Inner sheath

Illustrated explanation

Read the layers before measuring the cable

2Inner sheath
Multicore cable layers and outside diameterA conceptual circular section of an armoured multicore cable. Callout 1 points to conducting metal inside an insulated core, 2 to the inner sheath surrounding the cores, 3 to the outer sheath and 4 to a dimension across the complete cable outside diameter. Armour and core insulation are also shown, but their presence depends on the cable construction. Current term: Inner sheath, callout 2. 3 2 1 4 Core insulationWire armourComplete cable OD
  1. Conductor

    Conducting material sits inside each insulated core. Its area is an electrical specification, separate from the complete cable diameter.

  2. Inner sheathThis term

    The inner covering surrounds the laid-up cores beneath the armour. Check its actual diameter and suitability if the gland seals here.

  3. Outer sheath

    The outer sheath forms the external cable surface. Its material and condition affect the gland seal and gripping arrangement.

  4. Cable outside diameter

    Measure across the complete cable. Use the actual diameter and its tolerances when checking the gland cable range.

This example separates the conducting cores, inner covering and outer sheath. The full outside diameter includes every layer present in the actual cable construction.

Conceptual multicore cable with wire armour. Layer presence, names and materials vary; conductor area and complete cable outside diameter are different measurements.

ReferencesIEC 60228:2023 — Conductors of insulated cablesBS 6121-1:2005 — Mechanical cable glands and armour glandsIEC 62444:2010 — Cable glands for electrical installations