CUSTODIAN TEST PREP LATEST
UPDATE 2026
What does the gauge glass show in a boiler? - ANSWER --Water level
What does blowing down the water column help confirm? - ANSWER --That the level
passages are open and accurate
How is the operating pressure controlled on a steam boiler? - ANSWER --By the pressure
control
What is the operating control for temperature on a hot-water boiler? - ANSWER --
Aquastat
What does the safety valve protect the boiler from? - ANSWER --Overpressure
What is the most important steam-boiler safety principle? - ANSWER --Maintaining
proper water level
What should an operator do if no water is visible in the gauge glass of a steam boiler? -
ANSWER --Shut the burner down and determine true water level
What is the purpose of the low-water cutoff? - ANSWER --To shut off fuel when water falls
below a safe level
,What can cause a float-type LWCO to fail? - ANSWER --Sludge or scale in the chamber
What should never be done to a safety valve in service? - ANSWER --It should never be
plugged or isolated
What can scale buildup in an LWCO chamber cause? - ANSWER --False level sensing
What does grounding mainly help with? - ANSWER --Stabilizing the system and reducing
shock hazards
What is bonding in electrical systems? - ANSWER --Connecting metal parts together so
that fault current can clear safely
What is the main purpose of a GFCI? - ANSWER --To protect people from ground-fault
shock hazards
How should a warm receptacle with scorch marks be treated? - ANSWER --As a likely
overheating or arcing hazard
What is emergency lighting considered? - ANSWER --Life-safety equipment
What should exit signs do? - ANSWER --Remain illuminated and maintained
What is a relay best described as? - ANSWER --An electrically operated switch
What can overcurrent result from? - ANSWER --An overload or a short circuit/fault
, What is the main purpose of a circuit breaker? - ANSWER --To open the circuit during
unsafe current
What are signs of a bad switch or outlet? - ANSWER --Flickering, buzzing, and burning
smell
What should be considered if many fixtures in one area are out? - ANSWER --An upstream
circuit or control issue
What is the main purpose of emergency generators? - ANSWER --To power essential loads
during outages
What should you think about if many fixtures in one area are out? - ANSWER --An
upstream circuit or control issue
What is commonly used to control motors and larger loads? - ANSWER --A contactor or
starter
What can make non-current-carrying metal parts dangerous? - ANSWER --Lack of proper
bonding
Why is replacing a blown fuse with an oversized one unsafe? - ANSWER --It defeats circuit
protection
What type of protection is more likely needed for a receptacle in a wet location? -
ANSWER --GFCI protection
UPDATE 2026
What does the gauge glass show in a boiler? - ANSWER --Water level
What does blowing down the water column help confirm? - ANSWER --That the level
passages are open and accurate
How is the operating pressure controlled on a steam boiler? - ANSWER --By the pressure
control
What is the operating control for temperature on a hot-water boiler? - ANSWER --
Aquastat
What does the safety valve protect the boiler from? - ANSWER --Overpressure
What is the most important steam-boiler safety principle? - ANSWER --Maintaining
proper water level
What should an operator do if no water is visible in the gauge glass of a steam boiler? -
ANSWER --Shut the burner down and determine true water level
What is the purpose of the low-water cutoff? - ANSWER --To shut off fuel when water falls
below a safe level
,What can cause a float-type LWCO to fail? - ANSWER --Sludge or scale in the chamber
What should never be done to a safety valve in service? - ANSWER --It should never be
plugged or isolated
What can scale buildup in an LWCO chamber cause? - ANSWER --False level sensing
What does grounding mainly help with? - ANSWER --Stabilizing the system and reducing
shock hazards
What is bonding in electrical systems? - ANSWER --Connecting metal parts together so
that fault current can clear safely
What is the main purpose of a GFCI? - ANSWER --To protect people from ground-fault
shock hazards
How should a warm receptacle with scorch marks be treated? - ANSWER --As a likely
overheating or arcing hazard
What is emergency lighting considered? - ANSWER --Life-safety equipment
What should exit signs do? - ANSWER --Remain illuminated and maintained
What is a relay best described as? - ANSWER --An electrically operated switch
What can overcurrent result from? - ANSWER --An overload or a short circuit/fault
, What is the main purpose of a circuit breaker? - ANSWER --To open the circuit during
unsafe current
What are signs of a bad switch or outlet? - ANSWER --Flickering, buzzing, and burning
smell
What should be considered if many fixtures in one area are out? - ANSWER --An upstream
circuit or control issue
What is the main purpose of emergency generators? - ANSWER --To power essential loads
during outages
What should you think about if many fixtures in one area are out? - ANSWER --An
upstream circuit or control issue
What is commonly used to control motors and larger loads? - ANSWER --A contactor or
starter
What can make non-current-carrying metal parts dangerous? - ANSWER --Lack of proper
bonding
Why is replacing a blown fuse with an oversized one unsafe? - ANSWER --It defeats circuit
protection
What type of protection is more likely needed for a receptacle in a wet location? -
ANSWER --GFCI protection
