AAMI Comprehensive Review Exam
Practice Questions with Expert Rationale
Questions 1–100 | Domains: Electrical Safety & Test Equipment, Anatomy &
Physiology
,Domain 1: Electrical Safety & Test Equipment
Q1. A patient in a critical care area (e.g., ICU) requires equipment with a maximum
allowable chassis leakage current of:
A. 300 microamps
B. 100 microamps
C. 500 microamps
D. 10 microamps
Correct Answer: B
Rationale: Per AAMI ES60601-1 and NFPA 99, equipment used in patient care areas
classified as 'critical care' must limit chassis (enclosure) leakage current to 100
microamps (0.1 mA) to protect against microshock in patients with a direct electrical
pathway to the heart, such as those with pacing wires or intracardiac catheters.
Q2. What is the primary purpose of an isolated power system (IPS) in an operating
room?
A. To reduce equipment cost
B. To eliminate the risk of macroshock from a single ground fault and reduce
fire/explosion hazard from sparking
C. To increase available current
D. To simplify wiring
Correct Answer: B
Rationale: An isolated power system ungrounds one of the two power conductors
relative to ground through an isolation transformer, so a single fault to ground does
not complete a shock circuit and does not immediately trip a breaker, allowing
continued operation while alerting staff via a line isolation monitor (LIM).
Q3. A Line Isolation Monitor (LIM) alarms when total hazard current exceeds:
A. 2 mA
B. 5 mA
C. 10 mA
D. 1 mA
Correct Answer: B
Rationale: NFPA 99 sets the LIM alarm threshold at 5 mA of total hazard current,
representing the combined leakage that would flow if a second fault occurred, giving
staff warning before a truly hazardous condition develops.
,Q4. Which safety parameter measures the current that would flow through a 1 kilohm
resistor placed between two exposed conductive parts of a device?
A. Chassis leakage current
B. Patient leakage current
C. Earth leakage current
D. Patient auxiliary current
Correct Answer: B
Rationale: Patient leakage current is specifically measured using a network that
simulates the impedance of the human body (typically modeled as 1 kilohm)
connected between accessible patient-applied parts and ground or another applied
part, per IEC 60601-1 test methods.
Q5. The ground wire resistance for a hospital-grade power cord and plug should not
exceed:
A. 0.5 ohms
B. 0.2 ohms
C. 1.0 ohm
D. 5.0 ohms
Correct Answer: A
Rationale: AAMI/NFPA 99 standards specify that ground wire (chassis-to-ground pin)
resistance should be 0.5 ohms or less to ensure a low-impedance fault current path
that will reliably trip a circuit breaker in the event of a fault, minimizing shock hazard
duration.
Q6. Microshock hazard is a concern primarily because:
A. It causes visible burns
B. As little as 10-20 microamps applied directly to the heart via a catheter or pacing
wire can induce ventricular fibrillation
C. It only affects equipment, not patients
D. It requires over 100 mA to be dangerous
Correct Answer: B
Rationale: Because the skin's resistance is bypassed when a conductive pathway
(catheter, pacing wire) provides direct access to the heart, extremely small currents
in the microamp range can disrupt the heart's electrical rhythm and cause fibrillation,
far less current than would be needed to affect a person through intact skin
(macroshock).
, Q7. Which type of electrical safety analyzer test simulates a broken ground wire to
check leakage current?
A. Normal condition polarity test
B. Single Fault Condition (SFC) test
C. Continuity resistance test
D. Dielectric withstand test
Correct Answer: B
Rationale: A Single Fault Condition test intentionally opens the ground conductor (or
reverses polarity) during leakage testing to verify that leakage currents remain within
safe limits even when one protective mechanism has failed, simulating a real-world
fault scenario.
Q8. What does the term 'Type CF' applied part classification mean?
A. Chassis Floating, used only on non-patient equipment
B. Cardiac Floating, providing the highest degree of protection and suitable for
direct cardiac connection
C. Class F, fire-resistant enclosure
D. Current-Free, meaning no leakage is possible
Correct Answer: B
Rationale: Type CF (Cardiac Floating) applied parts have an isolated (floating) circuit
with the most stringent patient leakage current limits, making them suitable for
direct cardiac application such as ECG leads used during cardiac catheterization or
pacing procedures.
Q9. A ground fault circuit interrupter (GFCI) is generally NOT used in patient care areas
because:
A. It is too expensive
B. It could interrupt power to life-support equipment during a fault, which is more
dangerous than the fault itself
C. It only works with DC current
D. It requires special outlets
Correct Answer: B
Rationale: GFCIs trip and cut power entirely when they detect a small current
imbalance; in patient care areas this could unexpectedly de-energize life-sustaining
equipment, so redundant grounding and low leakage limits are preferred over
automatic disconnection.
Practice Questions with Expert Rationale
Questions 1–100 | Domains: Electrical Safety & Test Equipment, Anatomy &
Physiology
,Domain 1: Electrical Safety & Test Equipment
Q1. A patient in a critical care area (e.g., ICU) requires equipment with a maximum
allowable chassis leakage current of:
A. 300 microamps
B. 100 microamps
C. 500 microamps
D. 10 microamps
Correct Answer: B
Rationale: Per AAMI ES60601-1 and NFPA 99, equipment used in patient care areas
classified as 'critical care' must limit chassis (enclosure) leakage current to 100
microamps (0.1 mA) to protect against microshock in patients with a direct electrical
pathway to the heart, such as those with pacing wires or intracardiac catheters.
Q2. What is the primary purpose of an isolated power system (IPS) in an operating
room?
A. To reduce equipment cost
B. To eliminate the risk of macroshock from a single ground fault and reduce
fire/explosion hazard from sparking
C. To increase available current
D. To simplify wiring
Correct Answer: B
Rationale: An isolated power system ungrounds one of the two power conductors
relative to ground through an isolation transformer, so a single fault to ground does
not complete a shock circuit and does not immediately trip a breaker, allowing
continued operation while alerting staff via a line isolation monitor (LIM).
Q3. A Line Isolation Monitor (LIM) alarms when total hazard current exceeds:
A. 2 mA
B. 5 mA
C. 10 mA
D. 1 mA
Correct Answer: B
Rationale: NFPA 99 sets the LIM alarm threshold at 5 mA of total hazard current,
representing the combined leakage that would flow if a second fault occurred, giving
staff warning before a truly hazardous condition develops.
,Q4. Which safety parameter measures the current that would flow through a 1 kilohm
resistor placed between two exposed conductive parts of a device?
A. Chassis leakage current
B. Patient leakage current
C. Earth leakage current
D. Patient auxiliary current
Correct Answer: B
Rationale: Patient leakage current is specifically measured using a network that
simulates the impedance of the human body (typically modeled as 1 kilohm)
connected between accessible patient-applied parts and ground or another applied
part, per IEC 60601-1 test methods.
Q5. The ground wire resistance for a hospital-grade power cord and plug should not
exceed:
A. 0.5 ohms
B. 0.2 ohms
C. 1.0 ohm
D. 5.0 ohms
Correct Answer: A
Rationale: AAMI/NFPA 99 standards specify that ground wire (chassis-to-ground pin)
resistance should be 0.5 ohms or less to ensure a low-impedance fault current path
that will reliably trip a circuit breaker in the event of a fault, minimizing shock hazard
duration.
Q6. Microshock hazard is a concern primarily because:
A. It causes visible burns
B. As little as 10-20 microamps applied directly to the heart via a catheter or pacing
wire can induce ventricular fibrillation
C. It only affects equipment, not patients
D. It requires over 100 mA to be dangerous
Correct Answer: B
Rationale: Because the skin's resistance is bypassed when a conductive pathway
(catheter, pacing wire) provides direct access to the heart, extremely small currents
in the microamp range can disrupt the heart's electrical rhythm and cause fibrillation,
far less current than would be needed to affect a person through intact skin
(macroshock).
, Q7. Which type of electrical safety analyzer test simulates a broken ground wire to
check leakage current?
A. Normal condition polarity test
B. Single Fault Condition (SFC) test
C. Continuity resistance test
D. Dielectric withstand test
Correct Answer: B
Rationale: A Single Fault Condition test intentionally opens the ground conductor (or
reverses polarity) during leakage testing to verify that leakage currents remain within
safe limits even when one protective mechanism has failed, simulating a real-world
fault scenario.
Q8. What does the term 'Type CF' applied part classification mean?
A. Chassis Floating, used only on non-patient equipment
B. Cardiac Floating, providing the highest degree of protection and suitable for
direct cardiac connection
C. Class F, fire-resistant enclosure
D. Current-Free, meaning no leakage is possible
Correct Answer: B
Rationale: Type CF (Cardiac Floating) applied parts have an isolated (floating) circuit
with the most stringent patient leakage current limits, making them suitable for
direct cardiac application such as ECG leads used during cardiac catheterization or
pacing procedures.
Q9. A ground fault circuit interrupter (GFCI) is generally NOT used in patient care areas
because:
A. It is too expensive
B. It could interrupt power to life-support equipment during a fault, which is more
dangerous than the fault itself
C. It only works with DC current
D. It requires special outlets
Correct Answer: B
Rationale: GFCIs trip and cut power entirely when they detect a small current
imbalance; in patient care areas this could unexpectedly de-energize life-sustaining
equipment, so redundant grounding and low leakage limits are preferred over
automatic disconnection.
