Maryland Journeyperson Electrician Exam, Motors, HVAC, Generators and Transformers: all 59 questions

All questions from the Motors, HVAC, Generators and Transformers section for Maryland Journeyperson Electrician Exam, each with the correct answer.

• 8001Branch-circuit conductors supplying a single continuous-duty motor must have an ampacity of at least what percentage of the motor full-load current?
• 8002A continuous-duty motor has a table full-load current of 28 A. What is the minimum ampacity of its branch-circuit conductors?
• 8003When sizing motor branch-circuit conductors and short-circuit protection for a general-purpose motor, which current must be used?
• 8004Which value is used to size separate motor overload protection?
• 8005A motor with a marked service factor of 1.15 needs a separate overload device. What is the maximum rating as a percentage of nameplate full-load current?
• 8006A motor is marked with a temperature rise of 40 degrees C. What overload rating is permitted as a percentage of nameplate current?
• 8007A motor has a service factor of 1.0 and no temperature rise marking. What is the maximum overload rating?
• 8008A motor with a service factor of 1.0 has a nameplate current of 20 A. What is the maximum separate overload setting under 430.32(A)(1)?
• 8009The overload selected at 125 percent is not enough to start a motor with a service factor of 1.15. What is the highest rating the next step permits?
• 8010How many overload units are required for a three-phase ac motor?
• 8011What is the maximum rating of an inverse time breaker used as motor branch-circuit short-circuit and ground-fault protection for a standard squirrel cage motor?
• 8012What is the maximum rating of a dual-element time-delay fuse used as motor branch-circuit short-circuit and ground-fault protection?
• 8013What is the maximum rating of a nontime delay fuse used for motor branch-circuit short-circuit and ground-fault protection?
• 8014What is the maximum setting of an instantaneous trip breaker for a squirrel cage motor other than Design B energy efficient?
• 8015The calculated motor short-circuit protection value does not match a standard size. What does 430.52 permit?
• 8016A three-phase motor has a table full-load current of 40 A. What is the maximum inverse time breaker rating for its branch circuit, without using exceptions?
• 8017A motor has a table full-load current of 22 A. Dual-element fuses are used for branch-circuit short-circuit protection. What is the maximum standard fuse size, applying the next higher size rule?
• 8020Where must a motor disconnecting means be located in relation to the motor and driven machinery?
• 8021What does the NEC mean when it says equipment is in sight from other equipment?
• 8022What is the minimum ampere rating of a motor disconnecting means for a motor rated 1000 volts or less?
• 8023A motor disconnect switch for a 10 hp motor must be rated in which unit?
• 8024How many conductors must a motor disconnecting means open?
• 8025What must a motor disconnecting means clearly indicate?
• 8027What is the minimum rating of a motor controller?
• 8028Where must the disconnecting means for a motor control circuit be arranged?
• 8032What does the code letter on a motor nameplate indicate?
• 8034Feeder conductors supplying several motors must have an ampacity of at least what?
• 8035A feeder supplies three motors with table FLCs of 40 A, 20 A and 10 A. What is the minimum feeder conductor ampacity?
• 8036How is the maximum feeder short-circuit and ground-fault protective device for a motor feeder determined?
• 8037The largest motor on a feeder has a 100 A branch-circuit breaker. The other motors have FLCs of 20 A and 10 A. What is the maximum standard feeder breaker size?
• 8038When may several motors be connected to a single branch circuit?
• 8039Which nameplate value is used to size branch-circuit conductors for a packaged air conditioning unit?
• 8040An air conditioning unit nameplate shows a maximum overcurrent protection (MOCP) of 40 A. What breaker is permitted?
• 8041Where must the disconnecting means for an outdoor air conditioning condenser be located?
• 8043A rooftop HVAC unit requires a service receptacle. What is the maximum distance from the equipment?
• 8044What other location rule applies to the HVAC service receptacle?
• 8045May the HVAC service receptacle be connected to the load side of the equipment disconnecting means?
• 8046Branch-circuit conductors for a single hermetic motor-compressor must have an ampacity of at least what?
• 8047What is the normal maximum branch-circuit short-circuit protection for a single hermetic motor-compressor?
• 8048A single-phase cord-and-plug connected room air conditioner needs what protection device in or on the cord?
• 8049A room air conditioner is the only load on a 20 ampere individual branch circuit. What is its maximum marked rating?
• 8050A room air conditioner shares a branch circuit with lighting outlets. What is its maximum rating?
• 8052Conductors from generator terminals to the first overcurrent device must have an ampacity of at least what?
• 8053A 20 kW, 240 volt single-phase generator supplies a distribution panel. What is the minimum ampacity of the conductors from the generator terminals to the first overcurrent device?
• 8057Within how many seconds must an emergency system provide power after loss of normal supply?
• 8058Within how many seconds must a legally required standby system provide power after loss of normal supply?
• 8061A transformer rated 1000 volts or less has primary protection only, and the primary current is 9 A or more. What is the maximum primary overcurrent device rating?
• 8062A small control transformer has a primary current of 5 A and primary protection only. What is the maximum primary overcurrent device rating?
• 8063A transformer with primary-only protection has a rated primary current below 2 A. What is the maximum primary overcurrent device rating?
• 8064A transformer rated 1000 volts or less has both primary and secondary protection. What is the maximum primary device rating?
• 8065With primary and secondary protection, what is the maximum secondary device rating for a transformer with a secondary current of 9 A or more?
• 8066A 45 kVA, 480 volt three-phase transformer has primary-only protection. What is the maximum standard primary breaker size?
• 8067What must be done regarding the ventilation of a transformer?
• 8068A 75 kVA dry-type transformer is installed indoors. What is the minimum separation from combustible material without a fire-resistant barrier?
• 8072Oil-insulated transformers installed indoors are generally required to be installed in what?
• 8074Secondary conductors leave a transformer and do not exceed 10 ft in length. What may they terminate in without protection at the secondary terminals?
• 8075Capacitors rated 1000 volts or less must discharge their residual voltage to what level within what time after disconnection?
• 8076What is the minimum ampacity of conductors supplying a capacitor?
• 8078Why are capacitors installed in motor circuits in industrial plants?

More topics

• Definitions, Theory and Plans115 questions
• Services and Service Equipment49 questions
• Feeders and Overcurrent Protection47 questions
• Branch Circuits, GFCI and AFCI74 questions
• Grounding and Bonding59 questions
• Wiring Methods, Conductors and Boxes52 questions
• Equipment, Devices and Luminaires48 questions
• Special Occupancies28 questions
• Special Equipment, Pools, PV and EV44 questions
• Emergency, Limited Energy and Communications25 questions
• Load Calculations29 questions
• Electrical Calculations120 questions