There's no such thing as earth leakage per se. Normally speaking, neutral
is connected to the earth as well at some point, where the current goes in
one phase applications. Current normally "leaks" here.
Current on the grounding wire (not the neutral) is more accurate and
illuminating to the reader for visualization of this phenomena.
--
The RCBO (assuming this is the same as a GFCI) measures the difference in
current between the hot and neutral conductors. Any difference is leaking to
ground through some unintended path, most typically within the device
itself.
There's a spec for this, usually 5 mA of leakage is permitted. A device can
be tested with a 'hipot' tester. The RCBO/GFCI in the panel is designed to
trip when it senses 5 mA of difference between hot and neutral. This is all
good.
What might be happening is that the monitors each have something like 3 mA
of leakage, which isn't unusual for cheap ones. Same maybe for cheap power
supplies. Combined, all these devices may be exceeding the design limits of
the breaker in the panel. The only solution for this might be to use GFCIs
at the outlets rather than the panel.
Or, several years ago I had a customer with a similar problem but the
primary failure was leakage from the wires to the conduit that went to the
lab benches....old building and wiring.
This is an electrician's problem, IT guys shouldn't mess with it.
-John O
