Protection of cable through metallic structures

Advisory note5/2023
ForLicensees and contractors working in the electrical industry
ScopeApplies to all areas in New South Wales

Purpose

The purpose of this advisory note is to inform industry of some common non-compliances found when Fair Trading inspectors conduct inspections of electrical installations

What is the non-compliance?

The installed wiring system was passing through a metallic structure unprotected from the sharp metal edge of the in the structure

Clause 3.9.3.1 of AS/NZS 3000 Wiring Rules states, Where a wiring system consisting of sheathed cables is installed through metallic structural members, any aperture through which the cable passes shall be bushed or shaped to minimize abrasion of the cable. Where likely to be disturbed, the cable shall be fixed in position at a point adjacent to the aperture.

NOTE: Fixing of individual cores of a cable may be required where the risk of contact with conductive structural building materials exists (see Clause 5.4.6)

How to comply

As per the requirements of AS/NZS 3000 Wiring Rules:

Wherever sheathed cables are passing through a metallic structure, like steel framing, switchboard entries or metal enclosure or cable tray, the entry hole shall be bushed or shaped to protect the cable from damage to the sheath of the cables and potentially exposing a live conductor.

As per AS/NZS 3000:2018 3.3.1, Wiring systems shall be able to operate safely and shall function properly in the conditions to which they are likely to be exposed at the point of installation. It is important to remember that the protection of cabling must happen at installation in order to prevent unwanted damage during the install/construction stage of the job.

What we are finding

The requirement to have the cable protected from sharp metal edges is a common non-compliance in domestic and commercial setting found by our inspector.

Picture of inappropriate protection of wires

  • In this example the switchboard supply mains were passing over the cut edge of a cable tray lid exposing the potential for damage to the insulation of high current capacity supply.

Picture of inappropriate protection of wires

  • The edges of the tray how now been covered by a durable material that will prevent any potential damage to the live cables installed on the cable tray.

Architectural diagram of zone dimensions (elevation) of shower with fixed plumbing connection on ceiling or wall and a barrier

  • In this example the supply cable to a gas hot water service is passing through a cable entry unprotected, already causing damage to the insulation of the installed cable.

Protected cable covered in corrugated conduit

The cable for this installation has been protected by installing the cable with a corrugated conduit to protect the cable damaged thought the construction phase of the project.

Reference: AS/NZS 3000:2018 Wiring Rules


Contact:

For more information, please email: [email protected]

This advisory note has been approved for issue by the BSCU Technical Review Committee. Information contained within this document is current as of November 2023 and refers to codes and standards current at the time of writing.

NSW Fair Trading disclaims any liability (including for negligence) to any person in respect of anything done, or not done, by that person in whole or partial reliance on any of the information in this advisory note.