Ricardos 4th test
T/F Since the 1971 NEC, 3-phase motors only need two phases protected with properly sized overload protection.
False
T/F Supplementary overcurrent protective devices are permitted to be used as a substitute for a branch-circuit OCPD or where a branch-circuit OCPD is required (240.10).
False
T/F The internal parts of fuses require maintenance.
False
T/F To meet the selective coordination requirements of 700.32, 701.27, and 708.54, the selection of the overcurrent protective devices to achieve selective coordination must be completed by an Electrical Worker
False
T/F When analyzing circuit breakers in their instantaneous region, only the unlatching time of the circuit breaker is of concern.
False
T/F When increased sizing of the overcurrent protective device is utilized on the secondary side of a transformer, overcurrent protection on the primary side, sized closer to the load, is typically required.
False
T/F Secondary protection is not required for a transformer 1,000 volts or less, with primary overcurrent protection sized at 125% feeding a 3-phase, 4-wire panelboard NEC reference???
False NEC: Table 450.3(B)
T/F Series rated systems are used where a fuse is used on a circuit having an available fault current higher than the marked interrupting rating by being connected on the load side of an acceptable overcurrent protective device having a higher rating. NEC??
False, NEC: 240.86
T/F 700.32, 701.27, and 708.54 require that documentation of the overcurrent protective device selections be made available to those authorized in the various phases of the system life cycle, including installation
True
T/F A circuit breaker with an arc reduction maintenance switch (ARMS) provides an option where lower arc flash hazard levels can be achieved when it is necessary to do energized work.
True
T/F A current-limiting overcurrent protective device can greatly reduce the thermal energy and mechanical forces that an electrical component must withstand during a fault current.
True
T/F Because there is often not enough room in the panelboard to show all of the series rated combinations, UL 67 allows for a bulletin (or manual), which provides all of the acceptable series rating combinations, to be supplied with the panelboard.
True
T/F For existing systems, per 240.86(A), if the short-circuit current has increased beyond the circuit breaker's interrupting rating, engineering methods are permitted to investigate whether series rated combinations can be used to allow the continued use of the existing circuit breakers.
True
T/F For transformers 1,000 volts or less, the secondary overcurrent protection device can be split up to six devices, provided the sum of the ratings does not exceed that of the single device and the conditions of Article 240 and Article 408 are satisfied.
True
T/F Section 110.3 provides criteria and considerations for the evaluation of equipment and recognizes listing or labeling as a means of establishing suitability.
True
T/F Selective coordination is a benefit for any electrical distribution system and increases reliable power delivery to the loads. For most systems, it is a design consideration but not mandatory
True
T/F Selective coordination is an important consideration for reliability of emergency systems to deliver power to vital loads
True
T/F Selective coordination of the overcurrent protective devices increases the reliability of the electrical distribution system to deliver power to the loads.
True
T/F The intent of 110.10 is that the equipment short-circuit current ratings, OCPDs, and circuit parameters must be "selected and coordinated" so that under fault conditions up to the available short-circuit current value, the equipment will not sustain extensive damage (become a hazard).
True
T/F The transformer primary overcurrent protective device supplying a fire pump must be rated to carry the sum of the locked-rotor current of the fire and pressure pump motors plus the full-load current of the accessory equipment.
True
T/F When fault current is within the current-limiting range of a current-limiting OCPD, the thermal energy and magnetic (mechanical) forces can be greatly reduced. The levels of both thermal energy and magnetic forces are proportional to the square of the fault current that flows
True
When determining the overcurrent protection requirements for transformers in a circuit, other requirements from Article(s) ? may also need to be investigated .I. 230 II. 240 III. 408 IV. 517 a. I., II., and III. only b. I., II., III., and IV. c. I. and III. only d. II. and III. only
a. I., II., and III. only
A motor starter only protected to ___protection may sustain heater elements vaporizing and severe contact welding and vaporizing under short-circuit conditions, even though the short-circuit current rating is greater than the available short-circuit current. a. Type 1 (which is the same as UL 508 protection level) b. Type 2 c. Type 3 d. any of the above
a. Type 1 (which is the same as UL 508 protection level)
Separate motor overload protection shall be based upon the motor nameplate ___ rating. a. current b. efficiency c. power d. voltage NEC reference??
a. current NEC reference: 430.6(A)(2)
The scope of Article 450 indicates that this article covers the installation of all transformers. There are __ exceptions that modify this Article 450 scope statement. Select one: a. 3 b. 7 c. 8 d. 9
c. 8
Which of the following is a motor circuit function discussed in this lesson? a. At the motor or in sight from the motor disconnect b. Motor branch-circuit and controller disconnect c. Motor controller d. All of the above
d. All of the above
The values given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 are generally used to determine which of the following for motor branch circuit? a. Ampacity of conductors b. Branch-circuit short-circuit and ground-fault protection c. Motor overload protection d. a. and b. e. a. and c NEC reference??
d. a. and b. NEC reference: 430.6(A)(1)
The vertical axis of a time-current curve represents the___. a. average unlatching time in seconds b. current in amperes c. interrupting time in milliseconds d. time in seconds
d. time in seconds
Size the overcurrent protective device needed to feed one 25-horsepower, 480-volt, 3-phase motor-compressor with a rated load current of 42 amperes and a branch-circuit selection current of 45 amperes when starting current is not a problem.
70 ampere OCPD
Branch-circuit conductors supplying a single motor compressor shall have an ampacity not less than 125% of either the motor-compressor rated load current or the branch-circuit selection current, whichever is greater. For a wye-start, delta-run connected motor-compressor, the selection of branch-circuit conductors between the controller and the motor-compressor shall be permitted to be based upon ___ of either the motor-compressor rated-load current or the branch-circuit selection current, whichever is greater. a. 72% b. 115% c. 125% d. 225% NEC reference??
a. 72% NEC: 440.32
T/F Article 110.15 requires legible field marking of equipment enclosures for circuit breakers or fuses applied in compliance with series combination ratings in accordance with 240.86(A) and (B).
True
T/F For a motor branch circuit where the motor is within 50 feet and within sight of the branch-circuit disconnect, branch-circuit fuses (if properly sized) in conjunction with a UL 98 disconnect can be suitable for these four functions: motor branch-circuit disconnect, motor branch-circuit short-circuit and ground-fault protection, motor controller, and within sight motor disconnect.
True
T/F For the purposes of the application of Table 450.3(A), a "supervised location" is a location where conditions of maintenance and supervision ensure that only qualified persons monitor and service the transformer installation.
True
T/F Fuses can be selectively coordinated for all levels of overcurrents by following the fuse manufacturer's selective coordination ratios.
True
T/F If a series rated fuse-circuit breaker combination indicates a maximum 400-ampere Class J fuse is required, any manufacturer's fuse that is listed as UL Class J with 400 amperes or less can be used
True
T/F If a system is not selectively coordinated, unnecessary power loss can occur to loads that otherwise should be unaffected.
True
T/F Molded case circuit breakers (MCCBs) are the most prevalent circuit breakers in use for 15 amperes to 2,500 amperes.
True
The full-load current for a 7 1/2-hp induction-type squirrel cage motor which operates at 3-phase, 208 volts is ____ . a. 22.0 A b. 24.2 A c. 25.3 A d. 30.2 A NEC reference??
b. 24.2 A NEC: 430.23(C)
Part ? of Article 430 covers the requirements for the motor disconnecting means. Select one: a. IV b. VII c. IX d. XI
c. IX
What section of Article 450 details the basic ampere rating sizing requirements for overcurrent protection of transformers? Select one: a. 450.1 b. 450.3 c. 450.4 d. Table 450.3(B)
b. 450.3
How can a 600-volt or less branch-circuit OCPD be identified as being current limiting? a. Ask the manufacturer. b. Read the data sheet. c. The circuit breaker or fuse will be marked "current-limiting". d. There are no 600-volt current-limiting branch circuit OCPDs
c. The circuit breaker or fuse will be marked "current-limiting".
MCPs are recognized devices (not listed) and are permitted by _____ to provide motor branch-circuit short-circuit and ground-fault protection, if used as part of a listed combination with a starter. a. 430.32 b. 430.52(C)(1) c. 430.52(C)(3) d. 430.53
c. 430.52(C)(3)
The minimum size copper THW conductor for branch-circuit conductors that supply a 10-horsepower, 230-volt, single-phase, alternating-current motor is ___ . The terminals are rated at 75°C. a. 1/0 AWG b. 2 AWG c. 4 AWG d. 6 AWG NEC reference??
d. 6 AWG NEC: 430.22
Which of the following are included in what must be marked on a motor controller? a. Horsepower or current rating b. Manufacturer's name c. Short-circuit current rating d. Voltage rating e. All of the above NEC:
e. All of the above NEC: 430.8
Overcurrent protection for motor circuits are segmented into which of the following parts? a. Motor branch-circuit short-circuit and ground-fault protection b. Motor current conditioning for harmonics filtering c. Motor overload protection d. Motor speed overdrive protection e. Both a. and c.
e. Both a. and c.
T/F Circuit breakers with short-time delay and no instantaneous trip can be bought with an arc flash reduction maintenance switch which helps mitigate the arc flash incident energy for occasions such as when an Electrical Worker must perform diagnostics on energized equipment
True
T/F Electrical equipment is required to be adequately protected against short-circuit current conditions per NEC 110.10 and several other complementary NEC requirements. OSHA requires equipment short-circuit current protection in 1910.303(B)(viii)(5)
True
T/F Listed or labeled equipment must be installed and used in accordance with any instructions included in the listing or labeling.
True
T/F A motor is located 100 feet from the motor control center that provides the motor branch-circuit disconnect. An instantaneous-trip circuit breaker can be used for this application as long as it is within sight of the motor and the motor disconnect.
False
T/F A motor switch listed to UL 508 can be used as the motor branch-circuit disconnect
False
T/F Devices are permitted to only perform one motor circuit function.
False
T/F It is permitted to install equipment if its SCCR is not equal to or greater than the available short-circuit current.
False
Motor starters tested to ? short-circuit protection provide "no damage" protection. a. Type 1 b. Type 2 c. Type 3 d. any of the above
b. Type 2
Molded case circuit breakers, insulated case circuit breakers, and low voltage power circuit breakers are ____ . a. application-limited OCPDs which are suitable for specific branch circuit applications, under limited conditions per the NEC b. branch circuit overcurrent protective devices c. supplementary OCPDs
b. branch circuit overcurrent protective devices
The horizontal axis of a time-current curve represents the ___ . a. average unlatching time in seconds b. current in amperes c. interrupting time in milliseconds d. time in seconds
b. current in amperes
A ___ protective device is one that clears a fault current in one-half cycle or less and reduces the amount of short-circuit current let-through. a. branch circuit b. current-limiting c. motor circuit d. surge
b. current-limiting
Because of the ____ impedance path, a 3-phase bolted fault condition is typically assumed to be the highest level of fault current. a. high b. low c. reactive d. resistive
b. low
The minimum ampacity for branch-circuit conductors, which supply a 75-horsepower, 3-phase, induction-type squirrel cage motor which operates at 460 volts, is ____ . a. 77 A b. 96 A c. 120 A d. 192 A
c. 120 A
The minimum ampacity rating and size of the copper, THW branch-circuit conductors for a 3-phase, 125-horsepower, 460-volt squirrel cage induction motor is ___ and a ____conductor. The terminals are rated 75°C a. 125 A / 1/0 AWG b. 156 A / 2/0 AWG c. 195 A / 3/0 AWG d. 210 A / 4/0 AWG NEC reference??
c. 195 A / 3/0 AWG NEC: 310.15(B)
Identify the NEC section where the following provision is located: A circuit breaker is used on a circuit having an available fault current higher than its marked interrupting rating by being connected on the load side of an acceptable overcurrent protective device having a higher rating. In this section the circuit breaker shall meet the requirements specified in (A) or (B), and (C). a. 240.40 b. 240.41 c. 240.86 d. 240.87
c. 240.86
For a 7% impedance transformer over 1,000 volts, without coordinated thermal overload protection, in a supervised location, a primary fuse could be sized up to __ , or the next commercially available ampere rating without secondary protection. Select one: a. 115% b. 125% c. 250% d. 500%
c. 250%
If the industrial control panel is to be marked with its SCCR, then ? requires the available short-circuit current to be determined. This calculation and the date it was performed must be made available to the inspector or the Authority Having Jurisdiction (AHJ). a. 409.1 b. 409.22(A) c. 409.22(B) d. 409.110
c. 409.22(B)
A horsepower-rated switch or circuit breaker is permitted as both the motor controller and disconnecting means in accordance with NEC ? . Select one: a. 430.102(A) b. 430.109 c. 430.111 d. 430.225
c. 430.111
A 600-volt or less transformer equipped with coordinated thermal overload protection by the manufacturer and arranged to interrupt the primary current shall be permitted to have primary overcurrent protection rated or set at a current value that is not more than ____ times the rated current of the transformer for transformers having not more than 6% impedance and not more than ____ times the rated current of the transformer for transformers having more than 6% but not more than 10% impedance. Select one: a. 4 / 6 b. 4 / 10 c. 6 / 4 d. 6 / 10
c. 6 / 4
An emergency system overcurrent protective device is required to be selectively coordinated with all supply side overcurrent protective devices per NEC Section ___ of Article 700 Emergency Systems. a. 700.3 b. 700.10 c. 700.15 d. 700.32
d. 700.32
Which fuse type is not a branch circuit OCPD? a. UL Class J b. UL Class L c. UL Class R d. UL recognized high speed fuse
d. UL recognized high speed fuse
Determine the maximum overload protection trip or rating for a 3-phase, 75-horsepower, 240-volt squirrel cage motor with a nameplate current of 188 amperes, a temperature rise of 40°C, and a marked service factor of 1.15 when starting current is not a problem.
235 ampere overload trip or rating
T/F A fully loaded 3-phase motor protected by three properly-sized overload protective devices will be protected against single-phasing.
True
T/F A fully rated system is one in which all of the overcurrent protective devices have an individual interrupting rating at least as great as the available short-circuit current at their point of application.
True
T/F A motor branch-circuit disconnect listed to UL 98 or UL 489 can be used as a within sight of the motor disconnect.
True
T/F A transformer supplying a fire pump is not permitted to have secondary overcurrent protection.
True
T/F An Electrical Worker is dispatched on a service call to a high volume, continuous process company where its process is down and costing $100,000 per hour. Troubleshooting uncovers a 50-ampere branch-circuit circuit breaker that opened due to a short-circuit condition. By itself, losing the circuit protected by the 50-ampere circuit breaker would not have caused the process to be stopped. However, a 200-ampere feeder circuit breaker supplying the 50-ampere circuit breaker also opened, which resulted in the entire process shutting down. In all probability, this unnecessary outage to the process line was a result of a lack of selectively coordinated OCPDs.
True
T/F Each motor used in a continuous-duty application and rated more than one horsepower is required to be protected against overload. A separate overload device that is responsive to motor current is one of four options permitted to protect against overload.
True
T/F If an equipment SCCR is conditional on a specific type of OCPD and ampere rating, be sure to field install that specific OCPD and ampere rating in the supply circuit to the equipment.
True
Determine the maximum rating of time-delay fuses needed for a 3-phase, 75-horsepower, 240-volt squirrel cage motor with a nameplate current of 188 amperes, a temperature rise of 40°C, and a marked service factor of 1.15 when starting current is not a problem. Assume the motor will start with this selection.
350 ampere time delay fuse
Size the copper THW conductors needed to feed one 25-horsepower, 480-volt, 3-phase motor-compressor with a rated load current of 42 amperes and a branch-circuit selection current of 45 amperes when starting current is not a problem. The terminals are rated 75°C.
6 AWG THW copper conductors
A series rated system cannot be used where motors are connected on the load side of the higher-rated overcurrent device and on the line side of the lower-rated overcurrent device and the sum of the motor full-load currents exceeds ____ of the interrupting rating of the lower-rated circuit breaker. a. 1% b. 3% c. 6% d. 7% NECC?
a. 1% NEC: 240.86(C)
Determine the maximum standard size rating of the motor branch-circuit short-circuit and ground-fault protective device for a 5-horsepower, 208-volt, 3-phase, squirrel cage induction motor using dual element fuses when starting current of the motor is not an issue. a. 30 A b. 45 A c. 50 A d. 60 A NEC reference??
a. 30 A NEC: 240.6(A)
NEC ____ covers the requirements for the location of the motor controller disconnecting means. Select one: a. 430.102(A) b. 430.109 c. 430.111 d. 430.225
a. 430.102(A)
Motor branch-circuit short-circuit and ground-fault protection and motor overload protection shall be permitted to be combined in a single protective device where the rating or setting of the device provides the overload protection specified in 430.32. a. True b. False NEC reference??
a. True NEC: 430.55
Installing electrical equipment where its SCCR is less than the available short-circuit current creates serious safety hazards which does not include ___ . a. explosive dust b. fire c. projectiles d. shock
a. explosive dust
Fuses and circuit breakers are intended to protect conductors and equipment from the effects of potentially harmful _____. a. overcurrents b. overvoltages c. both a. and b.
a. overcurrents
NEC ___covers interrupting rating requirements for equipment. a. 110.3 b. 110.9 c. 110.21 d. 110.27
b. 110.9
A 3-phase, 750-kVA, 5.75% impedance transformer in an unsupervised location, with a primary voltage of 4,160 volts and secondary voltage of 480 volts, would have a secondary circuit breaker sized at a maximum of ___ . Select one: a. 800 A b. 1200 A c. 1500 A d. 1800 A
b. 1200 A
A 3-phase, 750-kVA, 5.75% impedance transformer in an unsupervised location, with a primary voltage of 4,160 volts and secondary voltage of 480 volts, could have on the transformer primary a maximum fuse size amp rating of ___ for the primary OCPD. Select one: a. 200 A b. 350 A c. 400 A d. 600 A
b. 350 A
_____ makes it clear that an industrial control panel cannot be installed when its marked short-circuit current rating is less than the available short-circuit current. a. 409.1 b. 409.22(A) c. 409.22(B) d. 409.110
b. 409.22(A)
The type of motor disconnecting means is covered by NEC ? . Select one: a. 430.102(A) b. 430.109 c. 430.111 d. 430.225
b. 430.109
Which NEC article applies to electric motor-driven air-conditioning and refrigerating equipment and to the branch circuits and controllers for such equipment? Select one: a. 430 b. 440 c. 445 d. 450
b. 440
For a part-winding connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125% of the motor full-load current as determined by 430.6(A)(1). The ampacity of the conductors between the controller and the motor shall not be less than___ of the motor full-load current rating as determined by 430.6(A)(1). a. 50% b. 62.5% c. 72% d. 125% NEC reference??
b. 62.5% NEC: 430.22(D)
The NEC defines ____ as "localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the selection and installation of overcurrent protective devices and their ratings or settings for the full range of available overcurrents, from overload to the maximum available fault current, and for the full range of overcurrent protective device opening times associated with those overcurrents." a. Circuit Breaker b. Coordination, Selective c. Interrupting Rating d. Overcurrent Protective Device
b. Coordination, Selective
Which of the following characteristics of motor branch circuits make them unique branch circuits? I. Circuit components such as starters, overload heaters, and contactors which have low short-circuit current withstands or SCCRs II. Combination of higher probability to incur faults III. The desire for various levels of functionality, such as remote push button control and automatic control IV. The harsh demand of motor loads, such as inrush and locked rotor currents V. The multitude of potential devices used in motor circuits a. I. and II. only b. I., II., III., IV., and V. c. I., III., and V. only d. II., III., and IV. only
b. I., II., III., IV., and V.
T/F 670.5(1) permits industrial control panels to be installed if the equipment's nameplate SCCR is less than the available short-circuit current.
False
T/F A 600-volt AC fuse or circuit breaker is considered to have a 600-volt DC rating, even if it is not marked with a DC voltage rating.
False
T/F Per Article 240, the standard ampere ratings of fuses and circuit breakers must be used in an electrical distribution center.
False
T/F Selective coordination is achieved when OCPDs are chosen such that whenever an overcurrent occurs, not only does the nearest lineside OCPD open to interrupt the overcurrent, one or more upstream larger ampere rated OCPDs open
False
T/F The maximum rating or setting of overcurrent protection for transformers under 1,000 volts per 450.3 is different for circuit breakers versus fuses.
False
Which of the following statements is not correct per Article 100 definition? a. Branch-circuit overcurrent protective devices are capable of being able to provide a full range of overcurrent protection from rated current to its interrupting rating. b. Branch-circuit overcurrent protective devices are intended for protection of a service, feeder or branch circuit of an electrical system. c. Branch-circuit overcurrent protective devices must be listed in combination with the specific device it is intended to protect. d. Branch-circuit overcurrent protective devices must have interrupting rating sufficient for the application, but not less than 5 kA.
c. Branch-circuit overcurrent protective devices must be listed in combination with the specific device it is intended to protect.
The motor-compressor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor. A protective device having a rating or setting not exceeding 175% of the motor-compressor rated load current or branch-circuit selection current, whichever is greater, shall be permitted, provided that, where the protection specified is not sufficient for the starting current of the motor, the rating or setting shall be permitted to be increased, but shall not exceed ___ of the motor rated-load current or branch-circuit selection current, whichever is greater. a. 72% b. 115% c. 125% d. 225% NEC reference??
d. 225% Nec: 440.22(A)
For industrial control panels, section ____ requires the panel builder to be marked with the SCCR on the equipment. a. 409.1 b. 409.22(A) c. 409.22(B) d. 409.110
d. 409.110
The requirements for motor-circuit overcurrent protection for motors over 1,000 volts are covered in what section of Article 430? Select one: a. 430.102(A) b. 430.109 c. 430.111 d. 430.225
d. 430.225
____ requires a motor control center (MCC) to be marked with its short-circuit current rating. a. 110.9 b. 110.10 c. 430.8 d. 430.98
d. 430.98
_____requires calculating the available short-circuit current where an MCC is to be installed and making the documentation of the calculation available to the Authority Having Jurisdiction. a. 110.9 b. 430.8 c. 430.98 d. 430.99
d. 430.99
Which statement about supplementary protectors is not correct? a. Cannot be used in place of branch-circuit protection b. Intended where branch-circuit protection not required c. Recognized to UL 1077 d. Suitable for branch-circuit protection
d. Suitable for branch-circuit protection
When selected under engineering supervision in existing installations, the series rated combination devices shall be selected by a(n) ____ engaged primarily in the design or maintenance of electrical installations. a. electrical contractor b. electrical engineer c. engineer d. licensed professional engineer NEC:
d. licensed professional engineer NEC: 240.86 (A)
The NEC selective coordination requirements notably are for systems or circuits in which the loads are vital for ___ . a. keeping continuous processing industrial plants operating b. life safety c. public safety d. a. and b. e. b. and c.
e. b. and c.
Magnetic motor starters listed to UL 508 are suitable for use _____ . a. as motor branch-circuit and controller disconnect b. as motor controller c. as motor overload protection d. at the motor or in sight from the motor disconnect e. both b. and c.
e. both b. and c.
T/F For a fuse to selectively coordinate with an upstream fuse of a larger ampere rating, the upstream fuse must clear before the downstream fuse melts
false
T/F If selective coordination of a system is required or important, it is not important to select the appropriate types of OCPDs and ampere ratings/settings in the design phase; it can easily be dealt with in the installation phase
false
T/F A component, such as a power distribution block, can have a marked high short-circuit current rating (greater than 10,000 amperes) when protected by marked specific type and ampere rating overcurrent protective devices
true
T/F Only fully rated systems may be able to be selectively coordinated.
true
Determine the branch-circuit conductor size (copper, THW) needed for a 3-phase, 75-horsepower, 240-volt squirrel cage motor with a nameplate current of 188 amperes, a temperature rise of 40°C, and a marked service factor of 1.15 when starting current is not a problem. The terminals are rated 75°C.
250 kcmil conductors
T/F The motor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor. NEC reference??
True NEC: 430.52
Overload protection for continuous-duty motors one horsepower or less, automatically started, is covered by NEC ? . Select one: a. 430.6(A)(1) b. 430.22(C) c. 430.32(B) d. 430.52(C)(1)
c. 430.32(B)
Article 450 covers the installation of transformers dedicated to supplying power to a fire pump installation as modified by Article ___ . a. 518 b. 695 c. 760 d. 770 NEC reference???
b. 695 NEC: 450.1
Part ? of Article 430 covers the requirements for motor controllers. Select one: a. IV b. VII c. IX d. XI
b. VII
Short-circuit current _____ the normal conducting path. a. flows in the reverse direction as overload current in b. flows outside c. is entirely confined to
b. flows outside
T/F Selective coordination is easily achievable with a series rated system.
false
T/F Primary inrush current characteristics can vary by transformer design.
True
T/F Series rated systems can cause problems or limitations with future expansions, upgrades, or system integrity.
true
T/F All fully rated systems are selectively coordinated.
False
T/F A Class H fuse (10 kA IR) can be series rated with a lineside Class R fuse (200 kA IR or more)
False
T/F A disconnecting means "in sight from the motor" is used for insulating the motor circuit for maintenance and serves as an emergency disconnecting means.
False
T/F A larger ampere rated OCPD feeding a lower ampere rated OCPD ensures that a circuit is selectively coordinated. For an example, if a 100-ampere feeder circuit breaker supplies a 20-ampere branch-circuit circuit breaker, selective coordination is achieved.
False
T/F A mini-circuit breaker (UL 1077 supplemental protector) or supplemental fuses are suitable for use as motor branch-circuit short-circuit and ground-fault protection.
False
T/F Adequate OCPD interrupting rating ensures load-side electrical equipment will be provided with adequate short-circuit current protection.
False
T/F Adequate equipment SCCR ensures low arc flash risk assessment levels
False
T/F Branch circuit fuses do not have to be marked with their ampere rating.
False
T/F For motor branch circuit applications, the motor branch circuit short-circuit and ground fault protective device can be located anywhere on the motor branch circuit since short-circuit currents stay within the normal conducting path.
False
T/F If an industrial control panel has a short-circuit current rating less than the calculated available short-circuit current at the point of installation, it is safe and permitted to install the panel at that point.
False
T/F NEC 240.10 permits a supplementary fuse to be used where a branch circuit OCPD is required.
False
T/F Once the OCPDs are installed per a selective coordination design, there is no concern that the Electrical Worker can unwittingly make an adjustment to a circuit breaker setting that adversely affects the circuit's selective coordination.
False
T/F The voltage rating of the OCPD must be equal to but never greater than the circuit voltage.
False
T/F 700.5(E) requires the SCCR for emergency system transfer equipment to be field marked on the equipment's exterior.
True
T/F Each class of current-limiting fuse has its own unique physical dimensions so that fuses of a different class are not interchangeable. For instance, Class R fuses cannot be installed in Class J fuse equipment.
True
T/F Motor controllers serve as the motor ON/OFF function.
True
T/F Normally, the builder of electrical equipment marks the SCCR on their equipment. Their means to determine the SCCR may be short-circuit current testing, analysis method, or device default SCCRs.
True
T/F Overcurrent protective devices on transformer primary may require increased sizing due to the magnetizing inrush current.
True
T/F Overload current is confined to the normal conductive path provided by the conductors, circuit devices, and loads of the distribution system.
True
T/F Table 450.3(A) provides provisions for both "any location" and "supervised locations only."
True
T/F The SCCR for a circuit breaker panelboard is dependent on the interrupting ratings of the circuit breakers installed in the panelboard and where the circuit breakers are part of a series combination rating scheme.
True
T/F The two tables of concern for transformer protection are Table 450.3(A) for transformers over 1,000 volts, nominal and Table 450.3(B) for transformers 1,000 volts or less.
True
T/F There are many requirements or limitations to series rated systems, but only one advantage: lower installed cost.
True
T/F When the conductor ampacity does not correspond to a standard OCPD ampere rating, the next standard OCPD ampere rating is permitted if that rating does not exceed 800 amperes, and if the conductors are not supplying a circuit with more than one receptacle for cord-and-plug portable loads
True
Where the value for a branch-circuit short-circuit and ground-fault protective device determined by Table 430.52 for a dual-element fuse or inverse time circuit breaker does not correspond to a standard ampere rating, a __ ampere rating or setting that does not exceed the next higher standard ampere rating shall be permitted. a. higher b. lower NEC reference??
a. higher NEC:430.52(C)(1) Exception No. 1
For a transformer 1,000 volts or less, with secondary current of 5 amperes, the secondary overcurrent protective device could be sized up to ? of the transformer-rated current where both primary and secondary protection is provided. a. 125% b. 167% c. 250% d. 300% NEC reference??
b. 167% NEC: Table 450.3(B)
_____ , with a few exceptions, requires that air conditioning and refrigeration, multi-motor, and combination-load equipment be marked with its SCCR. a. 110.10 b. 440.4(B) c. 440.10(A) d. 440.10(B)
b. 440.4(B)
A separate motor overload device for a continuous-duty motor more than one horsepower with a 1.15 service factor must be selected to trip or be rated at no more than ___ of the motor nameplate full-load current rating. Assume the motor starts and runs continuously without nuisance tripping for this selection. a. 50% b. 72% c. 115% d. 125%
d. 125%
Conductors that supply a single motor used in a continuous-duty application shall have an ampacity of not less than _____ of the motor full-load current rating, as determined by 430.6(A)(1), or not less than specified in 430.22(A) through (G). a. 50% b. 62.5% c. 72% d. 125% NEC reference???
d. 125% NEC reference: 430.22
The maximum size for an overcurrent protective device for a motor control circuit transformer with a primary current of less than two amperes is not more than __ . a. 115% b. 125% c. 250% d. 500% NEC reference??
d. 500% NEC: 430.72(C)(4)
A series rated system consists of a ___ that can be applied at short-circuit current above the interrupting rating of the load-side circuit breaker, but not above that of the main or line-side device. a. circuit breaker and a circuit breaker b. fuse and a circuit breaker c. fuse and a fuse d. a. or b. e. a. or c
d. a or b
For calculated applications selected under engineering supervision in existing installations, the series rated combination devices must be engineered to ensure that the downstream circuit breaker(s) that are part of the series combination remain ____during the interruption period of the line-side fully rated, current-limiting device. a. active b. calibrated c. intact d. passive NEC??
d. passive NEC: 240.86 (A)
What NEC section limits the use of slash voltage rated circuit breakers for solidly grounded wye systems only where the line-to-ground voltage does not exceed the lower of the two values and the line-to-line voltage does not exceed the higher value? a. 240.4 b. 240.67 c. 240.85 d. There is no such NEC requirement.
c. 240.85
Determine the maximum rating of the motor branch-circuit short-circuit and ground-fault protective device, when starting current is a problem for a 3-horsepower, 230-volt, single-phase, capacitor motor using time-delay fuses. a. 30 A b. 35 A c. 40 A d. 50 A NEC reference??
b. 35 A NEC: 240.6(A)
____ requires the equipment shall not be installed if its SCCR is not equal to or greater than the available short-circuit current. a. 110.10 b. 440.4.(B) c. 440.10(A) d. 440.10(B)
c. 440.10(A)
Identify the NEC reference that stipulates that selective coordination is required for multiple elevator circuits fed from a single feeder. a. 620.3 b. 620.21 c. 620.62 d. 700.32
c. 620.62
For a wye-start, delta-run connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125% of the motor full-load current as determined by 430.6(A)(1). The ampacity of the conductors between the controller and the motor shall not be less than ____ of the motor full-load current rating as determined by 430.6(A)(1). a. 50% b. 62.5% c. 72% d. 125% NEC reference??
c. 72% NEC reference: 430.22(C)
Each motor used in a continuous-duty application and rated more than one horsepower is required to be protected against overload. Which of the following are permitted to protect such motors from overload? Select one: a. A thermal protector integral with the motor, approved for use with the motor it protects on the basis that it will prevent dangerous overheating of the motor due to overload and failure to start b. A protective device integral with a motor that will protect the motor against damage due to failure to start if the motor is part of an approved assembly that does not normally subject the motor to overloads c. Either a. or b. d. Neither a. nor b.
c. Either a. or b.
A transformer utilizing primary and secondary protection with a primary current of 100 amperes at 480 volts, and secondary current of 200 amperes at 240 volts, would have the overcurrent primary overcurrent protection sized at a maximum of ____ and secondary protection sized at a maximum of _____ . a. 125 A / 125 A b. 125 A / 250 A c. 250 A / 125 A d. 250 A / 250 A NEC reference??
d. 250 A / 250 A NEC: Table 450.3(B)
A 20-ampere circuit breaker with an interrupting rating of 10,000 amperes can be applied at a fault current of 65,000 amperes only if it is series rated in combination with a lineside fuse or circuit breaker that has a series combination rating with the 20-ampere circuit breaker of _______ or greater. a. 10,000 A b. 35,000 A c. 42,000 A d. 65,000 A
d. 65,000 A
A 3-phase, 750-kVA, 5.75% impedance transformer in an unsupervised location, with a primary voltage of 4,160 volts and secondary voltage of 480 volts, could have a primary circuit breaker sized at a maximum of ___ . Select one: a. 130 A b. 400 A c. 500 A d. 700 A
d. 700 A
