Ik zit even snel te spieken, dit is niet mijn echte vakgebied, heeft wel mijn interesse
Zo te zien denk ik dat het inderdaad alleen van toepassing is bij machines die een grotere lekstroom dan 10mA hebben.
Veel pro CNC machines hebben dit wel maar ook dan kun je dit nog op andere manieren oplossen (bv optie e) zie onder).
Het kan ook van belang zijn als er overige ge-aarde systemen aan de machine hangen bv waterleiding voor schoonspoelen/koelvloeistof, trappen etc. en evt bij EMC problematiek.
Het is in ieder geval wel een extra bescherming tegen gevolgen van kabelbreuk van de aarddraad.
IEC 60204-1:2016
Additional requirements for electrical equipment having earth leakage currents higher than 10 mA
Where electrical equipment has an earth leakage current that is greater than 10 mA AC or DC
in any protective conductor, one or more of the following conditions for the integrity of each
section of the associated protective bonding circuit that carries the earth leakage current shall
be satisfied:
a) the protective conductor is completely enclosed within electrical equipment enclosures or
otherwise protected throughout its length against mechanical damage.
b) the protective conductor has a cross-sectional area of at least 10 mm2 Cu or 16 mm2 Al.
c) where the protective conductor has a cross-sectional area of less than 10 mm2 Cu or
16 mm2 Al, a second protective conductor of at least the same cross-sectional area is
provided up to a point where the protective conductor has a cross-sectional area not less
than 10 mm2 Cu or 16 mm2 Al. This can require that the electrical equipment has a
separate terminal for a second protective conductor.
d) the supply is automatically disconnected in case of loss of continuity of the protective
conductor.
e) where a plug-socket combination is used, an industrial connector in accordance with
IEC 60309 series, with adequate strain relief and a minimum protective earthing conductor
cross-section of 2,5 mm2 as part of a multi-conductor power cable is provided.