IEC year 2 final review
Refer to the information shown in Figure 234.151. When the tap for Motor 1 terminates in a breaker enclosure, the maximum permitted size for an ITCB in this enclosure would be ____ A.
70
A three-phase, 240-volt feeder is going to supply power to one 5 hp 3Ø motor, three 2 hp 3Ø motors, and two 1 hp 3Ø motors. The minimum size conductors permitted for this feeder are ___ AWG.
8
Refer to the nameplate shown in Figure 230.122. The branch circuit for the motor is supplied from a 240/120-volt, 3Ø, 4-wire panelboard. What is the minimum size (3 wire + ground) SO cord that could be used as a flexible connection for the motor?
8
The smallest copper service-drop conductors that can be installed for a service are ___.
8
Which of the following could be used in a concrete slab?
any of these
Apparent power is measured in ___.
volt-amps
Reactive power is measured in ___.
volt-amps reactive
In a 60 Hz circuit, containing a 1.3 mh inductor, the inductive reactance is ___ ohms.
.49
Generator overcurrent protection is covered in NEC ® Section ___.
445.12
The NEC ® permits the attachment cord and plug that is attached to an air compressor to be used as the disconnecting means. How does Section 110.22 require that this disconnecting means be identified?
Its purpose is obvious and not required to be marked.
___ power is power that passes through reactive components, which do not consume energy, and returns to the source.
Reactive
Refer to Figure 221.201. The transformer bank has a ___-connected primary ("H" leads).
delta
The output rating of generators is given on the nameplate in ___. I. KVA II. KW
either I or II
The conductor shown at point I in Figure 205.1 is the ___.
grounding electrode conductor
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
In an AC circuit containing resistance plus inductance, or resistance plus capacitance, or resistance plus inductance and capacitance, the opposition to current flow is called ___.
impedance
A steel plate is required to protect ___ where it is installed through wooden framing members. A 1? inch clearance from the edge of the framing member can NOT be maintained I. EMT II. Schedule 40 PVC III. RMC
neither I nor II nor III
Refer to the information shown in Figure 234.151. When th etap for Motor 3 terminates in a breaker enclosure, the maximum permitted size for an ITCB in this enclose would be ____ A.
none of these
The smallest wire that can be installed to serve a load that has a nameplate rating of 127 amps is ___ AWG. The OCPD has terminations rated at 75°C.
none of these
Transfer equipment for emergency systems shall be designed and installed to prevent the inadvertent interconnection of ___ sources of supply in any operation of the transfer equipment.
normal and emergency
Inductive reactance is measured in ___.
ohms
In an AC circuit containing only inductance and/or capacitance, the opposition to current flow is called ___.
reactance
The transformer shown in Figure 215.51 has two separate secondary windings. The secondary windings are rated 120/240 volts. If the secondary windings are connected to supply power to a 120/240-volt load, the windings would be connected in ___.
series
True power is measured in ___.
watts
A sine wave will hit its peak value ___ time(s) during each cycle.
2
A transformer is installed to serve a 240-volt, three-phase, 69 KW load. The smallest permitted secondary conductors are ___.
2/0 AWG
The primary of a 112.5 KVA transformer is 480-volt delta. The secondary is 240-volt delta and is delivering 100 amps to a 3Ø load. Given these conditions, ___ amps of current are flowing through each primary winding.
29
350A fuses are used in the safety switch shown in Figure 205.12. The flex to the motor contains three 4/0 AWG conductors. The minimum size of the Equipment Grounding Conductor (EGC) to the motor is ___ AWG.
3
What is the maximum number of 3 AWG THWN/THHN conductors that can be installed in a trade size 3 EMT that is installed between two enclosures that are 8 inches apart?
54
Refer to Figure 205.8, shown above. Where not subject to physical abuse, the smallest permitted GEC to the ground rod from Panel LC is ___ AWG. Panel LC has a 400 amp main breaker and is supplied power by the transformer with a set of 600 kcmil conductors.
6
Two lighting circuits are supplied from a multiwire branch circuit that originates in a 120/240 volt, 1Ø, 3-wire panelboard. Two, 20 Amp, 1-pole breakers are installed in spaces 22 & 24 for the multiwire circuit. Circuit 22 has 2600 watts of lights connected to it, and Circuit 24 has 2100 watts of lights connected to it. Which of the following should happen to Circuit 22?
An overload will occur and the breaker will trip.
Refer to the nameplate and heater selection table, shown above in Figure 230.122. For a correctly sized starter, the heater catalog number for the heaters is ___. This motor is supplied power from a 120/240-volt, 3-phase, 4-wire panelboard.
B32
Refer to Figure 221.101 (above). Drawing ___ (below) shows the transformer correctly connected.
C)
___ is the measure of a circuit's ability to store an electrical charge.
Capacitance
The classification of a location, where ignitable concentrations of flammable liquid-produced vapors or combustible liquid-produced vapors exist under normal operating conditions, is ___.
Class I, Division 1
___ is the output of an AC generator measured in cycles per second.
Frequency
Stainless steel ground rod electrodes ___. I. shall be at least 5/ 8 inch in diameter II. shall be at least 10 feet in length
I only
Bushings have been installed on all the conduits entering the box shown above in Figure 207.10. Where Conduit X contains 4 AWG, Conduit Y contains 2/0 AWG, and Conduit Z contains 1 AWG conductors, the NEC ® requires ___ to have a bushing. I. Conduit X II. Conduit Y III. Conduit Z
I, II, & III
Does the NEC ® permit the circuits from the panels to enter the same pull box, shown above in Figure 207.8?
Yes
The service disconnecting means for a 3-phase service is permitted to consist of ___.
any of the above
In generator set exhaust systems, excess horizontal and vertical exhaust piping distances produce increased back pressure and may require ___.
any of these
A set of wires (black, red, blue and green) are installed between a 3-pole safety switch and a 3Ø motor. The direction of rotation of the motor can be changed by swapping the ___ wire connections on the load side of the switch.
black and blue
Refer to Figure 207.14. The wiring method is PVC. The minimum distance permitted at Point C (below the brick building with a 6" concrete slab) is ___ inches.
0
Refer to Figure 207.14. The wiring method is RMC. The minimum distance permitted beneath the sidewalk at Point A (from the bottom of the 4" thick sidewalk to the top of the conduit) is ___ inches.
0
Individual dry-type transformers rated over 112½ kVA shall be enclosed in a fire-resistant room with materials having a ___-hour minimum fire rating.
1
Refer to the motor nameplate shown in Figure 230.108. A NEMA starter will be used for this motor. The fewest number of heaters that can be installed in the starter per the NEC ® is ___. The motor circuit is supplied from a 2-pole breaker in a 120/240-volt, 3Ø, 4-W panel.
1
The maximum cross-sectional area that can be occupied by conductor in a 40-foot run of conduit is 53% where the conduit contains ___ conductor(s).
1
Refer to the motor nameplate shown in Figure 230.109. The smallest branch circuit conductors that can be installed between the 2-pole circuit breaker in the 120/240-volt, 3Ø, 4-wire panelboard and the motor are ___ AWG.
10
Nontime-delay fuses are to be installed in a safety switch adjacent to a motor. See Figure 230.225. Fuses with a rating not exceeding ___ A are permitted.
100
The service panel feeds the subpanel with two parallel conduits from a 2P, 225-A breaker. There are two "hots" and one neutral in each conduit. AØ loads in the subpanel are pulling 210 amps and BØ loads in the subpanel are pulling 170 amps. Refer to the illustration and the information shown above in Figure 204.1. The AØ conductor in each conduit should be carrying ___ amps of current.
105
What maximum size inverse time circuit breaker is permitted for a single-phase, 7.5 hp motor operating at 208 volts?
110
The exact Code reference that requires electrical equipment to be securely fastened to the surface on which it is mounted is ___.
110.13(A)
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
Motor Nameplate Information: 208-230/460-V 3Ø 5 hp Supply: 3-pole breaker in a 120/208-V, 3-ph, 4-W panel Minimum size circuit conductors are ___ AWG.
12
Underground service laterals that are installed as direct buried cable and covered with 42 inches of dirt shall also have a warning ribbon installed at least ___ inches above the cable.
12
A 3-phase load draws 37.3 amps and is operating at 208 volts. This load is using ___ KVA of power.
13.438
The panel, shown above in Figure 207.6, is 120/240-volt, 1Ø, 3-wire. The load has a rating of 32.4 KW at 240 volts. Each ungrounded conductor will carry ___ amps.
135
Refer to Figure 221.404. The voltage applied to Heating Element B is ___ volts.
138.6
Three THHN/THWN copper circuit conductors are connected to a 3-pole breaker in a 480/277-volt, 3Ø, 4-wire panelboard. The circuit serves a load that draws 11.9 amps. The distance between the panel and the load is 176 feet. The smallest conductors you can install to the load are ___ AWG. The specifications limit the voltage drop to 2.1%. Use K = 10.86 to solve this problem.
14
Refer to the information shown in Figure 234.151. When the tap for Motor 3 terminates in a safety switch, the maximum permitted size for DETD fuses in this switch would be _____ A.
15
Refer to Figure 221.402. If Ammeter 2 indicates 38.5 amps, the generator is delivering ___ kW of power.
16.0
A three-phase 69 KVA load will be connected to a circuit that is fed from a 3-pole breaker in a 120/240-volt 3Ø, 4-wire panel. This load will draw ___ amps of current through each circuit conductor.
166
When a 3Ø load is drawing 48 amps at 208 volts, this is a ___ load.
17.29 KVA
Where a 2/0 AWG THHN/THWN copper is connected to a breaker with 75° terminations, its ampacity is limited to ______ amps.
175
Refer to Figure 207.14. The wiring method is Type USE cable. The minimum distance permitted at Point D is ___ inches.
18
Refer to the nameplate shown in Figure 230.122. This motor should draw ___ amps at rated voltage when connected to Circuit 4-6-8 that is fed from a 3-pole breaker in a 120/240-volt, 3Ø, 4-wire panelboard.
18.6
The minimum working clearance at Point X in Figure 201.15 is ___ feet. The panel is 277/480-volt, 3Ø, 4W.
3 1/ 2
Where (snap) switches are installed in multigang boxes without permanent barriers (partitions) the maximum voltage between adjacent switches is ___ volts.
300
For the 208/120-volt panelboard shown in Figure 201.18, the minimum width of the working space directly in front of the panelboard is ___.
34 inches
Refer to Figure 219.102. Each circuit conductor feeding the load connected to Circuit LB-10,12,14 will carry ___ amps.
35.0
The calculated minimum width (left-to-right) of the pull box shown in Figure 208.53 is ___ inches. Select the larger dimension required: straight pull dimension versus angle pull dimension.
37
The smallest standard size metal box that can be used for the following is a ___. All connectors are on the exterior. one- 14-2 w/ ground NM cable two- 14 AWG conductors to be connected to the NM cable with wire nuts one- 20 amp 240 volt duplex receptacle (single yoke) two- 12 AWG conductors to be connected to the receptacle one- 12 AWG equipment grounding conductor
3¾ x 2 x 3½ masonry box
A transformer supplies power to a 240-volt, 3Ø, non-continuous 32.286 KVA load. The smallest secondary circuit conductors that can be used are ___ AWG.
4
A transformer vault is located in the basement of a high-rise building. Where the vault is not protected by an automatic fire suppression system, the minimum concrete floor thickness is ___ inch(es).
4
As shown in Figure 205.5, one conduit will be installed for the service. The conduit will contain three 3/0 AWG conductors for the ungrounded conductors and one 3/0 AWG conductor for the grounded conductor. The smallest MBJ that can be installed in the panel is a ___ AWG.
4
The neutral is bonded to the frame and connected to a ground rod near a 3Ø, 4-wire 120/208-volt optional standby generator. The transfer switch supplying power to a building system from this generator is required to have ___ poles.
4
The smallest size copper wire permitted to be used as a main bonding jumper in a 200-A main breaker panelboard is ___ AWG. The panel is fed from a transformer with one set of 3/0 AWG wire.
4
AC cable is the wiring method to be used above in Figure 208.3. The length of the AC cable between luminaires is 10 feet. The maximum distance permitted between support #7 and support #8 is ___ feet.
4 1/ 2
Figure 207.3 Nameplate Information: Toaster - 9.2 A @ 110 V Television - 450 W @ 130 V Refer to the wiring diagram shown above in Figure 207.3. What will be the voltage applied (or dropped across) the toaster when the neutral is opened? Select the closest answer.
58
A 3/ 4-inch PVC conduit is to be run underground below an area adjacent to a house where a 6" thick driveway will be poured on top of the dirt surface after the trench is backfilled. The conduit will contain GFCI protected 15-Amp circuit conductors feeding a post luminaire in the front yard. The minimum depth the conduit must be below the present dirt surface level (future driveway) is ___ inches.
6
Refer to Figure 205.4. A 120/240-volt, 1-ph, 3-wire service is to be run to serve 125-A, main breaker Panel B. As shown, one conduit will be installed for the service. The conduit will contain two 1 AWG conductors for the ungrounded conductors. Most of the loads are 240-volt, 1Ø phase without neutrals. The smallest MBJ that can be installed in Panel B is a ___ AWG.
6
The depth ( d) of the 24" x 24" box, shown above in Figure 207.13, is 10 inches. Measured from the point in the box where the conductors emerge from the conduit, the minimum length of the conductors is ___ inches.
6
Voltage Drop Scenario #3 The distance between the panel and a load is 150 feet. The circuit to the load consists of two 12 AWG solid copper coated conductors that are connected to a 1-pole breaker in a 277/480-volt, 3Ø, 4-wire panel and the neutral bar. The load draws 9.8 amps. Refer to Voltage Drop Scenario #3. If the voltage drop is to be limited to 2.2%, this is ___ volts.
6.09
Motor Nameplate Information: 115/230-V 1Ø 3 hp Supply: 1-pole breaker in a 120/240-V, 1-ph, 3-W panel The maximum size DETD fuses permitted are ___ A.
60
A 480-volt motor circuit can be protected with a safety switch that is rated at ___ volts.
600
If a 4-wire, wye-connected supply system has a line-to-line voltage of 13.5 kV, what is the line-to-neutral voltage?
7,800
The vertical bathtub zone in which luminaires are not permitted is ___' from the bathtub rim.
8
What is the minimum size THHN/THWN wire permitted to serve a load that will draw 47 amps? The load will not operate continuously. The branch-circuit OCPD is a circuit breaker that is rated for 75°C.
8 Awg
A transformer has a primary rated voltage of 120 and a secondary rated voltage of 16. If the current in the circuit conductors connected to the primary is 1.1 amps, the load that is connected to the secondary must be drawing ___ amps.
8.25
What is the full load current of a 230v, 3ph, 30HP squirrel cage motor?
80
What is the maximum size branch-circuit OCPD permitted to serve a single load that is connected with 4 AWG THHN/THWN wire? The branch-circuit OCPD is a circuit breaker that is rated for 75°C. The connected load is NOT continuous and will draw 83 amps.
90
A single-phase transformer requires 32 amps at 480 volts on the primary to deliver 120-volt power to a 14.6 kW load. The efficiency of this transformer is ___ %.
95
You are to surface mount 128' of EMT on a wall between two boxes as shown above in Figure 208.11. You will use 1-hole straps to securely fasten the EMT to the wall. The minimum number of straps required is ___.
D
Heaters are installed in motor starters to protect ___. I. the motor against overload II. the branch circuit conductors against overload III. the motor against short circuits and ground faults
I & II only
Which of the illustrations shown in Figure 210.1 fails to satisfy the Code requirements of 240.22(1)?
I & III only
___ is permitted to be installed in a concrete floor slab. I. Schedule 40 PVC II. FMC III. aluminum MC cable
I only
Refer to Figure 207.8, shown above. The conductors from Conduit X are permitted to occupy the junction box with the conductors from Conduit Z.
True
Where circuit breaker terminals or safety switch lugs are marked on the equipment (or included with installation instructions) with a tightening torque by the manufacturer, this torque is required to be applied to the connections.
True
Statement(s) ___, shown below, is (are) true. I. efficiency = output power ÷ input power II. output power = input power - losses
both I & 2
Motor controllers must be marked with ___. I. maximum rated voltage II. maximum hp or current rating
both I & II
