Are Electrical Transformers Dangerous?

Electrical transformers are dangerous when damaged, improperly maintained, or exposed to high voltage. Risks include electric shock, fire, and explosions. Proper installation, insulation, and routine inspections reduce hazards. Most transformers used in homes or businesses are safe when handled correctly and meet safety standards.

Power transformers manufactured before 2004 represent a significant occupational health risk due to their potential to contain asbestos-containing materials (ACM). This hazard became starkly evident in January 2018 when electrical workers repairing a high voltage transformer were exposed to asbestos when a gland plate broke during removal. The workers discovered “Asbestos” stencilled on the underside of the plate, but were not wearing appropriate respiratory protection at the time of exposure. The disturbance of ACM releases fibres which, when inhaled, can lead to serious diseases such as mesothelioma. Following this incident, the Department of Mines, Industry, Regulation and Safety issued a Significant Incident Report highlighting the failure to identify ACM before commencing work and the absence of a Safe Work Method Statement [1].

Transformers pose substantial fire risks due to the large amounts of energy they manage. Australian Standard AS2067 specifically addresses these concerns by defining fire risk zones and required safety measures around transformer compounds. The standard mandates implementation of fire resistance level (FRL) walls and appropriate separation distances (clearances) as critical fire mitigation strategies.

Explosive failures represent one of the most dangerous transformer-related incidents. A notable example occurred in March 2017 at the Torrens Island switchyard, when a capacitor voltage transformer exploded, causing significant damage and disconnecting three generation units at Torrens Island Power Station. The incident also triggered the tripping of Pelican Point Power Station due to overcurrent protection operation. The restoration of connection points and substation took months to complete, highlighting the severe consequences of such failures.

Transformer boxes contain high voltage components that present significant safety hazards if mishandled or damaged. Particularly dangerous are Single Wire Earth Return (SWER) transformers, which use the earth as a return path for electric current. The earth leads running down electrical poles to connect these transformers to ground carry electric current and can be extremely hazardous if damaged or cut, with potential voltages reaching up to 12,700V.

Signs of hazardous situations related to damaged earthing systems include smoke or steam originating from the ground, dead livestock near the pole, or dried out ground or vegetation in proximity to the pole.

Ongoing transformer maintenance activities often require personnel to access the top of transformers and gas relays located at heights exceeding 4 metres above ground level. Activities such as maintaining on-load tap changers, taking oil samples, inspecting core and frame earthing, or performing condition-based tests present significant fall risks.

The risk assessment performed by AusNet Services identified “falling while working at heights” on transmission assets as having a significant risk rating, potentially resulting in severe irreversible disability or death. This led to implementation of improved safe maintenance access systems including galvanised fence/handrail systems with kick rails, ladder access points, working platforms, and harness attachment points.

Australian standards mandate specific clearances around transformers to ensure safety. For transformer boxes, it is recommended to maintain a minimum clearance of approximately 0.9 metres (about 3 feet) to prevent accidents and ensure utility workers have sufficient space. For outdoor transformer installations, the fire risk zone extends from the transformer bund perimeter to the edge of the separation distance, which is determined by the volume of insulating liquid.

Australian regulations also specify that construction within registered electricity easements is prohibited without permission, metallic structures must not be erected near powerlines, and a minimum clearance distance of 1.5 metres from energy infrastructure must be maintained.

Following asbestos exposure incidents, Australian authorities have implemented specific requirements for managing asbestos risks in transformers. These include:

• Surveying of power transformers manufactured before 2004 by a competent person, such as a licensed asbestos assessor
• Recording results in the site’s asbestos register
• Providing appropriate warning signage and labelling where ACM may be present
• Using competent persons to safely remove asbestos according to the relevant Code of Practice

The development of enhanced protection transformers, such as GSM™ transformers with FM Global certification, offers improved safety features including protection against high and lower energy faults, increased tank strength, and pressure relief. A key benefit of these enhanced protection transformers is the reduction in required clearances to buildings as per AS2067, providing safer operation in space-constrained environments.

Australian work health and safety legislation requires employers to ensure, so far as is reasonably practicable, the health and safety of workers. The Occupational Health and Safety Act 2004 specifies that in determining what is reasonably practicable, consideration must be given to the likelihood of the hazard eventuating, the degree of harm that would result, available knowledge about the hazard, ways to eliminate or reduce it, and the cost of elimination or reduction.

For electrical risks specifically, the Safe Work Australia Code of Practice for Managing Electrical Risks in the Workplace provides guidance on residual current devices (RCDs) requirements for certain higher-risk workplaces [2].

Living next to an electrical transformer in Australia is generally considered safe, as long as the infrastructure complies with established safety standards and regulations. The electromagnetic fields (EMFs) produced by transformers are low-level and diminish significantly within a few metres of the equipment. According to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), these EMFs are far below the exposure limits set for public safety and are not linked to adverse health effects, such as cancer. Additionally, Australian guidelines mandate minimum clearances of 4 metres between padmount transformers and habitable spaces, ensuring EMF levels remain comparable to everyday urban environments.

While physical risks such as fire or explosion are possible, they are rare due to stringent safety measures outlined in standards like AS2067, which regulate fire risk zones and transformer designs. Enhanced protection transformers further reduce these risks by incorporating reinforced tanks and pressure relief systems. However, in rural areas, Single Wire Earth Return (SWER) systems may pose unique hazards if damaged, electrifying the ground near transformers. These risks are mitigated through strict exclusion zones and emergency protocols enforced by energy regulators. Overall, living near a transformer in Australia poses minimal danger when safety measures are adhered to, though public perception may still be influenced by outdated concerns about EMFs.

Sources:

[1] https://www.wa.gov.au/

[2] https://www.safeworkaustralia.gov.au/