Tech Tips FAQs

Vertical Earth Stakes

Q: What are the requirements for vertical earth stakes (electrodes)?

A: An earth stake must be installed to a minimum depth, style, and size as per AS/NZS 3000:2018 Table 5.2.

• For domestic installations, most electricians utilise a 12mm copper-clad vertical electrode. The installation requirements for vertical electrodes are that they MUST be driven to a minimum depth of 1.2 metres, see Clause5.3.6.3. This means on a 1500mm earth stake that a maximum of 300mm is above finished ground level. If there is any more earth stake showing than this, it will result in an installation defect.
• The electrode shall be installed in effective contact with moist soil, main earth connection must be accessible (Clause5.5.1.2), separated from other services (Table 3.7) and external to the building, exposed to the weather. The location shall be identified on the main switchboard and as always, be written indelibly and legibly. See Clause 5.3.6.4.
• Protection of the main earth connection must be maintained as well. One of the best ways of doing this is to use a small piece of 20mm conduit slipped over the earth stake and then this conduit is saddled to the wall. This allows the earth clamp and main earth connection to be hard against the wall or structure reducing the possibility of the connection from being damaged easily. It also reduces the risk of anyone falling and being impaled on the earth stake itself. Do not use a metal saddle directly onto the earth stake. It will cause a galvanic reaction to occur resulting in corrosion of the earth stake.

Domestic and Non-Domestic Residential Installations

Q: In non-domestic and non-residential installations socket outlets, lighting, direct connected hand-held or direct connected electrical equipment 32 Amps and less need to be protected by an RCD?

A: Yes. However, there is an exception.

See Clause 2.6.3.2.3.3, Requirements for additional protection.

But before you think you don’t need an RCD, read on.

There is limited reason as to why the exception to this rule can be applied, especially if injury or death occur after negating the installation of an RCD. You could apply common sense, where for example; vehicle tunnel lighting that was mounted approximately 5 metres agl and was Class 2 constructed equipment including all cabling being double insulated in non-conductive conduit where the risk of light failure would be greater than the risk of electric shock. The risk being that in the event of the tunnel lighting failure, vehicles would have to transition rapidly from not having headlights on, to suddenly turning them on in pitch black conditions. Tunnel lighting requirements for lighting is always to remain on as per local road’s authority rules in conjunction with the minimum requirements of AS/NZS 1158 for the lighting of roadways.

Whilst this is not electric shock-related, the shock risk is negated by utilising double insulated light fittings and non-conductive conduit. In this case, there are two risks being minimised, traffic accident and electric shock. The other factors, in this case, would be that only authorised personnel are permitted to work in the tunnel, there was no public access, and everything was out of reach. You would also need to risk assess and record this, including appropriate warning labels with notification given to the client making sure that the client understood the ramifications.

Other cases such as VSDs, fixed cranes and 20A three-phase outlets for equipment would be extremely hard to apply the exception.

However, in Coronial Court, there will no argument that will support the defendant as to why they negated installing an RCD when there is a deceased person as a result of electrocution as an RCD is would have saved them.

My advice is, install RCDs for equipment in non-domestic and non-residential 32 amps and below, then you will be covered.

Installing multiple 20A 3 Phase Socket Outlets on one circuit

Q: Can I Install multiple 20A 3 phase socket outlets on one circuit?

A: Yes, however, this would not meet the criteria of Clauses 1.6.1 (e), 1.7.1 and 1.7.2. 

The main issue is that to install multiple outlets on one circuit, the cable and RCD would have to be currently matched to the load required by the outlets say at 20A each. Accounting for voltage drop and installation conditions, this circuit would be expensive to install compared to individual circuits for each outlet. The clauses above relate to faults and the reliability of the circuit including safe and sound work practices and sound principles 

So, would I install multiple 20A 3 phase socket outlets on a single circuit? No, it isn't best practice nor does it meet the requirements of the above clauses

Equipotential Bonding Conductor Connection Point

Q: Do I have to install an Equipotential Bonding Conductor Connection Point?

A: Yes. As stated in AS/NZS3000:2018 amendment 1 Clauses 5.6.2.6.2 and 5.6.2.6.3.  The connection must be accessible, identifiable on the originating switchboard or other permanent locations, protected against corrosion and mechanical damage and designed and constructed in accordance with Clause 3.7. 
There are purpose-built products on the market which suits this requirement and are easy to install and use. Remember that a pool builder cannot undertake equipotential bonding as they are not a licenced electrician

Pool Bonding 

Q: Do I have to bond a swimming pool and the pool fence?

A: Yes. A pool must be bonded. This has always been a rule. The current Wiring Rules AS/NZS 3000:2018 amendment 1 January 2020, clause 5.6.2.6 regarding Swimming and spa pools and the following clauses 5.6.2.6.1 to 5.6.2.6.3. And a picture is worth a thousand words so have a read of Figure 5.9 as well.

Basically, anything that is conductive within arm’s reach (1.25m) shall be bonded. However, there is an exception. Also, if you are trying to earth a glass pool fence, that being the supporting feet, suggest to the pool builder to use composite material instead of metal?

Installation of Smoke Detectors 

Q: How many smoke detectors do I need to install and what location in a Class 1a building (single dwelling)?

A: Depending on which state or territory the minimum requirement as per the NCC clause 3.7.2.3 shall be one on each storey containing bedrooms between each part of the dwelling containing bedrooms and where bedrooms are served by a hallway and any other storey not containing bedrooms. In Queensland, the requirement is to install smoke detectors in each room used for sleeping including egress paths from these rooms and on each level of a house. In NSW, Tasmania and the ACT, the minimum requirement is one on each level and one located outside a bedroom or group of bedrooms. Photoelectric and ionisation type alarms are OK to use in ACT, TAS and NSW, but QLD must be the photoelectric type.

Always check the local fire authority website for guidance in your state or territory and the National Construction Code for the minimum requirements.

Service and Installation Rules NSW Interpretation