Accumulating earth leakage not to be detected ?

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If normal earth leakage detection level is 30mA, this probably
is based on average 'dangerous current' ?

But when several offices are fed from a single earth leakage
detector, it is not appropriate for one user to bring all parallel
users down, by merely adding 5 mA extra leakage, to increase
the total from 26mA to 31 mA.

Do earth leakage detectors exists which only react to an
INCREASE in earth leakage ?

What are these 'self tuning' ELDs which I read about ?

Thanks for any info.

== Chris Glur.

 

[Andrew Gabriel]

If normal earth leakage detection level is 30mA, this probably
is based on average 'dangerous current' ?

Yes, earth leakage detection at <= 30mA is usually for additional
protection against electrocution. (In the UK, and I suspect all
country's wiring standards, earth leakage detection is never
allowed to be the primary protection against electrocution.)

But when several offices are fed from a single earth leakage
detector, it is not appropriate for one user to bring all parallel
users down, by merely adding 5 mA extra leakage, to increase
the total from 26mA to 31 mA.

I answered this already in a different thread, at least for the
UK, where this would be inappropriate use of a single earth
leakage detector to protect against electrocution.

 

[Dimitrios Tzortzakakis]

Andrew,
the 30mA leaking current is the most dangerous current if it passes through
the heart (path:right arm-left arm).Protection against electrocution is
done:
1) Earthing the neutral in the LV side of the local substation, thus the
center of the star of the secondary
2) Earthing the metal parts of the device
3)GFCI breaker
sometimes a GFCI trips when of course, nobody touches anything live and it
makes them annoying, that's why some people don't like them.Recently three
people were electrocuted by chinese irons without earthing here, one of them
was a technician of the company that imported them.