In article , A.Lee
scribeth thus
Ronald Raygun wrote:

Would you guys mind explaining why mains input filtering, or harmonics,
would "leak" current to earth? Surely *no* equipment should have *any*
connection to earth other than from the enclosure, and there should be
no current path to earth from any of the "gubbins". And why would
interference harmonics cause a leak?

No idea about the harmonics (that was skipped over during my course),
but IT equipment has a measurable line to earth leakage.
It is something to do with the transformers in them,

Capacitors I'll think you'll find..

which leak a
little. Add 10 computers in one room, and there is potential to trip an
RCD.

There are special rules in the 17th Ed. Regs. for rooms containing IT
equipment, especially concerning their earthing - not earthed properly,
and you then touch the casing of a computer, you can get a shock, so all
earth connections have to be in separate terminals,and must be in a
ring, even if the line circuit is a radial.

Alan.

--
Tony Sayer