Ex i

Illustrated explanation

Prevent ignition by construction or by limited circuit energy

2Ex i
Prevent ignition by construction or by limited circuit energyCallout 1: Increased safety. Callout 2: Intrinsic safety. Callout 3: Associated apparatus. Increased safety controls construction to reduce excessive temperature, arcs and sparks. Intrinsic safety limits energy in a defined circuit, including its connected associated apparatus. Current term: Ex i, callout 2. 1Spacing + secure connectionIncreased safety 2LimitFieldDefined limited-energy circuitIntrinsic safety 3AssociatedField circuitAssociated apparatus
  1. Ex e

    The construction reduces the probability of ignition sources in its stated operating conditions. Entry retention and enclosure requirements still apply.

  2. Ex iThis term

    Electrical and thermal energy are limited under defined conditions. Assess the entire circuit, including cable and connected apparatus.

  3. Associated apparatus

    The apparatus provides functions affecting intrinsic safety. Check its permitted location and compatible parameters for the connected circuit.

Increased safety controls construction to reduce excessive temperature, arcs and sparks. Intrinsic safety limits energy in a defined circuit, including its connected associated apparatus.

Conceptual protection relationships, not circuits for installation. Entity or system parameters, cable properties, equipment location and certification must be checked as a complete design.

ReferencesIEC 60079-7 — Equipment protection by increased safety “e”IEC 60079-14 — Electrical installations design, selection and installationIEC 60079-11 — Equipment protection by intrinsic safety “i”