Patent Application
20110011614
1. Field of the Invention
Embodiments of the invention relate to the field of electrical cable. More particularly, the present invention relates to improved cables employing a protective material thereon for antimicrobial and/or antifungal prevention.
2. Discussion of Related Art
In the construction industry, electrical wires are often run through various structures to safely deliver power to and from a panel and then onto different areas of a building or structure. Generally, conduit refers to a product in which the electrical conductors are pulled through a protective metal armor that may be flexible or rigid after the conduit is installed in a desired location. Conversely, cable refers to a metallic or polymeric flexible armor which is applied around electrical conductors during manufacture. Types of cable include Armored cable (“AC”) and Metal-Clad (“MC”) cable each of which provide electrical wiring for various types of construction applications. Generally, Type AC and Type MC cable have different internal constructions and performance characteristics and are governed by different standards. For example, Type MC cable is governed by the National Electric Code (NEC®) Article 330 and Type AC cable is governed by NEC® Article 320. Basically, these cables house electrical conductors within a metal armor. The metal armor may be flexible enabling the cable to bend while protecting the conductors against external damage during and after installation. The armor which houses the electrical conductors may be made from steel, aluminum or other materials. The metal armor is formed from steel, aluminum or other metallic materials, which are helically wrapped to define a series of interlocked “S” shaped sections along a longitudinal length of the cable to form the metal armor.
The size and type of cable used to run a particular electrical line depends both upon the length of the run, particular power requirements, and environmental and structural protection needed for the application. For example, cables used in places of public assembly are governed by NEC® 518 entitled Assembly Occupancies which requires the installation of armored or metal clad cable. Often cables are installed in these shared spaces with air handling equipment where certain organisms may proliferate. In addition the cable may be installed where the cable surface is exposed, as with lighting or heating and cooling elements, which may come in contact with microbes or fungi on their respective surfaces. In factories and processing plants where the atmospheric conditions may change considerably, protection through the use of polymeric coverings for such cable is necessary. Certain types of cables are installed in hospitals, nursing homes, medical centers and other health care facilities for use with various systems as well as other power and control applications. These cables must have a redundant grounding system pursuant to applicable section(s) of NEC® Article 517. These cables are referred to as health care facilities cable and may be installed in walls, ducts, and other environmental air-handling spaces. Along with other wiring methods, type AC and MC cable without an overall nonmetallic covering are permitted to be used in such air handling spaces pursuant to NEC® 300.22(C) (Other Space used for Environmental Air). However, cable used in healthcare facilities must have appropriate ratings when installed in such air-handling spaces which, in most buildings, is the area within ceilings or under raised floors.
When the metal armor requires corrosion protection, the metal is galvanized with a zinc coating at a desired thickness which must comply with the applicable standards test (e.g. Preece Test). Typically, galvanizing is a process in which the steel strip is either hot dipped or electroplated to apply zinc or other protective element onto the surface of the steel. The protective properties of zinc provide a corrosion resistant coating to the underlying steel. When the metal armor is made from aluminum, the aluminum does not require the added protection provided by galvanizing, but aluminum is generally more expensive than steel. Depending on where these various cable types are installed within a structure, the cable may be exposed to various microorganisms and may be susceptible to providing environments where certain fungi and microbes may proliferate. Present cable designs do not provide antimicrobial or antifungal properties for electrical cable. Thus, there is a need for electrical cable designed to overcome the deficiencies of present configurations.
Exemplary embodiments of the present invention are directed to electrical cables. In an exemplary embodiment, an electrical cable includes a flexible metallic armor having an outer surface and defining an interior hollow area. A plurality of electrical conductors are disposed within the hollow area. A coating is disposed over the outer surface of the armor where the coating includes an antimicrobial and/or antifungal additive. The metallic armor may be metal, aluminum, electroplated steel or other metallic material. A visual indicator may be applied over the coating where the visual indicator is also treated with an antifungal and/or antimicrobial additive.
A method of manufacturing an exemplary electrical cable includes galvanizing a metal strip and applying a protective coating over the galvanized metal. An antimicrobial and/or antifungal material is added to the protective coating. The strip is dried and taken up on a coil which is then supplied to a profiling die which forms an arcuate member. The arcuate member is supplied to an interlocking tool which interlocks the edges of the arcuate members around a plurality of electrical conductors. A visual indicator may also be applied over the protective coating where the visual indicator is also treated with an antifungal and/or antimicrobial additive.
In an alternative method of manufacturing an exemplary electrical cable, an antimicrobial material is added to a coating mixture and applied over a metallic strip. The metallic strip may be aluminum, electroplated steel, etc., and the coating mixture may be a non-pigmented paint. The coated strip is supplied to a profiling die to form an arcuate member. The arcuate member is supplied to an interlocking tool which interlocks the edges of the arcuate members around a plurality of electrical conductors. A visual indicator may also be applied over the coating where the visual indicator is also treated with an antifungal and/or antimicrobial additive.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbers refer to like elements throughout.
When armor 15 is made from steel, it undergoes a galvanizing process where a coating of zinc or other process material is applied to the steel to protect against corrosion before it is helically wound. A protective coating or other corrosion resistant surface treatment may also be applied over the surface of the zinc to enhance the corrosion resistance of cable 10. The protective coating or surface treatment is treated with an antimicrobial and or antifungal additive. As mentioned earlier, cable 10 may be installed in hospitals, nursing homes or other healthcare facilities as well as in other spaces and environmental air-handling areas of shared spaces within various structures. An antimicrobial and/or antifungal additive prevents the formation of, for example, MRSA (Methicillin-Resistant Staphylococcus Aureus) or Aspergillus Niger (commonly referred to as black mold), on cable 10 inhibiting the microbial from proliferating in a shared space environment. An exemplary antimicrobial additive is available from SteriTouch Ltd., and has the product name ST1100 (liquid form) or ST1006 (powder form). An exemplary antifungal additive is available from Rohm and Hass Ltd., and has the product name ROCIMA 200™. In addition, the antimicrobial additive available from SteriTouch also has antifungal properties and may also be used as both an antimicrobial and antifungal additive. These additives are introduced into the protective coating or surface treatment solution where the coating and the antimicrobial and/or antifungal additive bond to the galvanized metal. In some embodiments, the outer surface 16 of the armor 15 is painted. In particular, U.S. Pat. Nos. 5,350,885, 5,468,914, 5,557,071, RE38,345, 5,708,235, 6,825,418 incorporated herein by reference, disclose armored cables that are coded for easy visual identification. This coding indicates the characteristics of the cable, for example, number of conductors, type of insulation, type of cable, and/or type of application. This coding may take the form of various colors, patterns, etc, applied to the exterior surface of armor 15 using ink, dye, paint or other material. When a visual indicator is used on cable 10, the antimicrobial or antifungal material is added to the paint, dye, ink, etc., since the protective coating or surface treatment applied to the outer surface of armor 15 would be covered by the paint. Thus, the antimicrobial and/or antifungal additive would likewise be covered by the paint and rendered ineffective. By adding the antimicrobial and/or antifungal additive to the paint used as an indicator, the painted surfaces of armor 15 as well as the non-painted surfaces are similarly treated.
When armor 15 of
While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.
