High-density polyethylene (HDPE) pipes have become increasingly popular in various industries due to their durability, flexibility, and corrosion resistance. However, selecting the right HDPE pipe sizes is crucial for ensuring optimal performance and longevity of your piping system. This comprehensive guide will explore common mistakes to avoid when choosing HDPE pipe sizes and provide valuable insights to help you make informed decisions.
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Before delving into common mistakes, it’s essential to understand what HDPE pipe sizes entail. HDPE pipe sizes refer to the dimensions of the pipe, including its diameter and wall thickness. These measurements are critical in determining the pipe’s capacity, pressure rating, and suitability for specific applications.
An HDPE pipe size chart is a valuable resource for selecting the correct pipe size. These charts provide essential information about various pipe dimensions, including nominal size, outside diameter (OD), and wall thickness. Understanding how to read and interpret these charts is crucial for avoiding sizing errors.
The HDPE pipe OD size, or outside diameter, is a key measurement used in pipe selection. It represents the actual measured outer diameter of the pipe and is often used in conjunction with the wall thickness to determine the pipe’s pressure rating and flow capacity. When consulting an HDPE pipe size chart, you’ll notice that the HDPE pipe OD size is typically listed in both inches and millimeters for easy reference.
It’s important to note that the HDPE pipe OD size remains constant for a given nominal pipe size, regardless of the pipe’s pressure rating or SDR (Standard Dimension Ratio). This consistency in HDPE pipe OD size allows for easier system design and component compatibility across different pressure classes.
One of the most critical factors in selecting HDPE pipe sizes is the required flow rate for your application. Ignoring or miscalculating flow rate requirements can lead to significant problems later on.
To avoid this mistake:
Selecting a pipe that’s too small for the required flow rate can result in increased pressure loss, reduced efficiency, and potential system failure. Conversely, oversizing the pipe can lead to unnecessary costs and reduced flow velocity, which may cause sediment buildup in some applications.
HDPE pipe sizes come with specific pressure ratings that indicate the maximum internal pressure they can safely withstand. Overlooking these ratings when selecting pipe sizes can lead to catastrophic failures.
To avoid this mistake:
Remember that HDPE pipe sizes and pressure ratings are interconnected. Generally, larger-diameter pipes with thicker walls can withstand higher pressures. Always consult the HDPE pipe size chart to ensure you’re selecting a pipe that meets both your size and pressure requirements.
Temperature plays a significant role in the performance and longevity of HDPE pipes. Failing to account for temperature variations can lead to pipe failure or reduced lifespan.
To avoid this mistake:
In high-temperature applications, you may need to select a larger pipe size or a pipe with a higher pressure rating to compensate for the reduced strength of the material at elevated temperatures.
The Standard Dimension Ratio (SDR) is a crucial factor in the HDPE pipe size chart and in the selection of HDPE pipe sizes & often misunderstood. SDR is the ratio of the pipe’s outside diameter to its wall thickness and directly affects the pipe’s pressure rating.
To avoid this mistake:
Misinterpreting SDR can lead to selecting a pipe that doesn’t meet your pressure requirements or has an insufficient internal diameter for your flow needs.
When selecting HDPE pipe sizes, it’s crucial to think beyond current needs and consider potential future expansion or changes in system requirements.
To avoid this mistake:
While oversizing pipes can lead to higher initial costs, it may be more economical in the long run if you anticipate significant increases in demand. Conversely, undersizing to save on upfront costs can result in expensive system upgrades later.
The environment in which the HDPE pipe will be installed can significantly impact the required pipe size and specifications.
To avoid this mistake:
Different installation environments may require variations in pipe wall thickness or diameter to ensure long-term performance and safety.
Selecting the right HDPE pipe sizes isn’t just about the pipe itself; it’s also crucial to ensure compatibility with fittings, valves, and other system components.
To avoid this mistake:
When selecting fittings and valves, pay close attention to the HDPE pipe OD size. Many fittings are designed to match specific HDPE pipe OD sizes, so using the correct size is essential for a proper fit and seal. Remember that the HDPE pipe OD size is the key measurement for matching pipes with fittings, not the nominal pipe size or internal diameter.
Incompatibility between pipes and fittings can lead to leaks, reduced system efficiency, and increased maintenance costs. Always double-check that your chosen fittings are designed for the specific HDPE pipe OD size you’re using in your system.
Various industry standards and regulations govern HDPE pipe sizes and specifications. Neglecting these can result in non-compliant installations and potential legal issues.
To avoid this mistake:
Compliance with industry standards not only ensures legal operation but also assures quality and performance.
To help you avoid these common mistakes, several tools and resources are available:
Selecting the right HDPE pipe sizes is a critical decision that impacts the performance, efficiency, and longevity of your piping system. By avoiding these common mistakes and utilizing available resources like HDPE pipe size charts, you can ensure that your pipe selection meets both current needs and future demands.
Remember to consider all relevant factors, including flow rate, pressure requirements, temperature conditions, and installation environment. Pay attention to SDR values, plan for potential expansion, and ensure compatibility with other system components.
By taking a comprehensive approach to HDPE pipe size selection and avoiding these common pitfalls, you’ll be well-equipped to design and implement a piping system that performs optimally for years to come. Whether you’re working on a small residential project or a large industrial installation, the principles of proper pipe sizing remain the same. Take the time to do it right, and you’ll reap the benefits of a well-designed, efficient, and reliable HDPE piping system.
What is an HDPE pipe size chart, and why is it important?
An HDPE pipe size chart is a tool that provides essential information about various pipe dimensions, including nominal size, outside diameter (OD), and wall thickness. It is crucial to select the correct pipe size to ensure compatibility with system requirements and to avoid sizing errors.
How do I determine the correct HDPE pipe OD size for my project?
The HDPE pipe OD size, or outside diameter, is a key measurement used in pipe selection. It is determined by consulting an HDPE pipe size chart, which lists OD sizes in both inches and millimeters. This consistency helps in system design and ensures compatibility across different pressure classes.
What role does the HDPE pipe OD size play in pressure ratings? The HDPE pipe OD size, combined with wall thickness, determines the pipe’s pressure rating. A larger OD size with the same wall thickness can handle higher pressures. It’s important to consult the HDPE pipe size chart to ensure the selected pipe meets your system’s pressure requirements.
Why is it important to consider future expansion when selecting HDPE pipe sizes?
Considering future expansion ensures that the piping system can accommodate increased demand or flow requirements without requiring costly upgrades. Oversizing initially might be more economical in the long run if significant demand increases are anticipated.
General
What does the PPI Power & Communications Division do?
PPI is the major North American manufacturers’ trade association of advocacy and education for plastics use in pipe, conduit and infrastructure solutions. The mission of the Plastics Pipe Institute is to advance the acceptance and use of plastic pipe systems through research, education, technical expertise and advocacy. PPI has divisions representing the different end use applications for pipe and conduit. The Power & Communications Division (PCD) mission is to expand knowledge of the uses and benefits of HDPE conduit for Power and Communications applications.
Where can I find terminology specific to duct and conduit?
PPI Handbook of PE Pipe - Chapter 14 on Duct & Conduit has a useful glossary: link
What is the voltage of mainline power distribution and can HDPE conduit handle that voltage?
HDPE conduits up to 8 inches in diameter have had solid dielectric, high voltage cables, rated at 345kV installed inside them. Further, conduit through 6 inches is commonly used to protect underground distribution cables having voltage ratings from 600V to 35kV. Cable voltage ratings have not been a deterrent for utilities choosing to use conduit made from HDPE for underground power cables.
Is all plastic pipe that is orange conduit?
No. While modern gas pipe is yellow, when excavating piping infrastructure workers should be aware that certain older plastic gas pipe material was colored orange or tan. The predominant color for conduit today is orange but many other colors do exist. See FAQ question What colors are available? The American Gas Association has published a historical list of plastic gas pipe manufacturers which includes colors where pertinent. Contact the local gas company for further information. See also:
Can HDPE conduit be used for natural gas, propane, compressed air or water service?
HDPE conduit is not suitable for pressure service, whether it be for a gas or for water. Gas service includes, but is not limited to, natural gas, propane or compressed air applications. Short-term pressurization of HDPE conduit for pull-tape or cable installation by blowing is acceptable. Water service includes, but is not limited to, potable water and non-potable water applications. Products suitable for these applications have specific technical requirements, undergo specific testing, and potentially require specific 3rd party certifications.
Conduit Sizing
What size conduit do I need?
The size of the conduit you will need will depend on the type of cables to be installed, the method of cable installation, and method of conduit installation.
For further discussion on the sizing of conduit based on cable fill and cable installation method, see:
For further discussion on sizing of conduit based on conduit installation method, see:
Why are there many sizing systems for conduit?
There are a number of different sizing systems for conduit. These define the outside or inside diameter, wall thicknesses and tolerances. These include outside and inside diameter controlled sizes where the outside diameter, or inside diameter in the case of inside diameter controlled sizes, is fixed for a given size, and the wall thickness varies depending on the needs of the installation. Common sizes are IPS, SIDR, True Size, Schedule, EPEC and SDR. Selecting the right size of conduit is important so to ensure that the conduit is properly sized for the cable(s) to be installed and sufficiently robust for the installation and long term performance in the application. The PPI Power & Communications Division is working to harmonize the sizes across the ranges of standards. A more complete discussion of sizing systems is available within:
What do SDR and SIDR stand for?
SDR and SIDR values are indicators of wall thickness. SDR is the Standard Dimension Ratio, sometimes also referred to simply as DR (Dimension Ratio). Technically, it is the nominal outside diameter divided by the minimum wall thickness per specification. Similarly, SIDR is the ratio of the inside diameter of the conduit to the wall thickness of the conduit. The larger the SDR or SIDR, the thinner the wall thickness. The smaller the SDR or SIDR number the thicker the wall of the conduit.
Smaller SDR or SIDR numbers also mean that the conduit has higher tensile strength and greater resistance to deflection than a comparable product with a higher number. The combination of the outside diameter (OD) or inside diameter (ID) with the SDR or SIDR will define the ID of the conduit and the available space for the cables. See tables within conduit standards for available sizes and specific dimensions. A more complete discussion of sizing systems is available within:
Need help sizing the wall thickness for conduit in mini-HDD installations?
The Conduit Design Calculator is a software tool that aids in determining the most appropriate wall thickness of high-density polyethylene (HDPE) conduit installed via horizontal directional drilling (HDD) techniques.
How many power cables can be placed into a conduit?
It depends on the size and quantity of the cable. The NEC (National Electric Code) has guidelines on the number of conductors allowed in a HDPE Conduit. With one conductor, it can "fill" 53% of the inside diameter of the conduit. For 2 wires 31% and over 2 wires 40% fill ratio is allowed. Simply multiply the area of the conductors by the quantity and compare to the inside area of the conduit. For further discussion on the sizing of conduit based on cable fill and cable installation method, see:
What is the maximum number of HDPE conduit innerducts in a casing?
This is highly dependent on the installation. The straighter and shorter the run, the more you can fill the casing. The longer and more complex the casing installation is, the less fill is applicable. Generally, the recommended percentage fills for all combined innerducts being considered, based on areas, is:
For additional information on innerducts, please see:
Conduit Storage
How long can conduit be stored outdoors?
Black is recommended for any application where the conduit is exposed or stored over a long time period to sunlight (Carbon Black additive provides UV protection). Colors, even those with UV Stabilizers (other than black) cannot tolerate sunlight for extended periods of time without deterioration. ASTM F specifies the stabilizers in colored conduit should protect it in outside storage for a minimum of one year. Contact the manufacturer for recommendations for storage. For more information, see:
For more information, please visit 6 Inch HDPE Pipe.
Can conduit stored outdoors for more than one year still be used?
In some cases, yes, depending on storage conditions and location. Conduit can be recertified to meet the required standards for use in some situations. Please contact your manufacturer to see if they offer this service for the product you have a question about.
Conduit Installation
How do I join HDPE conduit?
HDPE conduit can be joined using mechanical couplings, fusion joining (including electrofusion), and adhesive bonding. The choice may depend on the conduit installation method, cable installation method, and in-service conditions. For additional information, please see:
How do I avoid overstretching the conduit during installation?
HDPE conduit can be over-stressed during laying or pulling resulting in undesirable necking that may result in internal restriction that will later impede cable or innerduct pulling or blowing. For this reason, it is important to avoid over stressing the product during installation. The Safe Pull Strength is dependent on conduit dimensions, conduit temperature and conduit material. It is recommended to always use a breakaway link swivel, or similar, sized based on the Safe Pull Strength of the conduit being installed. PPI provides several references:
What do I do about HDPE Conduit Memory, Ovality and Coil-set?
Due to its flexible nature, HDPE conduit can become oval or out-of-round when it is wound onto reels or coils. Ovality is a packaging condition that occurs when conduit is coiled, whereby conduit flattens out as it is coiled. This is allowed and limits are specified in industry standards. Coil-Set is an inherent tendency for conduit to conform over time to the curved shape or bend radius of the coil or reel on which it has been stored. Both of these are sometimes termed “memory” as the conduit wants to hold its packaged shape; the conduit will have a memory from winding on the reel because the molecules align themselves during the manufacturing process of reeling, or "bending" the conduit. You can envision, one side of the conduit will be in tension, while the opposite is in compression. The molecules align themselves, relax and "remember" their position. Once uncoiled, they start to relax into the new positions. The rate of relaxation is temperature dependent, with relaxation occurring faster at higher temperatures.
For more information on ovality and coil-set, causes and methods for mitigations, see:
For additional information on working safely with conduit, please see:
What is the temperature range over which HDPE conduit can be installed?
HDPE conduit can be installed in ambient temperature ranging between -30 °F to 180 °F (-34 °C to 82 °C). At low temperature, care should be made in handling to avoid dropping the conduit. At high temperature, and particularly in conjunction with solar heating, HDPE conduit will have reduced Safe Pull Strength. Expansion/contraction of the conduit as a result of temperature changes should be considered in the design phase for above ground applications and, below ground, conduit should be allowed to stabilize with the ground prior to trimming and completing connections.
For additional information on thermal expansion/contraction, please see:
What is the impact of temperature on conduit length (thermal expansion/contraction)?
HDPE conduit has a high degree of thermal expansion/contraction, approximately 10 times that of metal pipe, with a coefficient of thermal expansion of 1 x 10-4 in/in/°F. As a “rule of thumb,” temperature change for unrestrained HDPE conduit is about “1/10/100,” that is, 1 inch for each 10 °F temperature change for each 100-foot of conduit. A temperature rise results in a length increase while a temperature drop results in a length decrease.
In aerial conduit applications due to the potential for significant temperature variations resulting from ambient fluctuations and solar heating, the effects of thermal expansion/contraction of the conduit must be carefully considered in the design process. In buried applications, temperature variations are significantly moderated in service; however, during installation, sufficient extra conduit should be laid to allow for thermal contraction that may occur once installed.
For additional information on thermal expansion/contraction, please see:
Product Offering
What colors are available?
The National Public Works Association recommends
Colors, even those with UV Stabilizers (other than black) cannot tolerate sunlight for extended periods of time without deterioration. ASTM F specifies the stabilizers in colored conduit should protect it in outside storage for one year. For more information, see:
Note: While modern gas pipe is yellow, when excavating existing piping infrastructure workers should be aware that certain older plastic gas pipe material was colored orange or tan. The American Gas Association has published a historical list of plastic gas pipe manufacturers which includes pipe colors where pertinent. Contact the local gas company for further information. See:
Can conduit be ordered with more than one conduit and/or color per reel?
Yes. Most manufacturers provide special packaging called paralleling or segmenting. Conduit that is parallel packaged can have up to four (4) different colors per reel. For more information, see:
What is the longest length that can be put on a reel?
That depends on the Outside Diameter of the conduit. The larger the conduit the less material will fit on a reel. See the PPI manufacturer's web sites for their standard reel configurations. For safety information related to handling of reels, see:
Can the conduit be supplied in coils without a reel?
Yes. This type of packaging is usually for quantities of less than 1,000 feet per coil. Coils are generally secured at multiple points to keep them together and palletized for shipping. For safety information related to handling of coils, see:
Can a pull tape be installed in the conduit at the factory?
Yes. Most manufacturers can install a wide range of pull tapes, from inexpensive polypropylene rope (PP Rope) to expensive Kevlar pull tapes that are pre-lubricated, measured and marked. The conduit is extruded over the pull line. The extruder has an opening in the back side of the extrusion die that forms the HDPE tube. The pull line is inserted into this opening at the same rate as the HDPE tube is extruded providing a continuous pull line inside the conduit. Depending on your project the manufacturer can suggest the pull line that is best for your application. See also:
Can cable be installed in the conduit at the factory?
Yes. This is called Cable in Conduit (CIC). Many types of cable, power or communications, can be installed in the conduit. ASTM D and UL are the specifications for CIC for power applications. The requirements for the conduit used in these products are essentially the same as regular conduit.
What advantage does ribbed or lubricated conduit have?
Ribbed or lubricated conduit reduces the friction between cable and conduit to facilitate cable installation. The friction between the cable outer jacket and the conduit inner surface can be a limiting factor for the distance of cable installed. Friction can lead to excess heat that can damage conduit, cable or both. Reducing this friction can significantly increase the achievable cable install distance. Longitudinal ribs reduce the surface area reducing friction (note that these are still basically a smoothwall product). Lubricants are commonly added to cable surface during installation but conduit with the inner surface pre-lubricated at the factory may be available. It is important to consider the compatibility of the lubricant with the cable jacket and the installation method (pull or blown) when choosing a lubricant. For more on reducing the friction and selection of lubricants, see:
Why can't we get 4-inch Schedule 40 on a reel?
Theoretically, 4-inch schedule 40 conduit can be placed on a reel. However, it is not recommended. As the conduit is extruded, it is wound on a reel. As it is wound, the top of the conduit is in tension, while the bottom is in compression. This causes the conduit to ovalize. It is much more apparent in the larger diameters. ASTM F acknowledges the effect and allows for it in the specification. As 4-inch Schedule 40 has a relatively thin wall, it (and Schedule 40 diameters above 4-inch) can have a tendency to buckle. That is why 4-inch Schedule 40 on a reel is not recommended. Those diameters are typically available in stick form. Heavier walls, such as SDR 13.5, can be put on reels. Six inch (6-inch) diameter conduit is typically the maximum diameter that is coilable. For more information on ovality and coil-set, causes and methods for mitigations, see:
Conduit Materials
What is HDPE?
HDPE is the abbreviation for High Density Polyethylene, the preferred and most commonly used material to make conduit. HDPE is a polymer comprised primarily of ethylene and is different from polyvinyl chloride (PVC), polyethylene terephthalate (PET) and polypropylene (PP) plastics. HDPE is strong, tough, durable, flexible in all weather, and never gets brittle. These characteristics make it the ideal choice for conduit products. You may already be familiar with HDPE as it is successfully used in milk jugs and other consumer packaging products. In the case of conduit, a very specific durable grade of HDPE is selected to ensure appropriate long term performance in the application. For more information:
What does the cell classification of HDPE mean?
The cell classification is a method of identifying and specifying the raw material properties of HDPE Conduit. It is a series of six numbers and one letter which describe the properties of the resin per ASTM D. The numbers, in order, represent the density, melt index, flexural modulus, tensile strength, slow crack growth, hydrostatic design basis, and the letter represents whether the material is black or colored. It is used in the industry standards to specify the minimum properties of acceptable materials to be used in the fabrication of conduit. As the cell classification is specified within these standards, it is typically not required to specify the cell classification of the material if you are already specifying conduit that conforms to any of the ASTM, NEMA, UL or CSA conduit standards. For more information:
What is black or colored “masterbatch” concentrate?
In the manufacturing process for conduit, called extrusion, unpigmented polyethylene pellets are mixed with a small proportion of black or colored pellets. These black or colored pellets are also made of polyethylene but have had a high concentration of carbon black or colored pigments, and sometimes other additives, incorporated. These pellets are termed a “concentrate” or “masterbatch”. The extrusion process is specifically designed to melt and mix all the unpigmented and masterbatch pellets together distributing the black or color evenly throughout the entire material. Carbon black, color pigments and other additives are specifically selected to enhance the properties of the final product, such as outdoor weathering resistance.
Can I use conduit made with PE material?
The standard HDPE resin used in the manufacture of conduit, and as specified in conduit standards, provides the ideal combination of strength and flexibility for most applications. Occasionally, a higher strength conduit may be desirable due to high anticipated installation or frictional forces, e.g., long difficult HDD run; in such cases, a heavier wall conduit may be selected or, alternatively, a higher strength material may be selected, such as a PE pressure pipe grade with approximately 15% greater tensile strength. The PE product will likely be stiffer and more expensive than standard industry conduit. Not all manufacturer’s supply PE based conduit and UL or CSA certified products may not be available. PE based pressure pipe may not conform to the conduit standards unless all specified conduit tests have been conducted and the printline includes the conduit standard reference.
PPI has a number of resources explaining the materials used in conduit, how to estimate the safe pulling strength of conduit and calculating the appropriate wall thickness for your installation:
What is rework vs. recycle HDPE?
The use of rework, sometimes called regrind, HDPE is permitted in most conduit standards (e.g. ASTM, UL, NEMA, CSA). As defined by ASTM F412, rework is "plastic from a manufacturer’s own production that has been reground or pelletized for reuse by that same manufacturer." There are various sources of rework from the manufacturing process. In all cases rework is made from materials that are under the control of the conduit manufacturer and they are fully aware of the material composition of the rework. Typically, rework is used in combination with virgin resin anywhere from a 10 - 40% ratio. The use of rework eliminates waste in the production process, avoiding material going to landfill unnecessarily, thus reducing the carbon footprint of the product.
Recycled HDPE are HDPE materials sourced from outside a manufacturer’s plant. This can be post-consumer, post-commercial or post-industrial material. The PPI Power & Communications division is developing requirements to ensure conduit made with recycled HDPE has the required durable, long-term performance needed for the application.
Codes, Standards & Certification
What standards exist for Conduit and where can I find them?
A number of standards bodies develop standards for conduit. Different standards may be intended for different end-uses and applications. Always read the scope of the standard to learn about its intended end-use. Standards are issued by:
PPI provides several publications that may be helpful:
What does ASTM stand for?
ASTM was the American Society for Testing and Materials but has been renamed ASTM International to communicate the international scope and acceptance of its standards. It is an association of manufacturers, engineers, consultants and governmental officials who write standards for materials and products used in all types of construction, including conduit. ASTM Standards for conduit are ASTM F and D.
ASTM F vs. D, D or D?
ASTM F and D are ASTM standards specifically written for conduit products. ASTM D, ASTM D, ASTM F714 and ASTM D are ASTM water pipe specifications often referred to in conduit specifications. Dimensionally pipes conforming to ASTM F and the various water pipe ASTM standards are the same, but the material specification for water pipes include pressure strength requirements and may not have been tested to all the standard conduit requirements. Using water pipe ASTM standards for conduit applications can raise the price significantly because pressure rated resin is more expensive than conduit non-pressure rated resins.
What is UL or CSA Certification?
UL or CSA certified products are products that have been certified by a third party, in this case Underwriters Laboratories or Canadian Standards Association, to conform to a standard. Typically, it requires the manufacturer’s production facilities to be audited on a regular basis by the certifying agency and that samples from those facilities are tested periodically by the certifying agency to ensure conformance with the specified standards. UL or CSA certification may be required by certain customers or by code requirements in the power industry. In many applications third-party certification is not required as it adds cost. Not all products may be available with third party certification so check with the conduit manufacturer. Note that ASTM and NEMA do not provide certification services: In most cases, conduit manufacturers will attest to the fact that their products conform to one or more industry standards.
What is the difference between UL certified resin and ASTM F resin?
Not much in reality. Resins can have either or both classifications. Both are quality resins and meet the same requirements; however, UL will independently test and certify the resin. A manufacturer is required to use a UL certified resin for UL certified product. Blending or mixing is not allowed by UL standards.
Why can't I get SDR 11, UL listed conduit?
You may now be able to get SDR 11 conduit certified to UL651A or UL. SDR 11 wall thickness was not allowed within the previous UL standard but was added in 6th edition published in . UL 651A, Continuous Length HDPE Conduit, and UL , Nonmetallic Underground Conduit with Conductors, now has six categories of conduit wall thickness: EPEC-A, EPEC-13.5, EPEC-11, EPEC-9 as well as Schedule 40 and Schedule 80. ASTM D, ASTM D and NEMA TC7 also include SDR11 conduit.
When HDPE conduit is used in directional drilling, a heavier walled conduit may be required. Relevant PPI publications to assist in selecting wall thickness where the pulling forces may be of concern include:
What are the NEC requirements for HDPE Conduit?
The US National Electric Code (NFPA 70) is the code regulating HDPE conduit use in power applications. Section 353 ( edition) specifies that conduit and fittings shall be listed and indicates conditions under which it can be used. Generally, conduit must be buried or encased and cannot be used in applications with an ambient temperature greater than 50 °C (122 °F). The cable fill limits are defined. Conductors or cables rated at a temperature higher than
The listed temperature rating of HDPE conduit are permitted to be installed in HDPE conduit, provided the conductors or cables are not operated at a temperature higher than the listed temperature rating of the HDPE conduit. For more information see:
Can 90C and 105C rated cables be used with HDPE Conduit?
Yes, the NEC (NFPA 70) permits the use of 90C and 105C rated conduit under specific conditions, provided the conductors or cables are not operated at a temperature higher than the listed temperature rating of the HDPE conduit. For more information see:
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