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All information is explained based on UL 651 Eighth Edition, published on Oct 25, 2011, and all interpretation rights belong to UL.
Âmbito de aplicação
Conduíte e conexões de PVC rígido extrudado tipo EB e A, Schedule 40 e 80. UL651 se aplica a conexões relacionadas, incluindo cotovelos, acoplamentos, adaptadores, juntas de expansão, expansão-deflexão, deflexão e conexões de tubos rígidos para construção. No entanto, o material UPVC deve atender aos requisitos relevantes da ASTM 1784.
Os padrões relevantes da UL 651 cobriram os padrões relevantes no NEC (National Electrical Code) e NFPA 70. O conduíte e o encaixe de PVC rígido Schedule 40 e 80 podem ser usados para acabamento interno e externo ou uso externo. Eles devem ser protegidos da luz solar e dos efeitos do clima inclemente e podem ser usados diretamente no concreto.
Conduíte e conexão de PVC rígido Schedule 40 e 80 pode ser usado de 50°C (122°F) a 75°C (167°F)
Funciona bem e pode ser usado para necessidades de fiação de 90°C (194°F).
Dimensões Detalhes
Para materiais reciclados limpos ou materiais mistos, os fabricantes devem garantir que os padrões relevantes sejam atendidos, como UL746D e padrões relacionados à UL.
Aqui queremos expressar nossas opiniões. Embora, para o bem da proteção ambiental, o uso de materiais reciclados ou produção mista possa reduzir o desperdício de matérias-primas, a desvantagem é que isso leva a uma diminuição no desempenho.
Então haverá uma situação em que muitos produtos no mercado alegam ser certificados por padrões UL relevantes. De fato, eles também têm certificados de conformidade. Mas em termos de desempenho, há de fato um declínio, como resistência ao estiramento.
Os conduítes e conexões de PVC rígido Schedule 40 e 80 são resistentes a influências corrosivas comuns, incluindo vapores e névoas de ácido alcalino, fluorídrico e crômico, bem como decapagem e galvanoplastia, e atendem às necessidades dos usuários nesses cenários industriais.
As paredes internas do conduíte e encaixe de PVC rígido Schedule 40 e 80 devem ser lisas, e não deve haver risco de rebarbas causando danos aos fios. Além disso, não deve haver lascas, bolhas, rachaduras, lascas, escamações, calcário ou outros defeitos na superfície externa do tubo.
O corpo do tubo deve manter a ordenada vertical e não ter roscas. Use um micrômetro ou um medidor de manga cônica para medir, a escala precisa ser precisa para 0,001 polegadas ou 0,01 mm, e o desvio de precisão da medição não deve exceder ±1%. As dimensões medidas precisam estar em conformidade com as dimensões especificadas relevantes. Os dados relevantes já incluem a faixa de tolerância. As dimensões a serem atendidas incluem espessura externa, interna e de parede. Além disso, como acoplamentos, você precisa medir o comprimento, a profundidade do soquete, etc.
Os requisitos de tamanho para conduítes de PVC rígido Schedule 40 e 80 são claramente descritos na Tabela 4.1. Em termos gerais, a faixa de tolerância de OD é de ±0,004 a ±0,011 polegada, enquanto ID e espessura de parede são valores mínimos especificados para garantir que os parâmetros necessários sejam alcançados.
Para o Tipo A e EB, o método básico é similar. A diferença é que nesta versão, o OD e a espessura da parede do Tipo EB, a descrição oficial é que “Requisitos adicionais serão adicionados conforme esses tamanhos forem determinados como aceitáveis.”
Para os requisitos de qualidade dos acessórios, a UL651 também tem algumas regulamentações, como uma parede interna lisa sem rebarbas, que não pode afetar o movimento dos fios. Não permite detritos, bolhas, rachaduras, descamação, escamação, pulverização ou outros defeitos.
A UL 651 também especifica os valores máximos e mínimos de comprimento, espessura de parede, diâmetro do soquete e outros parâmetros para todos os acessórios para combinar com conduítes rígidos. Por exemplo, para acoplamento para conduítes tipo EB e A, sob a condição de tamanho comercial de 1/2 a 6 polegadas, a tolerância média do diâmetro interno na extremidade interna do soquete é de ± 0,008 a ± 0,014 polegadas, enquanto a tolerância média do diâmetro interno na entrada do soquete é de ± 0,015 a ± 0,023 polegadas, e os requisitos de tamanho são especificados na tabela relevante.
Há também alguns especiais, que listaremos brevemente aqui. Por exemplo, em um adaptador rosqueado adequado para fio e tubo de PVC rosqueado, a rosca deve ser clara e limpa, e o tamanho precisa atender aos requisitos da ASME B1.20.1-1983. Ao mesmo tempo, a porta rosqueada deve ter campo suficiente e atender ao teste de flexão.
Como há muitos acessórios, não os listaremos aqui.
Desempenho e Testes
Existem até 19 testes de desempenho no UL651, que é o teste definitivo para desempenho do produto. Selecionamos os seguintes itens para alguma explicação,
- Resistência à tracção
- Extrusão
- Absorção de água
- Resistência ao Impacto
- Resistência ao esmagamento
- Chama
- Resistência à luz solar
- Schedule 40 and 80 for use with 90°C wire
- Permanência da impressão
Resistência à tracção
The primary goal of this test is to determine the tensile strength of both aged and unaged specimens of rigid PVC conduit. The aged specimens must retain at least 95% of the tensile strength of their unaged counterparts to meet compliance requirements.
Specimen Preparation
- Six specimens are cut from finished conduit, with specific dimensions based on the conduit type.
- Measurements, including wall thickness and diameter, are taken using precision micrometer calipers with a minimum accuracy of 0.0001 inches (0.001 mm).
- The conduit must be clean and at a controlled temperature of 23.0 ±2.0°C (73.4 ±3.6°F) before testing.
Procedimento de teste
- Aging Process: Three specimens are subjected to 168 hours in a circulating-air oven at 113.0 ±1.0°C (235.4 ±1.8°F), then cooled in still air.
- Tensile Testing:
- The six specimens (three aged and three unaged) are tested within 16 to 96 hours after aging.
- A metal plug is inserted to prevent crushing during testing.
- Each specimen is subjected to tensile force on a power-driven machine, with grips separating at a controlled rate of 1/2 ±1/8 inch (10.0 ±2.5 mm) per minute.
- The maximum load before failure is recorded.
Results & Evaluation
- Tensile strength is calculated by dividing the maximum load by the cross-sectional area.
- The average tensile strength of aged and unaged specimens is compared to ensure compliance with UL651 requirements:
Schedule 40 & 80: Minimum 5,000 psi (34.5 MN/m²).
Type A & EB: Minimum 4,000 psi (27.6 MN/m²).
- The aged specimens must maintain at least 95% of the unaged specimens’ tensile strength.
Extrusão
Simulate extruding PVC pipes using anhydrous acetone to observe and test for incomplete fusion. In general, whether there is a large area of peeling, cracking, and other problems after soaking, test whether the product meets the standard requirements. It is a great test for PVC catheters’ raw material quality and production process.
Absorção de água
A UL651 exige que após o acabamento Conduíte de PVC é embebido em água destilada por 24 horas, a taxa de absorção de água não deve exceder 0,50% de seu peso. É muito fácil de entender. Se enterrarmos tubos de PVC no solo, eles serão inevitavelmente afetados pela umidade do solo. Se o conduíte de PVC absorver muita água e inchar, isso fará com que a junção do conduíte inche e se deforme, resultando em uma vedação ruim, e o resultado é que os fios não são protegidos como deveriam ser.
Resistência ao Impacto
The Resistance to Impact Test outlined in UL 651 evaluates the ability of rigid PVC conduit to withstand physical impact without cracking or tearing beyond an acceptable limit. This test is crucial in assessing the durability and mechanical strength of conduit under real-world conditions, ensuring that it remains intact and functional even when subjected to sudden force or impact.
Specimen
- Ten 6-inch (150 mm) specimens are cut from finished lengths of each trade size of rigid PVC conduit.
- The specimens must be free from cracks, tears, or other imperfections before testing.
Conditioning
- The specimens are conditioned in air at a temperature of 23.0 ±2.0°C (73.4 ±3.6°F) for at least 4 hours to ensure uniform testing conditions.
Impact Setup
- Each specimen is placed on a solid, flat, steel plate that is at least 1/2 inch (13 mm) thick and firmly anchored in a horizontal position.
Impact Mechanism
- UM steel weight, shaped as a solid, right-circular cylinder with a flat impact face and rounded edges, is dropped onto the specimen from a specified height.
- The impact conditions depend on the conduit type:
Schedule 40, Type A, and Type EB:
Weight: 20 lbs (9.1 kg)
Cylinder diameter: 2 inches (51 mm)
Schedule 80:
Weight: 75 lbs (34 kg)
Cylinder diameter: 6 inches (150 mm)
- O flat face of the weight strikes the center of the specimen across the diameter and along the longitudinal axis, ensuring a standardized impact force.
- A mechanism is in place to ensure the weight only strikes once per test.
Pass/Fail Criteria
- The rigid PVC conduit fails the test if more than three out of ten specimens develop a crack or tear longer than 1/32 inch (0.8 mm) along the outer surface.
- If seven or more specimens remain intact or develop cracks/tears within the allowable limit, the conduit passes the test.
Resistência ao esmagamento
The Resistance to Crushing Test evaluates the ability of rigid PVC conduit to withstand external pressure without significant deformation or structural failure. This test ensures that the conduit maintains its integrity under compressive forces, which is essential for its performance in underground, encased, or exposed installations where it may be subjected to heavy loads.
By simulating real-world conditions, the test verifies that the conduit does not buckle or excessively deform under specified loads. A key criterion for passing the test is that the minor axis of the inner diameter must not be reduced to less than 70% of its original measurement before loading.
Este teste é diferente do teste de resistência ao impacto porque o conduíte de PVC é embutido no solo ou na parede e fica sob pressão por um longo tempo. Este teste experimenta a capacidade compressiva do conduíte de PVC sob a ação da pressão, o que também a afeta. Fatores de longevidade.
Chama
The Flame Test in UL 651 evaluates the fire resistance of Schedule 40 and Schedule 80 rigid PVC conduit to ensure it does not sustain or spread flames in the event of a fire. This test is designed to confirm that the conduit self-extinguishes quickly and does not contribute to igniting nearby combustible materials.
During the test, the conduit is exposed to a 60-second flame application, repeated three times, with a 30-second interval between each exposure. The conduit must cease flaming within 5 seconds after each flame application and must not release flaming particles that could ignite surrounding materials. If the conduit fails to meet these criteria, it is considered unsuitable for applications where fire safety is a concern.
Este teste simula se o conduíte de PVC Schedule 40 e 80 pode fornecer proteção máxima quando ameaçado por fogo. Se o conduíte tiver excelente retardância de chama, ele pode garantir que os fios no conduíte estejam intactos quando a chama aberta for extinta para não causar um acidente mais sério.
Resistência à luz solar
The Sunlight Resistance Test in UL 651 evaluates the ability of Schedule 40 and Schedule 80 rigid PVC conduit to withstand prolonged exposure to UV radiation without significant degradation. Since outdoor electrical installations often expose conduits to direct sunlight, this test ensures that the material maintains its mechanical integrity and impact resistance over time.
The test involves Izod impact strength measurements on notched specimens prepared from both unaged and UV-conditioned conduit samples. These samples are exposed to UV radiation for up to 1440 hours, after which their impact strength is tested according to ASTM D 256 standards. To pass the test, the conduit must retain an acceptable level of impact resistance as specified in UL 651.
This testing process ensures that rigid PVC conduits remain durable and reliable in outdoor applications, providing long-term performance and protection against environmental factors such as UV exposure and weathering.
Conduit for Use with 90°C Wire
Among UL651 requirements, one key specification is the ability to support 90°C-rated wire, which indicates the maximum operating temperature of the conductors inside the conduit.
What Does 90°C Wire Mean and Why It Matters?
The 90°C rating refers to the maximum temperature the wire’s insulation can withstand without degrading over time. UL 651-certified PVC conduit is typically rated for 75°C conductors, but many electrical specifications now demand 90°C-rated conduit to accommodate higher-temperature wiring without requiring system derating. This higher temperature tolerance ensures that the electrical system operates at full efficiency while maintaining safety and reliability.
To achieve a 90°C rating, PVC conduit must pass additional long-term testing beyond the standard requirements for 75°C conduit. The testing process outlined in UL 651 extends over 360 days, exposing the conduit to various environmental stresses, including prolonged high temperatures, to evaluate its resistance to thermal degradation, mechanical integrity, and overall performance.
Testing Requirements
The test involves accelerated aging by placing conduit specimens in a circulating-air oven at 80°C (176°F) for up to 360 days. At specific intervals, impact tests are conducted using a steel cylinder drop method to determine impact strength retention over time. A smooth degradation curve is plotted, and the conduit must maintain at least 50% of its initial impact strength after prolonged exposure.
This rigorous evaluation ensures that Schedule 40 and 80 PVC conduits remain reliable and structurally sound when used with high-temperature wiring, providing long-term safety and performance in demanding electrical applications.
How to Tell If the PVC Conduit is Listed to the 90°C Requirements?
Compliant 90°C-rated conduit must also include permanent markings that explicitly state “maximum 90°C wire” or “max 90°C wire”. Listing agencies such as UL, ETL require these markings to confirm the conduit meets the standard.
If a conduit does not have this mandatory marking, it is not compliant with the 90°C specification, regardless of manufacturer claims. Using non-compliant conduits in systems designed for 90°C conductors can lead to serious consequences, including failed inspections, system rejection, costly replacements, and legal liabilities.
Permanência da impressão
Este teste requer que a amostra seja submetida a um teste de envelhecimento por 168 horas de antecedência, embebida em água da torneira por 24 horas e, em seguida, esfregada com óleo IRM902 para iniciar o teste. O teste usará um dispositivo automático simples para permitir que a fita entre em contato com a parte impressa do cateter em um ciclo fixo, com um movimento de vai e vem para cada ciclo, para um total de 50 ciclos.
Após os testes acima, os caracteres impressos devem ficar claramente visíveis para produtos qualificados.
Como a maioria dos fabricantes agora está gravando a laser, esse teste não é muito severo. Seu propósito é principalmente reter a impressão do cateter, que pode rastrear o fabricante, a data de produção, etc.
Marcações
A impressão usual em tubo rígido de PVC precisa incluir o seguinte:
1) Com as palavras 'Conduíte de PVC rígido';
2) Tamanho do comércio
3) O nome do fabricante ou proprietário da marca
4) Data de produção
5) As informações acima precisam ser impressas pelo menos uma vez a cada 10 pés.
6) Conforme dito no capítulo acima, a impressão é permanente
Além disso, há alguns requisitos detalhados para conduítes de PVC Schedule 40 e 80. Por exemplo, a impressão deve ser atualizada para conduítes de PVC rígido Schedule 40 ou Schedule 80 para esses dois conduítes.
Alguns são adequados para fios de 90°C (194°F), então o “fio máximo de 90°C” deve ser marcado na impressão. Existem também alguns requisitos especiais. Por exemplo, se Conduíte rígido Schedule 40 é adequado apenas para uso subterrâneo, então “Somente uso subterrâneo” deve ser impresso.
Quanto à impressão de produtos acessórios, como a maioria deles é produzida por tecnologia de moldagem por injeção, ela só precisa ser feita durante o projeto do molde e precisa atender aos requisitos permanentes. O conteúdo impresso geralmente é o nome do fabricante ou da marca e o modelo do produto. Semelhante ao conduíte de PVC rígido Schedule 40 ou Schedule 80, se ele só puder ser usado em cenários limitados, precisa ser observado, como enterrado no solo ou é adequado apenas para fios de 90 °C.
Conduit Applications and Installation - NEC Article 352
NEC (National Electrical Code) has outlined the installation and usage requirements of PVC conduit, to ensure compliance with electrical safety standards. Article 352 of NEC specifies the key applications, limitations, and installation requirements, follow are some key information:
Applications for PVC Conduit:
Applications for PVC Conduit:
Uses Permitted | Uses Not Permitted |
Concealed installations within walls, floors, or ceilings | In hazardous (classified) locations unless specifically permitted |
Wet and dry locations | As a means of support for luminaries (light fixtures) |
Corrosive environments where metal conduits could deteriorate | Where subject to severe physical damage |
Underground installations, including direct burial | In areas where temperatures exceed 50°C (122°F) |
Exposed applications, provided the conduit is rated for sunlight resistance | Where it may be used as a grounding conductor |
Some Installation Considerations:
Conduit Fill: The number of conductors must comply with NEC Chapter 9.
Conduit Fill Size Chart for PVC Conduit
Número de condutores | Cross-Sectional Area (%) |
1 | 53 |
2 | 31 |
Mais de 2 | 40 |
Support Requirements: Must be secured within 3 feet (900mm) of terminations and supported per NEC Table 352.30.
Expansion Fittings: Required when thermal expansions is expected to exceed 1/4 inch (6mm).
Aterramento: PVC conduit does not provide an equipment grounding path; a separate grounding conductor is required.
Composição do material: Must be made from non-plasticized PVC, resistant to moisture, chemicals, impact, and fire, and UV-resistant for above ground use.
Your Reliable Electrical Solution – Ledes
Ledes is a trusted manufacturer in high-quality electrical conduit solutions, committed to delivering safe, durable, and high-performance products that meet industry standards. Our extensive range of UL-listed PVC conduits and fittings ensures compliance with the UL standard, offering superior reliability for a variety of electrical applications.
Ledes provides UL-listed PVC conduits and fittings that for use with the conduits, including:
- Conduíte de PVC Anexo 40 – A versatile, lightweight option suitable for general-purpose electrical installations, both aboveground and underground.
- Conduíte de PVC Schedule 80 – Features a thicker wall for enhanced impact resistance, ideal for high-traffic or demanding environments.
- Elbows – Available in 45°, 90°, and other custom angles of standard elbows and special radius elbows, these elbows allow smooth directional changes in conduit runs without compromising wiring integrity.
- Acoplamentos – Essential for joining conduit sections, ensuring a seamless and secure connection for continuous wiring runs.
- Adaptadores – Including Male Terminal Adapters and Female Adapters, enabling smooth transitions between different conduit types, boxes, or enclosures.
- Pipe Straps – Strong and reliable conduit supports that securely fasten Schedule 40 and 80 conduits to walls, ceilings, or other structures.
- Gang Boxes – Designed for secure mounting of electrical devices and wiring connections.
- Conduit Bodies – Ideal for providing pull points, splicing spaces, and directional changes, available in multiple styles such as Type LB, LL, LR, T, and C to suit different installation needs.
Trusted by Major Infrastructure Projects
Champlain Hudson Power Express (CHPE) Project
The Champlain Hudson Power Express (CHPE) is a landmark high-voltage direct current (HVDC) transmission project, spanning 339 miles from Quebec, Canada, to New York City. This project is critical for:
- Delivering clean, renewable hydroelectric power to New York.
- Reducing carbon emissions and enhancing grid reliability.
- Creating thousands of jobs and modernizing the region’s energy infrastructure.
For this massive underground and underwater transmission line, Ledes’ UL-listed PVC conduits and fittings were selected due to their superior durability, corrosion resistance, and electrical safety. Our Schedule 40 and 80 PVC conduits provide secure cable protection over long distances, ensuring efficient energy transmission while withstanding underground conditions.
A.B. Brown Power Station Project
The A.B. Brown Generating Station is a 700-megawatt (MW) power plant located along the Ohio River in Indiana, just southwest of Evansville. This facility, owned by CenterPoint Energy (formerly Vectren), consists of:
- Two coal-fired units, each with a 265.2 MW nameplate capacity, primarily using bituminous coal with the capability to substitute natural gas.
- Two gas turbine units, each providing 88.2 MW of capacity for additional power generation.
As part of CenterPoint Energy’s modernization plan, there are ongoing infrastructure improvements and grid enhancements to support future energy needs. The company previously announced plans to retire the coal-fired units and transition to natural gas-powered generation, pending approval from the Indiana Utility Regulatory Commission.
To ensure a secure and reliable electrical system, Ledes’ UL-listed PVC conduits and fittings were selected for various electrical installations and upgrades within the A.B. Brown facility.
Por que escolher Ledes?
Listado pela UL – Ensuring compliance with safety and performance standards.
Durable & Corrosion-Resistant – Made from high-quality PVC for long-lasting performance in harsh environments.
Instalação fácil – Lightweight and designed for quick assembly.
Versatile Applications – Suitable for residential, commercial, and industrial electrical installations.
Ledes is proud to be a supplier for critical infrastructure projects that shape the future of energy. Our innovative, high-performance conduit solutions ensure safe and efficient electrical installations in the most demanding environments.
UL vs. CSA Standard PVC Conduits
UL (Underwriters Laboratories) and CSA (Canadian Standards Association) are two leading organizations establishing safety and performance benchmarks for electrical conduits. Their standards ensure products meet rigorous requirements for durability, fire resistance, and environmental adaptability, with distinct regional and technical emphases.
- UL Standards: Primarily recognized in the United States, UL standards focus on ensuring that electrical products, including PVC conduits, are safe to use within the U.S. infrastructure. The UL standard for PVC conduit (e.g., UL 651) addresses fire safety, impact resistance, temperature ratings, and more.
- CSA Standards: These are focused on ensuring that products are safe for use within Canada. CSA standards often align with international guidelines but may have specific adjustments to reflect local safety and regulatory needs. CSA C22.2 No. 211.2 is the standard for PVC conduit in Canada, outlining similar requirements to UL but tailored for Canadian safety regulations.
Performance Requirements for UL and CSA
Performance Requirements UL651 and CSA C22.2:
Aspects | UL651 | CSA C22.2 Nº 211.2 |
Temperature | Use at 50° C(122°F) or lower ambient temperatures; Use with 75° C (or maybe 90° C) wiring. | Use at a continuous operating temperature of 75° C.
|
Resistência ao impacto | Test at 23.0 ±2.0° C, with 20lbs (9.1 kg) weight for Schedule 40. | Test at –34 ± 2 °C, with 12 J impact energy for rigid conduit.
|
Resistência à tracção | 5,000 psi for Schedule 40 conduit | Not specified |
Resistant to Crushing | Detail required in section 6.9 | Not specified |
Compressão | Not specified | No cracks and decrease no more than 25% when subjected to certain forces. |
Chama | 3 times of 60-seconds flame application, no more than 5s flame after each application. No flaming drops. | Not burn than 30 seconds, no flaming or glowing particles. |
Resistência à luz solar | Same requirements with CSA | Same requirements with UL |
Conformidade com o Código
- National Electrical Code (NEC): UL-certified PVC conduits are recognized for compliance with the U.S. National Electrical Code (NEC), which is the standard governing electrical installations across the United States.
- Código Elétrico Canadense (CEC): CSA-certified PVC conduits are recognized for compliance with the Canadian Electrical Code (CEC), ensuring that products meet the specific safety and installation standards for electrical systems in Canada.
Marking and Labeling
- UL Mark: PVC conduit that is UL-listed typically displays the UL mark, which indicates that it meets the specific UL safety standards and is approved for use in the United States.
- CSA Mark: Similarly, PVC conduit that meets CSA standards is marked with the CSA logo, indicating that it is compliant with Canadian requirements.
Both UL and CSA standards are crucial for ensuring that PVC conduits meet the necessary safety, performance, and regulatory requirements in their respective regions. While there are similarities in the testing protocols and requirements, the key difference lies in their geographic applicability and specific regulations. For projects in the United States, UL-listed PVC conduit is the ideal choice, while CSA-certified conduit is essential for Canadian installations.
Conclusão
As we’ve explored throughout this guide, UL 651 PVC conduit plays a crucial role in modern electrical installations by offering a combination of durability, fire resistance, corrosion resistance, and compliance with NEC requirements. Its classification into Schedule 40 and Schedule 80 allows for flexibility in different applications, ensuring that electricians and contractors can choose the right type based on mechanical protection needs and environmental conditions.
Whether you’re working on an underground installation, a commercial building, or an industrial facility, using UL 651-compliant PVC conduit ensures that your electrical system meets safety standards and performs reliably over time. By selecting certified conduit from reputable manufacturers, you can guarantee long-term performance while ensuring compliance with industry regulations.
As the demand for sustainable, cost-effective, and reliable electrical solutions continues to grow, UL 651 PVC conduit remains a key component in safe and efficient wiring infrastructure. Now that you have a thorough understanding of UL 651, you can confidently choose the right conduit for your next project.
Se você tiver alguma dúvida ou estiver interessado em nossa série de produtos UL, você pode entre em contato conosco por e-mail ou mesmo What’s app, e geralmente responderemos a você dentro de 1 dia útil.
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