NYC CUSTODIAN ENGINEER EXAM
PREP 2026/2027 QUESTIONS AND
ANSWERS
1. What is the maximum allowable pressure for a low-pressure steam boiler according to the
NYC Boiler Code?
A. 15 psi
B. 5 psi
C. 30 psi
D. 100 psi
Answer: A
Conceptual Explanation: Low-pressure steam boilers are defined as those operating at
pressures not exceeding 15 psi.
2. A ‘hartford loop’ is primarily used in steam heating systems to:
A. Prevent boiler water from leaving the boiler in case of a return line break
B. Increase steam velocity
C. Filter out sediment from the condensate
,D. Balance the pressure between two different boilers
Answer: A
Conceptual Explanation: The Hartford Loop is a piping arrangement that prevents boiler
water levels from dropping below a safe point if a leak occurs in the return piping.
3. Which type of fire extinguisher is most suitable for an electrical fire involving a motor
starter?
A. Class C (CO2 or Dry Chemical)
B. Class B (Foam)
C. Class A (Water)
D. Class K (Wet Chemical)
Answer: A
Conceptual Explanation: Class C extinguishers are designed for fires involving energized
electrical equipment.
4. In a three-phase electrical system, what is the standard voltage between two hot legs in a
208/120V system?
A. 120V
B. 480V
C. 240V
D. 208V
, Answer: D
Conceptual Explanation: In a 208/120V Wye system, the voltage between any two phases
(hot legs) is 208V, while the voltage to neutral is 120V.
5. Which chemical is commonly used to scavenge dissolved oxygen in boiler feedwater to
prevent pitting?
A. Sodium Sulfite
B. Calcium Carbonate
C. Sulfuric Acid
D. Chlorine
Answer: A
Conceptual Explanation: Sodium sulfite reacts with dissolved oxygen to form sodium
sulfate, effectively removing oxygen and preventing corrosion.
6. According to NYC Local Law 97, what is the primary focus of the regulation?
A. Asbestos abatement in public schools
B. Carbon emissions limits for large buildings
C. Lead paint testing in residential units
D. Fire alarm system modernization
Answer: B
PREP 2026/2027 QUESTIONS AND
ANSWERS
1. What is the maximum allowable pressure for a low-pressure steam boiler according to the
NYC Boiler Code?
A. 15 psi
B. 5 psi
C. 30 psi
D. 100 psi
Answer: A
Conceptual Explanation: Low-pressure steam boilers are defined as those operating at
pressures not exceeding 15 psi.
2. A ‘hartford loop’ is primarily used in steam heating systems to:
A. Prevent boiler water from leaving the boiler in case of a return line break
B. Increase steam velocity
C. Filter out sediment from the condensate
,D. Balance the pressure between two different boilers
Answer: A
Conceptual Explanation: The Hartford Loop is a piping arrangement that prevents boiler
water levels from dropping below a safe point if a leak occurs in the return piping.
3. Which type of fire extinguisher is most suitable for an electrical fire involving a motor
starter?
A. Class C (CO2 or Dry Chemical)
B. Class B (Foam)
C. Class A (Water)
D. Class K (Wet Chemical)
Answer: A
Conceptual Explanation: Class C extinguishers are designed for fires involving energized
electrical equipment.
4. In a three-phase electrical system, what is the standard voltage between two hot legs in a
208/120V system?
A. 120V
B. 480V
C. 240V
D. 208V
, Answer: D
Conceptual Explanation: In a 208/120V Wye system, the voltage between any two phases
(hot legs) is 208V, while the voltage to neutral is 120V.
5. Which chemical is commonly used to scavenge dissolved oxygen in boiler feedwater to
prevent pitting?
A. Sodium Sulfite
B. Calcium Carbonate
C. Sulfuric Acid
D. Chlorine
Answer: A
Conceptual Explanation: Sodium sulfite reacts with dissolved oxygen to form sodium
sulfate, effectively removing oxygen and preventing corrosion.
6. According to NYC Local Law 97, what is the primary focus of the regulation?
A. Asbestos abatement in public schools
B. Carbon emissions limits for large buildings
C. Lead paint testing in residential units
D. Fire alarm system modernization
Answer: B
