Recent amendments to the National Electric Code (NEC) have permitted new and innovative methods for installing electrical equipment in both general purpose and classified locations, including modifications for cabling requirements. The addition of new cable types allows an alternative to traditional and more labor intensive installation methods like pulled wire and rigid metal conduit. When used with flexible wire management products like a wire basket cable tray, these new cable types greatly reduce the costs associated with the installation of electrical equipment.
One such cable, Type ITC cable (Instrumentation Tray Cable), provides a cost effective alternative for installation of low power instrumentation and control circuits. The NEC defines Type ITC cable and its permitted uses, which include ordinary (non-hazardous) and classified (hazardous) locations. These environments have specific installation requirements for electrical equipment, including requirements for cabling that passes between environments (from hazardous to non-hazardous locations). Traditionally, rigid metal conduit has been used to install instrumentation and control equipment, although ITC cables, along with other cables, are used in these environments due to the many benefits they provide. Utilizing cables, like Type ITC cable, in hazardous and non-hazardous locations benefits users by decreasing costs associated with installation time, commissioning and maintenance. By nature, systems using rigid metal conduit require more time to install because wires must be pulled and cut, and the conduit must be bent and fitted. Additionally, sealing and boundary fittings may be required in hazardous locations. This is generally not an issue when using cables, and those like Type ITC with quick-disconnects may not require precautionary measures (like sealing) to pass from hazardous to non-hazardous locations. Rigid metal conduit also requires hand wiring terminations, and is therefore more susceptible to human error, whereas pre-molded cables with quick-disconnects can be installed much more easily.What is ITC Cable?
Type ITC cable consists of two or more insulated conductors enclosed in a nonmetallic sheath, with or without grounding conductors for instrumentation and control circuits operating at up to 150 Volts and 5 Amps, per NEC (National Electrical Code) Article 727. This cable can be used as an alternative to conduit in many hazardous and non-hazardous environments, like those found in pharmaceutical industries, chemical plants and refineries. As with all cabling methods, the NEC requires that only qualified people service the installation, as they would notice if cables were damaged, understand associated hazards and repair the installation.
Where Can ITC Cable Be Used?
The NEC permits ITC cable to be used in cable trays, raceways, hazardous locations, or as open wiring in specified circumstances. Also, per NEC rules, the insulation on the conductors must be rated for 300 Volts, and the conductors to be 22 AWG through 12 AWG. Using this insulation results in a smaller diameter cable that is more flexible and does not require Class II power supplies. Type ITC cable is required by the NEC to follow specified installation rules. For instance, ITC cable without a metallic sheath can be used outside of cable trays in specified circumstances. If mechanically protected, the cable can be dropped as much as 50 ft. out of the tray. ITC cable that meets the crush and impact requirements of Type MC (metal clad) cable can be dropped as much as 50 ft out of trays without protection supported every 1.8 m (6 ft). In addition, ITC cable with a continuous metallic sheath or aluminum tape can be installed as open wiring in or out of a cable tray supported every 1.8 m (6 ft).
The ITC Advantage
In explosion-proof protection schemes, employing ITC cable as a wiring method has many advantages over traditional threaded rigid metal conduit. Explosion-proof methods are utilized for numerous reasons, such as when point requirements or equipment dictate the protection scheme. The gas-tight/vapor-tight construction of Type ITC cable allows for usage in hazardous locations, and may not require seals or fittings when entering/exiting an enclosure or when traveling from hazardous to non-hazardous areas.
hazardous location to a non-hazardous location, or between locations, i.e. from Division 1 to Division 2. Using ITC hazardous-rated cable may also eliminate the need for Class I, Division 1 & 2 boundary seals that are required when using conduit. This is due to the molded construction of the connector and the gas/vapor tight continuous sheath of the cable, and is consistent with NEC Article 501.5. Utilizing armored ITC cable can provide significant benefits when used in hazardous and non-hazardous locations, as there is no requirement for further mechanical protection. This metal-armored cable grounds itself and is rated for open wiring, making it particularly suitable for hazardous locations as allowed by the NEC.