229
The minimum size of transformer vault ventilation openings for transformers rated less than 50 kVA is ___ sq. ft.
1
For AC adjustable voltage, variable torque drive motors, the ampacity of conductors, or ampere ratings of switches, circuit breakers, or fuses, and ground-fault protection shall be based on the operating current marked on the nameplate. If the current does not appear on the nameplate, the ampacity determination shall be based on ___ of the values given in tables 430.249 and 430.250.
150%
In a battery rack, what is the minimum clearance between a cell container and any wall or any structure on the side not requiring access for maintenance?
1″
Where a transformer vault is located on the 2nd floor of a high-rise building, the minimum height of an oil-confining sill below the door into the vault is ___ inch(es).
4
Live parts of generators operated at more than ___ volts to ground shall not be exposed to accidental contact where accessible to unqualified persons.
50
The total rating of a plug-connected room air conditioner where lighting units or other appliances are also supplied shall not exceed ___ percent.
50
The locked-rotor current of a 75 hp, 460-volt, three-phase, Design B motor is ___ amps.
543
A motor control circuit ___.I. carries electric signals to the controller and carries the main powerII. does not carry electric signals to the controller but does carry the main powerIII. carries the electric signals to the controller but does not carry main power
III only
Which of the following provides clearance requirements from walls for proper ventilation of transformer enclosures?
Manufacturer's nameplate
Where wires pass through an opening in an enclosure, conduit box, or barrier, ___ shall be used to protect the conductors from the edges of an opening having sharp edges within generators.
a bushing
Instantaneous-trip circuit breakers can be installed ___.
as a part of listed combination with a motor controller
Motor controllers must be marked with ___.I. maximum rated voltage II. maximum hp or current rating
both I & II
What is the basic unit characterized by an anode and a cathode used to receive, store and deliver electrical energy?
cell
Transformers with ventilating openings shall be installed so that the ventilating openings are not blocked by walls or other obstructions. The required clearances shall be ___.
clearly marked on the transformer
Any motor application shall be considered at ___ unless the nature of the apparatus it drives is such that the motor will not operate continuously with load under any condition of use.
continuous duty
Generators shall be equipped with a ___ by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator.
disconnect
The value of branch-circuit selection current will always be ___ the marked rated-load current.
equal to or greater than
All 125-volt, single-phase, 15- and 20-ampere receptacle outlets that are a part of a 15-kW or smaller portable generator shall ___. This generator does not have a 125/250-volt locking-type receptacle.
have integral GFCI protection
A(n) ___ refrigerant motor-compressor is a combination compressor and motor in the same housing, having no external shaft or shaft seals, with the motor operating in the refrigerant.
hermetic
Batteries are permitted to be located where ___?
in rooms with sufficient diffusion and ventilation of gases from the battery
An individual disconnecting means shall be provided for each controller and shall disconnect the controller. The disconnecting means shall be located ___ the controller location.
in sight from
Which one of the devices listed is NOT permitted to be used to provide branch-circuit and short-circuit protection for motors?
knife switch
The requirement for generators is that they shall be of a type suitable for the ___ in which they are installed.
location
NEC® 430.102 requires that a ___ have a disconnecting means and that it be in sight.
motor motor's controller
The secondary circuits of wound-rotor ac motors, including conductors, controllers, resistors, and so forth, shall be permitted to be protected against overload by the ___.
motor-overload device
A motor is installed as part of a factory-wired piece of equipment. It is required to be grounded, and no additional connections are required at the motor terminal housing during the equipment installation. A separate means for motor grounding at the motor terminal housing shall ___.
not be required
Which of the following is not required on a motor nameplate?
watts
Individual dry-type transformers rated over 112.5 kVA shall be enclosed in a fire-resistant room with materials having a ___-hour minimum fire rating.
1
Individual dry-type transformers rated over 1121/2 kVA shall be enclosed in a fire-resistant room with materials having a ___-hour minimum fire rating.
1
The minimum size conductors needed to connect a three-phase generator to a fused disconnect switch are ___ AWG. The generator is rated for 90 KVA at 480 volts.
1
For a stationary motor rated at ___ hp or less that is normally left running and is constructed so that it cannot be damaged by overload or failure to start, such as clock motors and the like, the branch-circuit disconnecting means shall be permitted to serve as the controller.
1/8
When motors are ___ hp or greater, the motor nameplate shall include the rated horsepower.
1/8
Where the design and operation of the generator prevent overloading, the ampacity of the conductors shall not be less than ___ percent of the nameplate current rating of the generator.
100
The ampacity of conductors from the generator to the first distribution device(s) containing overcurrent protection shall not be less than ___ percent of the nameplate current rating of the generator.
115
The disconnecting means of a hermetic-type refrigerator compressor shall have an ampacity of at least ___ of the nameplate rated-load current.
115%
A 45 KVA, 480 to 208Y/120-volt dry-type transformer is suspended below the ceiling of an equipment room where the ceiling is plywood attached to wood joists. The general rule is that the minimum clearance from the transformer to the ceiling is ___ inch(es).
12
A toggle switch (standard AC only "light" switch) can be used as the controller (ON/OFF switch) for a stationary motor rated at 2 hp or less and 300 volts or less as long as the switch has an ampere rating that is at least ___ % of the motor ampere rating.Note: the NEC® considers a toggle switch to be a general-use snap switch. See the definition in Article 100.
125
Branch-circuit conductors supplying more than one motor shall have an ampacity of at least ___ percent of the FLC of the largest motor, plus 100% of the FLC of the other motor(s) in the group.
125
Continuous duty motors with a marked service factor not less than 1.15 shall have the minimum running overload protection sized at ___ percent of the nameplate rating of the motor.
125
Where secondary protection is not required, the general rule for transformers rated 600 V, nominal, or less is to protect the primary windings at not more than ___% of the rated primary current.
125
To provide protection for small air conditioner motor-compressors without the locked-rotor current marked on the nameplate, fused protection at ___ can be utilized.
125% of the rated current
Alternating current, general-use snap switches are UL-listed to control motors rated up to ___ horsepower.
2
Several motors, each not exceeding 1 horsepower in rating, shall be permitted on a nominal 120-volt branch circuit protected at not over ___ amperes.
20
When sizing fuses for a branch circuit serving a hermetic refrigerant motor-compressor, the device shall NEVER exceed ___ percent of the rated-load current marked on the nameplate of the equipment.
225
A liquid-filled transformer has a primary voltage of 12,470 volts. The transformer is surrounded by a 6-foot-high fence. The overall height of the fence must be extended 1 foot with at least ___ strands of barbed wire on top of the fence.
3
Disregarding exceptions, what is the minimum number of overload units required by the NEC® to protect a 3-phase motor?
3
Where a transformer vault is located on the 2nd floor of a high-rise building, the minimum fire rating of the door into the vault is ___ hour(s).
3
Where a transformer vault is not protected by an automatic fire suppression system, the minimum fire rating for the roof is ___ hour(s).
3
Open-type transformers are permitted to be installed in a ___. One of these transformers is shown at the right.I. stainless steel control cabinetII. fiberglass combination starter enclosureIII. sheetrock-covered furdown (soffit)
I or II only
When a flexible cord is used to supply a 240-volt room air conditioner, the length of such cord shall not exceed ___.
6 feet
50
Refer to the nameplate shown in Figure 233.133. The largest circuit breaker you could install is ___ A.
A code letter D is marked on a motor nameplate. What is its locked-rotor kVA per horsepower?
4.0 - 4.49
When a cord-connected window (room) air conditioner is the only connected load, the current drawn by the unit shall not exceed ___% of the branch circuit rating.
80
A fused safety switch feeds a 480 to 208Y/120-volt, 3Ø, 30 KVA transformer. The transformer supplies power to a 3Ø 100-amp main breaker panelboard. According to NEC® 450.3, the fuses in the safety switch are permitted to be not larger than ___ amps so that the transformer is adequately protected against overload.
90
Neither I nor II
Refer to Figure 232.103. ___ could be used as a disconnecting means for a 5 horsepower, 240-volt, single-phase motor.
20
Refer to the nameplate and information shown in Figure 230.131. The minimum hp rating of any manufacturer's safety switch must be ___ hp at the applied voltage.
70
Refer to the nameplate shown in Figure 233.134. The largest fuse you could install in a fused safety switch is ___ A.
The current from ___ is used to determine the branch circuit conductor size for a 1Ø motor.
T.430.248
In general, a motor disconnecting means must disconnect ___.
both the motor and controller
For a nonautomatically started motor, the overload protection shall be permitted to be shunted or cut out of the circuit during the starting period of the motor if the device by which the overload protection is shunted or cut out cannot be left in the starting position and if fuses or inverse time circuit breakers rated or set at not over ___ percent of the full-load current of the motor are located in the circuit so as to be operative during the starting period of the motor.
400
Conductors for a motor used in a short-time, intermittent, periodic, or varying duty application shall have an ampacity of not less than the percentages of the motor nameplate current ratings shown in Table ___.
430.22(E)
Generator overcurrent protection is covered in NEC® Section ___.
445.12
A disconnecting means shall be provided for all ungrounded conductors derived from a stationary battery system with a voltage over ___ volts dc.
60
The minimum size conductors permitted to be run between a generator and a fused safety switch are ___ AWG or kcmil. The 3Ø, 300 KVA generator delivers 480 volts.
600
Control circuit devices in a motor control starter with screw-type pressure terminals used with 14 AWG copper conductors shall be torqued to a minimum of ___ lb-in. unless identified for a different torque value.
7
The maximum size circuit breaker permitted by Note 1, to NEC® Table 450.3(A), to protect the primary of a 4160 to 480-V, 3Ø, 75 KVA transformer is ___ amps. The transformer has an impedance of 1.7% and is installed in a nonsupervised location.
70
The minimum clearance from the bottom of a 240-V pole-mounted transformer to the ground is ___ feet.
8
___ shall be placed in all service-entrance motor control centers to isolate service busbars and terminals from the remainder of the motor control center.
Barriers
Askarel-insulated transformers are permitted to be installed outdoors only.
False
6
Refer to the nameplate shown in Figure 233.134. The smallest wire you could use for the circuit conductors is ___ AWG.
4
Refer to the nameplate shown in Figure 233.135. The smallest wire you could use for the circuit conductors is ___ AWG.
