Prefabricated construction

Introduction

The information below provides advice regarding the electrical compliance requirements for prefabricated modular buildings and prefabricated modular rooms.

Definition

Prefabricated modular buildings and/or rooms

• are generally small buildings or rooms manufactured off-site and moved to the site where they are to be installed or fixed in position, and
• can arrive to a site either as semi- constructed or fully constructed.

Prefabricated modular buildings and/or rooms that include electrical wiring and/or electrical equipment are deemed to be electrical installations or form part of an electrical installation for the purposes of certification.

Current accepted practice

In Victoria, all electrical installations including installed electrical equipment must comply with the requirements of the Electricity Safety Act 1998, the Electricity Safety (General) Regulations 2019, AS/NZS 3000 Electrical installations (known as Australian/New Zealand Wiring Rules) and any other relevant Australian standards.

Manufacturers are required to install, inspect and test electrical equipment that form part of the prefabricated modular building or prefabricated modular room (electrical Installation) to the requirements of the Electricity Safety (General) Regulations 2019, the relevant Australian Standards and section 8 of AS/NZS 3000.

The current accepted practice in Victoria is for manufacturers of prefabricated modular buildings or rooms manufactured off-site to provide a certificate of electrical safety (COES) issued by a licensed electrician to their customer.

The manufacturer may:

• directly employ licensed electricians to perform the electrical installation work within or on the prefabricated modular building or room. In this case, the licensed electrician should issue a certificate of electrical safety (COES) for the work performed, or
• engage a Registered Electrical Contractor to perform the electrical installation work within or on the prefabricated modular building or room. In this case, the Registered Electrical Contractor should issue a certificate of electrical safety (COES) for the work performed.

Manufacturer to provide COES to onsite electrician

When the prefabricated modular building and/or room is delivered to site, the manufacturer should provide a COES for the prefabricated modular building and/or room to the onsite electrician.

The practice of manufacturers issuing a COES provides assurance to the onsite electrician that these products comply with the Act, Regulations, applicable Standards and has been inspected and tested and is safe to connect to the electricity supply. This negates the need for the onsite electrician to remove electrical accessories and/or cladding onsite to verify compliance.

Where a manufacturer does not provide a COES to the onsite electrician, the onsite electrician must inspect and test all wiring and electrical accessories in or on the prefabricated modular building and/or room and certify that the electrical installation complies.

The onsite electrician who carries out the required electrical work to connect the prefabricated modular building and/or room to the site’s electricity supply performs all the necessary testing to verify the electrical installation is safe and compliant. The onsite electrician then issues a COES for the connection, referring to the COES issued by the manufacturer in the description of work.

Prefabricated modular buildings and/or rooms are not transportable structures as defined in AS/NZS3001, Electrical installations – transportable structures including their site supplies.

References

1. Electricity Safety Act 1998
2. Electricity Safety (General) Regulations 2019,
3. AS/NZS 3000 Electrical installations (Known as the Australian/New Zealand Wiring Rules)
4. AS/NZS3001 Electrical installations – transportable structures including their site supplies