CompEx Ex01 is the unit covering the installation of electrical equipment in explosive atmospheres for gas groups IIA and IIB. Alongside Ex03 (inspection), Ex01 is one of the most commonly held CompEx units and is required for electricians who install, connect, or commission Ex equipment on process plants, petrochemical sites, and offshore installations.

What Does Ex01 Cover?

The Ex01 unit is based on IEC 60079-14 — the standard for the installation of Ex equipment. The knowledge required includes:

  • Zone classification and equipment selection — matching EPL to zone
  • Gas groups IIA and IIB — equipment requirements for each
  • Temperature class selection — T-class must exceed gas auto-ignition temperature
  • Cable and wiring systems — SWA cable requirements in hazardous areas
  • Cable gland selection — barrier vs non-barrier, threaded vs clearance entries
  • Stopping plug requirements — minimum 5 full thread turns for Ex d
  • Earthing and bonding — equipment earthing terminals, armour continuity
  • Protection type requirements — Ex d, Ex e, Ex i, Ex p installation rules
  • Intrinsically safe system installation — entity parameters, IS earth, segregation
  • Documentation and certification — installation records, Ex certificate requirements

Equipment Selection for Installation

Before installing any Ex equipment, you must verify it is appropriate for the area. The selection process follows this hierarchy:

  1. Zone — determines the EPL required (Zone 0 = EPL Ga, Zone 1 = EPL Gb, Zone 2 = EPL Gc)
  2. Gas group — equipment must be rated for the gas group present (IIA, IIB, or IIC)
  3. Temperature class — the equipment surface temperature must not exceed the gas auto-ignition temperature
  4. Certification — ATEX or IECEx certificate must be current and applicable

Cable Gland Selection for Installation

Correct cable gland selection is a major component of Ex01. The rules depend on the protection type of the enclosure and the type of cable entry:

  • Ex d threaded entry, ≤2L enclosure — non-barrier gland acceptable for SWA
  • Ex d threaded entry, >2L enclosure — barrier gland required for SWA
  • Ex d clearance entry, any volume — barrier gland always required for SWA
  • Ex e threaded entry — non-barrier gland, nylon IP washer required externally
  • Ex e clearance entry — non-barrier gland, nylon IP washer + serrated washer + locknut
Practice Installation Decisions

EX Academy's equipment selection simulator covers exactly these decisions — 15 scenarios where you specify the complete bill of materials for an installation including the correct gland type, stopping plugs, accessories, and earthing arrangements. Scenario 01 (Ex d junction box) and Scenario 03 (Ex de LCS) are particularly relevant for Ex01 preparation.