NYC CUSTODIAN ENGINEER EXAM 1
QUESTIONS AND ANSWERS 2026/2027
1. What is the primary purpose of a ‘Low Water Cut-Off’ (LWCO) on a steam boiler?
A. To maintain a constant water level during operation
B. To shut down the burner if the water level drops to a dangerous point
C. To automatically add water to the boiler when levels are low
D. To blow down the boiler to remove sludge
Answer: B
Conceptual Explanation: A Low Water Cut-Off is a safety device designed to shut off the
fuel supply to the burner if the water level in the boiler drops below a safe operating limit,
preventing boiler damage or explosion.
2. In a DC circuit, if the voltage is 120V and the resistance is 20 Ohms, what is the current in
Amperes?
A. 6 Amps
B. 4 Amps
C. 2 Amps
,D. 2400 Amps
Answer: A
Conceptual Explanation: Using Ohm’s Law (I = V / R), 120V divided by 20 Ohms equals 6
Amperes.
3. Which type of fire extinguisher is specifically designed for fires involving combustible
metals?
A. Class A
B. Class D
C. Class C
D. Class B
Answer: B
Conceptual Explanation: Class D fire extinguishers are used on combustible metals such
as magnesium, titanium, and sodium.
4. What is the function of a thermostatic trap in a steam heating system?
A. To remove air and condensate while preventing the passage of steam
B. To modulate steam flow based on room temperature
C. To increase the pressure of the returned condensate
D. To act as a safety valve for high pressure steam
, Answer: A
Conceptual Explanation: Thermostatic traps use temperature differences to open and
close, allowing air and cool condensate to leave the radiator while trapping steam inside.
5. According to NYC building codes, a standpipe system must be tested hydrostatically every
how many years?
A. 1 year
B. 3 years
C. 5 years
D. 10 years
Answer: C
Conceptual Explanation: NYC Fire Code typically requires a hydrostatic pressure test of
standpipe and sprinkler systems every five years.
6. What is the chemical name for the white, chalky substance that builds up inside boiler
tubes due to hard water?
A. Sodium Chloride
B. Magnesium Sulfate
C. Ferrous Oxide
D. Calcium Carbonate
Answer: D
QUESTIONS AND ANSWERS 2026/2027
1. What is the primary purpose of a ‘Low Water Cut-Off’ (LWCO) on a steam boiler?
A. To maintain a constant water level during operation
B. To shut down the burner if the water level drops to a dangerous point
C. To automatically add water to the boiler when levels are low
D. To blow down the boiler to remove sludge
Answer: B
Conceptual Explanation: A Low Water Cut-Off is a safety device designed to shut off the
fuel supply to the burner if the water level in the boiler drops below a safe operating limit,
preventing boiler damage or explosion.
2. In a DC circuit, if the voltage is 120V and the resistance is 20 Ohms, what is the current in
Amperes?
A. 6 Amps
B. 4 Amps
C. 2 Amps
,D. 2400 Amps
Answer: A
Conceptual Explanation: Using Ohm’s Law (I = V / R), 120V divided by 20 Ohms equals 6
Amperes.
3. Which type of fire extinguisher is specifically designed for fires involving combustible
metals?
A. Class A
B. Class D
C. Class C
D. Class B
Answer: B
Conceptual Explanation: Class D fire extinguishers are used on combustible metals such
as magnesium, titanium, and sodium.
4. What is the function of a thermostatic trap in a steam heating system?
A. To remove air and condensate while preventing the passage of steam
B. To modulate steam flow based on room temperature
C. To increase the pressure of the returned condensate
D. To act as a safety valve for high pressure steam
, Answer: A
Conceptual Explanation: Thermostatic traps use temperature differences to open and
close, allowing air and cool condensate to leave the radiator while trapping steam inside.
5. According to NYC building codes, a standpipe system must be tested hydrostatically every
how many years?
A. 1 year
B. 3 years
C. 5 years
D. 10 years
Answer: C
Conceptual Explanation: NYC Fire Code typically requires a hydrostatic pressure test of
standpipe and sprinkler systems every five years.
6. What is the chemical name for the white, chalky substance that builds up inside boiler
tubes due to hard water?
A. Sodium Chloride
B. Magnesium Sulfate
C. Ferrous Oxide
D. Calcium Carbonate
Answer: D
