IEC 61000-4-4: What Is EFT/Burst Testing?
The setup of IEC 61000-4-4, which measures immunity to fast pulse bursts created by relay and contactor switching, and the most common problems.
3 min readNovember 7, 2026
What Is a Surge?
A nearby lightning strike or large switching on the grid creates voltage pulses on power and communication lines that last a few microseconds but carry very high energy. These pulses can permanently damage devices' input stages.
IEC 61000-4-5 reproduces these pulses in the lab with standard waveforms. The voltage wave is defined as 1.2/50 microseconds and the current wave as 8/20 microseconds.
Levels and Coupling
Test levels are chosen by the environment where the device will be installed: 0.5–1 kV is common for indoor products and 2–4 kV for products connected to lines exposed outdoors. The surge is applied both line to line and line to ground.
The surge is repeated at phase angles matching different points of the mains cycle, trying to catch the device's weakest moment.
How Is Protection Done?
Surge protection is usually layered: a varistor or gas discharge tube at the input handles the high energy, and TVS diodes behind it clamp what remains. Correct sizing and short connections are critical.
For products connected to long outdoor cables, additional protection is needed where the cable enters the building. This follows similar filtering logic to what we explained for EMP and HEMP protection.
The Test Environment
Like ESD and EFT, surge testing doesn't need a shielded room, but the high energy calls for safety precautions. A controlled area away from flammable materials should be used in case the device is damaged during the test.
When setting up your pre-test bench, we recommend sizing the surge generator for your most demanding product. Our solutions for electronics manufacturers show how a complete test setup is planned.
Frequently Asked Questions
What if the device breaks during a surge test?
Permanent damage means the product fails. That's why starting pre-tests at a low level and increasing gradually is recommended.
Is surge applied to data lines too?
Yes, especially to communication lines that leave the building or run long distances.
How often are surge protection parts replaced?
Varistors wear after large surges; periodic checks are recommended in critical facilities.
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