Related to the discussion concerning North Korea HEMP threat I am updating my experiences with NEMP / lightning (hardening electronics, sensors, IT and communication equipment for MIL and NPP accident monitoring) with respect to the realistic influence (some papers deny the effects to power grids and transformers) and to the damage and down-time of complete power distribution networks and control. The unclassified papers on the high altitude tests in 1962 are not very helpful estimating the effects to modern grids. Who can provide for more information on E1/E2 time & frequency resulting from a 1Mton / 300 km high explosion)? I am prepared to share own data and to discuss any realistic theory.