How has NEC 2023 changed wiring requirements in hazardous locations?
Overview
11.7(A) focused only on the wiring requirements in Class I locations, neglecting Class II and III areas and the use of exposed run (ER) cables. NEC 2023 expanded the provisions to cover all classifications, and has allowed TC-ER, PLTC-ER, and ITC-ER cables to be used in specific locations with an equipment grounding conductor. The modification was made to enhance safety in all classified locations.
Industries handling hazardous substances require strict protocols to prevent fires and explosions. Previous NEC Section 5
Applying the 2023 Code
Numerous industries, such as oil and gas refineries, chemical manufacturing plants, pharmaceutical facilities, paint and coating operations, food processing plants, mining and milling operations, and grain handling facilities, produce hazardous and flammable substances as part of their manufacturing processes. These industries harbor flammable gases, vapors, combustible dust, and ignitable fibers, which pose a significant fire risk, capable of causing immense devastation from even the smallest spark. Consequently, strict handling, storage, and processing protocols must be implemented to prevent fires and explosions, and safeguarding workers and equipment.
In previous editions, NEC Section 511.7(A) outlined requirements for fixed conductors and wires within Class I locations, specifying the use of various fixed conduits, raceways, and tubing based on industry needs. However, there was no mention of wiring in Class II and Class III locations, nor was there guidance on the use and protection of exposed run (ER) variations of approved cables. In 2023, Section 511.7(A) underwent modifications to cover wiring installations in all classified locations (I, II, and III), now including provisions for exposed run cables such as TC-ER, PLTC-ER, and ITC-ER. These cables can now be utilized if they are equipped with an equipment grounding conductor (EGC) in addition to any drain wire. This change was implemented to expand the use of ER cables and address wiring installations across all classified locations.
What’s New for the 2023 NEC?
The comparison of 2020 NEC and 2023 NEC in terms of Sections 511.7, respectively, is given in the Table below.
2020 NEC |
2023 NEC |
| (A) Wiring in Spaces Above Class I Locations
(1) Fixed Wiring Above Class I Locations All fixed wiring above Class I locations shall be in metal raceways, rigid nonmetallic conduit, electrical nonmetallic tubing, flexible metal conduit, liquidtight flexible metal conduit, or liquidtight flexible nonmetallic conduit, or shall be Type MC, AC, MI, manufactured wiring systems, or PLTC cable in accordance with Article 725, or Type TC cable or Type ITC cable in accordance with Article 727. Cellular metal floor raceways or cellular concrete floor raceways shall be permitted to be used only for supplying ceiling outlets or extensions to the area below the floor, but such raceways shall have no connections leading into or through any Class I location above the floor. (2) Pendant For pendants, flexible cord suitable for the type of service and listed for hard usage shall be used. |
(A) Wiring in Spaces Above Hazardous (Classified) Locations
(1) Fixed Wiring Above Hazardous (Classified) Locations Fixed wiring above hazardous (classified) locations shall be permitted to be one or more of the following: (1) Rigid metal conduit (RMC) or intermediate metal conduit (IMC) with listed threaded or threadless fittings, or electrical metallic conduit (EMT) with listed fittings. (2) Rigid polyvinyl chloride conduit (PVC), reinforced thermosetting resin conduit (RTRC), or electrical nonmetallic tubing (ENT). (3) Flexible metal conduit (FMC), liquidtight flexible metal conduit (LFMC), or liquidtight flexible nonmetallic conduit (LFNC), with listed fittings. (4) Type MC cable, Type AC cable, Type TC cable, or Type TC-ER cable, including installation in cable trays. Type TC-ER cable shall include an equipment grounding conductor (EGC) in addition to any drain wire. All cable types shall have listed fittings. (5) Type MI cable terminated with listed fittings and supported in a manner to avoid tensile stress. (6) Manufactured wiring systems. (7) Type PLTC cable or Type PLTC-ER cable in Class I, Class 2, or Class 3 circuits. Type PLTC-ER cable shall include an equipment grounding conductor (EGC) in addition to any drain wire. (8) Type ITC cable or Type ITC-ER cable in accordance with 335.4 and 335.5, terminated with listed fittings. Type ITC-ER cable shall include an equipment grounding conductor (EGC) in addition to any drain wire. (9) Cellular metal floor raceways or cellular concrete floor raceways only for supplying ceiling outlets or extensions to the area below the floor. Such raceways shall have no connections leading into or through any Class I location above the floor. (2) Pendant For pendants, flexible cord suitable for the type of service and listed for hard usage shall be used. |
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