A power surge lasts a fraction of a second and can destroy a piece of equipment that took your business years to buy, install, and configure. Surge protection is what sits between the incoming voltage spike and the equipment you rely on every day.
For most commercial sites, surge protection is a low-cost, high-impact piece of the electrical setup. It’s also one of the most commonly overlooked. This guide covers what surge protection is, what causes surges in the first place, what proper commercial surge protection looks like, and why it matters for your business.
What Is Surge Protection?
Surge protection is the practice of limiting the voltage that reaches your electrical equipment during a power surge. The devices that do this work are called Surge Protection Devices, or SPDs.
An SPD detects when voltage exceeds a safe threshold and diverts the excess to earth. Your equipment continues to receive normal voltage. The spike gets grounded before it reaches anything sensitive.
In Australia, standard mains voltage is 230V single-phase or 400V three-phase. A surge can push voltage many multiples above that for microseconds at a time. That’s enough to fry a circuit board, destroy a motor controller, or wipe out data on a server.
What Causes Power Surges?
Power surges come from two sources: external and internal.
External sources include lightning strikes, faults on the electricity network, and equipment failures upstream of your site. A lightning strike anywhere on the network can send a spike through your incoming supply, even if the storm is kilometres away.
Internal sources include large electrical loads switching on and off inside your own building. Motors starting up, HVAC compressors, welders, laser printers, photocopiers, and lift equipment all generate transient voltage spikes on the internal network.
Industry estimates put internal surges at 70 to 85 percent of all transient events in a commercial building. Most of the damage happens from surges you generate inside your own site, rather than from external events like lightning.
What a Power Surge Does to Business Equipment
Some surges cause immediate, obvious damage: equipment stops working, fuses blow, circuit boards visibly burn out.
Most surges cause smaller, cumulative damage that adds up over time. Every time a piece of sensitive equipment takes a spike, the internal components degrade slightly. After enough surges, equipment fails without any single event you can point to.
The equipment most at risk in a commercial setting includes:
- IT infrastructure (servers, switches, routers, storage)
- Point-of-sale systems and payment terminals
- Refrigeration controls and monitoring systems
- HVAC and Building Management Systems (BMS)
- Manufacturing PLCs and CNC equipment
- Security systems, CCTV, and access control
- Lighting control systems
- Data cabling and network hardware
For most commercial sites, the cost of replacing this equipment (and the downtime while replacement happens) is many times the cost of installing proper surge protection.
The Three Types of Surge Protection
Australian and international standards classify surge protection into three types based on where the SPD sits in the electrical system.
Type 1 SPDs are installed at the main switchboard or service entrance. They handle direct lightning strikes on the incoming supply and the highest-energy external surges. Sites with overhead supply lines or exposed locations usually need Type 1 protection.
Type 2 SPDs are installed at distribution boards throughout the building. They handle residual surge energy that gets past Type 1 protection, plus the internal surges generated within the site. Type 2 is the workhorse of commercial surge protection and every commercial switchboard should have it.
Type 3 SPDs are installed at or near individual equipment. They handle the final cleanup of any residual voltage and protect specific sensitive loads. Type 3 devices are typically integrated into UPS units, point-of-use protectors, or dedicated SPDs at server racks and control panels.
Proper commercial surge protection uses all three types working together. Type 1 catches the biggest events at the entry point. Type 2 protects the distribution network. Type 3 protects individual sensitive equipment. Each layer reduces what the next layer has to deal with.
Australian Standards for Surge Protection
Commercial surge protection in Australia is governed by two main standards.
AS/NZS 61643 is the standard for the SPDs themselves. It specifies performance requirements, testing methods, and the Type 1, 2, 3 classification for SPDs installed in low-voltage electrical systems.
AS/NZS 1768 is the standard for lightning protection. It covers the design and installation of lightning protection systems for buildings and structures, including the coordination of surge protection with lightning protection.
Compliance matters for two reasons. Insurance claims for surge damage often require evidence the electrical system was compliant at the time of the event. And commercial property owners have general safety obligations under Queensland’s Electrical Safety Act to maintain electrical infrastructure to current standards.
The Real Cost of a Surge
For a typical commercial site, the cost of a significant surge event includes:
- Equipment replacement (hardware, servers, controls)
- Data loss and recovery
- Operational downtime while systems are replaced and restored
- Lost sales or production during downtime
- Business interruption claims on insurance
- Staff time managing the incident
A single lightning event can cost a commercial site tens of thousands of dollars in damage. A single HVAC compressor failure from years of cumulative surge damage can cost thousands in unplanned replacement. The cost of installing proper surge protection is typically a small fraction of a single incident’s total cost.
What Proper Commercial Surge Protection Looks Like
For a typical commercial site, proper surge protection is a layered system installed at the right points in the electrical infrastructure.
That means:
- Type 1 SPD at the main switchboard, particularly for sites with overhead supply, exposed locations, or lightning-prone areas
- Type 2 SPDs at every distribution board across the site
- Type 3 SPDs or integrated protection at sensitive equipment: server racks, control panels, POS terminals, and BMS controllers
- Surge protection on data and communications lines entering the building
- Documented installation compliant with AS/NZS 61643 and AS/NZS 1768
SPDs are also consumable. Every surge they absorb degrades the internal components. Most SPDs have an indicator showing when they’ve reached end of life and need replacing. Sites without a regular inspection schedule often have SPDs that have already failed and are offering no protection at all.
When to Review Your Surge Protection
There are five moments where reviewing your surge protection makes sense:
- When installing new equipment that increases the value or sensitivity of what’s on your electrical system
- After a lightning event or significant grid disturbance in your area
- When the age of existing SPDs is unknown or greater than five years
- Before storm season on the Sunshine Coast and across South East Queensland
- As part of a compliance audit or insurance review
For most commercial sites, a surge protection audit takes half a day and gives you a clear picture of what’s protected, what isn’t, and what needs replacing.
Talk to Us About Your Site’s Surge Protection
Terawatt installs and tests commercial surge protection across the Sunshine Coast, Moreton Bay, and Brisbane North. If you’re not sure whether your site has proper protection, or you want it reviewed against current standards, get in touch.
Common Questions About Business Surge Protection
Does my business really need surge protection if we haven’t had issues yet?
Yes. Most surge damage is cumulative rather than sudden, and most business owners don’t connect equipment failures back to surge events. If your site has computers, controls, refrigeration, POS systems, or any sensitive electronics, you’re accumulating surge damage whether you notice it or not.
Aren’t power boards with surge protection enough?
No. Power board SPDs are Type 3 devices designed for final cleanup of residual voltage. They aren’t sized to handle the full energy of a serious surge. Without Type 1 and Type 2 protection upstream, a power board SPD will fail during a significant event and take your equipment with it.
How long do surge protection devices last?
It depends on how many surges they absorb. Most Type 2 SPDs last five to ten years under typical conditions. Sites in lightning-prone areas or with high internal surge activity may need replacement sooner. Every SPD should have an indicator showing when it’s reached end of life.
Does my insurance cover surge damage?
It depends on your policy and whether your electrical system was compliant at the time. Many commercial policies exclude surge damage, or require evidence of proper surge protection to pay a claim. Check your policy wording and speak to your broker.
Do I need surge protection on my data and communications lines?
Yes. Surges can enter through data lines, phone lines, and coaxial cabling as easily as through power lines. Any equipment connected to external comms should have surge protection on those lines too.
Who should install commercial surge protection?
A licensed electrical contractor with experience in commercial installations and compliance testing. The install has to meet AS/NZS 61643 and any relevant lightning protection standards, and the SPDs have to be sized for the site’s actual electrical load.
