
目录
Flexible conduit, also known as flexible tubing or flexible conduit pipe, is a type of protective conduit used for routing and protecting electrical wires, cables, and other types of conductors. It is typically made of a durable and pliable material, such as plastic or metal, that allows it to bend and flex without breaking or damaging the wires inside. Flexible conduit is designed to provide flexibility and ease of installation in applications where rigid conduit may be impractical or difficult to use.
What are the two types of flexible conduit?
Like the rigid conduit, flexible conduit comes in two types, metal and non-metal, both of which can be subdivided into different types, so let’s get start.
电气非金属管 (ENT)

Electrical Nonmetallic Tubing (ENT) is the most commonly used plastic flexible conduit type. It is a type of pliable raceway used for the installation of electrical conductors. It is a thin-walled, corrugated tubing with a circular cross-section and is designed to be moisture-resistant and flame retardant.
ENT is composed of a nonmetallic material that offers resistance against moisture and chemical atmospheres, ensuring the protection of the electrical wiring. The raceway is pliable, which means it can be easily bent by hand with a reasonable amount of force, without requiring additional assistance or tools. However, it’s important to note that while the tubing itself is flexible, the associated fittings and connectors may not possess the same level of pliability.
Unlike threaded conduits, ENT features a corrugated shape, which eliminates the need for threading. While the tubing itself is not threaded, there are fittings available specifically designed for ENT installations that allow for secure connections. These fittings and connectors are integral or associated with the ENT raceway, ensuring a reliable and safe electrical installation.
Sizes of ENT Conduit

According to UL and CSA standards, 电气非金属管 (ENT) conduit is available in sizes ranging from 1/2 inch to 1/2-2 inch, with the 1/2-2 inch size being specific to Canada only.
In addition to the standard specifications of inner diameter (ID) and outer diameter (OD), UL and CSA have stringent requirements for the performance of ENT conduit. For example, in the Vertical Flame Test, the following description applies:
When subjected to the test in Clause 7.2, Sample of ENT shall not burn for more than 10s. Flaming or glowing particles shall not fall from the specimen at anytime during the test.Not more than 25% of the extended portion of the indicator flag shall be burned.
Compliance Codes and Standards
All ENT conduit products sold in North America must comply with UL1653 and CSA C22.2 No. 227.1 standards to ensure electrical construction and project safety. CSA C22.2 No. 227.1 offers the optional FT4 fire rating, and Ledes is proud to have obtained certification for all the mentioned standards.
Using products that do not meet these specifications can pose significant risks during construction and usage. UL and CSA have carefully considered the performance and safety of Electrical Nonmetallic Tubing in their relevant standards. For example, the impact resistance test in UL1653 requires that no more than 20% of the test samples exhibit damage or cracks. Imagine the consequences of installing non-compliant products underground, where a quality issue could lead to ENT conduit breakage, exposing wires and potentially causing a series of safety accidents, resulting in severe losses.
For PVC Corrugated conduit sold in Australia and the European Union, compliance with AS/NZS 2053.5:2001 and IEC61386 standards is mandatory. These standards cover physical performance and various additional testing requirements. Ledes also offers compliant products for these regions.
Flexible PVC Electrical Conduit Pros:

- 灵活性: ENT is designed for convenient installation, offering excellent flexibility that can accommodate various construction needs, especially in situations with corners, obstacles, or limited space. It significantly saves construction time and improves efficiency.
- 轻的: 耳鼻喉 is typically made of PVC material, which is lighter in weight compared to metal materials. This makes it easier to transport and reduces labor consumption during cutting and installation. It is the preferred choice for builders and contractors.
- Fire Rating: As mentioned earlier, ENT conduit undergoes the UL1653 Vertical Flame Test, ensuring that it does not burn for more than 10 seconds and does not release flaming or glowing particles during the test. Additionally, no more than 25% of the extended portion of the indicator flag should be burned. This outstanding fire resistance ensures construction and usage safety.
- Concrete Tight: Ledes offers optimized formulations and processes for concrete and underground environments, making quick and easy fixes possible with its quick-connect fittings. It ensures efficient and reliable installations.
- 耐腐蚀性: Plastic materials used in ENT do not rust, eliminating concerns about rusting even when buried for long periods. In addition, ENT undergoes relevant UL tests that consider factors such as antimicrobial properties and water absorption rates. This makes it suitable for both residential and commercial construction projects.
- 安全: ENT’s plastic material provides excellent insulation, significantly enhancing safety. It prevents electrical hazards and ensures a high level of protection.
Overall, ENT conduit offers flexibility, lightweight construction, excellent fire resistance, concrete tightness, corrosion resistance, and enhanced safety due to its insulation properties.
Flexible PVC Electrical Conduit Cons:
- Rigidity: ENT, being made of PVC or plastic, is not as rigid as metal flexible conduit. In certain extreme usage environments, this may pose some challenges.
- Sunlight Resistance: PVC or plastic materials used in ENT can undergo aging when exposed to direct sunlight for extended periods. In this aspect, metal flexible conduit offers better performance.
- 耐用性: Metal conduits, under normal circumstances without incidents like rusting, have a longer theoretical lifespan. Although current ENT plastic conduits also have a lifespan of over 100 years.
It’s important to consider these cons when choosing flexible electrical conduits, as they may have specific implications depending on the application and environment in which they are used.
Flexible Metal Conduit

Metal flexible conduit has several commonly used types, here are some introdcution for them.
Flexible metal conduit (FMC)
Flexible metal conduit (FMC), also known as greenfield or flex, is a type of conduit made by coiling a ribbed strip of aluminum or steel into a hollow tube. It provides a flexible solution for routing and protecting electrical wires in areas where installing rigid non-flexible conduits like EMT (Electrical Metallic Tubing) would be impractical. FMC offers the strength of a metal conduit while allowing for easy bending and flexing without maintaining a permanent shape.
Advantages of FMC Conduit:
- 耐用性: FMC conduit is made of metal, typically steel or aluminum, and most FMC conduits have effective rust prevention measures in place. They are designed to be strong, with high hardness and excellent impact resistance. Thin-walled conduit variants are commonly used, ensuring long-lasting durability once installed.
- 灵活性: Despite being made of metal, FMC conduit can be easily bent and flexed due to its unique manufacturing process. This flexibility greatly facilitates tasks such as wire pulling during construction, reducing installation difficulties.
- Rust Resistance: As mentioned earlier, FMC manufacturers incorporate rust prevention coatings during production. This significantly reduces the likelihood of rust formation, ensuring long-term use of FMC conduits.
- EMI/RFI Shielding: FMC’s metal structure provides electromagnetic interference (EMI) and radio frequency interference (RFI) shielding properties, making it suitable for installations where electromagnetic compatibility is a concern. However, the applicability of this feature may vary depending on the construction project, so careful consideration is necessary during selection.
Disadvantages of FMC Conduit:
- Weight: Due to its metal composition, usually steel or aluminum, FMC conduit is heavier compared to plastic conduit materials. This increased weight can add extra costs and considerations during installation and construction.
- Decline in Rust Resistance over Time: While FMC conduits come with rust prevention coatings, these coatings may deteriorate over time, leading to decreased rust resistance. Gradually, this may result in rust formation.
Applications of FMC Conduit:
Residential and Commercial Buildings: FMC conduit, like ENT, is suitable for both residential and commercial construction. Its primary purpose is to protect cables and wiring from damage in building structures.
户外设施: FMC conduit’s superior resistance to direct sunlight makes it a good choice for outdoor applications. It can be used for outdoor lighting, signage, surveillance systems, solar power systems, and more.
Machinery and Equipment: FMC conduit’s flexibility makes it ideal for cable protection in machinery and equipment. It can withstand the harsh environments typically found in industrial settings, ensuring the longevity of the cables.
Industrial Construction: Considering the demands of industrial construction and environments, FMC conduit can meet the higher requirements for wiring and conduit systems in facilities such as factories. It ensures the safety of internal wiring in these demanding applications.
Flexible metallic tubing (FMT)

Flexible metallic tubing (FMT), FMT is described in a separate article of the US National Electrical Code (NEC) and is considered a raceway rather than a conduit. FMT is circular in cross-section, flexible, metallic, and liquidtight without a nonmetallic jacket. It is available in smaller trade sizes (1/2″ and 3/4″) compared to the wider range of trade sizes for FMC (1/2″ to 4″).
Therefore, FMT conduit shares similar characteristics and features with FMC conduit, and further details will not be reiterated here.
防水柔性金属导管 (LFMC)

防水柔性金属导管 (LFMC), it is a metallic flexible conduit coated with a waterproof plastic layer, offering enhanced protection against moisture. It shares a similar interior design with FMC.
Advantages of LFMC Conduit:
- 耐用性: LFMC conduit is highly durable, making it suitable for applications that require protection against mechanical damage. Its plastic coating provides excellent resistance to rust, chemicals, and moisture, making it ideal for harsh environments.
- Waterproof: LFMC conduit exhibits good waterproof properties due to the low water absorption characteristics of PVC or plastic materials. This makes it suitable for underground installations in damp conditions.
- 灵活性: Like FMC, LFMC conduit is flexible, allowing it to be easily bent and maneuvered. This flexibility enables installation in tight spaces and corners where rigid conduits may be impractical.
- EMI/RFI Shielding: LFMC conduit, similar to FMC, utilizes galvanized steel, aluminum, or brass as its core material. This gives it electromagnetic interference (EMI) and radio frequency interference (RFI) shielding capabilities, making it suitable for special applications.
- Sunlight Resistant: The plastic coating on LFMC conduit is typically designed to be sunlight resistant, and the metal core itself provides good protection against direct sunlight.
Disadvantages of LFMC Conduit:
- Higher Weight: LFMC conduit is heavier due to the metal core and the additional plastic coating. This can result in increased transportation costs and may require additional considerations during installation.
- Larger Outer Diameter: The dual-layer structure of LFMC conduit (metal + PVC) increases the wall thickness and, consequently, the outer diameter. This needs to be taken into account during construction planning to avoid installation issues.
- Reduced Flexibility: The limited bending capability of LFMC conduit is due to the constraints of the plastic coating and its tight bond with the metal core. This is an important consideration during purchasing and installation processes.
Applications of LFMC Conduit:
Residential and Commercial Buildings: LFMC conduit can be used in various settings, including shopping malls, residential buildings, and other commercial structures. It is particularly suitable for areas prone to moisture, such as sewer lines, kitchens, and damp environments where cable protection is essential.
Aboveground Installation: LFMC conduit’s excellent resistance to direct sunlight makes it suitable for aboveground installations. It provides enhanced protection for cables exposed to sunlight, ensuring their longevity and performance.
Machinery and Equipment: LFMC conduit’s dual-layer protection (metal core + plastic coating) makes it well-suited for machinery and equipment in industrial settings. These environments often involve harsh conditions, such as oil or dust exposure, where LFMC conduit can provide superior cable protection.
Liquid Tight Flexible Non-Metallic Conduit (LFNC)

Liquid Tight Flexible Non-Metallic Conduit (LFNC), also known as FNMC, encompasses various types of non-metallic tubing that are flame-resistant and designed for electrical applications. These conduits feature either smooth or corrugated interior surfaces and may incorporate integral reinforcement within the conduit wall. They are specifically designed with a waterproof jacket to provide protection against water.
LFNC is a flexible conduit system that serves the purpose of enclosing and safeguarding electrical cables and wiring from moisture, liquids, abrasions, and external elements. Unlike traditional rigid metal conduits, LFNC is made from non-metallic materials like PVC (polyvinyl chloride) or thermoplastic rubber. This composition allows for enhanced flexibility while maintaining resistance to liquids. LFNC can be easily bent, twisted, and routed in various directions without compromising the integrity of the enclosed cables.
Advantages of LFNC Conduit:

- 灵活性: LFNC conduit, being a flexible tubing, offers the ability to bend and maneuver easily. Unlike LFMC conduit, it contains minimal or no metal components, making it relatively easier to bend without compromising its integrity.
- 轻的: Despite incorporating reinforcement in some variants, LFNC conduits are lighter compared to steel conduits like FMC. This can result in cost savings during transportation and installation.
- 成本效益: Due to the lower cost of raw materials, LFNC conduits are generally more affordable compared to FMC or LFMC conduits. This can help reduce project budgets without compromising cable protection capabilities. However, this factor should be considered in conjunction with specific project requirements.
- Waterproof: LFNC conduit exhibits good waterproof properties due to the low water absorption characteristics of plastic materials. This makes it suitable for underground installations in damp conditions.
- 耐腐蚀性: LFNC conduits, being non-metallic, eliminate the risk of corrosion commonly associated with metal conduits. This is particularly advantageous in installations where the conduit may be exposed to corrosive substances.
- UV & Sunlight Resistance: Some LFNC products are formulated with UV and sunlight resistance properties, providing protection against prolonged exposure to UV rays and direct sunlight.
Disadvantages of LFNC Conduit:
- 耐用性: As LFNC conduit is non-metallic, it may have lower physical strength and impact resistance compared to FMC or LFMC conduits. In theory, it may be less durable.
- Weight: While lighter than metal conduits, LFNC conduit is heavier than ENT (Electrical Nonmetallic Tubing) conduits. Its flexibility performance also does not match that of ENT conduits.
Applications of LNFC Conduit:
Residential and Commercial Buildings: LNFC conduit can be used in various settings, including shopping malls, residential buildings, and other commercial structures. It is particularly suitable for areas prone to moisture, such as sewer lines, kitchens, and damp environments where cable protection is essential.
Outdoor Installation. LFNC conduits have excellent resistance to direct sunlight and enhanced strength, so they can be used in scenarios with higher requirements, such as outdoor street lighting systems, security systems, and hydraulic irrigation system cable protection scenarios.
Industry or Chemicals Location. Because LFNC is resistant to chemical corrosion, it can be used for cable protection under harsh working conditions, such as cable protection for large mechanical equipment, chemical plants, etc.
How to install Flexible Metal Conduit?
Installing Flexible Metal Conduit (FMC) involves several steps to ensure a secure and proper installation. Here’s a general guide on how to install FMC:
- 收集必要的工具和材料: You’ll need FMC, connectors, a conduit cutter, a utility knife, a screwdriver, and appropriate fasteners.
- Plan the conduit route: Determine the path where the FMC will be installed, taking into account any obstacles, bends, or corners. Ensure compliance with local electrical codes and regulations.
- Measure and cut the FMC: Measure the required length of FMC for each section of the conduit route. Use a conduit cutter to cut the FMC to the appropriate size. Ensure the cut ends are smooth and free from burrs.
- Install connectors: Attach appropriate connectors to each end of the FMC. Connectors can be compression-type or set-screw type, depending on the specific FMC system being used. Follow the manufacturer’s instructions for proper installation.
- Secure the connectors: Fasten the connectors tightly to the FMC using a screwdriver or other suitable tool. Ensure a secure connection that prevents the conduit from detaching.
- Mount the FMC: Securely fasten the FMC to the desired surface using appropriate fasteners, such as straps or clamps. Ensure that the conduit is adequately supported at regular intervals to prevent sagging.
- Make bends and turns: If necessary, use a conduit bender or conduit vise to create bends and turns in the FMC. Follow the bending instructions provided by the manufacturer and avoid exceeding the bending radius limits.
- Connect to electrical devices: Attach the FMC to electrical boxes, junction boxes, or other electrical devices using appropriate connectors. Ensure proper grounding connections as required by electrical codes.
- Secure cables within the FMC: Place the electrical cables or wires inside the FMC and secure them using appropriate cable ties or clamps. This helps to prevent movement and protect the cables within the conduit.
- Verify the installation: Inspect the FMC installation to ensure it meets all applicable electrical codes and regulations. Check for proper support, secure connections, and correct routing.
It’s essential to consult local electrical codes and regulations and follow the manufacturer’s instructions for the specific FMC system being installed. If you are unsure about any aspect of the installation process, it is recommended to consult a licensed electrician for assistance.
How to choose the right flexible conduit?

在选择合适的波纹管产品时,最好考虑以下五个常见因素:
- 要求: 根据环境评估项目或应用的基本需求。导管会埋在典型的住宅建筑中还是会长期暴露在室外环境中?它会在持续潮湿的地方使用吗?通过考虑前面提到的各种波纹导管产品的优缺点,您可以做出明智的选择。如果您是项目承包商或经销商,请随时联系我们获取更多购买建议。
- 预算: 在预算范围内选择适合您项目的产品。这可确保您满足项目要求,同时最大限度地降低采购成本。此外,在考虑预算时,重要的是要包括运输和安装成本。例如,如前所述,金属导管更重,导致运输和安装费用增加。因此,这些成本应计入总体预算。
- 本地代码: 确定导管的材料和类型后,了解当地对此类导管的要求和规定至关重要。购买符合当地标准的波纹导管产品至关重要。不合规的产品将无法通过检查。例如,如果您在北美使用 ENT 导管,则必须购买符合 UL1653 和 CSA C22.2 No. 227.1 标准的产品,以满足当地安装要求并避免额外费用。
- 尺寸和数量: 确定单个导管内需要容纳的电线或电缆数量,以及安装所需的估计长度和数量。这可以帮助您控制预算并节省成本。
- 品牌: 不同类型的导管与不同的品牌相关。从知名品牌购买产品可能价格略高,但质量差异很大。知名品牌的产品均根据当地标准认证。选择不知名或通用产品可能会导致质量问题,导致损失远远超过产品本身的价值。如果当地品牌价格似乎太高或您需要大量产品,您也可以考虑直接从 Ledes 等制造商处购买。作为制造商,Ledes 提供具有竞争力的价格,因为没有品牌中介。凭借超过 14 年的出口经验,为数千名客户提供服务,我们可以确保在确认规格和要求后及时交付您的订单。如果您想就产品相关问题咨询我们, 请点击此处向我们发送电子邮件。
柔性导管可以埋地吗?

是的,某些类型的柔性导管可以埋入地下。在北美,NEC(国家电气规范)为不同类型的导管的允许用途提供了指导方针。
对于 ENT(电气非金属管)导管,根据 NEC 第 362.10 条“允许用途”,第 6 条规定:
“将 ENT 封装在浇筑的混凝土中或嵌入在地面的混凝土板中,其中 ENT 放置在沙子或经批准的筛分物上,并提供为此目的而指定的配件进行连接。”
对于 LFNC(液密柔性非金属导管)导管,根据 NEC 第 356.10 条“允许用途”,第 4 条规定:
“适用于列出并标记用途的直接埋葬。”
要确定您购买的特定柔性导管是否可以埋入地下,需要查阅当地相关的许可文件并遵守当地的法规。
塑料导管和金属导管哪个更好?

塑料导管和金属导管哪个更好,没有明确的答案。这取决于哪一个更适合您的特定需求,因为它们各有优缺点。
金属导管的优缺点:
金属导管通常是房主在其电气系统中首选的、更为传统的选择。它使用寿命长,通常是最耐用的选择。金属导管通常由铜、黄铜、铸铁或钢制成。金属导管的主要优点是其硬度更高,理论使用寿命更长。然而,金属导管更重,导致运输和安装成本更高,而且容易生锈,导致维护费用增加。制造商已经想出了解决生锈问题的解决方案,例如表面涂层或使用具有塑料涂层(通常由 PVC 制成)的防水柔性金属导管 (LFMC)。然而,这些解决方案会增加金属导管的重量和直径。
塑料导管的优缺点:
塑料导管的主要优点是重量轻和防锈,克服了金属导管的缺点。重量减轻意味着运输和安装成本的节省,而且更容易切割、连接和弯曲。随着技术的进步,塑料导管在耐热性、耐腐蚀性和其他性能方面也有所提高,使其适合大多数住宅和商业建筑的需求。塑料导管的主要缺点是它不像金属导管那样坚硬,因此在某些极端情况下可能容易损坏。此外,塑料导管可能不具备与金属导管相同的耐热性和抗紫外线性,如果在这样的环境中长期使用,可能会导致加速老化和破裂的风险。
因此,基于上述比较,塑料和金属导管各有优缺点,且相辅相成,根据您的具体需求或项目要求选择合适的材料是明智的选择。
怎样在拐角处布置导管?

- 导管弯曲: 不管是金属或塑料导管,您都可以使用工具将导管弯曲至所需的角度。具体过程可能因导管材料而异,但一般使用导管弯曲机或弯曲工具来实现所需的弯曲角度。
- 使用导管配件: 弯头或弯管等导管配件旨在提供平滑的拐角过渡,而不会损坏导管。例如,在北美,标准导管弯头配件有各种角度,如 22.5°、45°、90° 等。您可以根据导管尺寸选择合适的配件并将其连接起来,以实现所需的拐角角度。
值得注意的是,如果您使用 PVC 导管,则必须使用专门的 PVC 胶水或粘合剂来确保连接牢固且不会脱落。
- 使用 PVC 柔性导管: 如果拐角角度不是太尖锐,使用柔性 PVC 导管可能是一种方便的选择。PVC 柔性导管由塑料制成,可以轻松用手弯曲,无需专门的弯曲工具。这使得安装过程更加方便,尤其是对于较小的角度弯曲。
什么时候可以使用柔性导管?

根据 NEC(国家电气规范)指南,柔性导管可用于各种情况。以下是一般应用:
ENT(电气非金属管)和 LFNC(液密柔性非金属导管):这些导管适合封装在浇筑混凝土中、埋入地下或用于天花板和悬挂装置。它们也可以在地面上使用,例如用于太阳能系统或户外装置,因为塑料导管具有良好的抗紫外线和抗日光性。
FMC(柔性金属导管):FMC 适用于干燥环境,因为它的防锈能力较低。它可用于需要灵活性的各种应用,例如机械设备、高温环境以及太阳能系统或户外设施等地面设施。然而,在灰尘或油/气较多的环境中,使用防液系列导管以确保安全非常重要。
LFMC(防液柔性金属导管)和 LFNC(防液柔性非金属导管):这些导管专为潮湿环境而设计,具有良好的防水性。它们可用于潮湿环境,确保防水。LFMC 和 LFNC 导管适用于需要柔性的应用。
柔性导管防水吗?

并非所有柔性导管都是防水的。一般来说,FMC(柔性金属导管)和 ENT(电气非金属管)的设计都不防水。对于防水应用,应使用标有“液密”标识的导管,例如 LFMC(液密柔性金属导管)和 LFNC(液密柔性非金属导管)。
重要的是要了解,FMC 和 ENT 导管没有内置防水功能,包括其连接。ENT 由塑料制成,吸水率低,因此可以承受少量水而不会出现重大问题。另一方面,FMC 由金属制成,依靠薄涂层,无法提供实质性的防水性能。
另一方面,防水系列的导管具有增强塑料外层和防水连接,使其适合在潮湿环境中使用,确保电缆的安全。
结论
柔性电气导管为各种电气安装提供了多功能解决方案,并在广泛的应用中发挥着至关重要的作用。它们的重要性在于它们能够为电气布线系统提供灵活性、保护性和多功能性。
这些导管广泛用于住宅、商业和工业环境。
它们在混凝土包覆、地下埋设、天花板和悬挂安装以及太阳能系统等户外安装等应用中都是必不可少的。这些导管的灵活性使其能够轻松绕过障碍物进行安装,使其成为复杂布线设置的理想选择。
如果您有任何其他问题或需要有关柔性电气导管的帮助,请随时 通过电子邮件联系我们 或者 提交表格. 我们在此帮助您满足电气管道需求。