IEC 61000-4-4 is the International Electrotechnical Commission's immunity standard based on electrical fast transient (EFT) / burst transients.
[2] The goal of this standard is to establish a common and reproducible reference for evaluating the immunity of electrical and electronic equipment when subjected to electrical fast transient/bursts on supply, signal, control and earth ports.
The cause of electrical fast transients (EFT) come from an arc when mechanical contact is open due to a switching process.
[5] Given the fast rise time and voltage of these pulses having a solid ground connection is important during the testing process.
[6] Testing for EFT often requires a capacitive coupling clamp (CCL), which is employed to add disturbances to nominal signals.