Fire rated flush box

Abstract

The present invention is a comparatively thin layer of intumescent material that is adapted to be poured directly onto at least the surface of one interior wall of the flush box in a fluidic state such that the poured intumescent material then conforms to the shape of the inner wall upon which it is being applied, so that it flows across the inner surface of the wall upon which it is applied and subsequently form a consistent layer. Once the layer is allowed to set in situ, due to the intumescent layer being comparatively thinner than conventional intumescent materials used with other flush boxes, the layer takes up less internal space, the likelihood that a service person operating within the confines of the flush box interior will tamper with or remove any or all of the intumescent material is substantially mitigated.

Description

Fire Rated Flush BoxField of the Invention

[0001] This invention relates to flush mounted electrical and utility boxes that are colloquially known simply as a flush box. In particular this invention relates to flush boxes used on walls and ceiling in a building that have a comparatively high fire rating over conventional flush boxes.Background of the Invention

[0002] Flush boxes are a common feature upon walls and ceilings in buildings. These flush boxes are potentially a hazard in the case of a fire within the building. Their existence within the building structure can significantly degrade the fire rating of that building. The relevant authorities in many areas mandate minimum fire ratings for a building to be certified as complying with prevailing regulations and thereby have the building deemed as safe for human occupation.

[0003] To mitigate the hazards associated with fire and to minimise the potential spread of the fire, most buildings are separated into fire cells. The building’s walls and floors form building fire separations within the structure of the building. In many areas, the relevant authorities require a fire design report which dictates the required fire resistance of the building elements within each zone, in order to provide occupants and fire fighters adequate safe passage in the event of a fire, and to impede the spread of the fire from zone to zone. These elements need to be tested and proved fit for purpose, in order to provide the required fire resistance level, as per the fire engineers design and to meet the prevailing regulations to which the building needs to comply.

[0004] One major area of concern are the inevitable holes and other openings within walls and ceilings that are required to provide passageways for utility services such as water, electrical, data networking, waste water, conduits and cables. At least some of these utilities pass through a flush box. These flush boxes penetrate the wall structure within the building and require means to mitigate the risk of fire spreading from one fire zone to another through the opening covered by the flush box. If this fire mitigation is not done properly, orsubsequently tampered with, or removed, then in the event of a fire, the plastic face of electrical switchgear combusts, and this enables the fire to pass through the wall, thereby voiding the original fire resistance designed into the structure.

[0005] Previous attempts have been made to mitigate this problem via the use of intumescent pads, glued into flush boxes.

[0006] For example, in US 2020 / 0119534 Al in the name of Munzenberger et al, an attempt to mitigate this problem is disclosed. In this disclosure, either a single sided insert, having either a double or single sided intumescent pad, adhered to a substrate, is provided. This insert can then be cut to shape and placed into or subsequently adhered into at least one inner wall of a fuse box. So in summary, either the insert simply sits within the flush box or is adhered using adhesive.

[0007] Similar techniques are disclosed in WO 2023 / 084272 Al in the name of 3M Innovative Properties Company, US 2016 / 0339281 Al, in the name of Muenzenberger, and AU 2021221816 Al in the name of BOSS Products (Australia)

[0008] The intumescent pads are designed to expand many times from its original size, under exposure to fire, thereby forming an expanded char like material that forms a plug, preventing the passage of fire and smoke through the wall.

[0009] The problem with this approach is that in order to get sufficient expansion of the intumescent material so that it will form an effective plug, the inactivated pad of intumescent material has a minimum thickness of at least 6mm or more. Even thicker if the pad insert is double sided. This is a very bulky inclusion within the small space within the confines of the flush box. To further exacerbate the problem, many of the flush boxes used have the pads retro-fitted to at least some of the inner walls of the flush box. This is typically done using adhesive pads of the bulky intumescent material. Due to the confined space within the flush box, it is easy for a service person, to either by accident, or by intent, dislodge or entirely remove the pad to free up space within the flush box. This may then go unnoticed by a building inspector and the subsequent structure may then be incorrectly deemed as meeting the prevailing regulations for fire safety for that building. That particular flush box’s ability to resist the progress of a fire through it may be severely or completely removed, therebyposing a serious health and safety problem for people occupying the building. It is common for uninformed or culpable service people to remove said pads with ease, thereby creating more space for their works, so they can complete their job in a more timely and cost effective manner, at the expense of fire safety. There is also the potential risk of forgetting or neglecting to install a retro-fit pad within a particular flush box.

[0010] It is therefore an object of the present invention to provide a flush box and intumescent pad assembly that at least ameliorates the abovementioned problems.Disclosure of the Invention

[0011] Accordingly, in a preferred form, the present invention is a comparatively thin layer of intumescent material that is applied to at least one inner wall of a flush box. The application of the intumescent material is achieved by pouring the intumescent material directly into the flush box in a fluidic state that then conforms to the shape of the wall upon which it is being applied. Due to the unique formula of the intumescent material, the expansion rate when activated by a fire event, is at least 40% more superior to any other intumescent material available, so therefore only a comparatively thin layer is required, thereby freeing up more valuable internal space within the flush box cavity. Once it is allowed to set in situ, due to the intumescent layer being comparatively thinner than conventional intumescent materials used with other flush boxes, the likelihood that a service person operating within the confines of the flush box will tamper with or remove any or all of the intumescent material is substantially mitigated. Further, because the intumescent layer is poured onto the surface and allowed to set, the bond is superior to an adhesive, thereby making it more difficult for a service person to try and remove the layer from the flush box.

[0012] Preferably, because the intumescent layer is poured directly into the flush box inner wall, there is no need for a carrier substrate, unlike that of conventional intumescent pad inserts. This further reduces the thickness of the intumescent layer and thereby frees up the maximum amount of internal cavity space while maintaining the fire rating requirement.

[0013] Preferably, because there is no substrate that interacts with the adhesive to fasten the intumescent material to the inner wall of the flush box, it is far more difficult for a service person to attempt to remove the intumescent layer. Attempts to do to will only break offpieces of the layer, thereby significantly increasing the time and effort to completely remove the layer, again mitigating the likelihood that a service person will attempt to remove it.

[0014] Preferably, the layer of intumescent material once poured and set upon the internal wall of the flush box is within the range of 2.0mm and 3.0mm thick.

[0015] Preferably, the poured and set layer of intumescent material expands approximately 3900% (40X) when activated in a heat generating event, such as a building fire and thereby significantly increases the fire rating of the flush box.

[0016] Preferably, the poured and set layer of intumescent material is adapted so that any openings that may need to be cut in the flush box can be cut through the poured and set layer of intumescent material, if required, without affecting the surrounding layer of intumescent material.Brief Description of the Preferred Embodiments

[0017] Figure la shows a typical installation of a flush box, in this installation, it is used with a conventional light switch.

[0018] Figure lb shows a pad that includes a layer of intumescent material supported on a layer of substrate in accordance with the prior art.

[0019] Figure 1c shows the cut to shape portion of prior art pad having adhesive applied to it so it may be affixed to an inner wall of the flush box.

[0020] Figure Id shows a ready to use flush box with several prior art pads adhered to various internal walls of the flush box.

[0021] Figure le shows a common problem with the prior art where a service person removes the prior art intumescent pad using a tool to jimmy up a comer so it can be manually pulled out.

[0022] Figure 2a illustrates a flush box with an intumescent layer that is in accordance withone embodiment of the present invention.

[0023] Figures 2b & c illustrate how apertures can be drilled into the portion of the flush box featuring the intumescent layer, in accordance with the present invention.

[0024] Figure 2d illustrates how the intumescent layer cannot be easily removed, in accordance with the present invention.

[0025] Figures 3a & b illustrate how the intumescent layer that accords with the present invention operates during a fire event.Description of the Preferred Embodiments

[0026] Turning firstly to Figure la, we are shown a typical use of a flush box 1 that is used in conjunction with a conventional light switch 5 on a building wall 3. In Figure lb we can see how fire mitigation is added to a flush box using a pad 7 comprising a layer of intumescent material 11 supported on a layer of substrate 9 that accords with the prior art. The pad is cut to size to suit the particular job at hand. In Figure 1c we can see that after the pad 7 is cut to size, in many cases, an adhesive 13 needs to be s applied so that the pad 7 can be affixed to an inner side wall of the flush box. In other cases, the substrate may include a self-adhesive layer. Slits 31 may then be cut into the pad wherever it overlays an aperture in the side wall of the flush box 1 after it is affixed to allow a service person to manipulate cables and conduits through the aperture and pad and into the flush box.

[0027] There are several problems with the prior art. Firstly, the pad 7 is comparatively thick. Not only does conventional intumescent material layer 11 is required to be thicker than the intumescent material used in the present invention to achieve the same fire rating performance, but you also need to include the thickness of the substrate 9. This combination consumes more of the tight internal space of the flush box than the present invention. Secondly, it takes time to prepare a pad 7 for use. It first needs to be cut to size, then in many cases it requires the use of an adhesive 13. Then once affixed to the inner wall of the flush box 1, the adhesive needs to be allowed to set before the slots 31 can be cut into the pad 7 where it overlays an aperture in the flush box 1, this adds time and cost to the job. Another major problem with the prior art is shown in Figure le. Here we are shown a servicetechnician using a hand tool such as a screen driver 15 to jimmy up a comer of the pad 7. Once a comer is raised, the service person may then manually rip the pad out of the flush box to free up internal space. Service people are typically pressed for time and wish to get the job done in the shortest amount of time. Because conventional intumescent material and pads made therefrom are comparatively bulky and interfere with the technician’s access and ability to manipulate cabling within the interior of the flush box 1. As a result, many technicians simply rip out conventional bulky intumescent material to free up the internal space it would otherwise occupy so that the cabling may then be manipulated inside the flush box more freely, timely and cost effectively. In some cases, the technician may remove the intumescent pad 7 with good intentions to replace it after the work is done, however they may inadvertently forget. Relevant building inspectors may also not check that it has been replaced either, and therefore a serious defect in the overall fire rating of the stmcture goes undetected, and that may have fatal consequences.

[0028] The ultra-thin non-pad design of the intumescent material used in the present invention significantly mitigates these significant problems. As shown in Figure 2a, the present invention features a pourable intumescent material 17 that is applied to an interior wall of the flush box. The poured material 17 flows across the internal surface and conforms to any changes in the topography on the surface of the inner wall. Also, the layer so formed from the pouring of the unset fluidic intumescent material 17 naturally forms a strong adhesive bond with the surface of the internal wall of the flush box 1. A sufficient quantity of intumescent material 17 is poured via spout 19 onto the surface so that is forms a layer of suitable thickness that meets the fire rating requirements of the particular job. One the layer 17 has been allowed to cure in-situ, any subsequent need to cut an aperture into the flush box 1 wall that includes the layer 17 can simply be drilled or hole cut as shown in Figure 2b & c. If this needs to be done, the superior bonding of the layer 17 with the side wall of the flush box 1 prevents any damage occurring to the intumescent layer 17 that is left behind in the vicinity of the cut. Another major advantage of the present invention is that once the layer 17 is poured directly onto the internal wall surface of flush box 1 , it is then very difficult to remove. As shown in Figure 2d, any attempt to jimmy out the intumescent layer 17 using tool 15 merely chips away at the material. There is no substrate to lift up and when subsequently pulled, carry away the intumescent layer. This significantly mitigates the aforementioned problems.

[0029] Finally as shown in Figure 3a and 3b, when a fire event 24 occurs, the intumescent layer 17 of the present invention expands to fill the entire internal cavity 27 of the flush box 1 and either meets or exceeds prevailing fire rating requirements.

[0030] While the above description includes the preferred embodiments of the invention, itis to be understood that many variations, alterations, modifications and / or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

[0031] It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.

[0032] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.

Claims

Claims1. A comparatively thin layer of intumescent material that is adapted to be poured directly onto at least the surface of one interior wall of the flush box in a fluidic state such that the poured intumescent material then conforms to the shape of the inner wall upon which it is being applied, so that it flows across the inner surface of the wall upon which it is applied and subsequently form a consistent layer, and wherein once it is allowed to set in situ, due to the intumescent layer being comparatively thinner than conventional intumescent materials used with other flush boxes, and therefore takes up less internal space, the likelihood that a service person operating within the confines of the flush box interior will tamper with or remove any or all of the intumescent material is substantially mitigated.

2. The intumescent material as defined in claim 1 wherein when the poured intumescent material flows into a consistent layer and is allowed to set, layer of intumescent material forms a strong adhesive bond to the inner wall’s surface.

3. The intumescent material as defined in claim 2 wherein because the intumescent layer is poured directly onto the flush box inner wall, there is no need for a carrier substrate, thereby further reducing the thickness of the intumescent layer and thereby freeing up the maximum amount of internal cavity space while meeting or exceeding the fire rating requirement.

4. The intumescent material as defined in claim 3 wherein the direct bond is sufficient, and also due to that direct bond and due to the fact that there is no substrate layer required, it is very difficult for a person to either deliberately or accidently remove the intumescent material from the flush box.

5. The intumescent material as defined in claim 4, any attempt by a person to jimmy out the layer using a tool such as a screw driver will only break off chunks of the layer, thereby significantly increasing the time and effort to completely remove the layer, again mitigating the likelihood that a service person will attempt to remove it.

6. The intumescent material as defined in claim 5 wherein the layer of intumescent material once poured and set upon the internal wall of the flush box is within the range of 2.0mm and 3.0mm thick.

7. The intumescent material as defined in claim 6 wherein the poured and set layer of intumescent material expands approximately 2000% (40X) when activated in a heat generating event, such as a building fire and thereby significantly increasing the fire rating of the flush box.

8. The intumescent material as defined in claim 7 wherein the poured and set layer of intumescent material is adapted to allow any openings that may need to be subsequently cut in the flush box side wall can be cut using a drill or hole cutter and this is able to also cut through the poured and set layer of intumescent material, if required, without affecting the surrounding layer of intumescent material left behind.

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