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| Advisory note | 7/2023 |
|---|---|
| For | Licensees and contractors working in the electrical industry |
| Scope | Applies 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 conductive reinforming of the concrete slab where a bath or shower is installed has not been bonded to the earthing system of the installation.
Clause 5.6.2.5 of AS/NZS 3000 Wiring Rules states, Any conductive reinforcing within a concrete floor or wall of a room containing a shower or bath shall be bonded to the earthing system of the electrical installation.
An equipotential bonding conductor, in accordance with Clause 5.6.3, shall be connected between the reinforcing material and any part of the earthing system. For a combined outbuilding, each structure within that outbuilding that contains a shower or bathroom shall contain its own individual bonding connection to the conductive reinforcing within that structure.
Providing the reinforcement is electrically continuous across the whole of the combined outbuilding (refer to Note 3), one bonding conductor connecting the reinforcement to the earth bar or link of the switchboard that supplies all of the combined outbuilding is satisfactory.
NOTES:
- This requirement is intended to avoid any potential differences that may occur between conductive material connected to, or in contact with, the electrical installation earthing system or earthed electrical appliances and the concrete floor or wall.
- A conductive grille or reinforcement mesh laid in the floor and connected to the equipotential bonding conductor may also be used.
- Conductive tie-wires used during construction of reinforced concrete structures are considered to be an adequate electrical bond between the conductive reinforcing components. Provided that the reinforcement is satisfactorily electrically connected together, one point of connection of the bonding conductor to the reinforcement is sufficient.
- In existing electrical installations, the bonding requirement of this Clause for concrete floors and walls containing conductive reinforcing need not apply, but should be adopted wherever practicable.
How to comply
As per the requirements of AS/NZS 3000 2018 Wiring Rules:
- To comply with Clause 5.6.2.5 of AS/NZS 3000 2018 Wiring Rules, a connection shall be made between the main earthing system and the concrete reinforcement of the slabs that contain baths or showers being sure to use a 4mm cable as per Clause 5.6.3.2 (b) of AS/NZS 3000 2018.
What we are finding
In most cases during inspections, we are finding that the slab bond has been missed. Inspectors identify this by a single earth cable running out of the meter panel indicating only one connection has been made to the main earth stake or the electrician has connected to a piece of exposed slab reinforcing the continue on the main earth rod which is also non-compliant as per Clause 5.5.1.1 of AS/NZS 3000 2018.
- In this example the inspector identifed only 1 earth cable leaving the switch board on a class 1 site where the rough-in had been completed and sheeting about to start, after removing some insulating material the slab bonding provision left by the builder had not been connected to the earthing system.
- The Electrician has rectified this by running an additional 4mm earth cable (AS/NZS 3000 – 5.6.3.2. b.) to the provided slab reinforcing material and clamped it the same manner in which a main earth attaches to a earth rod, then protecting the connection from corrosion.
In this example the electrician has missed the opportunity to connect a slab bond as the job had been completed and ready for hand over, they then had to run a cable external to the dwelling and access the slab reinforcement from outside attaching in a similar manner the previous example then patch the area of the concrete slab that had been disturbed.
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.
Reference: AS/NZS 3000:2018 Wiring Rules