CME Special Occupancies and Equipment Questions and Answers 1 — Questions and Answers
Question 1: In a hospital's essential electrical system (EES), which of the following loads is required to be connected to the critical branch?
- The hospital's main HVAC system.
- Task illumination and select receptacles in the intensive care unit (ICU). (Correct answer)
- Elevators selected to provide service to patient floors.
- Selected receptacles in the main lobby.
Correct answer: Task illumination and select receptacles in the intensive care unit (ICU).
According to NEC 517.34, the critical branch of the essential electrical system is required to supply power for task illumination, fixed equipment, and select receptacles serving critical patient care spaces, such as intensive care units, where interruption of power could be life-threatening. The main HVAC system and selected elevators are typically on the equipment branch of the EES, while lobby receptacles are generally on the normal power system.
Question 2: An electrician is replacing a single-phase, 240-volt pool filter motor at a residential dwelling. According to NEC Article 680, what is the primary requirement for the branch circuit supplying this motor?
- It must be hard-wired using Type MC cable.
- It must have short-circuit and ground-fault protection not exceeding 125% of the motor FLC.
- It must be protected by a ground-fault circuit-interrupter (GFCI). (Correct answer)
- It must be supplied from a dedicated transformer.
Correct answer: It must be protected by a ground-fault circuit-interrupter (GFCI).
NEC 680.21(C) mandates that outlets supplying pool pump motors connected to single-phase, 120-volt through 240-volt branch circuits must be provided with Class A ground-fault circuit-interrupter protection for personnel, whether supplied by a receptacle or by direct connection.
Question 3: In a commercial garage used for repair and service where adequate ventilation is not provided, what is the default classification for the area extending from the floor up to a level of 18 inches?
- Unclassified.
- Class II, Division 1.
- Class I, Division 1.
- Class I, Division 2. (Correct answer)
Correct answer: Class I, Division 2.
Per NEC 511.3(C)(1)(b), in a major repair garage without four or more air changes per hour, the area from the floor up to 18 inches is classified as a Class I, Division 2 location. This is because flammable gasoline vapors are heavier than air and can accumulate near the floor. Any pit or depression below floor level is considered Class I, Division 1.
Question 4: When installing an equipotential plane in a concrete floor area of an agricultural building where livestock are confined, which of the following is a key requirement according to NEC 547.10?
- The plane must be connected to the electrical grounding system with a copper conductor, not smaller than 8 AWG. (Correct answer)
- The equipotential plane is only required if the building has a metal frame.
- The plane must be made of non-conductive materials to isolate the livestock.
- The equipotential plane must be connected only to a separate, dedicated grounding rod.
Correct answer: The plane must be connected to the electrical grounding system with a copper conductor, not smaller than 8 AWG.
NEC 547.10(C) requires the equipotential plane to be bonded to the building's electrical grounding system. The bonding conductor must be copper (insulated, covered, or bare) and not smaller than 8 AWG. This practice helps to reduce voltage gradients (stray voltage) across the concrete surface, which can be harmful to livestock.
Question 5: Which of the following best describes the overcurrent protection requirement for a feeder supplying an electric fire pump motor, according to NEC Article 695?
- The overcurrent device must be omitted and replaced with an alarm that indicates an overcurrent condition.
- The overcurrent device must be selected or set to carry the motor's locked-rotor current indefinitely. (Correct answer)
- GFCI protection is required for all fire pump circuits regardless of voltage.
- The overcurrent device must be set to trip at 125% of the motor's full-load current.
Correct answer: The overcurrent device must be selected or set to carry the motor's locked-rotor current indefinitely.
According to NEC 695.4(B)(2), the overcurrent protective device for a fire pump must be rated to carry the sum of the locked-rotor currents of the fire pump motor(s) and the full-load current of any associated accessory equipment indefinitely. The primary objective is to ensure the fire pump operates without interruption during a fire, prioritizing its function over protecting the motor from overload.
Question 6: An electrician is installing 125-volt, single-phase, 20-ampere receptacles to provide shore power to boat slips at a new marina. What specific requirement must these receptacles meet per NEC Article 555?
- Each receptacle must be located at least 48 inches above the dock surface.
- Each receptacle must be of the locking and weather-resistant type.
- Each single receptacle providing shore power must be provided with GFCI protection. (Correct answer)
- Each receptacle must be supplied by a multi-wire branch circuit.
Correct answer: Each single receptacle providing shore power must be provided with GFCI protection.
NEC 555.33(A) requires that 125-volt and 125/250-volt, single-phase, 15-, 20-, 30-, and 50-ampere receptacles that provide shore power for boats be protected by a ground-fault circuit-interrupter. This is a critical safety measure in a wet environment to protect against electric shock drowning (ESD).
CME Special Occupancies and Equipment Questions and Answers 1
In a hospital's essential electrical system (EES), which of the following loads is required to be connected to the critical branch?