This part of IEC 61000 defines a set of typical radiated and conducted HPEM environment waveforms that may be encountered in civil facilities. Such threat environments can produce damaging effects on electrical and electronic equipment in the civilian sector@ as described in IEC 61000-1-5. It is necessary to define the radiated and conducted environments@ in order to develop protection methods. For the purposes of this standard@ high-power conditions are achieved when the peak electric field exceeds 100 V/m@ corresponding to a plane-wave free-space power density of 26@5 W/m2. This criterion is intended to define the application of this standard to EM radiated and conducted environments that are substantially higher than those considered for "normal" EMC applications@ which are covered by the standards produced by IEC SC 77B. The HPEM environment can be:?? radiated or conducted;?? a single pulse envelope with many cycles of a single frequency (an intense narrowband signal that may have some frequency agility and the pulse envelope may be modulated); ?? a burst containing many pulses@ with each pulse envelope containing many cycles of a single frequency;?? an ultrawideband transient pulse (spectral content from tens of MHz to several GHz);?? a burst of many ultrawideband transient pulses. The HPEM signal could be from sources such as radar or other transmitters in the vicinity of an installation or from an intentional generator system targeting a civilian facility. Radiated signals can also induce conducted voltages and currents through the coupling process. In addition@ conducted HPEM environments may also be directly injected into the wiring of an installation. There is a critical distinction between the HEMP (high-altitude electromagnetic pulse) environment and the HPEM environment@ in terms of the range or the distance of the affected electrical or electronic components from the source. In the context of HEMP@ the range is immaterial@ as the HEMP environment propagates downward from space to the earthapos;s surface and is therefore relatively uniform over distances of 1 000 km. On the other hand@ in the HPEM context the environment and its effects decrease strongly with range. In addition@ the HEMP waveshape is a series of time domain pulses while the HPEM environment may have a wide variety of waveshapes. Consequently@ the standardization process for HPEM environments is more difficult. The recommended approach is to investigate the various types of HPEM environments that have been produced to date and are likely to be feasible in the near future@ and then to develop suitable HPEM standard waveforms from such a study. Such HPEM environment standard waveforms can be amended in due course@ depending on emerging technologies that make it possible to produce them.