A surge protective device clamps voltage spikes before they reach the driver. IEC 61643-11 defines three types, one for the service entrance, one for the panel, one at the fixture. Skip any of them and you replace LEDs after every Saudi storm season.
Four ideas to carry into the next specification conversation you have.
A direct strike is rare. Indirect (induced) surges from distant strikes and switching of motors, transformers, capacitor banks are constant. SPDs protect against both.
Type I = service entrance (10/350 µs lightning). Type II = distribution panel (8/20 µs). Type III = at the load (residual). All three together = full protection.
Type I 25 kA. Type II 40 kA Imax. Type III 6 kA. Wrong order or under-rated component lets the surge through to the next stage.
A small surge does not always trip the breaker. It degrades the driver's input cap, which fails 6 months later. Surge events leave no trace, until the warranty claim.
Per IEC 61643-11. Saudi installations should default to coordinated Type I + II + III for outdoor/industrial.
| Type | Where it goes · waveform | Typical rating |
|---|---|---|
| Type 1 (Class I) | Service entrance · 10/350 µs | Iimp 12–25 kA |
| Type 2 (Class II) | Sub-distribution · 8/20 µs | Imax 40–60 kA · In 20 kA |
| Type 3 (Class III) | At the load (fixture) · combination | Imax 6–10 kA · Uoc 6 kV |
| Type 1+2 combo | Single device covers entrance + panel | Iimp 12.5 kA · Imax 40 kA |
| Type 2+3 combo | Sub-panel + load in one box | Imax 40 kA · Up < 1.5 kV |
| Streetlight in-line SPD | Inside the pole/fixture body | 10 kA · Up < 1.2 kV |
| DC-side SPD (solar streetlight) | PV input on hybrid systems | 10 kA DC |
Five practical points that turn a spec line into a working installation.
Three SPDs in series only work if the upstream device clamps to a lower voltage than the downstream device can survive. Manufacturers (Phoenix Contact, OBO, Citel, DEHN) publish coordination tables. Pick a single brand for the system or you risk uncoordinated firing.
Every metre of cable between the SPD and the protected device adds ~1 µH inductance. At a 1 kA/µs surge rise, that's a 1 kV extra drop. SPD-to-load cable should be < 0.5 m where possible, and the protective earth path equally short.
Most SPDs use Metal-Oxide Varistors. Every clamping event slightly degrades the MOV. A status indicator (green = OK, red = failed, sometimes a remote contact) tells you when to replace. Industrial sites schedule SPD inspection annually.
If the building has a lightning protection system (LPS) per IEC 62305, the LPS must terminate into a Type 1 SPD at the service entrance, designed for the full 10/350 µs lightning waveshape. Type 2 alone will not survive a direct strike's energy.
Streetlights and outdoor LED highbays should ship with a 10 kA in-line SPD between the live input and the driver. This is the third stage of coordination, and the difference between replacing a 30 SAR SPD vs a 700 SAR fixture after a storm.
We supply and install IEC 61643-coordinated SPD systems, Type 1 at the service entry, Type 2 at distribution, and Type 3 at every NLC outdoor fixture by default.
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