Electrical safety
13
Mana Sezdi
Istanbul University-Cerrahpasa, Istanbul, Turkey
What is electrical safety?
Electrical safety is a concept that involves the safe use of all devices powered
electrically. These devices have many electrical risks because they work with electricity. Every year, thousands of people are injured or die in electrical incidents.
The electrical incidents may be electric shock, fire, or explosion. In addition to the
damage to people, the financial loss is also very high. Because of this, it is essential
to control the devices powered electrically to determine whether there is a risk that
will cause electrical accidents. In order to control the devices periodically, an
electrical safety program is required.
The electrical safety program requires electrical devices to be kept under electrical
control. The following questions are asked in electrical safety studies: Does the
device have an electrical leakage current? Can the device cause fire or explosion? If
there is any risk, necessary measures are taken.
Why is it important in medical applications?
The electrical risk found in all other electrical devices is also available for medical
devices. In fact, the shock caused from medical devices is a much greater danger.
Medical devices may be connected to the patient directly, and it increases the risk
of electro shock (Barbosa, Iaione, & Spalding, 2010; Chakrabartty & Panda, 2010).
Especially in the catheter laboratory, it is often not thought that the reason of the
death of the patient after the electrical shock is an electrical leak. Instead, because
the person is a patient, it is thought that the death of the patient is normal. For this
reason, the cause of the death is not investigated, and the problem of the electrical
leakage cannot be solved. This situation is very dangerous (Sezdi, 2009).
To better understand the importance of electrical safety at the hospital, the
following factors must be considered:
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The patient cannot react to electrical current danger because the natural defense reflex
diminishes or disappears (for example, a patient under narcosis).
Skin resistance is reduced due to applications such as catheters or electrodes.
Bioelectronics and Medical Devices. DOI: https://doi.org/10.1016/B978-0-08-102420-1.00018-2
Copyright © 2019 Elsevier Ltd. All rights reserved.
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The heart is in danger due to leakage current during the catheter and electron applications.
Intensive care or operating rooms require the use of multiple devices at the same time.
Sometimes fire hazards can occur with the use of flammable anesthesia, disinfectants, and
cleaning agents.
In the electrical safety programs of the hospitals, medical devices powered electrically must be controlled at least one time in a year. In hospitals, an electrical
safety program is the responsibility of the clinical engineer or biomedical engineer
of the hospital. Leakage currents must be measured by using electrical safety analyzers.
All electrical outlets must be checked. If these controls are not performed, the
possible leakage current in the medical device is not recognized and poses a great
risk to both the patient and the user (Emergency Care & Research Institute, 2008).
Physiological effects of electricity
Electricity has physiological effects on the human body. Electricity generates
effects ranging from slight tingling of muscles to death. The physiological effects
of electricity can be summarized as the following:
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From 0.5 to 10 mA are threshold of perception.
From 6.0 to 50 mA are accepted as let-go current before sustained muscular contraction.
From 75 to 400 mA cause ventricular fibrillation.
From 1 to 10 A cause myocardial contraction, burns, and injury.
Time is also important, as much as the amount of current. As the duration of
exposure to electricity increases, the effect increases, even if the current is low.
Leakage current
Leakage current is undesirable current that escapes to the ground from the feeding
energy source or the insulation of devices. Since there is no material that ideally
isolates a current source, leakage current as related to the current source and to the
conductor or cable system always flows.
Leakage currents are four types in accordance to the international standards. The
leakage current types are as below:
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Earth leakage
Body (chassis) leakage
Patient leakage
Patient auxiliary current
Earth leakage current: It flows down to the ground conductor of the device.
Body (chassis) leakage current: It flows to the ground through the patient. It
occurs when the patient touches the medical device’s chassis.
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Patient leakage current: It flows to the ground from the patient through application parts. Or it flows to the ground from the application parts.
Patient auxiliary current: It flows from one application part to the other through
the patient. It is the leakage current between the application parts.
Leakage currents should be kept small enough to avoid danger. In devices with
protection class II, the leakage currents flow to the ground through the person
touching the device’s body or from the place where the device is installed. In
devices with protection class I, if the earth or protective conductor breaks or fails
over the protection conductor, it flows to the earth from the person touching the
device. The magnitude of the leakage current flowing through the following leakage
current paths is important:
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Between main and body
Between main and application part
Between application part and body
If there is a leakage current on the chassis of the medical device, there is a risk
that the patient may be exposed to the leakage current. In this situation, if the
chassis has a very good grounding, the risk disappears because the leakage current
flows through the earth resistance. The earth resistance must be small to generate
an alternative road with low resistance for the leakage current.
If the chassis of the medical device is not grounded, the leakage current flows
into the human body and causes the physiological effects mentioned earlier.
Electrical shock
Electrical shock is defined as the passage of electric current through the human
body. Its effect of electrical current is related to the amount of electrical current.
Everybody thinks that voltage is effective during electrical shock. Contrary to
what everyone thinks, the factor affecting electrical shock is the amount of current
(Carr & Brown, 1981; Webster, 1992).
When electricity comes into contact with the human body, it first encounters
skin resistance. Skin resistance limits the electrical current that will pass through
the body. Skin resistance is determined by the epidermis layer. While subcutaneous
electrical resistance of the body is about 50 Ω for the body, it is about 200 Ω for
arms and legs. These values are higher in obese people. The skin resistance
increases as the epidermis layer thickens. But, even if the skin thickness is great,
the skin resistance reduces with increasing frequency of the electrical current. Low
skin resistance increases electrical effect on the human body.
In hospitals, patients are in danger of two types of electrical hazards because of
the leakage current. They are known as
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Macroshock
Microshock
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Macroshock
The macroshock occurs when the electric current exceeds skin resistance. For this,
the current must be higher than the limit value. The first effect of macroshock on
the human body is a deeply slight tremor (Aston, 1991; Webster, 1992). After that,
as the electric current value increases, the events given below may occur,
respectively.
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Muscle spasms and contractions
Respiratory strength
Ventricular fibrillation
Burns and injuries
Death
The macroshock was simulated in Fig. 13.1. The figure shows that the leakage
current enters into the patient’s body via the skin. The current comes face to face
with the body resistance. Because of this, the effect of the shock will be light if the
amount of current is not very high. The leakage currents causing the macroshock
are approximately 1 100 mA.
Microshock
The electrical shocks that are seen in patients with heart catheters due to the leakage currents are called microshock. During catheter applications and electrocardiography measurements, the skin resistance decreases because of the solution in the
catheter and the gel of electrodes (Aston, 1991; Webster, 1992). The solution in
the catheter behaves like a conductor. Microshock may occur during invasive blood
pressure measurements, external pacemaker, endocardial, and epicardial electrode
applications (Sezdi, 2009). A similar situation was screened in Fig. 13.2. It is seen
in Fig. 13.2, the leakage current enters the patient body via a catheter. It flows
through the heart. Even if the current is very, very small, because it passes from the
heart, it causes the ventircular fibrillation. The result is the death of the patient.
Microshock currents are approximately 10 100 μA.
Figure 13.1 A scenario for macroshock (Webster, 1992).
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Figure 13.2 A scenario for microshock (Webster, 1992).
Measurement of electrical leakage current
There are three types of medical electrical equipment according to their electrical
safety degrees:
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Class I devices
Class II devices
Class III devices
Class I: There is a connection between the conductive surface of the device and
the ground for protection against electrical shock in class I devices. This connection
is grounded via a protective conductor inside the electrical installation. The diagram
of the class I device is shown in Fig. 13.3. Protection is provided when the plug is
inserted into the prize. This grounding removes the possible voltage on the tactile and
conductive portions. The state free from this voltage maintains its function even if
there is a fault current on the main insulation. If the leakage current exceeds the rated
value of the protection scheme in the electrical installation, this device cuts off the
power supply. In many devices, breakdown of the protection conductor affects the
function of the device. This protection conductor failure may not be recognized and
the device may continue to be used. This is a very important reason for the continuous visual inspection of the conductive connections of the device. Class I devices
are marked with the grounding symbol in a circle that is shown in Fig. 13.4A.
Class II: Class II devices are marked with a double square. The symbol can be
seen in Fig. 13.4B. This symbol indicates that in addition to the main insulation of
this device, there is a second insulation.
Main insulation protects this second insulation against electric current danger. In
these devices, the leakage current does not flow through the protection conductor. It
flows through the human body touching the device. For this reason, the device
regulations allow very small leakage currents in class II devices. The diagram of
the class II device is shown in Fig. 13.5.
Class III: Class III devices have no voltage higher than safety extra low voltage
(SELV). SELV is approximately 25 V AC or 60 V DC. These devices are batteryoperated devices.
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Figure 13.3 The diagram of a class I device.
Figure 13.4 The symbols of (A) class I and (B) class II medical devices.
Since most of the medical devices come into contact with the patient, the electrical
risk that may result on the patient via the application parts should also be considered.
The application part is, by definition, a part that is touched to the patient physically,
contacted by the patient, or touched by the patient when necessary for the device’s
function. Application parts are classified as three types. Each type of applied part has
different characteristics. The types of applied parts are as below:
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Type B application parts
Type BF application parts
Type CF application parts
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Figure 13.5 The diagram of a class II device.
Figure 13.6 The symbols of (A) B, (B) BF, and (C) CF application parts.
Type B application part is grounded. This type of application part is not used in
cardiac applications. If there is a leakage current, it flows through the device’s chassis. Centrifuge, blood storage refrigerator, and radiant heater are examples of Type B.
Type BF application part has a connection to the patient. There is no any cardiac
application in this type. Aspirators and pulse oximeters are examples of Type BF.
Type CF application part presents the highest degree of protection. It is used in
cardiac applications. Electrocardiography, electrosurgical units, and invasive blood
pressure meters are examples of type CF.
Each application part is marked with a different symbol to identify the specifications of the medical devices that are caused from the application. The symbols of
the application parts are as shown in Fig. 13.6.
The electrical safety measurements are taken in different electrical conditions.
In addition to the normal condition (NC), during the conditions that have a fault to
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be generated consciously, the electrical safety measurements are performed
(International Electrotechnical Commission, 2005; 2014). These conditions are
called single fault condition (SFC).
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Normal supply voltage (NV)
NV 1 open neutral
NV 1 open earth
Reversed supply voltage (RV)
RV 1 open neutral
RV 1 open earth
International standards in electrical safety
The international standards that are references in the interpretation of the electrical safety measurement results are “IEC 60601-1:2005 Medical Electrical
Equipment—Part 1: General Requirements for Basic Safety and Essential
Performance” and “IEC 62353:2014 Medical Electrical Equipment—Recurrent
Test and Test After Repair of Medical Electrical Equipment.” IEC stands for
İnternational Electrotechnical Commission. The standards were produced by this
commission. While IEC 60601-1 was developed for manufacturers, IEC 62353
contains all tests that can be used in hospitals (Emergency Care & Research
Institute, 2008). The difference between two standards is the technique of leakage
current measurement and the limit value of leakage current. There are also other
standards related to the electrical safety. These are “IEC 61010-1:2001, Safety
Requirements for Electrical Equipment for Measurement, Control, and Laboratory
Use—Part 1: General Requirements” and “NFPA 99:2005, Standard for Health
Care Facilities” (National Fire Protection Association, 2005; International
Electrotechnical Commission, 2001b). But these are not used for electrical safety
measaurement’s interpretation.
IEC 60601-1:2005 standard
IEC 60601 standard presents the general requirements for basic safety and essential performance of medical electrical devices—“IEC 60601-1:2005 Medical
Electrical Equipment—Part 1: General Requirements for Basic Safety and
Essential Performance.” It was first published in 1977. It includes two substandards, IEC60601-1 and 60601-2. IEC 60601-1 consists of 11 collateral standards
from IEC 60601-1-1 to IEC 60601-1-11. All of them are related to the electrical
safety of the devices.
While IEC 60601-1-1 explains the medical electrical equipment and general
requirements for basic safety and essential performance, the other collateral standards refer to the following:
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IEC 60601-1-2: Electromagnetic compatibility, requirements, and tests
IEC 60601-1-3: General requirements for radiation protection in diagnostic X-ray equipment
IEC 60601-1-4: Programmable electrical medical systems
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IEC 60601-1-6: Usability
IEC 60601-1-8: General requirements, tests, and guidance for alarm systems in medical
electrical equipment and medical electrical systems
IEC 60601-1-9: Requirements for environmentally conscious design
IEC 60601-1-10: Requirements for the development of physiologic closed-loop
controllers
IEC 60601-1-11: Requirements for medical electrical equipment and medical electrical
systems used in home care applications (International Electrotechnical Commission, 2010a)
IEC 60601-2 is especially for some medical devices like defibrillators, electrocardiography, etc. IEC 60601-2 consists of 58 collateral standards from IEC
60601-2-1 to IEC 60601-2-58. They include the procedures of the performance
measurements of the medical devices. For example, IEC 60601-2-1 is related to the
performance measurements of electron accelerators, while IEC 60601-2-4 is related
to cardiac defibrillators. In addition, IEC 60601-2-12 is for lung ventilators, and
IEC 60601-2-22 is for laser equipment (International Electrotechnical Commission,
2001a, 2010b, 2012).
Here, IEC 60601-2 standard will not be explained in detail. Only IEC 60601-1
will be explained thoroughly. IEC 60601 standard is used generally during the testing
of the device after manufacturing.
IEC 60601-1 has some inspections:
Visual inspection
Earthbond testing
Leakage measurements
1. Visual inspection: It is the visual examination of the characteristics of the device’s external
appearance. These items are visually inspected:
a. damage on the chassis
b. problematic cables
c. fuse rating
d. safety markings
e. contamination
2. Earthbond testing: It tests whether there is a low resistance between the ground conductor
and the metal part of the device. For earthbond testing, the test current is applied between
the ground pin of the main supply plug and any metal part by using the probe of the safety
analyzer. 25 A AC is used as the test current.
3. Leakage measurements: All leakage measurements mentioned earlier are performed:
a. Earth leakage test: It measures the current flowing from the insulation of the medical
device to the ground conductor. This test is performed under the NC and reverse condition and the neutral open. This leakage test is performed for class I medical devices.
The medical device that will be tested with earth leakage test may have B, BF, and CF
applied parts. Under the SFC, “open earth” cannot be applied to the devices because
the measurement result will be zero.
Fig. 13.7 shows the test circuit of the earth leakage test. As it is seen in Fig. 13.7,
in NCs, earth leakage is measured during S1 closed, S5 normal, and then S5 reversed.
To take a measurement in a SFC, this test should be repeated by opening S1.
b. Enclosure leakage test: It measures the current flowing to ground via a person who
touches the medical device. This test is performed under the NC, reverse condition,
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Figure 13.7 Test circuit of the earth leakage test. AP, Applied parts; ESA, electrical safety
analyzer (Backes, 2007a; International Electrotechnical Commission, 2005).
Figure 13.8 Test circuit of the enclosure leakage test. AP, Applied parts; ESA, electrical
safety analyzer (Backes, 2007a; International Electrotechnical Commission, 2005).
and the neutral open and open earth. This test is performed for all classes of medical
devices. The medical device that will be tested with enclosure leakage test may have
all types of application parts. Under the SFC, open tests cannot be applied to the class
II devices.
Fig. 13.8 shows the test circuit of the enclosure leakage test. As is seen in
Fig. 13.8, in NC, enclosure leakage is measured during S1 closed, S8 closed, and S5
normal and reversed.
To take a measurement in a SFC, this test should be repeated by opening S1 (S1
open, S8 closed, S5 normal and reversed). This is known as “enclosure leakage test
during SFC, supply open.”
To generate a second SFC, this test is repeated by closing S1 and opening S8 (S1
closed, S8 open, S5 normal and reversed). This is known as “enclosure leakage test
during SFC, earth open.”
c. Patient leakage test: It measures the current flowing from the application part to
ground via a person. This test is performed under the NC, reverse condition, and the
neutral open and open earth. This test is performed for all classes of medical devices
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like the enclosure leakage test. The medical device that will be tested with the patient
leakage test may have all types of application parts. But earth open tests cannot be
applied to the class II devices.
The patient leakage current for CF equipment is measured from each application part.
It is measured by connecting all application parts together for B and BF devices.
Fig. 13.9 shows the test circuit of the patient leakage test. As seen in Fig. 13.9,
in NC, patient leakage is measured during S1 closed, S8 closed, and S5 normal and
reversed.
To take a measurement in a SFC, this test should be repeated by opening S1 (S1
open, S8 closed, S5 normal and reversed). This is known as “patient leakage test
during SFC, supply open.”
To generate a second SFC, this test is repeated by closing S1 and opening S3
(S1 closed, S8 open, S5 normal and reversed). This is known as “patient leakage
test during SFC, earth open.”
d. Patient auxiliary leakage test: It measures the current flowing between application parts. Current is measured between an application part and the other parts
connected together. The test is repeated until all single parts have been measured.
This test is performed under the NC, reverse condition, and the neutral open and
open earth. This test is performed for all classes of medical devices like the patient
leakage test. The medical device that will be tested with patient auxiliary leakage
test may have all types of application parts. But earth open tests cannot be applied
to the class II devices.
Fig. 13.10 shows the test circuit of the patient auxiliary leakage test. As is seen
in Fig. 13.10, in NC, patient auxiliary leakage is measured during S1 closed, S8
closed, and S5 normal and reversed.
To measure patient auxiliary leakage with a SFC, the test is repeated by opening
S1 (S1 open, S8 closed, S5 normal and reversed). This is known as “patient auxiliary leakage test during SFC, supply open.”
Figure 13.9 Test circuit of the patient leakage test. AP, Applied parts; ESA, electrical safety
analyzer (Backes, 2007a; International Electrotechnical Commission, 2005).
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Figure 13.10 Test circuit of the patient auxiliary leakage test. AP, Applied parts; ESA,
electrical safety analyzer (Backes, 2007a; International Electrotechnical Commission, 2005).
Table 13.1 Leakage current limits in different applied parts according to the IEC
60601-1:2005 (Backes, 2007a; International Electrotechnical Commission, 2005).
Excluding power cable
, 0.1 Ω
Including power cable
, 0.2 Ω
B
BF
CF
Application parts
Application parts
Application parts
Leakage current (mA)
Normal
Single
fault
Normal
Single
fault
Normal
Single
fault
Earth leakage
Enclosure leakage
Patient leakage
(direct current)
Patient leakage
(alternative current)
Patient leakage (F type)
Patient auxiliary
(direct current)
Patient auxiliary
(alternative current)
0.5
0.1
0.01
1
0.5
0.05
0.5
0.1
0.01
1
0.5
0.05
0.5
0.1
0.01
1
0.5
0.05
0.1
0.5
0.1
0.5
0.01
0.05
NA
0.01
NA
0.05
NA
0.01
5
0.05
NA
0.01
0.05
0.05
0.1
0.5
0.1
0.5
0.01
0.05
NC, Normal condition; SFC, single fault condition.
To generate a second SFC, this test is repeated by closing S1 and opening S3
(S1 closed, S8 open, S5 normal and reversed). This is known as “patient auxiliary
leakage test during SFC, earth open.”
The leakage current limits are defined in IEC 60601 standard. The values can
change according to the type of applied part, B, BF, or CF. They can be seen in
Fig. 13.7 and described in Table 13.1.
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IEC 62353:2014 standard
IEC 62353 standard presents the needs for the in-service safety of devices. Its title
is “IEC 62353:2014 Medical Electrical Equipment—Recurrent Test and Test
After Repair of Medical Electrical Equipment.” In this standard, there are no laboratory conditions presented in IEC 60601 because laboratory conditions are not
required for in-service medical device. While IEC 60601 is used for device testing
by manufacturers, IEC 62353 is used for in-service testing of the devices in
hospitals.
A medical device requires some tests during life circle:
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Acceptance test
Routine testing
Repair testing
Acceptance test is the initial test for the medical device before usage. But the
acceptance test also includes some performance measurements in addition to
the electrical safety measurements. If there is no any calibration certificate of
the medical device purchased new, the hospital management wants acceptance
tests to be performed, including both electrical safety and performance
measurements.
Routine testing is the testing that is performed periodically. This test includes
both electrical safety testing and the performance measurement of the medical
device. The measurements are performed one or two times in a year.
Repair testing is the testing that is performed after technical service or repair. If
a component is replaced, the electrical safety testing must be performed.
The 62353 standard presents practical measurement and reduces the complexity of the measurement defined in the IEC 60601-1 standard. It also consists
of several tests such as visual inspection, earthbond testing, and leakage measurements, like IEC 60601. But there are some differences during application of
these testing. In addition to the earthbond and leakage measurements, IEC
62353 also has an insulation resistance test, unlike IEC 60601. These tests are
explained following:
1. Earthbond testing: This is the same with the testing in IEC 60601-1. Only, the test current
is 200 mA instead of 25 A.
2. Insulation resistance test: Insulation testing is performed to measure three settings:
a. Insulation between earth and mains parts: It is controlled whether the mains parts are
completely insulated from ground. It can be applied to both Class I and Class II
devices.
b. Insulation between earth and application parts: It is controlled whether the application
parts are completely insulated from ground. It can be applied to both Class I and Class
II devices. The devices with BF or CF parts can be tested.
c. Insulation between application parts and mains parts: It is controlled whether the
application parts are completely insulated from mains parts. It can be applied to both
Class I and Class II devices. The devices with BF or CF parts can be tested (Backes,
2007b; International Electrotechnical Commission, 2014).
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3. Leakage measurements: Leakage measurements performed according to IEC 62353 use
the root mean square value. It does not use separate AC and DC values. IEC 62353 has
three methods to measure the leakage currents:
a. Direct method: In this method, the leakage current is measured similarly to the IEC
60601-1 standard. Because of this, measurement results can be compared directly with
the measurements made in IEC 60601-1. AC and DC leakage current can be measured
in this method. It is the method with the highest accuracy.
b. Differential method: The leakage current is measured between hot and neutral conductor. Measurement results give the total equipment leakage current. Potential secondary
earth connections do not influence the measurements. The measurement results change
according to the polarity of the main supply. Because of this, the polarity of the main
supply must be changed during measurement. It is difficult to measure the low leakage
currents of less than 75 μA.
c. Alternative method: In this method, first, the hot and neutral conductors are combined.
Then the current limited voltage is applied between the main parts and other parts of the
device. The polarity of main supply does not influence the measurement results.
Because of this, only one measurement is taken. There is no effect of the secondary
earth connections on the measurements. But this technique is different from the techniques in IEC 60601-1. Therefore, the measurement results cannot be compared with the
measurements made in IEC 60601-1 (International Electrotechnical Commission, 2014).
i. Equipment leakage: To measure equipment leakage current, all the preceding methods mentioned are used. By this way, the equipment measurements in the IEC
62353 are named as follows:
Equipment leakage direct method: Equipment leakage current is measured by using
the body model of the IEC 60601-1 standard. Measurement is performed for two
polarities of the main parts.
Equipment leakage differential method: The body model of the IEC 60601-1 standard is not used, unlike the direct method. Again, measurement is performed for
two polarities of the main parts.
Equipment leakage alternative method: The body model is used. All applied parts
are connected together during the measurement.
ii. Applied part leakage: To measure applied part leakage current, only two methods,
direct and alternative method, are used. The measurements of the applied part leakage are as follows:
Applied part leakage direct method: Applied part leakage current is measured by
using the body model of the IEC 60601-1 standard. Measurements are repeated for
normal and reversed polarities.
Applied part leakage alternative method: The body model is used. All applied parts
are connected together during the measurement.
The leakage current limits defined in IEC 62353 standard can be seen in
Fig. 13.8. The limit values can change according to the type of applied part, B, BF,
or CF (Table 13.2).
Electrical safety analyzer
Electrical safety analyzer is used to test the devices powered electrically. The
device is designed specifically to measure electrical current and to interpret
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Table 13.2 Leakage current limits in different application parts according to IEC
62353:2014 (Backes, 2007b; International Electrotechnical Commission, 2014).
Current in microampere
Application part
B (μA)
BF (μA)
CF (μA)
1000
500
1000
500
500
100
500
100
5000
50
5000
50
Equipment leakage (alternative method)
Class I device
Class II device
1000
500
Equipment leakage (direct or differential method)
Class I device
Class II device
500
100
Patient leakage (alternative method)
Class I and II
Patient leakage (direct method)
Class I and II
the measurement results. An example of electrical safety analyzer is shown in
Fig. 13.11.
During electrical safety measurements, the current is simulated as if flowing
through a patient. Because of this, the electrical safety analyzers have the simulation reflecting the electrical characteristics of the human body. The system is named
the body model. Because it is first identified in IEC 60601-1 standard, it is known
as IEC 60601-1 body model. But this model is also used in IEC 62353 standard.
The model can be seen in Fig. 13.12.
The international acceptance criteria of the electrical safety standards are embedded into the analyzer. The international electrical safety analyzers are “IEC 606011:2005 Medical Electrical Equipment—Part 1: General Requirements for Basic
Safety and Essential Performance” and “IEC 62353:2014 Medical Electrical
Equipment—Recurrent Test and Test After Repair of Medical Electrical Equipment.”
While the first designed analyzers include only IEC 60601-1, the new designed analyzers include both IEC 60601-1 and IEC 62353.
An electrical safety analyzer should have the following characteristics:
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It must be regulated to 25 A AC for IEC 60601-1 standard.
It must meet the frequency response of the model in Fig. 13.12.
It must have high accuracy and repeatability of the measurements.
It must store the measurement results.
It must have the traceability; in other words, it must have the calibration certificate.
It must present test convenience.
It must have a printer on it, and it must print the reports easily.
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Figure 13.11 Electrical safety analyzer.
Figure 13.12 IEC 60601 body model (R1 5 10 kΩ 6 5%, R2 5 1 kΩ 6 5%,
C1 5 0.015 μF 6 5%) (International Electrotechnical Commission, 2005).
After measurements, all results must be reported as a certificate. The parameters
that must be entered into the certificate are as follows:
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Test location (e.g., hospital, department)
Name of the person who performed the measurements
Device information (e.g., manufacturer, model, serial number)
Electrical safety
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Type of the device (class I or class II)
Information about the electrical safety analyzer (e.g., manufacturer, model, serial number)
Measurement results
Evaluation of the measurement results
Date of the measurement
Signature of the person who prepared the evaluation
Conclusion
Electrical safety is one of the most important issues in hospitals. It must be ensured
that devices are electrically safe for both patient and user safety. Because of this, all
medical devices powered electrically must be controlled as to whether there is any
leakage current or not. According to the international standards, all medical devices
must be tested by performing electrical safety testing at least once per year. To obtain
this, an electrical safety program must be established. It is also required for the quality and the accreditation studies of health institutions, especially for the accreditation
studies of The Joint Commission on Accreditation of Healthcare Organizations.
The measurements must be performed by the biomedical personnel who must be
qualified to test the medical devices electrically. They must be trained about electrical safety measurements. Only training is not sufficient—they must also be familiar
with the relevant standards and regulations (Sezdi & Sezdi, 2017). They must be
aware of the risks that incorrect measurement results may cause.
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Further reading
Sezdi, M. (2012). Medical technology management and patient safety. In S. Kara (Ed.), A
Roadmap of biomedical engineers and milestones (pp. 183 208). Croatia: InTech.