Decoupling of earth leakage for flat planar carbon fiber heater

Abstract

A heating device includes an electrically conductive heating element layer having at least two conductive strips electrically connected to a first surface of the electrically conductive layer over a predetermined length, positioned adjacent opposite ends of the electrically conductive layer, and configured to be electrically connected to a power source having a neutral line. The heating element also includes an outer grounding foil spaced from a second surface of the electrically conductive layer; at least two non-conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer; and an inner grounding foil arranged between two of the at least two non-conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer. The inner grounding foil is connected to the neutral line.

Description

[0001] DECOUPLING OF EARTH LEAKAGE FOR FLAT PLANAR CARBON FIBER HEATER

[0002] CROSS REFERENCE TO RELATED APPLICATION

[0003] This application claims priority to U.S. Provisional Patent Application No. 63 / 637,426 filed on April 23, 2024, the contents of which are incorporated herein by reference in their entirety for all purposes.

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to heating systems, and more specifically, to heated surfaces coverings, such as floors, walls, and ceilings, which are embedded in thm multilayer structure.

[0006] BACKGROUND OF THE INVENTION

[0007] Laminar heating elements, such as but not limited to those developed by LaminaHeat® of Greenville, SC, such as PowerFilm™ or PowerFabric™ heaters (hereinafter referred to as "laminar heaters" or "flat heaters," generally, to refer to any type of materials of construction and any manufacturer, without limitation, characterized by heaters in the shape of a sheet, film, or fabric in which the thickness is much smaller than the length and width) are very efficient heaters and provide uniform heat over the entire surface of the heater.

[0008] A planar flat carbon fiber heater, such the LaminaHeat® Comfort Film™, for example, provides full electrical surface heating on a floor compared to a typical electric cable wire heater which applies discrete heating covering only 10% of the floor surface due to the small surface area of the cable wire (e.g., with typically a 3.5 / 4mm diameter).

[0009] It is desirable to use a flat full surface heater because it is typically 50% more efficient than an electric cable wire heater.

[0010] There is a growing trend to reduce the electrical earth leakage current occurring in underfloor heating, and this has been done already in various countries in the world, including North America (e.g., Canada and USA).

[0011] The new requirement is for a maximum allowable current leakage of 5 mA on a single circuit in a domestic dwelling with typical 3Kw power capacity. This new requirement is a reduction from the 30mA typical current leakage maximum requirement in Europe and other jurisdictions.

[0012] Unfortunately, although not bound to any theory of operation, it is believed that the flat planar heater exhibits an intrinsic capacitance effect caused by the dielectric insulating materials used in the laminate design, the large covering area, and the minimal thickness, all of which create a greater leakage of current to ground. A schematic electrical drawing is provided in FIG. 4 illustrating this intrinsic capacitance effect believed to be the underlying cause of excess earth leakage. FIG. 4 is an electrical schematic representation of, e.g., heater 200 of the prior art and the differential resistance Rh and the stray capacitance Cs induced therein during normal operation. Because the current-carrying, resistive layer 205 of the heater 200 is very close to the bottom aluminum layer 202, for example, this close proximity induces a charge in the aluminum layer 202, which causes the undesirable current leakage.

[0013] This phenomenon of earth leakage and the new regulatory requirements for a maximum allowable current of 5 mA on a single circuit can limit the use of flat planar heaters, because for a typical installation of a single circuit of 2.8 / 3KW, the heaters may exhibit 12-14mA leakage compared to l-2mA for cable heaters. The earth leakage is typically identified by measuring the current in the Live and Neutral cables using an earth leakage clamp meter. Here, the leakage indicates a difference in the current of the Live and Neutral cables.

[0014] It is therefore desirable, to provide a flat planar heater and a method of manufacturing of a flat planar heater that reduces the earth current leakage of the heater, and is simple to implement and cost effective, while satisfying the new regulatory requirements.

[0015] SUMMARY OF THE INVENTION

[0016] The following presents a simplified summary of the invention in order to provide a basic understanding of some example aspects of the invention. This summary is not an extensive overview of the invention. Moreover, this summary is not intended to identify critical elements of the invention or to delineate the scope of the invention. The sole purpose of the summary is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0017] According to one aspect of the invention, a heating device includes an electrically conductive heating element layer having at least two conductive strips electrically connected to a first surface of the electrically conductive layer over a predetermined length, positioned adjacent opposite ends of the electrically conductive layer, and configured to be electrically connected to a power source having a neutral line; an outer grounding foil spaced from a second surface of the electrically conductive layer; at least two non-conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer; and an inner grounding foil arranged between two of the at least two non-conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer, the inner grounding foil connected to the neutral line.

[0018] In embodiments, the electrically conductive heating element layer can comprise a non-woven fiber layer comprising a plurality of conductive carbon fibers. The non-woven fiber layer can comprise a wet-laid layer comprising a plurality of individual unentangled fibers in an absence of conductive particles, the plurality of fibers having an average length of less than 12 mm.

[0019] In embodiments, the inner grounding foil can comprise aluminum.

[0020] In embodiments, the outer grounding foil can comprise aluminum.

[0021] In embodiments, the inner grounding foil can have a thickness of 10 microns.

[0022] In embodiments, the outer grounding foil can have a thickness of 10 microns.

[0023] In embodiments, the inner grounding foil is configured to redirect current toward one of the at least two conductive strips.

[0024] In embodiments, the at least two conductive strips can be copper.

[0025] In embodiments, the heating element can be arranged on or in a surface of a building.

[0026] The surface can be at least one of a floor, a wall, or a ceiling.

[0027] In embodiments, the electrically conductive layer further comprises one or more binder polymers and optionally, a fire retardant.

[0028] In embodiments, the electrically conductive layer further comprises a plurality of non-conductive fibers.

[0029] In embodiments, the electrically conductive layer consists of a plurality of conductive carbon fibers, one or more binder polymers, optionally one or more fire retardants, and optionally a plurality of non-conductive fibers.

[0030] In embodiments, the heating device further comprises a first adhesive dielectric layer adhered to a first surface of the electrically conductive layer, and a first insulating layer disposed above the first adhesive dielectric layer; and wherein the at least two non-conductive layers comprises a second adhesive dielectric layer adhered to a second surface of the electrically conductive layer, and at least second insulating disposed below the second adhesive dielectric layer.

[0031] In embodiments, the first adhesive dielectric layer and second adhesive dielectric layer each comprises PET or a composite thereof and the first insulating layer and second insulating layer each comprises a fiberglass layer.

[0032] In embodiments, the inner grounding foil is disposed between the second adhesive dielectric layer and a third adhesive dielectric layer.

[0033] According to another aspect of the invention, a method of producing a heating element includes arranging an electrically conductive layer in a stacked configuration; electrically connecting at least two electrically conductive strips spaced apart from one another relative to a first surface of the electrically conductive layer and positioned adjacent opposite ends of the electrically conductive layer, to a power source having a neutral line; arranging an outer grounding foil underneath, and spaced from, a second surface of the electrically conductive layer; arranging at least two non-conductive layers between the outer grounding foil and the second surface of the electrically conductive layer; and arranging an inner grounding foil between the electrically conductive layer and the outer grounding foil, the inner grounding foil configured for electrical connection to the neutral line of the power source.

[0034] According to another aspect of the invention, a method of installing a heating device includes providing a heating device that includes an electrically conductive heating element layer having at least two conductive strips electrically connected to a first surface of the electrically conductive layer over a predetermined length, positioned adjacent opposite ends of the electrically conductive layer, and configured to be electrically connected to a power source having a neutral line; an outer grounding foil spaced from a second surface of the electrically conductive layer; at least two non- conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer; and an inner grounding foil arranged between two of the at least two non-conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer, the inner grounding foil connected to the neutral line; disposing the heating device on a surface of a building, providing the power source, and electrically connecting one of the at least two conductive strips to a live line of the power source and connecting the other of the at least two conductive strips and the inner grounding foil to the neutral line of the power source.

[0035] In embodiments, the power source and the heating device can be connected to a single circuit having a power capacity of equal to or less than 3Kw, and the method of installing the heating device further includes supplying power to the heating device and measuring an earth leakage of less than 5 mA.

[0036] BRIEF DESCRIPTION OF THE FIGURES

[0037] Figure 1 is a perspective view illustration of a prior art embodiment of a flat planar heater.

[0038] Figure 2 illustrates a cross-sectional view of certain layers of the prior art flat planar heater of FIG. 1.

[0039] Figure 3 illustrates a cross-sectional view of an exemplary flat planar heater according to an aspect of the invention.

[0040] Figure 4 is an electrical schematic diagram of an exemplary flat planar heater illustrating the capacitance effect believed to be causing undesired earth leakage in prior art heater embodiments.

[0041] Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience.

[0042] DETAILED DESCRIPTION OF THE INVENTION

[0043] The invention will now be described by reference to exemplary embodiments and variations of those embodiments. Although the invention is illustrated and described herein with reference to specific embodiments, the illustrated examples are not intended to be limited to the details shown and described. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention. For example, one or more aspects of the disclosed embodiments can be utilized in other embodiments and even other types of devices. Moreover, certain terminology is used herein for convenience only and is not to be taken as a limitation.

[0044] According to exemplary embodiments of the invention, a flat full surface heating element and a method for manufacturing the flat full surface heating element are provided. The heating element and method incorporate an additional aluminum grounding foil (e.g., 10-micron deflector grounding ply) between the carbon fiber heater layer and the existing outer grounding foil, which has the effect of decoupling the capacitance effect caused by the dielectric insulating materials used in the laminate design. The deflector ply is electrically connected to the Neutral cable and diverts the leakage current to Neutral; thus, reducing or substantially eliminating the leakage current.

[0045] Referring now to the figures, selected embodiments of the invention are illustrated as non-limiting examples.

[0046] Details of a flat full surface heating element, such as a fabric heating element, for example, are described in U.S. Patent No. 10,925,119, which is incorporated by reference herein in its entirety and for all purposes. As described therein, a preferred fabric heating element may a non-woven fiber layer comprising a wet-laid layer comprising a plurality of individual unentangled carbon fibers (preferably in an absence of conductive particles), the plurality of fibers having an average length of less than 12 mm and consisting of conductive fibers or a combination of conductive fibers and non- conductive glass fibers; and at least two conductive strips electrically connected to the fiber layer over a predetermined length (e.g. over an entire length or width of the fiber layer), positioned adjacent opposite ends of the fiber layer, and configured to be electrically connected to a power source. The fiber layer may further include one or more binder polymers and a fire retardant and may consist of a combination of the plurality of conductive carbon fibers a binder, and one or more fire retardants. Exemplary binder polymers may include: Poly vinyl alcohol, Co-polyester, Cross linked polyester, Acrylic and Polyurethane. Preferably, the fiber layer has a uniform electrical resistance in any direction. Each of the conductive fibers and non-conductive may have a length in the range of 6-12 mm. One or more of the plurality of conductive fibers may comprise a non-metallic fiber having a metallic coating. As is known in the art, the fiber layer may have a plurality of perforations (e.g. defining an open area in the fiber layer in a range of 18-20%) that increases the electrical resistance in a perforated portion of the fiber layer relative to resistance in the absence of perforations. Exemplary carbon fiber layers may have an arial weight of about 8-60 gsm, preferably 20 gsm 12K carbon fiber derived from, e.g., High Strength Polyacrylonitrile (PAN) acrylic precursor fiber (although other precursors, such as rayon or pitch base may be used) and having a surface electrical resistance in the range of about 4 ohms / square and a tensile strength of about 36 N / 15mm. n one example, a multi-ply heating element includes a heating element comprising an electricaily-conductive inner non- continuous fibrous web layer with integrated conductive busbar strips. The inner layer is bonded and sandwiched between two outer insulating layers of woven or non-woven material, (e.g., continuous fiber) material. In some embodiments, such as those in which the inner layer is perforated, the resulting construction may comprise adhesive extending between the inner and outer layers as well as through the perforations in the inner layer.

[0047] The inner electrically conductive layer of the flat heating element typically includes fine conductive fibers, typically carbon fibers, dispersed homogeneously in the inner heater element to form a dense network, which convert electricity into heat by the act of resistive heating. By applying a voltage across the conductive (e.g. metallic copper) strips, the resistance of the electrically conductive layer causes a uniform current density, which in turn produces the uniform heating. In preferred embodiments, the carbon fiber layer as described herein is a non-woven fiber layer comprising a wet-laid layer comprising a plurality of individual unentangled fibers in an absence of conductive particles, the plurality of fibers having an average length of less than 12 mm and consisting of conductive fibers or a combination of conductive fibers and non-conductive glass fibers, as discussed in more detail in U.S. Pat. 10,925,119.

[0048] Figure 1 illustrates a prior art embodiment of a flat full surface heating element 100. In this embodiment, the heating element 100 is depicted as having nine layers of material that form a hybrid construction of busbars and fabric. These layers are shown in the cross-sectional view of FIG. 1 as layers 101, 102, 103, 104, 105, 106, 107, 108, and 109a-109b. It should be understood, however, that the heaters may have fewer or more layers than those shown. Layers 101 and 108 are outer insulating and reinforced layers (e.g., woven fiber glass fabric with an aerial weight in the range of 200 gsm).

[0049] Layer 102 is an aluminum grounding layer (e.g., aluminum foil, having a thickness of 10 microns, for example). The aluminum layer may comprise a film predisposed on the fiberglass layer.

[0050] Layers 103, 104, 106, and 107 are non-conductive adhesive layers, such as thermoplastic Polyethylene terephthalate (PET-GAG or PET-G) film, having a thickness of 100-500 microns, for example. As is known in the art PET-GAG is a composite of A- PET (obtained by extrusion molding of resin modified by polyester with isophthalic acid and diethylene glycol) and PET-G (a non-crystalline PET resin modified with cyclohexanedimethanol) stacked PETG-APET-PETG. By "adhesive" it is meant that these layers are thermoplastic or thermoset layers (e.g. a thermoplastic web having an aerial weight of 15 gsm) that melts into the carbon fiber layer and encapsulate or impregnates the fibers due to the heat of the lamination process use for assembling the layers of the heater. However, embodiments are not limited to any particular dielectric material, with or without adhesive properties, and other dielectric materials, such as but not limited to thermoplastic polyurethane (TPU), ethylene-vinyl acetate (EVA), polyimide, polyolefin, epoxy, polyimide, and the like, may be used for layers 103, 104, 106, and 107 instead of PET.

[0051] Layer 105 is an inner electrically conductive non-woven fiber layer, preferably a non-woven, wet-laid carbon fiber layer as described herein above, but not limited thereto.

[0052] Turning back to FIG. 1, layer 109a-109b refers to metallic (e.g., copper) strips having predetermined dimensions (e.g., 20 mm wide and 50 microns thick), which act as busbars.

[0053] Figure 2 illustrates a cross-sectional view of selected layers of an exemplary flat full surface heating element 200 of the prior art, with optional layers above the busbars (e.g. akin to layers 101, 103 and 104 of FIG. 1) omitted to reduce clutter. As shown, the heating element 200 includes six layers of material that form a hybrid construction of busbars and fabric. These layers are shown in the cross-sectional view of FIG. 2 as layers 202, 204, 205, 207, 208, and 209a-209b.

[0054] Layer 208 is an outer insulating and reinforced layer (e.g., woven fiberglass fabric with an aerial weight in the range of 200 gsm).

[0055] Layer 202 is an aluminum grounding layer (e.g., aluminum foil, having a thickness of 10 microns, for example), which may be provided as a film predisposed on layer 208. Layers 204 and 207 are non-conductive adhesive layers, such as thermoplastic Polyethylene terephthalate (PET-GAG or PET-G) film, having a thickness of 100-500 microns, for example. However, embodiments are not limited thereto, and other dielectric, preferably thermoplastic or thermoset, materials may be used for layers 204 and 207 instead of PET.

[0056] Layer 205 is an inner electrically conductive non-woven fiber layer (e.g., carbon fiber having aerial weight of 8-60 gsm). As described above, an exemplary electrically conductive carbon fiber sheet is known in the art.

[0057] Layer 209a-209b refers to metallic (e.g., copper) strips having specific dimensions (e.g., 20 mm wide and 50 microns thick), which act as busbars.

[0058] Figure 3 illustrates a cross-sectional view of an exemplary flat full surface heating element 300 according to an aspect of the invention. The flat full surface heating element 300 depicted in FIG. 3 is similar to the one illustrated in FIG. 2, except for an additional, inner aluminum grounding layer 310 (which may be disposed on a fiberglass layer, similar to the combination of layers 202 and 208 discussed herein above). In this embodiment, the heating element 300 is depicted as having six layers of material that form a hybrid construction of busbars and fabric. These layers are shown in the cross-sectional view of FIG. 3 as layers 302, 304, 305, 307, 308, and 309a-309b.

[0059] Layer 308 is an outer insulating and reinforced layer (e.g., woven glass fabric with an aerial weight in the range of 200 gsm).

[0060] Layer 302 is an outer aluminum grounding layer (e.g., aluminum foil, having a thickness of 10 microns, for example), which may be provided predisposed on layer 308.

[0061] Layers 304 and 307 are non-conductive adhesive layers, such as thermoplastic Polyethylene terephthalate (PET-GAG or PET-G) film, having a thickness of 100-500 microns, for example. However, embodiments are not limited thereto, and other dielectric, preferably thermoplastic or thermoset materials, may be used for layers 304 and 307 instead of PET.

[0062] In one embodiment, layer 304 may have a thickness of 100 microns, and layer 307 may have a thickness of 500 microns.

[0063] Layer 305 is an inner electrically conductive non-woven fiber layer (e.g., carbon fiber having aerial weight of 8-60 gsm). As described above, an exemplary electrically conductive carbon fiber sheet is known in the art.

[0064] Layer 309a-309b refers to metallic (e.g., copper) strips having predetermined dimensions (e.g., 20 mm wide and 50 microns thick), which act as busbars. The copper strips ensure uniform current flow throughout the electrically conductive non- woven web, and hence uniform heating due to the resistance. These conductive strips also facilitate connection of power cables to the heater. Although often referred to herein as "copper" strips, it should be understood that the strips are not limited to any particular conductive materials.

[0065] As shown in FIG. 3, electrical wires (Live and Neutral) are connected to the busbars 309a-309b to apply a voltage to the busbars and produce an electrical current flowing through the layers of the heater 300. Supply of power to the busbars 309a- 309b may be provided via a low voltage transformer 24-48 V DC or alternatively 220 / 240 V AC supply. A low voltage supply typically requires only two bus bars (Live / Neutral) in the busbar assembly, whereas high voltage typically requires three bus bars (L / N / E) including the earth (ground) connection. A typical power supply for a floor installation of 4 meters x 4 meters may be 2.3KW. For low voltage (e.g., 48 V DC), 2.3KW of power may be provided using a transformer with primary voltage of 240 V AC, at 10 amps, and secondary voltage at 48 V DC, at 50 amps.

[0066] Many factors may determine the amount of electrical current flowing through the layers of the heater 300 and therefore the amount of heat produced by the heater 300. These factors include, but are not limited to, distance between the busbars 309a- 309b (e.g., closer busbars provide a lower resistance electrical path and therefore produce higher current / temperature), level of voltage applied to the busbars (e.g., higher voltage produces higher current / temperature), etc.

[0067] In the embodiment illustrated in FIG. 3, an additional, inner aluminum grounding layer 310 is arranged between the carbon fiber layer 305 and the outer aluminum grounding layer 302, specifically between insulating films 304 and 307. Similar to the outer aluminum grounding layer 302, the inner aluminum grounding layer 310 may be an aluminum foil, having a thickness of 10 microns, for example, and may be predisposed on a fiberglass layer (not shown), similar to layers 302 and 308.

[0068] The leakage of current associated with flat planar heater typically occurs from the top layer (e.g., carbon fiber layer 305) of the heater 300 downwards toward earth ground. An objective of the embodiment illustrated in FIG. 3 is to stop, or substantially reduce, this undesirable (and now strictly regulated) current leakage. Current leakage El (shown as top arrow in FIG. 3) flows from the top (e.g., carbon fiber layer 305) of the heater 300 down toward the inner aluminum grounding layer 310.

[0069] The additional inner aluminum grounding layer 310 is configured to act as a grounding foil deflector that has the effect of decoupling the capacitance effect caused by the dielectric insulating materials used in the laminate design.

[0070] The additional inner aluminum grounding layer 310 is electrically connected to the Neutral cable and diverts the leakage current to the Neutral cable. This arrangement redirects current leakage, instead of downward toward the bottom of the heater 300, back toward the top of the heater 300, in particular toward the copper strip 309b. As a result of this configuration, current leakage E2 (shown as bottom arrow in FIG. 3) that flows from the inner aluminum grounding layer 310 toward the bottom of the heater 300, or the earth line, is substantially reduced to a current between 0 and 0.3 mA. As a result of this configuration, the additional inner aluminum grounding layer 310 reduces or substantially eliminates the leakage current E2.

[0071] The presence of the additional inner aluminum grounding layer 310 affects the amount of electrical current flowing through the layers of the heater 300. The minimum dielectric breakdown voltage flowing through the adhesive layers 304 and 307 should be between 2.5 kV and 4 kV, depending upon requirements of the application. The materials of the layers of the heater 300 illustrated in the embodiment of FIG. 3 achieve the required range of the minimum breakdown voltage between 2.5 kV and 4 kV.

[0072] In the embodiment of FIG. 3, the inner aluminum grounding layer 310 is illustrated as being arranged between the adhesive layers 304 and 307. However, embodiments are not limited thereto, and other configurations are possible. For example, the inner aluminum grounding layer 310 can be arranged between the carbon fiber layer 305 and the adhesive layer 304, so long as there is another non-conductive layer between the carbon fiber layer 305 and the grounding layer 310 (such as if the grounding layer 310 is predisposed on a fiberglass layer that is positioned adjacent the carbon fiber layer. Alternatively, the inner aluminum grounding layer 310 may be arranged between the adhesive layer 307 and the glass fabric layer 308.

[0073] It should be understood that although described herein with reference to exemplary materials of a preferred embodiment, the invention is not limited to any particular material compositions. In particular, while carbon fiber heaters are favored, the implementation of a grounding layer as described herein may be useful in connection with other types of planar heating element layers, such as heater elements comprised of conductive ink, graphene, and the like, without limitation. Notably in all of the configurations herein described, additional layers may be present. The invention is not limited to any of the exemplary thickness or materials as described herein.

[0074] While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.

Claims

CLAIMS1. A heating device comprising: an electrically conductive heating element layer having at least two conductive strips electrically connected to a first surface of the electrically conductive layer over a predetermined length, positioned adjacent opposite ends of the electrically conductive layer, and configured to be electrically connected to a power source having a neutral line; an outer grounding foil spaced from a second surface of the electrically conductive layer; at least two non-conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer; and an inner grounding foil arranged between two of the at least two non-conductive layers disposed between the outer grounding foil and the second surface of the electrically conductive layer, the inner grounding foil connected to the neutral line.

2. The heating device of claim 1, wherein the electrically conductive heating element layer comprises a non-woven fiber layer comprising a plurality of conductive carbon fibers.

3. The heating device of claim 2, wherein the non-woven fiber layer comprises a wet-laid layer comprising a plurality of individual unentangled fibers in an absence of conductive particles, the plurality of fibers having an average length of less than 12 mm. %4. The heating device of claim 1, wherein the inner grounding foil comprises aluminum.

5. The heating device of claim 1, wherein the outer grounding foil comprises aluminum.

6. The heating device of claim 1, wherein the inner grounding foil has a thickness of 10 microns.

7. The heating device of claim 1, wherein the outer grounding foil has a thickness of 10 microns.

8. The heating device of claim 1, wherein the inner grounding foil is configured to redirect current toward one of the at least two conductive strips.

9. The heating device of claim 1, wherein the at least two conductive strips are copper.

10. The heating device of any of claims 1-9, wherein the heating element is arranged on or in a surface of a building.

11. The heating device of claim 10, wherein the surface is at least one of a floor, a wall, or a ceiling.

12. The heating device of any of claims 1-11, wherein the electrically conductive layer further comprises one or more binder polymers and optionally, a fire retardant.

13. The heating device of any of claims 1-12, wherein the electrically conductive layer further comprises a plurality of non-conductive fibers.

14. The heating device of any of claims 1-13, wherein the electrically conductive layer consists of a plurality of conductive carbon fibers, one or more binder polymers, optionally one or more fire retardants, and optionally a plurality of non-conductive fibers.

15. The heating device of any one of the foregoing claims, further comprising: a first adhesive dielectric layer adhered to a first surface of the electrically conductive layer, and a first insulating layer disposed above the first adhesive dielectric layer; and wherein the at least two non-conductive layers comprises a second adhesive dielectric layer adhered to a second surface of the electrically conductive layer, and at least second insulating disposed below the second adhesive dielectric layer.

16. The heating device of claim 15, wherein the first adhesive dielectric layer and second adhesive dielectric layer each comprises PET or a composite thereof and the first insulating layer and second insulating layer each comprises a fiberglass layer.

17. The heating device of claim 16, wherein the inner grounding foil is disposed between the second adhesive dielectric layer and a third adhesive dielectric layer.

18. A method of producing a heating device, the method comprising: arranging an electrically conductive layer in a stacked configuration; electrically connecting at least two electrically conductive strips spaced apart from one another relative to a first surface of the electrically conductive layer and positioned adjacent opposite ends of the electrically conductive layer, to a power source having a neutral line; arranging an outer grounding foil underneath, and spaced from, a second surface of the electrically conductive layer; arranging at least two non-conductive layers between the outer grounding foil and the second surface of the electrically conductive layer; andarranging an inner grounding foil between the electrically conductive layer and the outer grounding foil, the inner grounding foil configured for electrical connection to the neutral line of the power source.

19. A method of installing a heating device, the method comprising providing the heating device of claim 1, disposing the heating device on a surface of a building, providing the power source, and electrically connecting one of the at least two conductive strips to a live line of the power source and connecting the other of the at least two conductive strips and the inner grounding foil to the neutral line of the power source.

20. The method of claim 19, wherein the power source and the heating device are connected to a single circuit having a power capacity of equal to or less than 3Kw, further comprising supplying power to the heating device and measuring an earth leakage of less than 5 mA.

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