LEAKAGE
CURRENT
WHAT IS LEAKAGE CURRENT?
Leakage current is the current that flows through the protective
ground conductor to ground. In the absence of a grounding
connection, it is the current that could flow from any conductive
part or the surface of non-conductive parts to ground if a
conductive path was available (such as a human body). There are
always extraneous currents flowing in the safety ground conductor.
Causes Of Leakage Currents
If any conductor is raised to a potential above that of
earth, some current is bound to flow from that conductor
to earth. This is true even of conductors that are well
insulated from earth, since there is no such thing as
perfect insulation or infinite impedance. The amount of
current that flows depends on:
the voltage on the conductor.
thecapacitive reactance between the conductor and
earth.
the resistance between the conductor and earth.
Type Of Leakage Current
• Earth leakage current
• Enclosure leakage current
• Patient leakage current
• Patient auxiliary current
Earth Leakage Current
• Earth leakage current is the current that
normally flows in the earth conductor of a
protectively earthed piece of equipment.
• IEC 60601 defines ELC as a current flowing
down the protective earth conductor of
the main inlet lead.
• The earth leakage test is important as it
demonstrates the total leakage from
EUT/DUT/UUT.
Earth Leakage Current
• Shows the current flowing through or via the insulation
of the medical device into the protective earth
conductor.
Earth Leakage Current Measurement
Earth Leakage Current Measurement
• Applicable to B / BF / CF (class I only)
• Conditions
• Normal supply
• Normal supply, open neutral
• Reversed supply
• Reversed supply, open neutral
• Limits 0.5mA / 1mA (SFC)2nd edition
• Limits 5mA / 10mA (SFC)3rd edition
Enclosure Leakage Current
• Enclosure leakage current is defined as the current that flows from
an exposed conductive part of the enclosure to earth through a
conductor other than the protective earth conductor.
Enclosure Leakage Current (Touch Current)
• The current that flow if a person would come in contact
with the housing ( or any accessible part not intended
for treatment or care) of the medical device.
Enclosure Leakage Current or Touch Current
Measurement
Enclosure Leakage Current or Touch
Current Measurement
• Applicable to B / BF / CF
• Conditions
• Normal supply
• Normal supply, Open Neutral
• Normal supply, Open Earth (class I only)
• Reversed supply
• Reversed supply, Open Neutral
• Reversed supply, Open Earth (class I only)
• Limits 0.1mA/0.5mA (SFC)
Patient Leakage Current
• Patient leakage current is the leakage current that flows
through a patient connected to an applied part or parts.
• It can either flow from the applied parts via the patient to
earth or from an external source of high potential via the
patient and the applied parts to earth.
Patient Leakage Current Path From Equipment
Patient Leakage Current Path To Equipment
Patient Leakage Current Measurement
Measurement Of Patient Leakage Current With
Applied Parts Connected Together
Measurement Of Patient Leakage Current For
Each Applied Part In Turn
Patient Leakage Current Measurement
Applicable to B / BF /CF
▪ Patient connection shorted
within applied part for B and
Condition BF.
Normal supply ▪ Patient connection measured
Normal supply, Open Neutral separately within applied part
Normal supply, Open Earth for CF.
(class I only)
▪ Limits B / BF (AC) 0.1mA /
Reversed supply
0.5mA (SFC)
Reversed supply, Open Neutral
Reversed supply, Open Earth
▪ Limits CF (AC) 0.01mA /
(class I only) 0.05mA (SFC)
▪ Limits B / BF / CF (AC)
AC and DC reading
0.01mA / 0.05mA (SFC)
Patient F-type Leakage Measurement
Patient F-type Leakage Measurement
Applicable to BF / CF only
▪ Patient Connection shorted within
Current Limited to 5mA max
at 110% of mains Applied Part for BF
▪ Patient Connection measured
Condition separately within Applied Part for
Normal Supply, Source Normal CF
Normal Supply, Source Reversed
Reversed Supply, Source Normal
▪ Limits BF (AC) 5mA
Reversed Supply, Source ▪ Limits CF (AC) 0.05mA
Reversed
RMS reading
Patient Auxiliary Leakage Current
• The patient auxiliary current is defined as the current that normally
flows between parts of the applied part through the patient, which is
not intended to produce a physiological effect.
Patient AUX Leakage Current Measurement
Patient AUX Leakage Current Measurement
Applicable to B / BF /CF ▪ Each Patient Connection to all
Conditions other Connection shorted within
Normal supply
Applied Part.
Normal supply, Open Neutral ▪ Limits B / BF (AC) 0.1mA /
Normal supply, Open Earth (class I
0.5mA (SFC)
only) ▪ Limits CF (AC) 0.01mA /
Reversed supply 0.05mA (SFC)
Reversed supply, Open Neutral ▪ Limits B / BF / CF (AC)
Reversed supply, Open Earth 0.01mA / 0.05mA (SFC)
(class I only)
AC and DC reading
Summary of Type Leakage Current
Measurement (IEC60601)
Earth Leakage Current
Earth Leakage Current test measure the current flowing in
the DUT’s protective earth circuit
Enclosure Leakage Current
Enclosure Leakage Current test measure the current flowing
between the DUT’s enclosure and protective earth
Patient Leakage Current
Patient Leakage Current test measures the current flowing between a
selected applied part, selected group of applied parts, or ALL applied parts
and the Mains PE
Patient Auxiliary Leakage Current
Patient Auxiliary Leakage Current measure the leakage current through each
applied part or lead and selected combination of lead connections (all other or
between two)
Summary of Leakage Current
Measurement (IEC62353)
Leakage Current Measurement
(IEC62353)
• Equipment Leakage Current: Total leakage deriving
from the Applied Parts, Enclosure & Mains Parts
combined to real Earth.
• Applied Part Leakage Current: Total leakage deriving
from the combined Patient Connections within an Applied
Part to Earth & any conductive parts on the enclosure [4].
Direct Method
The Direct Equipment
Leakage Current test
measures the leakage
current between all applied
parts and the exposed
conductive surface on the
housing, to mains earth
Direct Equipment Leakage Current
Direct Method
The Direct Applied Part Leakage
Current test measures the leakage
current between all applied parts of
a single function and the exposed
conductive surface on the housing,
to mains earth. For equipment with
multiple applied parts, each group
of a single function should be
tested each in turn with all other
floating during the test. This test
Direct Applied Part Leakage Current should only be done for equipment
with F-Type applied parts.
Differential Method
The Differential Leakage Current
test measures the magnitudes of
the differential current flowing in
the Equipment Outlet live and
neutral, with power applied to
the equipment outlet. All
applied parts should be
connected during this test, if
equipment has applicable
applied parts
Differential Leakage Current
Alternative Method
• During the Alternative Equipment Leakage
test, the voltage source is applied between
short-circuited equipment outlet mains live,
neutral, and equipment outlet earth, the
exposed conductive surface on the housing
and all applied parts short-circuited
together.
• Equipment is separated from mains during
the test. The current which flows over the
insulation of the DUT is measured. This test is
not applicable for equipment with internal
Alternative Equipment Leakage Current electrical power source. The switches in
mains part shall be closed during
measurement
Alternative Method
• During the Alternative Applied
Part Leakage test, the test
voltage is applied between
short-circuited applied parts
of a single function and the
short-circuited equipment
outlet mains live, neutral,
equipment outlet earth, and
exposed conductive surface
on the housing.
Alternative Applied Part Leakage Current
• This test should only be done
for equipment with F-Type
applied parts
