62 Modern Commercial Wiring Copyright Goodheart-Willcox Co., Inc. list of all wiring methods approved in the Code. The reader is encouraged to look into all methods of wiring and techniques covered in the Code. 5.1 General Rules and Requirements The Code, under Article 300—General Requirements for Wiring Methods and Materials, addresses the acceptable methods of installing conductors. Choosing the right method for a wiring job depends on the environment where the wir- ing is to be installed. Certain wiring methods are only permitted in a limited range of condi- tions. Others are acceptable in a broad variety of situations. Regardless of the specifi c wiring method, there are some general rules common to many of the methods. These provisions should be understood before beginning any wiring instal- lation. A brief look at these general provisions follows: Goodheart-Willcox Publisher Figure 5-1. Code sections for common wiring methods. • Whether in cable or as single individual units, conductors should be used within the voltage and temperature range for which they are designed. • Normally, single conductors may only be installed as part of a wiring method recognized by the Code. Thus, routing individual conductors without the protection or support of an approved wiring method is strictly prohibited. • For a circuit, the current-carrying conductors, neutral conductor (where used), and equipment grounding conductor must all be run within the same conduit, cable, duct, tray, or enclosure. Failure to comply with this requirement could lead to inductance problems. • Circuits of different voltage may be run in the same raceways or occupy the same spaces (enclosures, equipment) providing that the voltage is less than 1000 volts and the conductors each have insulation ratings greater than or equal to that of the circuit with the highest voltage rating. For example, conductors rated for 300 volts can be run in the same raceway as conductors rated for 600 volts as long as the maximum circuit voltage is 300 volts. SAFETY NOTE Conductors placed in service where the voltage or temperature may exceed their specifi c rating will represent a serious hazard to the electrical system, equipment, structure, and personnel. CODE ALERT Same Circuit Conductors According to Section 300.3(B), all conductors of the same circuit and, where used, the grounded conductor and all equipment grounding con- ductors shall be contained within the same raceway, cable tray, trench, cable, or cord. See exceptions in the Code. Wiring Methods in the Code Wiring Methods Code Article Armored Cable Auxiliary Gutters Busways Cable Trays Electrical Metallic Tubing Electrical Nonmetallic Tubing Flexible Metal Conduit Flexible Metallic Tubing Intermediate Metal Conduit Liquidtight Flexible Conduit Metal-Clad Cable Multioutlet Assembly Nonmetallic-Sheathed Cable Rigid Metal Conduit Rigid Polyvinyl Chloride Conduit Service-Entrance Cable Surface Raceway Underground Feeder Cable Wireways 320 366 368 392 358 362 348 360 342 350, 356 330 380 334 344 352 338 386, 388 340 376, 378