Key Differences in Electrical Conduits Types:SCH40 vs SCH80 vs DB60 vs DB100 vs DB120 vs Type A vs Type EB

1. Introduction

1.1 Why Conduit Specifications Matter

Electrical conduits protect wiring from environmental damage, physical impact, and corrosion. Specifications like SCH40, SCH80, DB60, DB100, DB120, Type A, and Type EB define critical differences in wall thickness, durability, and application suitability. These classifications ensure compliance with safety codes (e.g., National Electrical Code®) and performance standards. These specific designations are universally understood and mandated by readers in North America due to historical adoption, regulatory frameworks, and material availability.

1.2 Referencing Key Standards

This article references industry standards to clarify conduit requirements:

UL 651: Safety Standard for Rigid PVC Conduit and Fittings (covers SCH40, SCH80, Type EB, and Type A).

NEMA TC 2 : Standard for Electrical Polyvinyl Chloride (PVC) Conduit (overs SCH40, SCH80).

NEMA TC 6 & 8 : Standard for Polyvinyl Chloride (PVC) Plastic Utilities Duct for Underground Installations (governs DB60, DB100, DB120, and EB20 and EB35).

Note to Readers: For detailed technical specifications, always consult the official documents:

Purchase UL 651 directly from UL Solutions.

Access NEMA TC 6 & 8-2013 via the National Electrical Manufacturers Association (NEMA).

2. Understanding Different Conduit Series: SCH VS DB VS EB VS A

In the classification of rigid PVC conduits, SCH, DB, EB, and Type A share certain similarities but also have distinct characteristics that set them apart. To provide a clear understanding, we will present these conduit types separately, highlighting their differences, common features, and specific applications.

According to UL 651, SCH 40, 80, Type EB (Encased Burial) and Type A are often discussed together for comparison, as they are both designed for concrete-encased installations but differ in strength and application scope. Meanwhile, in NEMA TC 6 & 8, DB (Direct Burial) and EB conduits are compared, as both are intended for underground use but differ in their burial methods and load-bearing capabilities.

To avoid confusion and make it easier for readers to follow, we will analyze each type separately in the following sections.

2.1 What Are Conduit Schedules?

A conduit’s “schedule” (abbreviated as “Sch”) refers to its wall thickness. The bigger the number, the thicker the wall. For example, Schedule 80 has a thicker wall than Schedule 40, even though both have the same outer diameter.

2.2 SCH 40 VS 80 PVC Conduit

SCH 40 Electrical conduit designed for normal-duty applications above ground; concrete-encased applications or direct burial. May be referred to as “heavy wall.”

SCH 80 Electrical conduit designed for heavy-duty (areas of physical damage) applications above ground; concrete-encased applications or direct burial. May be referred to as “extra heavy wall.”

Schedule 80 rigid PVC conduit is thicker-walled than Schedule 40, providing enhanced mechanical protection. It can be used in any application where Schedule 40 is permitted, including pole installations in compliance with NEC standards (NFPA 70).

2.3 What is Type DB Conduit?

Underground electrical conduit systems require proper protection to ensure longevity and reliability. Direct Burial (DB) conduits are specifically designed for direct burial applications, eliminating the need for encasement in concrete. Type DB products can also be used for concrete encased applications where specified.

However, not all DB-rated conduits are the same—DB60, DB100, and DB120 are categorized based on their wall thickness, mechanical strength, and suitability for different burial depths and load conditions.

Wall thickness and material strength increase as the DB rating number increases, making higher DB-rated conduits suitable for deeper burial and heavier loads.

2.4 What is Type EB Conduit?

EB (Encased Burial) conduit is a type of PVC conduit specifically designed for burial encased in concrete. It is commonly used in underground electrical systems where protection against soil pressure and mechanical impact, typically is type EB20 and EB 35.

2.5 What is Type A Conduit?

Type A rigid PVC conduit is a high-strength, durable electrical conduit designed for various installation environments.

Unlike Type EB conduit, which is limited to concrete encasement in trenches outside buildings, Type A conduit offers broader applications, making it an ideal choice for demanding electrical infrastructure projects.

3. Key Differences in Different Types of PVC Conduit

3.1 Size & Wall thickness of Different Types of Conduits

We take the same size to see the results of the wall thickness of the different conduits in the same case as follows: SCH 80 ＞ SCH 40 ＞ Type A ＞ DB120 ＞ DB100＞ DB60 ＞ EB35 ＞ EB20

3.2 Material Requirements: ASTM D1784

ASTM D1784 establishes a classification system for rigid PVC and CPVC compounds, focusing on key material properties critical for manufacturing conduits.

Base resin type: Ensures chemical consistency.

Impact resistance: Minimum notch impact strength (e.g., 12123 includes impact resistance ≥1 ft·lb/in).

Tensile strength: Minimum 6,500 psi (for PVC).

Modulus of elasticity: Minimum 400,000 psi (stiffness).

Deflection temperature: Resistance to deformation under heat.

Flammability: Compliance with fire safety standards.

Recycled Materials:Both standards permit recycled PVC if they meet mechanical and chemical requirements, ensuring sustainability without compromising performance.

3.3 Usage Restrictions and Temperature Ratings

According to the requirement mentioned in UL 651, we conclude as the following.

3.3.1 SCH 40 and 80 Conduit

Both Schedule 40 and Schedule 80 conduits are designed for use in environments with ambient temperatures up to 50°C (122°F).

When used with 75°C (167°F) wiring, they function under standard conditions.

The conduits may support 90°C (194°F) wiring if they meet the construction requirements specified for high-temperature applications.

3.3.2 Type EB and A Conduit

Type EB and Type A conduits are suitable for environments at 50°C (122°F) and below.

Type A rigid PVC conduit supports wiring rated up to 75°C (167°F).

When encased in concrete in outdoor trenches, both Type A and Type EB can be used with wiring rated up to 90°C (194°F).

While the document does not explicitly specify the temperature range for the DB series conduit, its operational limits can be inferred by comparing it to similar products. Many manufacturers exceed standard requirements in their designs—for example, testing revealed that Ctube’s PVC conduit can withstand temperatures as low as -15°C and as high as 105°C, demonstrating performance beyond typical industry benchmarks.

3.4 Other Requirements

Color of SCH 40 and 80 should be gray, and PVC duct should be either gray or white in color. All the conduit can be other colors and they are acceptable if agreed to by the parties involved.

Tensile Strength: 5,000 psi (34.5 MN/m2)(3.45 kN/cm2)(3515 gf/mm2) for Schedule 40 and 80 rigid PVC conduit and 4000 lbf/in2 (27.6 MN/m2 or 2.76 kN/cm2 or 2812 gf/mm2) for Type A, Type EB and Type DB rigid PVC conduit.

4. PVC Conduit Application introduce: SCH 40, SCH 80, Type EB, Type DB, Type A

4.1 General Applications of PVC Conduit

Regardless of type, PVC conduit is widely used in indoor and outdoor settings, aboveground and underground installations, and areas requiring corrosion resistance and durability. The selection of conduit type depends on factors such as impact resistance, pressure tolerance, and regulatory compliance.

4.1.1 Industrial & Commercial Facilities

Used for protecting electrical wiring in warehouses, factories, and processing plants.

Schedule 40 is suitable for general applications where moderate mechanical protection is sufficient.

Schedule 80 is recommended for environments with high impact risks, such as chemical plants and areas with frequent equipment movement.

4.1.2 Parking Garages & Driveways

Installed in parking structures, tunnels, and access roads to safeguard electrical lines.

Schedule 40 is used in elevated or wall-mounted installations, while

Schedule 80 is preferred for ground-level placements subject to vehicular impact.

4.1.3 Corrosive & Hazardous Locations

PVC conduit is ideal for gas stations, oil refineries, and coastal installations, thanks to its resistance to corrosion, moisture, and chemicals.
In hazardous zones (as defined by NEC Article 352.10), Schedule 80 is required for impact resistance in areas exposed to flammable gases and vapors.

4.1.4 Underground Installations

Used in utility networks, road crossings, and heavy traffic areas to protect underground wiring.

Type DB and Type EB conduits are specifically designed for underground applications, with Type DB suitable for direct burial and Type EB requiring concrete encasement for additional structural support.

In high-pressure zones, such as under highways or airport runways, Schedule 80 is often used for added strength, while Type A conduit is preferred when extreme durability is required within concrete structures.

4.2 Differences in Specialized Applications

While all PVC conduit types share common applications, key differences lie in their structural requirements and burial methods:

4.2.1 Schedule 40 vs. Schedule 80

Both are suitable for general electrical conduit applications.

Schedule 40 is cost-effective and widely used in standard installations.

Schedule 80 provides greater wall thickness and is preferred in high-risk environments with potential impact or crushing forces.

4.2.2 Type DB vs. Type EB

Type DB is designed for direct burial, eliminating the need for concrete encasement. It also can be buried in concrete encasement.

Type EB is intended for use within concrete-encased duct banks in commercial and municipal projects.

4.2.3 Type A Conduit

Offers enhanced durability for high-load underground networks, including manholes, utility vaults, and structural concrete slabs.
Suitable for extreme temperatures and demanding applications.

5. How to Choose Between SCH 40, SCH 80, Type DB, Type EB, and Type A

When choosing the appropriate PVC conduit for your project, several factors such as cost, durability, installation environment, and compliance with industry standards must be considered.

5.1 Mechanical Strength and Durability

SCH 80 is the most durable option with thicker walls that provide superior impact resistance. It is recommended for high-risk environments where the conduit may be exposed to physical stress or heavy impacts.

SCH 40, while still durable, has a thinner wall and is less impact-resistant than SCH 80, making it suitable for general-use installations that do not require high mechanical protection.

Type A offers moderate strength and is designed to handle the physical demands of concrete-encased applications, making it a good fit for underground installations that require additional support from surrounding concrete.

Type DB and Type EB are intended for underground use and provide adequate durability. Type DB is designed for direct burial, while Type EB is used in applications where the conduit is embedded in concrete, providing protection against impact in harsh conditions.

5.2 Installation Environment: Underground vs. Aboveground

Aboveground Installations: Both SCH 40 and SCH 80 are ideal for aboveground applications, with SCH 80 being preferred in areas exposed to high mechanical stress.

Underground Installations: Type DB and Type EB are better suited for underground use. Type DB is designed for direct burial, and Type EB provides added protection when encased in concrete. However, SCH 40 and SCH 80 can be used underground in high-impact areas where additional mechanical strength is needed.

5.3 Cost and Budget Considerations

SCH 80 is typically the most expensive option due to its thicker walls and higher durability, making it the best choice for high-risk, high-impact environments. SCH 40 is more affordable than SCH 80, offering a cost-effective solution for general-purpose installations. Type DB, EB and A are cost-effective option for underground applications.

Specific prices need to be consulted with the supplier. And it worth to mentioned that, due to the different weights, the time and cost of transportation and labor for installation may vary.

5.4 Compliance and Regulatory Standards

When selecting PVC conduit, it’s crucial to ensure compliance with relevant standards such as the NEC (National Electrical Code), which specifies requirements for materials and installation practices. Additionally, local building codes and regulations from agencies like OSHA and the EPA may impose specific requirements for installations in hazardous environments. Compliance with these standards guarantees the conduit system’s safety, performance, and longevity.

6. Conclusion

In conclusion, there is no single “best” choice when it comes to selecting electrical conduit. The most suitable conduit depends on the specific needs of the project, such as the installation environment, budget, and compliance with relevant safety and regulatory standards. It is essential to consider factors like strength, durability, and the potential for exposure to harsh conditions to ensure the conduit maximizes safety and meets project requirements.

Ctube is a electrical conduit supplier, we offer a variety of high-quality PVC conduits, including Schedule 40, Schedule 80, Type DB, Type EB, and Type A, to cater to diverse project needs. We also provide specialized solutions such as LSZH (Low Smoke Zero Halogen) conduits for applications requiring fire safety and minimal toxicity in case of fire, and solar UPVC conduit designed for solar energy systems, offering enhanced UV resistance and durability for outdoor use.

All our products are rigorously tested to meet international standards, ensuring reliable performance in diverse applications.If you’re interested in learning more about our products or receiving a quote, feel free to reach out to us! Thanks for reading, and good luck with your projects.