Umair Gaines
Electrical Metallic Tubing (EMT) is a type of electrical conduit that protects wiring systems within buildings and infrastructure. EMT is a thin-walled, unthreaded raceway with a circular cross-section designed to physically protect conductors and cables. It is typically made of steel or aluminium and is available in various sizes and lengths. The outside diameter (OD) of EMT refers to the trade size, which can differ depending on the application. For example, the trade size of PVC pipes refers to the inner diameter, while for copper pipes, it refers to the outer diameter. The OD of EMT can vary depending on the manufacturer and the specific EMT product, and it is important to note that the listed size on the sticker may not always correspond to the actual OD.
| Characteristics | Values |
|---|---|
| Definition | Electrical Metallic Tubing (EMT) is an unthreaded thin-wall raceway of circular cross-section designed for the physical protection and routing of conductors and cables. |
| Material | EMT is generally made of steel (ferrous) with protective coatings or aluminum (nonferrous). |
| Temperature Range | EMT is designed to handle temperatures from –10°C to 60°C (14°F to 140°F), with some variations handling –30°C to 60°C (–22°F to 140°F). |
| UV Resistance | EMT is not designed for high UV resistance. Prolonged exposure to ultraviolet (UV) rays can lead to deterioration of the coating. |
| Standard Length | The standard length of EMT is 3.05 m (10 ft) ±6 mm (±1/4 in). |
| Colors | EMT is available in various colors, but there are no official color codes established by the NEC or other NFPA/UL standards. Color choices are often influenced by architectural preferences. |
| Trade Sizes | EMT is available in trade sizes 1/2 through 4, and 10' and 20' lengths. |
| Corrosion Protection | The outside tube is galvanized for corrosion protection, and the inside has a corrosion-resistant coating. |
| Support Requirements | According to the National Electric Code, a conduit must be supported at intervals no longer than 3 m (10 ft) and fastened no more than 0.9 m (3 ft) from a box, fitting, etc. |
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What You'll Learn
EMT conduit's protective coating
EMT (Electrical Metallic Tubing) is a type of electrical conduit that provides physical protection and routing of conductors and cables in buildings and infrastructure. It is typically made of steel or aluminium and is designed to handle a wide range of temperatures, making it suitable for most indoor and moderate outdoor conditions.
One of the key features of EMT conduits is their protective coating, which plays a crucial role in enhancing their durability and performance. These coatings are applied to resist corrosion and degradation caused by environmental factors. Here's a detailed look at EMT conduits' protective coatings:
Protective Coatings for Corrosion Resistance
EMT conduits are typically coated with a protective layer to resist corrosion. This coating helps prevent the conduit from deteriorating due to moisture, chemicals, or salt, thereby enhancing its longevity. However, it's important to note that EMT is not designed for high UV resistance. Prolonged exposure to ultraviolet (UV) rays can lead to the deterioration of the coating, affecting its protective properties. In installations exposed to direct sunlight or harsh outdoor conditions, alternative conduit materials with better UV resistance, such as PVC or specially treated metal conduits, may be more suitable.
Galvanization for Enhanced Protection
Some EMT conduits undergo a galvanization process, where a protective coating is applied over the galvanizing layer. This process results in a smooth and uniform surface finish, further enhancing the conduit's corrosion resistance. The galvanization provides a barrier that makes it difficult for corrosive agents to adhere to the conduit. This treatment ensures that the conduit remains free from flaking, chipping, or other signs of extreme stress, extending its lifespan.
Coatings for Wet and Corrosive Environments
While EMT conduits are generally not recommended for wet or corrosive locations, they can be used in such environments with additional protection. Special coatings or treatments can be applied to make the conduits more resistant to moisture and corrosive substances. For example, PVC coatings or specially coated metal conduits are often used in areas with significant moisture or corrosive substances to provide enhanced water resistance.
Aesthetic and Functional Coatings
EMT conduits are also valued for their aesthetic appeal, particularly in exposed installations or modern architectural designs. The smooth and clean surface of EMT contributes to its sleek appearance. Additionally, EMT conduits are available in various colours, making it easy to identify critical circuits without spray painting or taping. These coloured coatings not only enhance the visual appeal but also provide functional benefits, such as reducing electromagnetic field exposure and shielding against electromagnetic interference.
In conclusion, the protective coatings applied to EMT conduits serve multiple purposes, including corrosion resistance, enhanced durability, and aesthetic appeal. By understanding the specific requirements of an installation, electricians and contractors can select the appropriate coating type to ensure the safety, functionality, and longevity of the electrical installation.
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EMT conduit's temperature range
EMT, or Electrical Metallic Tubing, is a thin-walled steel or aluminium pipe used to protect and route electrical wires. It is generally coated with a protective layer to resist corrosion, but it is not designed for high UV resistance. EMT conduits are available in a range of sizes and lengths to suit different wiring needs.
When selecting an EMT conduit, it is important to consider its temperature range. Typically, EMT conduits are designed to operate within a temperature range of -30°C to 60°C (-22°F to 140°F). This range covers most standard indoor and moderate outdoor conditions. However, it is important to note that EMT may not perform well in extreme temperatures beyond this range.
The temperature tolerance of EMT conduits can vary among different suppliers due to variations in raw materials and protective coatings. For example, some EMT conduits may have a temperature range of -10°C to 60°C (14°F to 140°F). It is always best to check with your supplier to determine the specific temperature range of the EMT conduit you are considering.
In certain environments, such as those exposed to direct sunlight or harsh outdoor conditions, special considerations or alternative conduit materials may be necessary. For instance, using UV-resistant coatings or alternative conduit materials like PVC or specially treated metal conduits may be required to prevent the deterioration of the coating and maintain the protective properties of the conduit.
Additionally, when using EMT conduits in outdoor or rooftop applications, it is important to consider the temperature correction factor and the number of conductors in the pipe, as these factors can affect the overall temperature rating.
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$15.47
EMT conduit's sizing
EMT (Electrical Metallic Tubing) is an unthreaded thin-wall raceway of circular cross-section designed to protect and route conductors and cables. EMT conduits are available in a wide range of sizes and lengths. The standard length of EMT is 3.05 m (10 ft) ±6 mm (±1/4 in).
It is important to note that the size listed on the sticker of an EMT conduit is not the inside or outside diameter but the trade size. The trade size refers to the maximum bundle size that can fit in the pipe. For example, a 1/2" EMT Conduit has an actual inner diameter of 0.622", indicating that it is not recommended to run a bundle of wires larger than 0.50".
The inside and outside diameters of an EMT conduit are crucial in determining the number of wires that can fit within it. A conduit fill table can be used to make wiring decisions, helping to ensure that the conduit tubing can safely contain the desired number of wires.
When selecting an EMT conduit size, it is important to consider the temperature range of the application. EMT is typically designed to handle temperatures from about −10°C to 60°C (14°F to 140°F), although some EMTs can operate within a range of −30°C to 60°C (−22°F to 140°F). The temperature rating depends on the raw materials used, so it is essential to consult with the supplier to ensure the EMT is suitable for the intended environment.
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EMT conduit's corrosion protection
EMT (Electrical Metallic Tubing) is a popular choice for protecting electrical wiring in various environments due to its versatility, durability, and cost-effectiveness. However, EMT is not inherently corrosion-resistant and requires additional protection to prevent corrosion in certain environments.
EMT conduits are typically made of steel or aluminium and are coated with a protective layer to resist corrosion. This protective coating is usually zinc galvanizing, which provides corrosion protection in two ways. Firstly, zinc corrodes much slower than steel, and secondly, zinc is sacrificial to steel on the galvanic scale. Additionally, zinc provides better environmental protection than paint, forming a tight bond with the underlying steel that slows potential corrosion.
While zinc galvanizing offers excellent corrosion protection, EMT conduits are still susceptible to corrosion in certain conditions. Prolonged exposure to ultraviolet (UV) rays can cause deterioration of the coating, compromising the conduit's protective properties. Therefore, EMT is not suitable for areas with direct sunlight or harsh outdoor conditions without additional protection. In such cases, using UV-resistant coatings or alternative conduit materials, such as PVC or specially treated metal conduits, is recommended.
Furthermore, EMT is not recommended for wet or damp locations without proper protection or special coatings. In environments with significant moisture or corrosive substances, alternative conduit types with enhanced water resistance should be considered. For example, PVC conduits or specially coated metal conduits are better suited for these conditions.
To ensure adequate corrosion protection, manufacturers often apply multiple layers of protective coatings to EMT conduits. After the initial zinc coating, a conversion coating of trivalent chromium is applied, followed by a thin topcoat of lacquer or another organic coating for additional corrosion protection. These organic coatings are tested for electrical continuity, flexibility, and flame resistance to ensure they meet the required standards.
Overall, while EMT conduits offer versatility and cost-effectiveness, they require careful consideration of the environment in which they will be installed. Additional protection or special coatings may be necessary to prevent corrosion and ensure the long-term durability of the electrical installation.
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EMT conduit's use cases
EMT conduits, or Electrical Metallic Tubings, are unthreaded thin-walled conduits designed for the protection and routing of conductors and cables. They are generally made of steel with protective coatings or aluminium. EMTs are lightweight, flexible, and easy to cut, bend, and install. They are also more affordable than other types of conduits.
EMT conduits are used in a variety of settings, including industrial, commercial, and residential buildings. They are suitable for both exposed and concealed installations and can be used in indoor and moderate outdoor conditions. However, EMTs may not perform well in extreme temperatures and are not designed for high UV resistance.
In industrial settings, EMT conduits are used in almost all electrical projects, especially in commercial and industrial buildings. They are also used in food processing plants, where their resistance to corrosion makes them suitable for environments with large amounts of water and cleaning chemicals.
In commercial buildings, EMT conduits are used to allow electrical and communication outlets to be installed in large open areas, such as retail display cases and open-office areas. They can be bent to fit the building's profile without the need for multiple manufactured fittings.
In residential homes, EMT conduits are used in electrical projects and can be easily procured from local hardware stores. They are available in various colours, which can be advantageous when multiple types of conduits are required for a project.
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Frequently asked questions
EMT stands for Electrical Metallic Tubing. It is a type of electrical conduit designed to protect electrical wiring. EMT conduits are typically made of steel or aluminium and are used in both exposed and concealed installations in buildings.
EMT conduits come in various sizes and lengths, and the listed size on the sticker is not the outside diameter but the trade size. The outside diameter will depend on the specific EMT conduit you are looking at. Three common sizes of EMT conduit that work with Maker Pipe Connectors are available.
The standard length of EMT electrical conduits is 3.05 metres or 10 feet, with a tolerance of +/- 6mm or 1/4 inch. EMT conduits are also available in lengths of 20 feet.
EMT conduits are typically available in a range of colours, including standard metallic colours like grey and silver, as well as other colours like red, blue, and green. The colour choices are often influenced by architectural preferences rather than functional purposes, as there are no official colour standards for EMT conduits.
