inserted into the heart, the way medical metal cover surface, and on account of the
equipment are grounded to avoid the macro potential difference between the two equipments
shock as seen in figure 11 is not enough to metal cover surface, a current begins to flow
prevent a micro shock. In figure 12 two medical from equipment 1 to equipment 2 throughout the
equipment are normally grounded, a fault has patient, if this current is over the limit of 10
occurred in the equipment 1 and a dangerous micro-amperes and pass throughout the heart,
potential (110V) appears on the metal cover the patient could be exposed to a ventricular
surface, so a great amount of electric current fibrillation, so the way to ground a medical
goes throughout the low resistance ground equipment to prevent the macro shock is not
conductor, if the conductor were an ideal proper for avoiding the micro shock.
conductor the 110V potential would disappear,
but because of the length of the ground In figure 13, it shows another way to ground
conductor and the great amount of electric equipment when two or more equipment are
current flowing, this is no more considered as an connected at the same time to a patient, the low
ideal
conductor,
it
behave
as
a
resistor resistance ground conductor of equipment 1 and
provoking that a potential remains at the source 2 is not the same as the one commonly used,
of the current, but the source of the current is which is together with others two conductors
the medical equipment metal cover surface,
inside the power supply cable, these are
additional conductors, also their colors are
green and yellow and are connected to the
equipment back end, the connection point
labeled with the symbol “equip-potential” seen in
figure 13. In figure 12 the ground conductors go
to different sockets and then to the common
ground terminal, but in figure 13 the equipment
Fig 12
ground conductors do not go to the common
ground terminal, instead they are connected to
the same point (equip-potential point) which is
if the resistance of the ground conductor is 0.2
Ω and the electric current is 5A, the potential on
the metal cover surface is 1V. The equipment 2
is running without problem, so there is 0V on its
commonly connected on the wall near the bed,
this WV