Why Surge Protection Is Essential – Even If There’s Already Surge Protection on the Street

What is Surge Protection?

Surge protection is the practice of limiting transient over-voltages (short, high-energy voltage spikes) that can damage electrical and electronic equipment. These surges typically last only microseconds but can reach several thousand volts – enough to destroy sensitive components instantly.

Surge protective devices (SPDs) are installed to divert this excess energy safely to earth, keeping voltage levels within safe limits for connected equipment.

Why Do We Need Surge Protection?

Voltage surges can come from a variety of sources:

• Lightning strikes (either direct or indirect via induction on power lines).
• Switching transients caused by large motors, variable speed drives, or HVAC equipment.
• Utility network switching and fault clearing on the grid.
• Backfeed from solar inverters or generators.

Modern buildings are full of electronic devices – computers, PLCs, automation systems, security systems, lighting control, communications equipment – all of which are extremely sensitive to overvoltage. Even a small transient can shorten equipment life, cause data corruption, or lead to intermittent faults that are hard to trace.

But Doesn’t the Distribution Transformer Already Have Surge Protection?

It does – but that protection is for the utility’s equipment, not yours.

Street transformers are typically fitted with high-energy surge arresters designed to protect the transformer windings from lightning and switching surges on the high-voltage (HV) and low-voltage (LV) sides. Their purpose is to keep the transformer operational and prevent flashover – not to clamp surges to a level that’s safe for sensitive electronics downstream in your building.

Once the supply leaves the transformer and travels through overhead lines or underground cables, it is exposed to induced surges, switching transients, and disturbances generated within your own site. By the time the power reaches your main switchboard, it can easily carry transient voltages high enough to damage equipment.

Layered Protection – The Real Solution

Effective surge protection is achieved through a coordinated, layered approach:

1. Main switchboard SPD (Type 1 or Type 1+2):

Handles large external surges, typically from lightning or utility disturbances. Installed at the main switchboard or point of supply.

2. Distribution board SPD (Type 2):

Protects against residual surges that pass through the main board, or those generated within the building by switching operations.

3. Local equipment SPD (Type 3):

Fine protection at the point of use – for example, protecting data racks, servers, or control panels.

Each stage reduces the surge energy to a level suitable for the next stage, ensuring full protection of connected loads.

The Bottom Line

• The transformer’s surge arresters protect the network, not your equipment.
• Transients are created inside buildings every day, even without lightning.
• Layered surge protection reduces downtime, prevents damage, and extends the life of electrical and electronic systems.

For critical facilities, offices, or industrial sites – investing in proper surge protection is not a luxury, it’s a safeguard for reliability, safety, and long-term performance.

For homeowners with high value electronic equipment, surge protection is essential to ensure the protection of your valuable assets.