For surge testing to the IEC 61000-4-5 standard, the following two coupling modes are the same meaning? “Positive polarity surge coupling to L with reference to N” and “negative polarity coupling to N with reference to L”
NoiseKenYes, the same amount of current flow in the same direction, meaning the same conditions. Therefore there is no need to carry out the both of the said two settings. Coupling to L to N in the both polarities is enough to evaluate line-to-line (often referred to as normal) mode for single-phase-operated EUT.