AAMI Exam Questions with Answers| Latest Update
Covers: electrical safety & testing, patient monitoring, defibrillators & life support,
infusion devices, ventilators & anesthesia equipment, sterilization/infection control,
risk management & regulatory standards, and facilities/medical gas systems.
Page 1 of 32
,Q1. During routine electrical safety testing of a patient-connected device, the chassis
(enclosure) leakage current is measured with the device's ground wire intact and the
power switch on. This test primarily verifies:
A) That the device draws the correct operating current
B) That leakage current from the enclosure to ground stays below the allowable limit,
protecting anyone who touches the case
C) The device's display accuracy
D) The battery capacity of the device
Correct Answer: B) That leakage current from the enclosure to ground stays below
the allowable limit, protecting anyone who touches the case
Rationale: Chassis leakage current testing measures the current that could flow from
an equipment enclosure to ground (and potentially through a person touching it)
under normal and single-fault conditions. Keeping this below the applicable limit (per
AAMI/IEC 60601-1) protects operators and patients from shock hazards even though
the enclosure is not intentionally part of the electrical circuit.
Q2. A biomedical equipment technician measures patient lead (source) leakage
current on a cardiac monitor with an isolated patient connection. Compared to chassis
leakage limits, the allowable leakage current for an applied part in direct cardiac
contact (CF classification) is:
A) Much higher, since cardiac leads carry more current normally
B) Much lower, because current applied directly to or near the heart can cause
fibrillation at extremely small levels
C) Identical to chassis leakage limits in all cases
D) Not regulated for cardiac applications
Correct Answer: B) Much lower, because current applied directly to or near the
heart can cause fibrillation at extremely small levels
Rationale: Type CF (cardiac floating) applied parts have the strictest leakage current
limits of any classification because current delivered directly in or near the heart can
induce ventricular fibrillation at levels as low as tens of microamps — far below the
threshold of perception through intact skin.
Q3. The term “ground wire resistance test” on a medical device measures:
A) The resistance between the hot and neutral conductors
B) The resistance of the protective earth conductor from the equipment's ground pin
to its exposed metal chassis
C) The insulation resistance of the power cord
Page 2 of 32
, D) The battery internal resistance
Correct Answer: B) The resistance of the protective earth conductor from the
equipment's ground pin to its exposed metal chassis
Rationale: This test verifies that the protective earth (ground) conductor provides a
low-resistance path (typically required to be well under 1 ohm) from the plug's
ground pin to any exposed conductive chassis parts, ensuring that fault current can
safely return to ground and trip upstream protection rather than energizing the case.
Q4. A device fails its ground wire resistance test with a reading of 0.5Ω, but the typical
acceptance limit is 0.2Ω or less (per many test protocols). The most appropriate
immediate action is to:
A) Return the device to clinical service since 0.5Ω is a very small number
B) Remove the device from service and investigate the ground path (power cord,
connections) before further use
C) Ignore the reading since ground resistance rarely affects safety
D) Increase the applied test voltage to compensate
Correct Answer: B) Remove the device from service and investigate the ground
path (power cord, connections) before further use
Rationale: Even seemingly small increases in ground resistance can indicate a
degraded or partially broken ground conductor, corroded connection, or damaged
power cord — any of which could compromise protective grounding under fault
conditions. The equipment should be pulled from service and the ground path traced
and repaired until it meets the acceptance criteria.
Q5. Which classification describes a medical device's applied part that is designed to
be used in direct contact with the heart (e.g., an intracardiac catheter) and requires
the most stringent isolation and leakage current limits?
A) Type B
B) Type BF
C) Type CF
D) Type H
Correct Answer: C) Type CF
Rationale: Type CF (cardiac floating) applied parts provide the highest degree of
protection against electric shock and are specifically intended for direct cardiac
application, with an isolated (floating) patient circuit and the lowest allowable
leakage currents of any applied-part classification.
Page 3 of 32
, Q6. An isolated power system (IPS), commonly used in operating rooms, is designed
primarily to:
A) Increase available fault current for faster breaker tripping
B) Ungrounded the power supply from earth so that a single fault to ground does not
immediately trip power or create a shock hazard, allowing continued operation while
the fault is located
C) Eliminate the need for any grounding of equipment
D) Reduce equipment cost by removing circuit breakers
Correct Answer: B) Ungrounded the power supply from earth so that a single fault
to ground does not immediately trip power or create a shock hazard, allowing
continued operation while the fault is located
Rationale: An isolated power system floats the power conductors relative to ground
through an isolation transformer; a single line-to-ground fault does not complete a
shock or fault-current path and does not interrupt power, which is critical during
surgery. A line isolation monitor (LIM) continuously alerts staff if the isolation is
compromised, allowing corrective action before a second fault could create a hazard.
Q7. A line isolation monitor (LIM) alarm in an operating room indicates:
A) The room has lost all electrical power
B) The total hazard current that would flow if a second ground fault occurred has
exceeded a preset threshold, warning staff of a developing insulation fault
C) A specific piece of equipment has caught fire
D) The isolation transformer has been correctly installed
Correct Answer: B) The total hazard current that would flow if a second ground
fault occurred has exceeded a preset threshold, warning staff of a developing
insulation fault
Rationale: The LIM continuously monitors the isolated power system's balance to
ground and calculates the potential hazard current that would result if a second fault
occurred; an alarm signals that this potential current has exceeded the safety
threshold (commonly 5 mA), prompting staff to identify and disconnect the faulty
equipment.
Q8. When performing a polarity test on a standard hospital-grade AC receptacle, a
technician is primarily checking that:
A) The receptacle can supply at least 100 amps
B) Hot, neutral, and ground conductors are correctly wired according to the standard
configuration, without reversed or open conductors
Page 4 of 32
Covers: electrical safety & testing, patient monitoring, defibrillators & life support,
infusion devices, ventilators & anesthesia equipment, sterilization/infection control,
risk management & regulatory standards, and facilities/medical gas systems.
Page 1 of 32
,Q1. During routine electrical safety testing of a patient-connected device, the chassis
(enclosure) leakage current is measured with the device's ground wire intact and the
power switch on. This test primarily verifies:
A) That the device draws the correct operating current
B) That leakage current from the enclosure to ground stays below the allowable limit,
protecting anyone who touches the case
C) The device's display accuracy
D) The battery capacity of the device
Correct Answer: B) That leakage current from the enclosure to ground stays below
the allowable limit, protecting anyone who touches the case
Rationale: Chassis leakage current testing measures the current that could flow from
an equipment enclosure to ground (and potentially through a person touching it)
under normal and single-fault conditions. Keeping this below the applicable limit (per
AAMI/IEC 60601-1) protects operators and patients from shock hazards even though
the enclosure is not intentionally part of the electrical circuit.
Q2. A biomedical equipment technician measures patient lead (source) leakage
current on a cardiac monitor with an isolated patient connection. Compared to chassis
leakage limits, the allowable leakage current for an applied part in direct cardiac
contact (CF classification) is:
A) Much higher, since cardiac leads carry more current normally
B) Much lower, because current applied directly to or near the heart can cause
fibrillation at extremely small levels
C) Identical to chassis leakage limits in all cases
D) Not regulated for cardiac applications
Correct Answer: B) Much lower, because current applied directly to or near the
heart can cause fibrillation at extremely small levels
Rationale: Type CF (cardiac floating) applied parts have the strictest leakage current
limits of any classification because current delivered directly in or near the heart can
induce ventricular fibrillation at levels as low as tens of microamps — far below the
threshold of perception through intact skin.
Q3. The term “ground wire resistance test” on a medical device measures:
A) The resistance between the hot and neutral conductors
B) The resistance of the protective earth conductor from the equipment's ground pin
to its exposed metal chassis
C) The insulation resistance of the power cord
Page 2 of 32
, D) The battery internal resistance
Correct Answer: B) The resistance of the protective earth conductor from the
equipment's ground pin to its exposed metal chassis
Rationale: This test verifies that the protective earth (ground) conductor provides a
low-resistance path (typically required to be well under 1 ohm) from the plug's
ground pin to any exposed conductive chassis parts, ensuring that fault current can
safely return to ground and trip upstream protection rather than energizing the case.
Q4. A device fails its ground wire resistance test with a reading of 0.5Ω, but the typical
acceptance limit is 0.2Ω or less (per many test protocols). The most appropriate
immediate action is to:
A) Return the device to clinical service since 0.5Ω is a very small number
B) Remove the device from service and investigate the ground path (power cord,
connections) before further use
C) Ignore the reading since ground resistance rarely affects safety
D) Increase the applied test voltage to compensate
Correct Answer: B) Remove the device from service and investigate the ground
path (power cord, connections) before further use
Rationale: Even seemingly small increases in ground resistance can indicate a
degraded or partially broken ground conductor, corroded connection, or damaged
power cord — any of which could compromise protective grounding under fault
conditions. The equipment should be pulled from service and the ground path traced
and repaired until it meets the acceptance criteria.
Q5. Which classification describes a medical device's applied part that is designed to
be used in direct contact with the heart (e.g., an intracardiac catheter) and requires
the most stringent isolation and leakage current limits?
A) Type B
B) Type BF
C) Type CF
D) Type H
Correct Answer: C) Type CF
Rationale: Type CF (cardiac floating) applied parts provide the highest degree of
protection against electric shock and are specifically intended for direct cardiac
application, with an isolated (floating) patient circuit and the lowest allowable
leakage currents of any applied-part classification.
Page 3 of 32
, Q6. An isolated power system (IPS), commonly used in operating rooms, is designed
primarily to:
A) Increase available fault current for faster breaker tripping
B) Ungrounded the power supply from earth so that a single fault to ground does not
immediately trip power or create a shock hazard, allowing continued operation while
the fault is located
C) Eliminate the need for any grounding of equipment
D) Reduce equipment cost by removing circuit breakers
Correct Answer: B) Ungrounded the power supply from earth so that a single fault
to ground does not immediately trip power or create a shock hazard, allowing
continued operation while the fault is located
Rationale: An isolated power system floats the power conductors relative to ground
through an isolation transformer; a single line-to-ground fault does not complete a
shock or fault-current path and does not interrupt power, which is critical during
surgery. A line isolation monitor (LIM) continuously alerts staff if the isolation is
compromised, allowing corrective action before a second fault could create a hazard.
Q7. A line isolation monitor (LIM) alarm in an operating room indicates:
A) The room has lost all electrical power
B) The total hazard current that would flow if a second ground fault occurred has
exceeded a preset threshold, warning staff of a developing insulation fault
C) A specific piece of equipment has caught fire
D) The isolation transformer has been correctly installed
Correct Answer: B) The total hazard current that would flow if a second ground
fault occurred has exceeded a preset threshold, warning staff of a developing
insulation fault
Rationale: The LIM continuously monitors the isolated power system's balance to
ground and calculates the potential hazard current that would result if a second fault
occurred; an alarm signals that this potential current has exceeded the safety
threshold (commonly 5 mA), prompting staff to identify and disconnect the faulty
equipment.
Q8. When performing a polarity test on a standard hospital-grade AC receptacle, a
technician is primarily checking that:
A) The receptacle can supply at least 100 amps
B) Hot, neutral, and ground conductors are correctly wired according to the standard
configuration, without reversed or open conductors
Page 4 of 32
