NEC Article 310 provides detailed requirements for the installation, identification, and use of conductors in general wiring applications. This article ensures that conductors are correctly selected and installed to maintain the safety and reliability of electrical systems. Here is a comprehensive overview of NEC Article 310, covering sections 310.1 to 310.104:

310.1 Scope

This section establishes the scope of Article 310, which covers the general requirements for conductors used in wiring systems. This includes specifications for insulation types, conductor sizes, and ampacities.

310.2 Definitions

Defines key terms used in Article 310 to ensure clarity and consistency. This includes terms such as “conductor,” “ampacity,” and “insulation.”

310.3 Conductors

Specifies the general requirements for conductors, including material and construction:

• 310.3(A) Material: Conductors must be made of copper, aluminum, or copper-clad aluminum unless otherwise specified in the NEC.
• 310.3(B) Stranding: Conductors may be solid or stranded, with specific requirements for each type.

310.4 Temperature Limitations of Conductors

Outlines the temperature limitations for conductors based on their insulation types to prevent overheating and ensure safe operation.

310.5 Minimum Size of Conductors

Specifies the minimum size of conductors for various applications to ensure they can safely carry the expected load:

• 310.5(A) General: Minimum size requirements for conductors in different installations.
• 310.5(B) Small Conductors: Restrictions on the use of small conductors in certain applications.

310.6 Wet Locations

Provides guidelines for using conductors in wet locations, ensuring they are properly insulated and protected from moisture.

310.7 Direct Burial Conductors or Cables

Specifies the requirements for conductors or cables intended for direct burial, ensuring they are suitable for underground installations and protected from physical damage.

310.8 Locations Exposed to Direct Sunlight

Outlines requirements for conductors exposed to direct sunlight to ensure they are UV resistant and adequately protected.

310.10 Uses Permitted

Lists the specific uses for various types of conductors, ensuring they are used in appropriate applications:

• 310.10(A) General: General uses permitted for conductors.
• 310.10(B) Dry Locations: Requirements for conductors used in dry locations.
• 310.10(C) Wet Locations: Requirements for conductors used in wet locations.
• 310.10(D) Direct Burial: Guidelines for direct burial conductors.

310.11 Marking

Requires that conductors be clearly marked with information such as type, size, and insulation rating to ensure proper identification and use.

310.12 Conductor Material

Specifies the acceptable materials for conductors, ensuring they are suitable for the intended application and meet safety standards:

• 310.12(A) Copper Conductors: Guidelines for using copper conductors.
• 310.12(B) Aluminum Conductors: Guidelines for using aluminum conductors.
• 310.12(C) Copper-Clad Aluminum Conductors: Guidelines for using copper-clad aluminum conductors.

310.13 Conductor Construction and Applications

Details the construction requirements and applications for various types of conductors to ensure they are suitable for their intended use:

• 310.13(A) Insulated Conductors: Requirements for insulated conductors.
• 310.13(B) Bare Conductors: Guidelines for using bare conductors.
• 310.13(C) Covered Conductors: Specifications for covered conductors.

310.14 Allowable Ampacities of Insulated Conductors

Specifies the allowable ampacities for insulated conductors based on their insulation type, size, and installation conditions:

• 310.14(A) General: General guidelines for determining ampacity.
• 310.14(B) Tables: Ampacity tables for different conductor types and conditions.

310.15 Ampacities for Conductors Rated 0-2000 Volts

Provides detailed ampacity tables for conductors rated between 0 and 2000 volts, ensuring they are correctly sized for their load and installation conditions:

• 310.15(A) General: Guidelines for using ampacity tables.
• 310.15(B) Tables: Specific ampacity tables for various conductor types and conditions.

310.16 Ampacities for Conductors Rated Over 2000 Volts

Specifies the ampacities for conductors rated over 2000 volts, ensuring they are correctly sized and installed for high-voltage applications.

310.17 Installation Methods for Conductors

Outlines the approved installation methods for conductors to ensure safe and reliable installations:

• 310.17(A) General: General requirements for installing conductors.
• 310.17(B) Conduits and Raceways: Guidelines for installing conductors in conduits and raceways.
• 310.17(C) Cable Trays: Requirements for installing conductors in cable trays.

310.18 Grounding Conductors

Provides guidelines for the use and installation of grounding conductors to ensure they provide effective grounding and fault protection.

310.19 Conductors for Parallel Installations

Specifies the requirements for conductors installed in parallel, ensuring they operate safely and effectively together.

310.20 Conductor Connectors and Splices

Details the requirements for conductor connectors and splices to ensure they provide secure and reliable connections.

310.21 Conductors in Vertical Raceways

Specifies the requirements for installing conductors in vertical raceways to ensure they are properly supported and protected.

310.22 Conductors in Free Air

Provides guidelines for installing conductors in free air, ensuring they are adequately supported and protected from physical damage.

310.23 Conductors in Hazardous Locations

Specifies the requirements for installing conductors in hazardous locations to ensure they are properly protected and meet safety standards.

310.24 Conductors in Wet Locations

Provides guidelines for installing conductors in wet locations, ensuring they are properly insulated and protected from moisture.

310.25 Conductors Exposed to Chemicals

Specifies the requirements for installing conductors exposed to chemicals to ensure they are properly protected from chemical damage.

310.26 Conductors in Corrosive Locations

Provides guidelines for installing conductors in corrosive locations to ensure they are adequately protected from corrosion.

310.27 Conductors in Direct Sunlight

Specifies the requirements for installing conductors exposed to direct sunlight to ensure they are UV resistant and properly protected.

310.28 Installation of Conductors in Conduit or Tubing

Details the requirements for installing conductors in conduit or tubing to ensure safe and reliable installations:

• 310.28(A) General: General guidelines for installing conductors in conduit or tubing.
• 310.28(B) Bends: Requirements for bending conductors to prevent damage.

310.29 Conductor Identification

Requires that conductors be clearly identified by color or marking to ensure proper identification and use.

310.30 Conductors in Cables

Provides guidelines for installing conductors in cables, ensuring they are properly protected and meet safety standards.

310.31 Conductors in Cable Trays

Specifies the requirements for installing conductors in cable trays to ensure they are adequately supported and protected.

310.32 Conductors in Raceways

Provides guidelines for installing conductors in raceways to ensure they are properly supported and protected from physical damage.

310.33 Conductors in Busways

Specifies the requirements for installing conductors in busways to ensure they are properly supported and protected.

310.34 Conductors in Trunking Systems

Provides guidelines for installing conductors in trunking systems to ensure they are adequately supported and protected.

310.35 Conductors in Underfloor Raceways

Specifies the requirements for installing conductors in underfloor raceways to ensure they are properly supported and protected from physical damage.

310.36 Conductors in Riser Systems

Provides guidelines for installing conductors in riser systems to ensure they are adequately supported and protected.

310.37 Conductors in Ventilated Systems

Specifies the requirements for installing conductors in ventilated systems to ensure they are properly protected and meet safety standards.

310.38 Conductors in Hazardous Locations

Provides guidelines for installing conductors in hazardous locations to ensure they are properly protected and meet safety standards.

310.39 Conductors in Wet Locations

Specifies the requirements for installing conductors in wet locations to ensure they are properly insulated and protected from moisture.

310.40 Conductors in Corrosive Locations

Provides guidelines for installing conductors in corrosive locations to ensure they are adequately protected from corrosion.

310.41 Conductors in Free Air

Specifies the requirements for installing conductors in free air to ensure they are properly supported and protected from physical damage.

310.42 Conductors in Direct Sunlight

Provides guidelines for installing conductors exposed to direct sunlight to ensure they are UV resistant and properly protected.

310.43 Conductors in Cables

Specifies the requirements for installing conductors in cables to ensure they are properly protected and meet safety standards.

310.44 Conductors in Conduit or Tubing

Provides guidelines for installing conductors in conduit or tubing to ensure safe and reliable installations.

310.45 Conductors in Raceway Systems

Specifies the requirements for installing conductors in raceway systems to ensure they are properly supported and protected.

310.46 Conductors in Busways

Provides guidelines for installing conductors in busways to ensure they are properly supported and protected.

310.47 Conductors in Raceways

Specifies the requirements for installing conductors in raceways to ensure they are properly supported and protected.

310.48 Conductors in Cable Trays

Provides guidelines for installing conductors in cable trays to ensure they are adequately supported and protected from physical damage.

310.49 Conductors in Surface Raceways

Specifies the requirements for installing conductors in surface raceways to ensure they are properly protected and meet safety standards.

310.50 Conductors in Ducts

Provides guidelines for installing conductors in ducts, ensuring they are adequately protected and meet safety standards.

310.60 Conductors Rated 2001 to 35000 Volts

Specifies the requirements for conductors rated between 2001 and 35000 volts, ensuring they are properly sized, insulated, and installed to handle high-voltage applications:

• 310.60(A) General: General guidelines for high-voltage conductors.
• 310.60(B) Ampacity: Provides ampacity tables for high-voltage conductors.

310.70 Minimum Size of Conductors

Specifies the minimum size of conductors for various applications to ensure they can safely carry the expected load:

• 310.70(A) General: Minimum size requirements for high-voltage conductors.
• 310.70(B) Small Conductors: Restrictions on the use of small conductors in high-voltage applications.

310.80 Conductors Rated 35001 to 1000000 Volts

Specifies the requirements for conductors rated between 35001 and 1000000 volts, ensuring they are properly sized, insulated, and installed for ultra-high-voltage applications:

• 310.80(A) General: General guidelines for ultra-high-voltage conductors.
• 310.80(B) Ampacity: Provides ampacity tables for ultra-high-voltage conductors.

310.90 Minimum Size of Conductors for Ultra-High Voltage

Specifies the minimum size of conductors for ultra-high-voltage applications to ensure they can safely carry the expected load:

• 310.90(A) General: Minimum size requirements for ultra-high-voltage conductors.
• 310.90(B) Small Conductors: Restrictions on the use of small conductors in ultra-high-voltage applications.

310.100 Special Equipment and Conditions

Provides guidelines for installing conductors in special equipment and conditions to ensure they are adequately protected and meet safety standards:

• 310.100(A) General: General requirements for special equipment.
• 310.100(B) Specific Equipment: Guidelines for specific types of equipment.

310.104 Conductor Construction and Insulation

Details the construction and insulation requirements for various types of conductors to ensure they are suitable for their intended use:

• 310.104(A) Insulated Conductors: Requirements for insulated conductors.
• 310.104(B) Bare Conductors: Guidelines for using bare conductors.
• 310.104(C) Covered Conductors: Specifications for covered conductors.

Conclusion

NEC Article 310 provides comprehensive guidelines for the selection, installation, and identification of conductors in general wiring applications. These requirements ensure that conductors are properly sized, insulated, and installed to maintain the safety and reliability of electrical systems.

For detailed information and further context, referring to the NEC Handbook and other resources provided by the NFPA is highly recommended.