A lightning strike a kilometre away is enough to destroy the driver on your pole. Most outdoor LED driver failures attributed to quality are actually unprotected installations. This guide covers how surge protection works, how to choose between 10kV and 20kV, and what to check beyond the headline rating.
A lightning strike does not have to hit your pole to destroy the driver on it. A strike a kilometre away induces a multi-kilovolt transient on nearby overhead LV distribution lines. That spike travels down the line, into the luminaire, and into the driver — which is designed to withstand perhaps 2kV to 6kV, and which encounters considerably more than that.
The driver dies instantly. The failure looks like a driver quality problem. It is not: it is an unprotected installation.
This is why street-light tenders, rural electrification projects and any pole-mounted outdoor lighting in India should treat a Surge Protection Device as a line item, not an upsell. The economics are not subtle — an SPD costs a fraction of a driver, and the driver it protects costs a fraction of the truck roll needed to replace it on a 9-metre pole.
An SPD sits inline between the AC supply and the LED driver. Under normal conditions it does nothing — it is effectively invisible to the circuit. When the voltage across it exceeds a safe threshold, it becomes conductive within nanoseconds and diverts the surge current to earth, clamping the voltage the driver sees to a survivable level. Once the transient passes, it reverts to its non-conducting state automatically.
Two technologies do the work. A Metal Oxide Varistor (MOV) responds fast and handles moderate energy. A Gas Discharge Tube (GDT) handles far higher energy but responds slightly slower. Combining both gives fast clamping and high energy capacity — which is why our SPDs use a GDT and MOV together rather than either alone.
| Rating | Specify it when |
|---|---|
| 10 kV | Urban and semi-urban street lighting, underground or short overhead feeds, campus and parking lighting, commercial façades, signage in moderate-exposure locations. Covers the large majority of installations. |
| 20 kV | Long overhead distribution runs, rural pole-tops, high-mast and main-road lighting, coastal and eastern-monsoon regions, telecom compounds near towers, and any site with a history of repeated driver failures. |
If a site has already burned through drivers more than once, treat that as evidence rather than bad luck and step up to 20kV. The cost difference is trivial against a second replacement cycle.
An SPD addresses transients — events lasting microseconds. It does not, by itself, protect against a sustained over-voltage condition or a deep brown-out, both of which are common on weak Indian rural feeds and both of which kill drivers. Some SPDs integrate HV/LV cut-off to cover this; most do not.
Ask: does this device protect against sustained over-voltage, or only transients?An SPD absorbs energy every time it operates, and eventually degrades. A device that has silently reached end-of-life offers no protection while appearing perfectly normal — the installation is unprotected and nobody knows until a driver dies. A status indicator turns this from an invisible failure into a visible one.
Ask: is there an end-of-life indicator, and what does it show?An SPD mounted inside a pole-top luminaire is exposed to the same water ingress, condensation cycling and dust as the driver beside it. IP67 potting is not optional at the top of a pole in a monsoon climate.
Ask: what is the IP rating and is the device fully potted or merely enclosed?Three production models, all IP67 silicon-potted with automatic reset. Full details on the SPD product page.
| Model | Surge | Distinguishing feature | Install |
|---|---|---|---|
| SP-1545 | 10 kV | GDT + MOV, IP67 potted. Compact enough for typical luminaire driver compartments. | Series or parallel |
| SP-1245 | 10 kV | Adds HV and LV cut-off — protects against sustained over-voltage and brown-out as well as transients. | Series, in-luminaire |
| SP-1448 | 20 kV | Highest rating in the range, with a status LED showing end-of-life after sustained surge events. | Series or parallel |
All three reset automatically after a surge event. The SP-1448 resets automatically until it reaches end of life, at which point the indicator shows it needs replacement.
A Surge Protection Device is a component installed inline between the AC supply and the LED driver. It diverts lightning-induced and switching transients to earth, clamping the voltage the driver sees to a survivable level, then resets automatically. It is required in practice for any outdoor pole-mounted lighting — street lights, floodlights, signage, rural installations — because a lightning strike up to a kilometre away can induce a multi-kilovolt spike on nearby overhead lines that will destroy an unprotected driver instantly.
The rating is the surge voltage the device is designed to clamp. A 10kV SPD covers most urban and semi-urban street lighting, campus lighting, commercial façades and moderate-exposure signage. A 20kV SPD is specified for higher-exposure sites: long overhead distribution runs, rural pole-tops, high-mast and main-road lighting, coastal and eastern-monsoon regions, and telecom compounds near towers. If a site has already lost drivers repeatedly, step up to 20kV.
A Metal Oxide Varistor responds very fast and handles moderate surge energy. A Gas Discharge Tube handles much higher energy but responds slightly more slowly. Using both together gives fast initial clamping from the MOV and high energy absorption from the GDT. Smooth Power SPDs combine GDT and MOV rather than relying on either technology alone.
Not by default. A standard SPD addresses transients lasting microseconds, not sustained over-voltage or brown-out conditions — both of which are common on weak Indian rural feeds and both of which damage LED drivers. Some devices integrate HV/LV cut-off to cover sustained conditions; the Smooth Power SP-1245 does this alongside 10kV surge clamping, while the SP-1545 and SP-1448 are surge-only devices.
An SPD absorbs energy each time it operates and degrades over its service life. A device that has reached end-of-life provides no protection while appearing normal, which means the installation is unprotected without anyone knowing. Devices with a status indicator make this visible — the Smooth Power SP-1448 includes a status LED showing end-of-life after sustained surge events.
Smooth Power Private Limited manufactures IP67-potted SPDs for LED lighting at its Sahibabad Industrial Area plant in Ghaziabad, Uttar Pradesh, in 10kV and 20kV ratings including variants with HV/LV cut-off and end-of-life status indication. BIS registration R-81008324, GSTIN 09AAZCS0655B1Z2.
Send your fixture specification, wattage and current target, and compliance requirement to sales@smoothpower.in or call +91-82872 62090. Ask for engineering rather than sales.
Our factory is at Plot No A-2/77, Site-IV, Sahibabad Industrial Area, Ghaziabad 201010, with a second unit at Durga Industrial Park. If you are in Delhi NCR, come and look at the line. See also our guide to choosing an LED driver manufacturer in India.