Air Circuit Breakers (ACB's)
Maintenance | Service | Testing
Specialists in ACB servicing and testing accross all major brands - keeping electrical systems safe, compliant and performing under fault conditions when reliability matters most
Safeguarding critical power infrastructure
Air Circuit Breakers (ACBs) are high-capacity protection devices used in buildings with large power supplies. They protect against overloads, short circuits and equipment failures, ensuring safe operation of electrical distribution networks in commercial and industrial facilities.
Regular testing and servicing extend the life of this equipment and guarantee it responds correctly under fault conditions — protecting your building, your people and the wider network supply.
Why maintain your ACB's?
Safety first
Reduce the risk of arc flash, fire or dangerous faults.
Stay compliant
Meet AS/NZS standards, insurance obligations and regulatory guidelines.
Avoid downtime
Prevent unexpected outages and costly disruptions.
Protect your assets
Extend the life of switchboards, transformers and critical infrastructure
Brands we service
Prolux Technicians are trained to maintain and test all leading ACBs
Schneider (Masterpact, RM6) I Terrasaki (Termbreak) I General Electric I NHP Modpower
GEC Alstom I Mitsubishi I Metasol I ABB I F&G
Prolux technicians are trained across all major ACB brands, providing reliable maintenance that keeps your electrical systems safe and compliant.
What's included in ACB servicing?
- Mechanical and electrical inspections
- Primary & secondary injection testing
- Trip unit calibration
- Contact resistance testing
- Cleaning, lubrication and adjustments
- Verification of interlocks and safety mechanisms
- Detailed compliance reporting for audits and insurance
Although not always mandated by law, ACB maintenance is regarded as best practice for managing electrical risk. Regulatory bodies such as EnergySafe require owners of large electrical installations to keep equipment in good working order and prevent interference with the supply network. Failing to do so may lead to penalties as well as serious operational consequences.
Common failure risks
Fails Open
The breaker trips correctly to clear a fault but cannot be reclosed due to wear or damage. This leaves the installation without power until the equipment is repaired or replaced.
Fails Closed
The breaker fails to operate during a fault, allowing extreme fault current to flow. In high-demand buildings, this can cause catastrophic damage, equipment destruction and dangerous arc flash events.
Recommended service intervals for ACBs and switchgear vary depending on the asset and operating conditions. Manufacturer guidelines generally recommend servicing every two to three years, based on environment and load. However, best practice is to carry out annual servicing, often aligned with a planned building “black-out” or shutdown test to ensure full system reliability. For high-voltage assets, building owners with private HV switchgear have an obligation to implement a High Voltage Safety Management Plan, including defined switching procedures and routine inspections, to maintain compliance and reduce risk.
