Chapter 6 Conductors 91 Copyright Goodheart-Willcox Co., Inc. 6.2.9 Temperature Limitation Section 310.15(A)(3) of the Code prohibits the use of any conductor, in any manner, where its oper- ating temperature will be greater than that des- ignated for its insulation type. Further, different conductors are not to be associated together in a way that would cause the limiting temperature of any conductor to be exceeded. The operating temperature of a conductor is determined by the heat produced by the resis- tance to current fl ow and the rate at which this fl heat is dissipated to the surroundings. Greater current fl ow and greater resistance in the con- fl ductor produce more heat. An aluminum conductor will produce more heat than a cop- per conductor of the same size with the same current because the aluminum conductor has greater resistance. Several factors affect the rate of heat dis- sipation. The warmer the temperature of the air surrounding the conductor, the less heat dissipated. If there are many conductors close together, they will all release heat, raising the temperature of the surrounding air, reducing the amount of heat they can release. Insulation greatly reduces the heat flow between the con- fl ductor and the surrounding air. 6.2.10 Conductor Marking All conductors and cables must be marked to show the following information: • Maximum rated voltage • The proper letter(s) designation for the type of wire or cable • The manufacturer’s name, trademark, or other distinctive marking by which the organization responsible for the product can be readily identified fi • The size of the conductor in AWG or circular-mil area. Cables are marked with surface markings, tape, or tags. The type of marking is determined by the type of cable or conductor. Refer to Sec- tion 310.120(B) of the Code for the type of mark- ing required for a specific cable or conductor. fi 6.2.11 Conductor Identifi cation (Color) Grounded conductors (neutral) 6 AWG or smaller must be insulated white, gray, or three continuous white stripes on other than green insulation along its entire length. Larger sizes may be white, gray, or three continuous white stripes or may be painted white at all junction and termination locations. Equipment grounding conductors that are insulated must be insulated solid green or green with yellow stripes if 6 AWG or smaller. Larger sizes must either be bare at all boxes and outlets or have the insulation painted green at every box and outlet. See Section 250.119 of the Code. Ungrounded (hot) conductors may have insu- lation of any color other than green, white, gray, or green with yellow stripes. 6.2.12 Conductor Application Application and insulation types for conductors are listed in Table 310.104(A) of the Code. Consult this extensive table prior to installing any wir- ing. The table gives several attributes for insu- lated conductors: • Trade name of the insulation • Letter designation assigned to that type of insulation • The maximum operating temperature allowable for the type of insulation or outer covering • The conditions suitable for application • The insulation composition • Size availability • Insulation thickness • Outer covering. NOTE Per Sec e ct ion 110 0. 15, the h hi hi gh leg of a fou ur -wire 5 delta distribution u system te must st be ide en tified fi with h orange markings.s .