IEC Year 1 Final

What is the result if the neutral wire becomes open on a multiwire circuit having unequal loads?

The load of higher resistance would overheat and probably be damaged.

The Code reference that specifies the type of disconnecting means (circuit breaker for example) that can be used on a multiwire branch circuit that feeds devices mounted on the same yoke [a stack switch or a duplex receptacle for example] is ___.
Note: Select N/A (not applicable) if there is not an NEC® requirement.

240.15(B)(1)

A 12/3 cable is installed from a 120/240-V, 1Ø panel and feeds a split-wired duplex receptacle. One “hot” is connected to a 20-A breaker in panel space 1. The second “hot” is connected to a 20-A breaker in space 3. A 16-amp load is connected to the upper receptacle and a 14-amp load is connected to the lower receptacle. Which of the following will happen if the neutral is removed from the receptacle?

Because a higher voltage will be applied, 120-volt equipment could be destroyed.

For the circuit shown in Figure 128.206, the line current that should be indicated on Ammeter #2 is ___ amps. This is the current flowing through the terminal on Breaker 16.

A=21.67

4600w/240vac=19.2a

75w/120v=0.63a

3-wire 3×0.63a=1.89a

19.2+1.89=21.09 closest

How much current is flowing in the neutral conductor at C in Figure 128.209?

2

Refer to Figure 128.201. The resistance of Lamp 2 is ___ ohms.

E²/P=R

130v²/300w

= 56.33 ohms

All three loads in the above illustration have equal ratings (same “wattage” and “voltage” ratings).

Refer to Figure 128.215. If the current flowing in Line 1 is 8 amps and the current flowing in Line 2 is 4 amps, this would mean that ___ amps of current are flowing in the neutral.

8a-4a=4a

4a

Both the schematic (near right) and the pictorial drawing (far right) are shown. The fixed resistance of EACH of the four elements in the furnace is 40 ohms.

Refer to Figure 129.104. When connected to the circuit, the total current drawn by the furnace (all four heating elements together) is ___ amps.

I=E/R

240v/40ohms=6a

6a

The neutral has been removed from the neutral bar in the circuit shown in Figure 128.407. Lamp 3 is connected in ___ with Lamps 1 and 2.

series

Each battery shown in Figure 128.524 is fully charged at 12 volts. The voltage applied to the load is ___ volts.

36

Trade size ___ is the minimum size RMC (rigid metal conduit) that can contain six each 8 AWG copper THHN/THWN conductors.

³/₄

A furnace with four resistance-heating elements installed is shown above at the left. The schematic for this equipment is shown at the right. Each element is rated at 1,200 watts at 250 volts.

What is the total power delivered by the furnace (all four heating elements together) when connected to the 480-volt circuit shown in Figure 128.303?

E²/P=R

250²v/1200w=52.08ohms

P=E²/R

480²vac/52.08ohms=4,424w

4,424w

The duct heater contains 4 heating elements that are equally rated. Each has the same power and voltage rating. An equivalent schematic is shown at the right.

Refer to Figure 129.105. The voltage applied to element R₂ is ___ volts.

240v

This piece of equipment contains 4 heating elements that are equally rated. Each has the same power and voltage rating.

Refer to Figure 129.106. With the equipment energized and the power used by the element connected at T3 and T4 is 1.2 kW, the power used by the equipment (all 4 elements) ___.

1.2KW

4elements

1.2×4=4.8kw

4.8kw

What is the minimum size EMT required where ten each 14 AWG and fourteen each 12 AWG conductors are to be installed? Assume that this is a new installation and that THHN/THWN copper conductors are used.

1

CH.9 Tables 4+5

What is the minimum size RMC required for a new installation where six 1/0 AWG and nine 3/0 AWG THHN/THWN copper conductors are to be installed?

3¹/₂

CH.9 Tables 4+5

When they are installed in a conduit with other circuits, 12 AWG THHN/THWN circuit conductors can carry ___ amps. There are a total of 10 current-carrying conductors in the conduit. The conduit is installed through the bar joists above the ceiling where the temperature is 139°F. Don’t forget to use NEC® Table 310.16  in the 90°C column.

10.65

310.16

How much current can a #10 THHN/THWN conductor carry when it is installed in a conduit with other wires? There are twelve current-carrying conductors in the conduit. The conduit is installed through the bar joists above the ceiling where the temperature is 141°F. Don’t forget to use the 90°C column in Table 310.15(B)(1) for ampacity corrections.

13

310.15(B)(1)

Seven 1/0 AWG THHN/THWN copper current-carrying conductors are installed in a conduit. How much current can each of these carry (corrected ampacity) where the conduit is installed in an area where the summertime temperature is 142ºF?

77.35

310.15

310.16

A 20A, 240V receptacle located in a finished basement laundry room requires the following:

Select one:

a.Ground-fault circuit protection

b.Tamper-resistant

c.Both of these

d.Neither of these

c.Both of these

___ can be described as the point of demarcation between where the serving utility ends and the premises wiring begins.

Service point

Service conductors shall have a clearance of not less than ___ feet from windows, doors, or similar locations that open.

3 feet

Refer to Figure 130.106 that shows Panel A. A ___ circuit breaker feeds the water pump.

2-P, 20-A

Refer to Figure 130.106. How many 1-pole, 15-amp circuit breakers are contained in Panel A?

11

Refer to Figure 130.105. The maximum permitted mounting height dimensions given in the NEC® is for Point ___ on the drawing.

II

When mounting switches, such as safety switches (disconnects), the NEC® specifies the highest mounting position at ___.

404.8(A)

What is the monthly energy cost to operate a 200-watt, high-pressure, sodium lamp? Electricity costs $0.11 per kW-hr and the lamp will be ON for 12 hours per day. There are 30 days in a billing month.

.2kw x 12h = 2.4kwh/day

2.4kwh x 30days = 72kwh/month

72kwh x $0.11 = $7.92

$7.92

If a 95-watt lamp operates for 11 hours, the utility will bill for ___ kWh.

.095kwh x 11hours = 1.045kwh

1.045 kwh

All openings in an electrical panel must be closed. These openings include ___ that have been removed and remain open.

Select one:

a.conduit knockouts

b.breaker knockouts

c.Both a and b

d.Neither a nor b

c. Both a and b

Maintain an aisle in front of an electrical panel that is at least ___ feet wide.

three

Self-tapping sheet metal screws (TEK screws) ___ permitted to be used to connect the equipment grounding conductor to a metal box.

are not

To minimize conductor insulation damage and arcing damage to electrical equipment during a ground fault or a short circuit, ___ should be minimized.

time duration of the fault

Article ___ in the NEC® covers grounding and bonding of electrical systems.

250

The grounding blade on an attachment plug is ___ than the current-carrying conductor blades. This is to ensure that the grounding connection is made before the current-carrying conductor connections and breaks its connection after the current-carrying conductor connections (first make-last break).

Select one:

a.more tarnish-resistant

b.more durable

c.longer

d.larger

longer

An equipment grounding conductor (EGC) is the conductor that is ___.

Select one:

a.connected to the neutral bar in the service panel, the ground rod, the incoming main water service pipe, and/or the steel building structure

b.connected between the hot and cold water pipes at a water heater

c.installed with the branch-circuit conductors in a conduit or cable run

d.installed between the neutral bar and the ground bar in the service panel

installed with the branch-circuit conductors in a conduit or cable run

When determining the minimum size of a grounding electrode conductor, Table ___ is used.

250.66

Which of the tools shown in Figure 131.201 would be used to screw together PVC-coated steel conduits?

II

The main bonding jumper (a green bonding screw, for example) that is shipped with and installed in a 120/240-volt, single-phase circuit-breaker panel at the service connects (bonds) the ___ to the metal panel enclosure.
I.  branch-circuit neutrals          II.  branch-circuit “hots”

I only

An equipment bonding jumper (BJ) is the connection between two or more portions of the ___ conductor.

equipment grounding

According to Article 250, a metal underground water pipe that is in direct contact with the earth for 10 ft. or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors would be a good ___.

grounding electrode

Generally, an overcurrent protective device is not permitted to be continuously loaded to more than ___ percent of its rating.

80

The panel shown in Figure 132.101 is 120/208-volt, 3Ø, 4-wire. The disconnect switch is fused with plug fuses and supplied from a 2-pole breaker in space 6-8 in the panel. This ___ a Code violation.

is not

A fused switch is permitted to be located ___.
  I.      in the bathroom in a house
 II.      in an electrical room in a school
III.      in a bathroom in a hotel room

II only

Which of the following types of current travel through a circuit breaker?

Select one:

a.Short-circuit

b.Ground-fault

c.Normal

d.Overload

e.All of these

e.All of these

When a load calculation results in an ampere rating that does not match the ampacity of the conductor, which of the following is permitted?

Select one:

a.Select an OCPD rated at not more than twice the ampacity of the conductor.

b.Select an OCPD of the next higher standard ampere rating.

c.Select an OCPD rated at not more than 125% of the ampacity of the conductor.

Select an OCPD of the next higher standard ampere rating.

Which of the following are standard size circuit breakers?
I.  90           II.  100

Both I & II

Plug fuses can be used on which of the following voltage systems?
  I.      120/240-volt, 1-ph, 3-wire
 II.      120/208-volt, 3Ø, 4-wire
III.      277/480-volt, 3Ø, 4-wire

I & II only

Which of the following circuit conditions will cause a circuit breaker to trip?
I.  Short-circuit          II.  Overload          III.  Normal

I & II only

If a circuit breaker trips, you should ___.

Select one:

a.determine why it tripped before resetting the breaker

b.immediately reset the breaker

determine why it tripped before resetting the breaker

A 15-amp circuit breaker opens very quickly (within 1 second) when subjected to ___.
  I.      a ground fault of 250 amps
 II.      a short circuit of 450 amps
III.      an overload of 16 amps

I or II only

Electric vehicle charging systems are covered extensively in NEC® Article ___.

625

For purposes of calculating a residential service, the general-purpose lighting load is calculated at ___ per square foot of area.

3 volt-amperes

Which of the following is a 3/0 AWG conductor?

Select one:

a.0000

b.00

c.000

d.0

c.000

When calculating the size of the required service, you should consult household electric clothes dryer demand factors given in Table ___.

Select one:

a.220.56

b.220.12

c.220.42

d.220.55

e.220.54

220.54

Loads, such as heating and air conditioning, that do not operate at the same time are said to be noncoincident loads. While separate circuits must be designed to serve each load, when calculating service load, only the ___ of two noncoincident loads needs to be included.

larger

When calculating residential service load, ___ is allowed for each branch circuit serving laundry receptacles.

1,500 volt-amperes

The minimum size service disconnect for a single-family dwelling with a computed load of 10 kVA is ___ amperes.

100

What type of light fixture is located in front of the main electrical panel? (EWR Print)

Pull switch

The circuit breaker for the electric dryer in the EWR residence is located in ___.

spaces 1-3 in Panel B

The most common eye injuries are caused from ___.

Select one:

a.dust

b.horseplay

c.foreign bodies in the eye

d.flying objects

e.All of these

e.All of these

Article ___ of the NEC® is the article that gives requirements for swimming pool installations.

680

Without exceptions, all metal parts of an indoor spa or hot tub must be bonded.

true

Tests have shown that a voltage gradient of ___ volts per foot can cause paralysis.

1.5 v

What is the minimum number of 125-volt, 15- or 20-ampere convenience receptacles that the NEC® requires to be installed near a permanently installed pool? The pool is located in your neighbor’s backyard.

one

You have a set of plans that requires lighting fixtures (luminaires) to be installed on the ceiling directly above an indoor pool. The ceiling height is 10 feet above the decking around the pool. You should make sure that these fixtures are ___.
  I.      of a totally enclosed type     
 II.      connected to a branch circuit that is GFCI protected
III.      at least 7 ft-6 in above the maximum water level

I, II, & III

A disconnecting means (or disconnect switch) for a swimming pool circulation pump must be installed ___.

Select one:

a.at least 5 feet from the inside wall of the pool

b.readily accessible

c.so that it is visible from the pump

d.All of these

d.All of these

For electrically-operated swimming pool covers, the electric motor and controller shall be connected to a circuit protected by a(n) ___.

ground-fault circuit interrupter

Metal signs installed inside a fountain are required to be grounded.

true

The Code requires that all metal parts of a pool installation be bonded to a common bonding grid by ___ AWG or larger solid copper wire.

8 awg

The Standard for Electrical Safety in the Workplace requires that all electrical equipment operating at over ___ volts to ground be de-energized and locked out before anyone is permitted to work on or near the equipment.

50

It is permitted to run normal power conductors and optional standby power conductors in the same raceway or enclosure.

true

Residential standby power system generator is typically ___.

permanently installed

Carbon monoxide (CO) can cause ___.

Select one:

a.fainting

b.death

c.nausea

d.Any of these

d.Any of these

When installing any audio/video/data cables, the cable runs should ___.

Select one:

a.be bundled loosely with other cables

b.not be kinked or knotted

c.be secured with rounded or depth-stop staples

d.All of these

d.All of these

While installing Cat 5 cable, pulling too hard can damage the ___.

Select one:

a.conductor

b.jacket

c.insulation

d.All of these

d.All of these

Cat 5 cable should be installed so that bends are not less than ___ times the diameter of the cable.

4

When portable generators are stored until needed by a homeowner or small business owner to operate cord-connected equipment, these are commonly referred to as ___ power sources.

backup

NEC® Section ___ requirement is that an optional standby system shall be capable of supplying the full load that is transferred by the automatic transfer equipment.

702.4

When installing any audio/video/data cables, the conductors should be untwisted about ___ inch(es) at the point of termination.

¹/₂

Transfer switches use a ___ to prevent the feedback of electricity between the generator power and the normal utility power.

mechanical interlock