Ass pale! ...measurement of earth electrode resistance with the 2-clamp method (ERR:current too low) 

It is the fastest method and can be performed on objects in which the earth electrodes can not be disconnected (eg Ex zones or operating energy objects), but unfortunately also endowed with the highest measurement uncertainty (error) and - as this video shows - measurement could not be feasible at all with this method. The 2-clamp measurement can be performed ONLY for multiple groundings (the object has many terminals with "pins" LPS type A) that are NOT galvanically connected to each other underground and - which is also important (and probably not here met) are well connected with each other on the site/roof. In this case, the LPSes were only connected to the roofing (metal and conductive sheet), but probably the connections between the sheets on the roof had too much resistance for this type of measurement. You can not fool the physics R = U / I, i.e. I = U / R, if U = const (is constant and known) then the current I is inversely proportional to the resistance R (I ~ 1 / R), i.e. 'too small current' = 'too high resistance' TADA! ;-)

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