the high volumes in which the clips are used by contractors.

It has been found that plastic cable clips of this type present a safety hazard in the event of fire. Many buildings now include significant numbers of routed cables extending throughout the building, particularly commercial premises and office blocks, which are held in position by standard plastic cable clips. During a building fire these clips may melt, leaving the cables unsupported and allowing them to fall and create an obstruction which in the worst case may trap people within the burning building. Therefore, new regulations (BS7671: 512.11.201) state that wiring/cabling in at least the fire escape routes of a building must be supported by fire-resistant fastenings and fixings that cannot prematurely collapse under conditions of extreme heat.

Therefore, an alternative to the plastic cable clips of the prior art is required that is fire resistant. For commercial reasons it is also preferable that any alternative fastening is able to be easily and rapidly manufactured at a relatively low unit cost.

It is therefore desirable to provide an improved cable fastener which addresses the above described problems and/or which offers improvements generally.

According to the present invention there is provided a cable fastener as described in the accompanying claims.

In an embodiment of the invention there is provided a cable clip or fastener comprising a body formed from a fire-resistant material. The body includes a clamp element having an opening at its base for receiving a cable; a lower fixing plate arranged proximate the base of the clamp section including a fixing aperture for receiving a fixing member such as a nail or screw; an upper fixing plate spaced vertically from the lower fixing plate relative to the height of the clamp section including a fixing aperture for receiving a fixing member that is aligned with the fixing aperture of the lower fixing plate; and at least one support member arranged to support the upper fixing plate in said spaced relationship with the lower fixing plate. The body is formed from metal and at least one of the fixing plates includes a polymer coating at least in the region of the fixing aperture. The pair of fixing plates enable a nail or similar fixing to be held by the plates in a substantially vertical orientation. The vertical support members hold the upper fixing member at its spaced vertical location and prevent it from collapsing downwardly when a downward force is applied to the upper fixing plate as the nail is hammered home. This enables a downward force to be applied through the fastener to allow the nail to fix the fastener to the support surface. The fire-resistant material from which the fastener is formed is preferably a metal, and this configuration enables the fastener to be readily formed from a single piece of flat strip metal through a series of bending operations, thereby enabling a cost effective yet robust clip to be formed. The polymer coating enables the clip to better grip the fixing member.

The clamp element preferably has an arched configuration including a pair of limbs spaced either side of the opening connected by an upper bridging section. The arched configuration may be a curved, circular form with the side parts of the circular form defining the side limbs and the upper curved part forming the bridging section.

Alternatively, the arched configuration may be formed by a pair of straight side walls and a straight upper bridging section linked by a series of bends in the metal.

The lower fixing plate preferably extends horizontally from the base of one of the limbs of the clamp section. It will be appreciated that the terms 'vertical', 'horizontal', 'upper' and lower' are relative terms used in relation to the vertical height of the clamp section, and the 'vertical' orientation of nail in use, and relative to the horizontal plane defined by the support surface to which the fastener is secured.

The cable fastener may include more than one clamp element along its length to enable the fastener to secure more than one cable.

The fastener is preferably formed from a single elongated piece of metal having a first bend at said base of one of the limbs forming the lower fixing plate, a second upward bend at the opposing end of the lower fixing plate forming a first one of the support members and a third substantially horizontal bend at the upper end of the first support member forming the upper fixing plate.

The upper and lower fixing plates and first and second supports form a boxed fixing section having upper and lower walls formed by the upper and lower fixing plates and side walls formed by the first and second support members which is able to retain its rigidity under the application of a vertical force.

The cable fastener may comprise a further downward bend at the opposing end of the upper fixing plate forming the second support member. The free distal end of the upper fixing plate is bent downwardly to form a vertical support leg.

The second support member preferably extends vertically downwards to a position proximate to the lower fixing plate such that it may engage the lower fixing plate in use to vertically support the upper fixing plate. The term 'proximate' includes an arrangement in which the free end is touching the lower fixing plate and in which the free end is slightly spaced therefrom. In use, in either the spaced or touching configurations, the free end touches the lower fixing plate once a downward force has been applied to the upper fixing plate by the nail.

s The first and second support members preferably define a pair of substantially vertical support legs.

The opposing distal end of the upper fixing plate may extend substantially horizontally to the clamp element and is vertically supported thereon such that the clamp element defines the second support member. Preferably the height of the first support member and the height of the lamp element is such that the horizontally extended free end of the upper fixing plate seats on top of the clamp element. Alternatively, it may seat on any part of the clamp element that provides vertical support beneath the upper fixing plate. This arrangement provides an additional advantage in that the upper fixing plate applied a compressive force to the upper surface of the clamp element urging it downwards against the cable.

The bends in the metal body formed in the lengthwise direction along the body, meaning the body bends along its length. The upper fixing plate may include a pair of tabs extending from its outer edges and bent downwardly in a direction lateral to the length of the body to form legs defining third and fourth downwardly extending support members which provide additional vertical support for the upper fixing plate.

At least one of the fixing plates may include a plurality of slots extending radially outwards from the fixing aperture. The slots defined tabs which are able to bend on insertion of the nail or other fixing to grip and hold the nail.

The slots are preferably arranged in a cross configuration.

A shield member may be provided that is formed from an electrically insulating material.

The shield is located within the clamp element such that in use it is located between the clamp element and the cable, the shield member having an inner profile formed to receive a cable.

The clamp element may include a deformable tab extending inwardly into the cable receiving part of the clamp section from the upper bridging portion that is arranged to deform upwardly when urged against a cable located within the clamp element.

The present invention will now be described by way of example only with reference to the following illustrative figures in which: Figure 1 shows a cable clip according to an embodiment of the present invention; Figure 2 is a side view of the clip of Figure 1; Figure 3 is a view from above of a cable clip according to an embodiment of the invention; Figure 4 shows a cable clip according to an alternative embodiment of the invention; Figure 5 shows a cable clip according to a further alternative embodiment of the invention; Figure 6 is a side view of the clip of Figure 5; Figure 7 shows a cable clip according to a yet further embodiment of the invention including an electrically insulating sheath; Figure 8 shows a cable clip according to a further alternative embodiment of the invention; and Figure 9 shows a cable clip according to another embodiment of the invention.

Referring to Figure 1, a cable clip 1 comprises a body 2 formed from an elongate, substantially rectangular strip of metal. The body 2 includes a clamp element 4 configured to hold the cable, and a fixing section 6 for securing the clip to a support surface.

The clamp section 4 is formed to hook or clip over a cable to hold the cable against the support surface. The term 'clamp' refers here to any arrangement in which a member at least partially extends over a cable to hold the cable in position between the member and the support surface. The clamp may hook, grip, clasp or otherwise engage the cable to hold it in position. In the arrangement of Figure 1 the clamp section 4 is arcuate and substantially circular in form. The diameter of the arcuate clamp section is selected to correspond to a given cable diameter such that the cable fits closely within the clamp section. The clamp section 4 comprises side parts 5 and an upper bridge section 7. The side parts 5 define vertical legs which support the bridge section 7. In the arrangement of Figure 1 the side parts 5 and bride section 7 are curved, forming part of a continuous circular form. Alternatively the side legs 5 and/or the bridge section may be straight of have a further alternative form. In use the bridge section 7 extends over the upper surface of the cable and bears down on the cable to hold it in position, with the side legs 5 providing lateral restraint.

The clamp section has an opening 8 at its base 10 for receiving the cable. The width of the opening 8 is less than the diameter of the clamp section 4 such that the clamp section curves inwardly towards the base 10. This allows the clamp section to form around and hold the cable more securely. The metal clamp section 4 is able to flex to widen the opening on insertion of the cable with this flex creating a return spring force that may bias the clamp section against the cable. A flange 12 projects horizontally from the free end of the clamp section 4 that forms a support foot for supporting the clamp section 4 against the support surface.

The clamp section 4 has a vertical axis A-A which in use is arranged substantially perpendicular to the support surface. An extended flange section extends horizontally from the proximal end of the clamp section 4 in the opposing direction to the foot 12, away from the clamp section 4. The horizontal direction is a direction perpendicular to the vertical axis A-A and in use parallel to the support surface. This further flange section forms a lower fixing plate 14. The lower fixing plate 14 includes a lower fixing aperture 16 for receiving the lower end of a nail 18. The lower aperture 16 has a diameter selected to provide a close tolerance fit or interference fit with the nail 18, such that the nail 18 is able to be held closely within the aperture 16 with no lateral play.

The body 2 curves upwardly at the end of the lower fixing plate 14 at a lower bend 20 to form a first support leg 22. The first support leg 22 extends upwardly and then bends horizontally inwardly in the opposing horizontal direction at a bend 24 towards the clamp section 4. The bends 20 and 24 may be part of a continuous curved support leg, as in Figure 1. However, in an alternative arrangement the support leg 22 may be straight in part. The part of the body section 2 extending from the bend 24 forms an upper fixing plate 26. The upper fixing plate 6 includes an upper fixing aperture 28 that is substantially laterally aligned with the lower aperture 16. As will be discussed below, the apertures 16,28 may be aligned at an angle such that they are laterally arranged in a slightly offset manner.

The upper fixing plate 26 extends towards the clamp section 4 and then curves downwardly at bend 30 forming a downwardly extending second support leg 32. The second support leg 32 terminates a vertically spaced location from the lower fixing plate 14. This allows a degree of tolerance for the bending operation that form the clip 1, rather that requiring the leg 32 to precisely abut the lower fixing plate 14. In use the leg 32 is supported on the lower fixing plate 14 as the fixing section 6 bends slightly under compression from the nail 18.

The clip 1 is provided with the nail 18 pre-inserted in the fixing apertures 16,28 as shown in Figure 1. The nail 18 is gripped closely within at least one of the two apertures 16,28 to hold it within the clip 1. The tip 34 of the nail 18 projects through the lower aperture 16. To secure the cable, the clip 1 is inserted over the cable, with the cable being received in the clamp section 4 through the opening 8. With the clamp section 4 secured over the cable, the clip 1 is manipulated to a suitable location and the nail 18 is then hammered into the support surface 38, as shown in Figure 2.

The head 40 of the nail 18 is greater in diameter than the upper aperture 28 as hence the head begins to apply a downward force to the upper fixing plate 26 once the head 40 reaches the upper fixing plate 26. The downward force cause the fixing section 6 to compress downwardly until the tip of the second support leg 32 engages the lower fixing plate 14. At this point the upper fixing plate 26 is vertically supported by both support legs 21,32 at a fixed vertical spacing from the lower fixing plate 14 and the clip is secured to the support surface 38. At the opposing end the support foot 12 is engaged against the support surface and the cable 42 is securely held within the confines of the clamp section 4.

As shown in Figure 3 the upper aperture 28 is longitudinally offset from the lower aperture 16 such that the two apertures 28,16 are aligned at an angle. This slight offset angle is such that the nail 18 is aligned at an angle when inserted through the apertures 28,16. Therefore, when the nail is hammered into the support surface 38 it enters the support surface 38 at an angle. The angular entry of the nail provides the nail 18 and thus clip 1 with an improved grip and retention on the support surface 38 and makes vertical retraction of the clip 1 more difficult.

To enable the nail 18 to be securely gripped and held with one or both of the apertures 16,28 the clip 1 is preferably provided with a nylon coating, or other suitable polymer.

The nylon coating has a minimal thickness but provides increased grip within the region of the apertures 16,28. The nylon coating also enables the clips to be colour coded. The minimal thickness of the nylon coating is such that the performance clip in retaining the cable is not effected should the coating melt during a fire.

In addition, or alternatively to the nylon coating, the fixing apertures may be provided with grip slots 44, as shown in Figure 4. The slots 44, which are shown extending from the upper aperture 26 may also or alternatively be provided in the lower aperture 16. The slots 44 extend radially outwards from the aperture 28 and are arranged at 90 degrees to each other to form a cross configuration. A plurality of tabs 46 are defined between the slots 44. The aperture may be formed to have an interference fit with the nail 18. As the nail 18 is inserted through the aperture 28 the tabs 46 are caused to bend downwardly to accommodate the diameter of the nail 18. This bending causes the tabs to grip the nail 18 and also to inhibit retraction of the nail 18 from the clip 1.

In an alternative embodiment shown in Figure 5, the bridge section 7 of the clamp section 4 includes a spring tab 48 for accommodating cables of varying sizes. The spring tab 48 is formed by a pair of parallel, laterally spaced, longitudinal slits 50. The tab 48 is bent downwardly into the cable section 4, as can be seen in Figure 6. The tab 48 engages cables 42 within the clamp section 4 which have diameter less than the height of the clamp section 4. In the event that the cable has a diameter closer to the height of the clamp section 4 than the height of the low point of the tab 48, the tab 48 is deformed upwardly as the clip 1 is pushed onto the cable to enable the cable 42 to be accommodated within the clamp section 4.

A further alternative arrangement is shown in Figure 7 in which an electrical shield 52 is provided within the clamp section 4. The shield 52 is formed from a non-conductive material, and is preferably moulded. The outer surface of the shield 52 conforms to the inner surface of the clamp section 4. An open bottomed channel 56 is formed within the shield 52 that is sized to receive and grip a cable. In the event that the cable 42 is a data cable the shield 52 protects the cable 42 from network bandwidth interference that may be caused by the metal body 2.

In a further embodiment shown in Figure 8, the upper fixing plate 26 extends horizontally such that it located above and is arranged parallel with the upper surface of the clamp section 4, defined by the bridge section 7. This embodiment does not include a second support formed by a downwardly extending leg. Instead the free end 58 of the upper fixing plate 26 is supported directly on the clamp section 4, with the clamp section 4 defining the second support.

In a yet further embodiment shown in Figure 9, the fixing section 6 comprises a pair of side tabs 60. The tabs 60 extend laterally outwards from the fixing plate 26 and are bent downwardly to form secondary support legs. The legs 60 may extend to and engage with the lower fixing plate, or as shown in Figure 10 be accommodated in cut away recesses in the lower fixing plate 14 such that they are able to engage the support surface 38 directly.

This may be particularly advantageous for larger sized clips where the support legs are longer and more prone to bending.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS1. A cable fastener comprising a body formed from a fire resistant material including: a clamp element having an opening at its base for receiving a cable; a lower fixing plate arranged proximate to the base of the clamp section including a fixing aperture for receiving a fixing member such as a nail or screw; an upper fixing plate spaced vertically from the lower fixing plate relative to the height of the clamp section including a fixing aperture for receiving a fixing member that is aligned with the fixing aperture of the lower fixing plate; at least one support member arranged to support the upper fixing plate in said spaced relationship with the lower fixing plate; wherein the body is formed from metal and at least one of the fixing plates includes a polymer coating at least in the region of the fixing aperture, said polymer coating enabling the clip to better grip the fixing member.
2. A cable fastener according to claim 1 wherein the clamp element has an arched configuration including a pair of limbs spaced either side of the opening connected by an upper bridging section.
3. A cable fastener according to claim 2 wherein the lower fixing plate extends horizontally from the base of one of the limbs of the clamp section.
4. A cable fastener according to claim 3 wherein the fastener is formed from a single elongate piece of metal having a first bend at said base of one of the limbs forming the lower fixing plate, a second upward bend at the opposing end of the lower fixing plate forming a first one of the support members and a third substantially horizontal bend at the upper end of the first support member forming the upper fixing plate.
5. A cable fastener according to claim 4 wherein the at least one support member comprises first and second substantially vertically arranged support.
6. A cable fastener according to claim 5 wherein the upper and lower fixing plates and first and second supports form a boxed fixing section having upper and lower walls formed by the upper and lower fixing plates and side walls formed by the first and second support members.
7. A cable fastener according to claim 5 or 6 further comprising a further downward bend at the opposing end of the upper fixing plate from the third bend that forms the second support member.
8. A cable fastener according to claim 7 wherein the second support member extends vertically downwards to a position proximate the lower fixing plate such that it may engage the lower fixing plate in use to vertically support the upper fixing plate.
9. A cable fastener according to claim 8 wherein the first and second support members define a pair of substantially vertical support legs.
10. A cable fastener according to claim 4 wherein the opposing distal end of the upper fixing plate extends horizontally to the clamp element and is vertically supported thereon such that the clamp element defines the second support member.
11. A cable fastener according to any one of claims 4 to 10 wherein the bends are formed in the lengthwise direction along the body, and the upper fixing plate includes a pair of tabs extending from its outer edges and bent downwardly in a direction lateral to the length of the body to form legs defining third and fourth downwardly extending support members.
12. A cable fastener according to any preceding claim wherein at least one of the fixing plates includes a plurality of slots extending radially outwards from the fixing aperture.s
13. A cable fastener according to claim 12 wherein the slots are arranged in a cross configuration.
14. A cable fastener according to any preceding claim further comprising a shield member formed from an electrically insulating material located within the clamp element such that in use it is located between the clamp element and the cable, the shield member having an inner profile formed to receive a cable.
15. A cable fastener according to any preceding claim wherein the clamp element includes a deformable tab extending inwardly into the cable receiving part of the clamp section from the upper bridging portion that is arranged to deform upwardly when urged against a cable located within the clamp element.