Class 1, Division 2 electrical requirements are part of the National Electrical Code (NEC) and are designed to ensure safety in hazardous locations where flammable gases, vapours, or liquids may be present. Class 1 locations deal with gases or vapours, and Division 2 refers to environments where these substances are not normally present but could exist under abnormal conditions, such as during leaks or equipment failures. Here are the key electrical requirements for such environments:

Equipment design and installation:

• Explosion-proof equipment: Electrical enclosures and devices must be explosion-proof to prevent sparks or heat from igniting flammable gases or vapours. However, since Division 2 indicates that hazardous materials are not present under normal conditions, equipment may not need to be fully explosion-proof but must be designed to prevent ignition if gases are present.
• Sealed or purged enclosures: Equipment that could generate sparks or heat must be housed in sealed or purged enclosures to prevent contact with the hazardous atmosphere.
• Intrinsically safe circuits: Low-energy circuits that are incapable of causing ignition may be used, even in the presence of a hazardous atmosphere.

Wiring methods:

Wiring in Class 1 and Division 2 areas must minimize the risk of gas migration and prevent sparks or heat from reaching hazardous atmospheres. The following wiring methods and cables are approved for use:

• Rigid Metal Conduit (RMC): Commonly used for Class 1 and Division 2 installations, RMC provides strong protection for conductors and can contain any internal explosion. Proper sealing is essential at the boundaries between classified and unclassified areas.
• Intermediate Metal Conduit (IMC): Lighter than RMC but provides similar protection. It is often used for hazardous areas with the same sealing requirements as RMC.
• Electrical Metallic Tubing (EMT): EMT can be used in Class 1, and Division 2 areas if compression-type fittings are employed to ensure a tight seal. EMT is more economical and easier to install compared to RMC or IMC but must follow specific NEC guidelines to prevent gas migration.
• Rigid Nonmetallic Conduit (RNC) and Flexible Nonmetallic Conduit (FNC) can be used if specifically listed for hazardous locations. RNC is lightweight and, cost-effective and great for corrosion resistance, and FNC is used in environments where movement or vibration occurs. Nonmetallic conduits must be installed with gas-tight fittings specifically listed for hazardous locations. These fittings prevent hazardous gas migration through the conduit system.
• Type MI (Mineral-Insulated) Cable: MI cables are composed of a solid copper sheath and mineral insulation, offering high mechanical and fire resistance. These are well-suited for hazardous locations due to their durable and gas-tight construction. It offers maximum protection
• Type MC (Metal-Clad) Cable: MC cables are accepted for Class 1, Division 2 locations when equipped with gas-tight continuous sheathing, and are not used without it. These cables must be terminated with approved fittings that prevent gas migration. MC-HL (Hazardous Location) cables offer enhanced protection with metal armour and gas-tight construction, making them ideal for hazardous environments.
• Type TC (Tray Cable): Tray cables can be used in Class 1, and Division 2 areas if installed in conduit or cable trays that comply with hazardous location standards. Proper sealing of any exposed sections of the tray is necessary.

Additional cable types for Class 1, Division 2:

• Type ITC (Instrumentation Tray Cable): Used for control circuits, ITC cables feature flame-retardant and shielded designs, ideal for Class 1, and Division 2 environments when enclosed in cable trays or conduits.
• Type PLTC (Power-Limited Tray Cable): Designed for power-limited circuits, PLTC cables are allowed in Class 1, Division 2 areas when installed in conduits or trays with protective sealing.
• Type XHHW-2 (Cross-Linked High Heat Water-Resistant): These cables are commonly used in industrial wiring with cross-linked polyethene insulation that offers resistance to heat, water, and chemicals. XHHW-2 cables are acceptable for hazardous locations when installed in approved conduits.

Sealing requirements:

• Conduit systems: Sealing fittings must be installed at specific points, such as within 18 inches of enclosure boundaries, to prevent the migration of flammable gases or vapors through the conduit system into unclassified areas.

Bonding and grounding:

In Class 1, Division 2 areas, grounding and bonding are crucial for safety. Key components that must be grounded or bonded include:

1. Conduit Systems (e.g., RMC, IMC, EMT).
2. Enclosures (junction boxes, control panels).
3. Electrical Equipment (motors, transformers, lighting fixtures).
4. Cable Trays (if metal ic).
5. Bonding Jumpers to ensure continuity between metallic components.
6. Flexible Metal Conduits and Cables.
7. Nonmetallic Conduit (metallic parts like fittings must be grounded).
8. Metallic Structures and Supports (e.g., racks, frames).