311 – Medium Voltage Conductors and Cable

Change at a Glance:

In order to consolidate the medium voltage requirements found in Articles 310 and Article 328, and to improve the usability of the Code, the requirements are combined into a new Article 311.

Article 311 Medium Voltage Cable.

Part I. General
311.1 Scope.
311.2 Definitions.
311.6 Listing Requirements.

Part II Construction Specifications
311.10 Conductor Constructions and Applications.
Table 311.10(A) Conductor Application and Insulation Rated 2001 Volts and Higher
Table 311.10(B) Thickness of Insulation and Jacket for Nonshielded Solid Dielectric Insulated Conductors Rated 2001 to 5000 Volts
Table 311.10(C) Thickness of Insulation for Shielded Solid Dielectric Insulated Conductors Rated 2001 to 35,000 Volts
311.12 Conductors.
311.14 Conductor Identification.
311.16 Marking.

Part III. Installation
311.30 Installation 311.32 Uses Permitted.
311.36 Direct-Burial Conductors.
311.40 Support.
311.44 Shielding.

Part IV Ampacities
311.60 Conductors Rated 2001 to 35,000 Volts.
Table 311.60(D)(4) Ambient Temperature Correction Factors
Table 311.60(C)(67) Ampacities of Insulated Single Copper Conductor Cables Triplexed in Air
Table 311.60(C)(68) Ampacities of Insulated Single Aluminum Conductor Cables Triplexed in Air
Table 311.60(C)(69) Ampacities of Insulated Single Copper Conductor Isolated in Air
Table 311.60(C)(70) Ampacities of Insulated Single Aluminum Conductor Isolated in Air
Table 311.60(C)(71) Ampacities of an Insulated Three-Conductor Copper Cable Isolated in Air
Table 311.60(C)(72) Ampacities of an Insulated Three-Conductor Aluminum Cable Isolated in Air
Table 311.60(C)(73) Ampacities of an Insulated Triplexed or Three Single-Conductor Copper Cables in Isolated Conduit in Air
Table 311.60(C)(74) Ampacities of an Insulated Triplexed or Three Single-Conductor Aluminum Cables in Isolated Conduit in Air
Table 311.60(C)(75) Ampacities of an Insulated Three-Conductor Copper Cable in Isolated Conduit in Air
Table 311.60(C)(76) Ampacities of an Insulated Three-Conductor Aluminum Cable in Isolated Conduit in Air
Table 311.60(C)(77) Ampacities of Three Single- Insulated Copper Conductors in Underground Electrical Ducts (Three Conductors per Electrical Duct)
Table 311.60(C)(78) Ampacities of Three Single- Insulated Aluminum Conductors in Underground Electrical Ducts (Three Conductors per Electrical Duct)
Table 311.60(C)(79) Ampacities of Three Insulated Copper Conductors Cabled Within an Overall Covering (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct)
Table 311.60(C)(80) Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall Covering (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct)
Table 311.60(C) (81) Ampacities of Single Insulated Copper Conductors Directly Buried in Earth
Table 311.60(C)(82) Ampacities of Single Insulated Aluminum Conductors Directly Buried in Earth
Table 311.60(C)(83) Ampacities of Three Insulated Copper Conductors Cabled Within an Overall Covering (Three-Conductor Cable), Directly Buried in Earth
Table 311.60(C)(84) Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall Covering (Three-Conductor Cable), Directly Buried in Earth
Table 311.60(C)(85) Ampacities of Three Triplexed Single Insulated Copper Conductors Directly Buried in Earth
Table 311.60(C)(86) Ampacities of Three Triplexed Single Insulated Aluminum Conductors Directly Buried in Earth
FIGURE 311.60(F)(6) Cable Installation Dimensions for Use with Table 311.60(C)(77) Through Table 311.60(C)(86)

(See NEC for complete text)