2014 NEC Instructor Manual and Student Worksheets Level 1

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2014
ELECTRICAL INSPECTOR
INSTRUCTORS’ MANUAL
LEVEL I
NC Code Officials Qualification Board
322 Chapanoke Road
Raleigh, NC 27603
2014 NEC Instructor Manual and Student Worksheets -- Level 1
1
Article
90
100
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Title
INTRODUCTION TO THE NEC
DEFINITIONS
REQUIREMENTS FOR ELECTRICAL INSTALLATIONS
USE AND IDENTIFICATION OF GROUNDED CONDUCTORS
BRANCH CIRCUITS
FEEDERS
BRANCH CIRCUIT, FEEDER AND SERVICE CALCULATIONS
OUTSIDE BRANCH CIRCUITS AND FEEDERS
SERVICES
OVERCURRENT PROTECTION
GROUNDING AND BONDING
SURGE ARRESTOR
WIRING METHODS
CONDUCTORS FOR GENERAL WIRING
CABINETS, CUTOUT BOXES, AND METER SOCKET ENCLOSURES
OUTLET, DEVICE, PULL, AND JUNCTION BOXES; CONDUIT BODIES;
FITTINGS; AND HANDHOLE ENCLOSURES
ARMORED CABLE : TYPE AC
FLAT CABLE ASSEMBLIES: TYPE FC
FLAT CONDUCTOR CABLE: TYPE FCC
METAL-CLAD CABLE: TYPE MC
NONMETALLIC-SHEATHED CABLE: TYPES NM, NMC, AND NMS
SERVICE-ENTRANCE CABLE: TYPES SE AND USE
USE
UNDERGROUND
FEEDER AND BRANCH-CIRCUIT CABLE: TYPE UF
INTERMEDIATE METAL CONDUIT: TYPE IMC
RIGID METAL CONDUIT: TYPE RMC
FLEXIBLE METAL CONDUIT: TYPE FMC
LIQUIDTIGHT FLEXIBLE METAL CONDUIT: TYPE LFMC
RIGID POLYVINYL CHLORIDE CONDUIT: TYPE PVC
NONMETALLIC UNDERGROUND CONDUIT WITH CONDUCTORS: TYPE
NUCC
ELECTRICAL METALLIC TUBING: TYPE EMT
AUXILIARY GUTTERS
MULTIOUTLET ASSEMBLY
SURFACE METAL RACEWAYS
SURFACE NONMETALLIC RACEWAYS
CONCEALED KNOB-AND-TUBE WIRING
FLEXIBLE CORDS AND CABLES
FIXTURE WIRES
SWITCHES
RECEPTACLES, CORD CONNECTORS, AND ATTACHMENT PLUGS (CAPS)
SWITCHBOARDS AND PANELBOARDS
2014 NEC Instructor Manual and Student Worksheets -- Level 1
Code Page
Manual Page
70-23
70-27
70-36
70-49
70-51
70-64
70-66
70-76
70-83
70-94
70-106
70-139
70-142
70-154
70-180
70-184
3
9
13
20
25
33
37
49
57
63
73
89
92
101
106
110
70-193
70-195
70-196
70-200
70-203
70-207
70-208
70-209
70-210
70-212
70-214
70-215
70-219
70-225
70-229
70-240
70-244
70-245
70-257
70-262
70-273
70-277
70-281
70-285
115
118
121
124
127
134
138
142
174
155
158
163
169
172
175
178
182
182
188
193
197
200
207
211
2
410
411
422
424
430
440
504
514
517
518
545
547
550
551
552
553
555
590
600
605
680
690
702
705
800
LUMINAIRES, LAMPHOLDERS, AND LAMPS
LIGHTING SYSTEMS OPERATING AT 30 VOLTS OR LESS AND LIGHTING
EQUIPMENT CONNECTED TO CLASS-2 POWER SOURCES
APPLIANCES
FIXED ELECTRIC SPACE-HEATING EQUIPMENT
MOTORS, MOTOR CIRCUITS, AND CONTROLLERS
AIR-CONDITIONING AND REFRIGERATING
EQUIPMENT SAFE SYSTEMS
INTRINSICALLY
MOTOR FUEL DISPENSING FACILITIES
HEALTH CARE FACILITIES
ASSEMBLY OCCUPANCIES
MANUFACTURED BUILDINGS
AGRICULTURAL BUILDINGS
MOBILE HOMES, MANUFACTURED HOMES, AND MOBILE HOME PARKS
RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS
PARK TRAILERS
FLOATING BUILDINGS
MARINAS AND BOATYARDS
TEMPORARY INSTALLATIONS
ELECTRIC SIGNS AND OUTLINE LIGHTING
OFFICE FURNISHINGS
SWIMMING POOLS, FOUNTAINS, AND SIMILAR INSTALLATIONS
SOLAR PHOTOVOLTAIC (PV) SYSTEMS
OPTIONAL STANDBY SYSTEMS
INTERCONNECTED ELECTRICAL POWER PRODUCTION SOURCES
COMMUNICATIONS CIRCUITS
70-292
70-301
216
70-302
70-308
70-323
70-351
70-410
70-443
70-462
70-481
70-501
70-502
70-504
70-514
70-526
70-535
70-536
70-540
70-543
70-550
70-604
70-623
70-661
70-662
70-709
229
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248
265
273
276
281
284
288
291
295
299
303
306
309
314
317
325
329
336
342
346
227
349
THE PAGE NUMBER LISTED ABOVE CORRESPONDS TO THE ARTICLE LOCATION IN THE NORTH
CAROLINA ELECTRIC CODE BOOK (THE NEC 2014). THE “TM” NUMBERS TO THE RIGHT OF THE ARTICLE
NUMBERS CORRESPONDS TO THE PAGE NUMBERS IN THE TRAINING MANUAL FOR THE STARTING PAGE
FOR EACH ARTICLE LISTED.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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INTRODUCTION TO THE NATIONAL ELECTRIC CODE
ARTICLE 90
LEVEL I
OBJECTIVES:
Each student should become familiar with:
1. The purpose and scope of the National Electrical Code.
2. The definitions and Fundamental rules covered by the Code.
MATERIALS NEEDED:
National Electrical Code (NEC) most recent edition 2014 with NC Amendments.
INTRODUCTION:
This may be the student’s first contact with the National Electrical Code. The Inspector
will be working by these rules for their entire career in the electrical industry. The importance
of learning the purposes and organization of t*he Code cannot be overemphasized.
This lesson should give the students a clear picture of how the Code is organized so they
may find information more easily in later assignments and on the job. The Code is not a set of
laws; it is a set of rules. It is intended for use by governmental bodies exercising legal
jurisdiction over electrical installations and for use by insurance inspectors.
PRESENTING THE LESSON:
The National Electrical Code, Article 90, Introduction, outlines the purpose and explains
the scope, arrangement, enforcement, and formal interpretations of the Code. It also contains
details of safety examinations of equipment, future wiring expansion and units of
measurement used in the Code.
The purpose of this code is to safeguard people and property from electrical hazards by
outlining provisions that are necessary for safety. Many hazards that occur are due to
overloading wiring systems or exceeding the provisions of this Code; therefore, it is important to
plan for future increases in the use of electricity.
This code is not an instruction manual for untrained persons. Many areas are covered by
this Code, but there are also a lot of areas not covered. Pay close attention to the requirements
listed in Section 90.2.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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90.2 Scope
90.2(b)(5) Explain #5 “controlled by electric utilities”.
90.2(c) Special Permission. See Administration and Enforcement Code(Sec. 308)
90.4 Enforcement. See Administration and Enforcement.
90.5 Mandatory Rules, Permissive Rules and Explanatory Materials.
90.6 Formal Interpretations. See Administration and Enforcement Code.
90.7 Examination of Equipment for Safety. See Administration and Enforcement Code.
90.8 Wiring Planning
Remind the students that the chief electrical inspectors usually exercise legal jurisdiction
over electrical installations through city ordinances or laws based on the NEC.
The instructor should lead a class discussion of the material contained in the appropriate
sections of the code. After each section distribute the worksheets for the students to
complete and answer any questions they may have.
APPLICATION:
If time will allow, go over the questions on the worksheet. This is usually a good point to
remind them to work outside of the class on their worksheets.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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INTRODUCTION TO THE NATIONAL ELECTRIC CODE
ARTICLE 90
LEVEL I
WORKSHEET
1.
Which of the following is the purpose of this code?
a. The protection of persons and property from hazards arising from the use of
electricity.
b. The practical use of electricity and the protection of property.
c. The safeguarding of persons and property from electrical hazards.
d. The practical safeguarding of persons and property from hazards arising from the use of
electricity.
2.
This code contains provisions considered necessary for which of the following?
a.
b.
c.
d.
3.
Efficient, convenient, and adequate installations.
Allowance for good service or expansion of electrical use.
Installation that allows for ease of operation and safety.
Safety.
This code is not intended for which of the following?
a.
b.
c.
d.
4.
As an instructional manual.
As a design specification.
Neither of the above.
Both of the above.
This code does not cover which of the following?
a.
b.
c.
d.
5.
carnivals
aircraft
floating buildings
recreational vehicles
Chapter 8 and Chapter 9 cover which of the following?
a.
b.
c.
d.
communication, tables and annexes.
wiring methods, tables and appendixes.
tables, appendixes and conduit bodies.
references, standards and tables.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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6. This code is intended to be suitable for mandatory application by which types of bodies
exercising legal jurisdiction over electrical installations and for use by which type of
inspectors?
a.
b.
c.
d.
Legal and local.
Local and State.
State and Federal.
Governmental and insurance.
7. The authority having jurisdiction may waive specific requirements in this code or permit
alternate methods by which of the following?
a.
b.
c.
d.
By special legislation.
By special administrative ruling.
By special hearings.
By special permission.
8. If specified equipment has been listed by a qualified electrical testing laboratory, then under
any circumstances it is the intent of the Code not to require inspection of the factory-installed
internal wiring at the time of the installation, except for which of the following purposes?
a.
b.
c.
d.
To determine compliance with UL.
To determine compliance with NFPA.
To detect alterations or damage.
To determine proper wiring clearances.
9. Limiting the number of circuits in a single enclosure will minimize the effects from which
of the following from occurring?
a.
b.
c.
d.
short circuits
ground faults
neither of the above
both of the above
10. For the purpose of this Code, metric units of measurement are in accordance with the
modernized metric system known as which of the following?
a.
b.
c.
d.
SI units
IS units
Centigrade units
Fahrenheit units
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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INTRODUCTION TO THE NATIONAL ELECTRIC CODE ARTICLE 90
LEVEL I
ANSWER KEY
1-d.
practical safeguarding
[90.1(a)]
2-d.
Safety
[90.1(b)]
3-d.
4-b.
Both of the above.
aircraft
[90.1(a)]
[90.2(b)(1)]
5-a.
communication, tables, annexes
[90.3]
6-d.
governmental, insurance
[90.4]
7-d.
by special permission
[90.4]
8-c.
to detect alterations or damage
[90.7]
9-d.
both of the above
[90.8b]
10-a.
SI units
[90.9(b)]
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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DEFINITIONS
ARTICLE 100
LEVEL I
OBJECTIVE:
Each student should become acquainted with definitions peculiar to and essential to the
proper use of the NEC.
INTRODUCTION:
This lesson should give the inspector a clear understanding of terms used in the NEC. The
definitions included in Article 100 are terms used in one or more articles of the Code.
Definitions specific to only one section are given in that section. This lesson is limited to Part
A of Article 100 which contains definitions applicable to terms used throughout the Code. It
serves as an example for the instructor to use as various other definitions are discussed.
PRESENTING THE LESSON:
The instructor should lead a class discussion on definitions, giving illustrations of each.
Example:
Branch Circuit – The circuit conductors between the final overcurrent device
protecting the circuit and the outlet(s)
(Show examples with slides, on chalkboard, or using actual materials if available) Stress
these key definitions:
Accessible and Readily Accessible
Bathroom
Bonded
Branch Circuit
Continuous Load
Dwelling Units
Feeder
Ground and Grounded
All definitions pertaining to grounding
Ground-Fault Circuit-Interrupter
Ground-Fault Protection of Equipment
In sight from
Labeled and Listed (refer to
NC General Statute 66)
Outlet
Overcurrent
Overload
Receptacles
Separately Derived Systems
Services
Thermally Protected and
Protector
APPLICATION:
If time allows, have the students answer the questions on the worksheet. CHECKING AND
FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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DEFINITIONS
ARTICLE 100
LEVEL I
WORKSHEET
1. The definition of approved is which of the following?
a. listed by “UL”
b. any product that has been tested and labeled by a third party independent
safety testing laboratory
c. acceptable to the authority having jurisdiction
d. acceptable when a letter is written by the factory
2. Which of the following is the current in amperes a conductor can carry continuously under the
conditions of use without exceeding the temperature rating of the conductor?
a.
b.
c.
d.
full load current
volts
ohms
ampacity
3. Which of the following is a remote control circuit?
a.
b.
c.
d.
a circuit with a thermal overload or equivalent device
an electrical circuit with a service factor
an electrical circuit that controls any other circuit through a relay or equivalent device
an electrical circuit controlled by a master circuit controller
4. What is a Service Cable?
a. Service conductors made up in the form of a cable.
b. The overhead service conductors from the last pole connecting to the serviceentrance conductor at the building.
c. Conductors between the terminals of the service equipment and the point tapped to
the service drop
d. None of the above.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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5. A “dwelling unit” is defined as which of the following?
a. A single unit, providing complete and independent living facilities for one or more
persons, including permanent provisions for living, sleeping, cooking, and sanitation
service.
b. A one or two-family, providing complete and independent living facilities for three or
more persons, including permanent provisions for living, sleeping, cooking, and
sanitation.
c. A room in a motel with permanent cooking facilities.
d. An apartment with permanent cooking facilities.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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DEFINITIONS
ARTICLE 100
LEVEL I
ANSWER KEY
1. c, acceptable to the authority having jurisdiction
2. d, Ampacity
3. c, an electrical circuit that controls any other circuit through a relay or an equivalent
device.
4. a, Service conductors made up in the form of a cable
5. a, A single unit, providing complete and independent living facilities for one
or more persons, including permanent provisions for living, sleeping,
cooking, and sanitation.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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REQUIREMENTS FOR ELECTRICAL INSTALLATIONS
ARTICLE 110
LEVEL I
OBJECTIVES:
Each student should become familiar with the terminology used in the NEC and basic rules not found
elsewhere in the Code.
INTRODUCTION:
This article introduces students to the wording used in the Code. This should prevent misinterpreting
certain terminology used in the Code. It also covers basic rules that in general do not fit elsewhere in
the Code.
PRESENTING THE LESSON:
Mandatory rules in the Code will be indicated by the word “shall”. Anything meant to be
explanatory will be done in a Fine Print Note (FPN).
Any wiring of both equipment and conductors required or permitted by this code shall only be
acceptable if approved. (110.2)
All equipment must be examined and judged as to their approval. Any and all equipment
must be installed according to all listing and labeling. (110.3(B))
All conductors shall be copper unless otherwise stated and sizes shall be that of copper.
(110.5) Conductor sizes shall also be in AWG or circular mills. (110.6)
All wiring and equipment shall be used according to the environment in which it has been approved
(110.11)
All equipment shall be installed in a neat and workmanlike manner. All unused openings in
equipment enclosures shall be closed to the equivalent of the walls of the enclosure. Enclosures of
size large enough for persons to enter for maintenance shall have conductors racked to provide safe
and ready access. [110.12(A & B)]
(This item is covered in more detail in other Sections).
Equipment shall be firmly mounted on the surface on which it is attached and wooden plugs in
masonry shall not be approved. In equipment mounting, consideration shall be given to circulation of
air and heat dissipation so as not to block with adjacent walls and ceilings. [110.13(A & B)]
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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When splicing conductors, approved devices shall be used and installed according to
manufacturer’s instructions. Soldered splices shall be made mechanically secure before
soldering. Dissimilar metals (i.e., copper and aluminum) shall not be intermixed unless the
device is approved for that purpose. Terminals shall be designed so as not to damage the
conductor and shall be by pressure connector (including set screw), solder lugs, or splices to
leads. Wire binding screws and upturned lugs shall not be used on wire sized larger than #10.
[110.14(A)] Underground connectors or splicing means shall be listed for such use.
[110.14(B)]
Ampacity of a conductor is selected so as not to exceed the lowest temperature rating of the
termination. [110.14(C)]
110.14(C)(1)(a) Circuits rated 100 amperes or less or marked for 14 AWG through 1 AWG
shall be terminated with conductors rated 60° C (140° F) unless the equipment is listed and
marked otherwise
110.14(C)(1)(b) Circuits rated over 100 amperes or marked for conductors larger than 1 AWG
shall be terminated with conductors rated 75° (167° F).
All 600 volt and less equipment that requires either inspection or servicing while
equipment is energized requires a space at least 30 inches wide and a depth according to
that in Table 110.26(A).
Refer to Table 110.26(A)(1) Working Spaces:
Condition #1 is when there are exposed live parts on one side of the working space and no
grounded parts on the other or exposed live parts on both sides, insulated or cut off.
Condition #2 consists of exposed live parts on one side and grounded parts on the other.
Condition #3 has exposed live parts on both sides of the working space.
Working space for equipment operating at 600 volts, nominal, or less to ground and likely to
require examination, adjustment, servicing, or maintenance while energized shall comply with
the dimensions of 110.26(A)(1), (A)(2), and (A)(3) or as required or permitted elsewhere in this
Code.
For equipment rated 1200 amperes or more and over 6 feet wide that contains overcurrent
devices, switching devices, or control devices there shall be an entrance to and egress from
each end of the working space. These entrances shall be at least 24 inches wide and 6 1/2 feet
high. 110.26(C)2 Where the location permits a continuous and unobstructed way of exit travel,
or where the depth of the working space is twice that required by 110.26(A)(1), a single
entrance shall be permitted. 110.26(C)(2) a & b. In all cases where live parts are normally
exposed on switchboards, panelboards, or motor control centers, that may require servicing
while energized, the depth of the workspace in front shall not be less than 3 feet. Table
110.26(A)
Illumination shall be provided for all working spaces about service equipment,
switchboards, switchgear, panelboards, or motor control centers installed indoors and
shall not be controlled by automatic means only. 110.26(D)
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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The minimum headroom of working spaces about service equipment, switchboards,
panelboards, or motor control centers shall be 2.0 m (61/2 ft). 110.26(E)
Equipment with exposed live parts operating at over 50 volts shall be guarded by one of the
following: 110.27(A)
(1) A room or vault accessible only to qualified persons.
(2) Suitable permanent, substantial partitions or screens high enough to permit only qualified
persons.
(3) Located on a suitable balcony, gallery or platform elevated and arranged so as to
exclude unqualified persons.
(4) By elevation above the floor or other working surface of 8 feet for 50 to 300 volts
and 8.5 feet for 301 to 600 volts.
Guards or enclosures shall be so arranged and be of sufficient strength to protect from
physical damage. 110.27(B)
Entrances to rooms and other guarded locations that contain exposed live parts shall be
marked with conspicuous warning signs forbidding unqualified persons to enter. 110.27 (C)
All equipment producing arcs and sparks shall be enclosed and isolated from
combustible material. (110.18)
All equipment shall be marked with manufacturer’s name, trademark or other descriptive
marking, identifying the organization responsible for the product, voltage, current, wattage,
or other ratings required elsewhere in the Code. (110.21)
All disconnecting means for feeders or branch circuits shall be identified. (110.22)
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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INTRODUCTION TO THE NATIONAL ELECTRIC CODE
ARTICLE 110
LEVEL I
WORKSHEET
1.
Equipment must be installed and used:
a. according to code only
b. according to listing and labeling instructions of the equipment and the
installation requirements of the Code.
c. to meet the needs of the inspector.
d. to meet the needs of the owner.
2.
Equipment can be mounted by all of the following except:
a.
b.
c.
d.
3.
The largest wire that can be connected by wire binding screws is:
a.
b.
c.
d.
4.
#14
#12
#10
#8
The minimum width of the working space about equipment required to be serviced while
energized is:
a.
b.
c.
d.
5.
toggle bolts
lead anchors
wood screws into wood framing members
wooden plugs driven into masonry
30 inches
36 inches
48 inches
not specified in the Code
In all cases work space shall permit a panel door to swing to which of the following
degrees?
a.
b.
c.
d.
40
45
75
90
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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6.
The working clearance from a sheetrock wall opposite a 120/240 volt panel is which of
the following in inches?
a.
b.
c.
d.
7.
Illumination is required for service equipment located indoors in:
a.
b.
c.
d.
8.
6 1/4 feet
6 1/2 feet
7 feet
8 feet
Termination provisions for equipment rated 100 amperes or less shall be considered to
have a temperature rating of which of the following unless the equipment is marked
otherwise.
a.
b.
c.
d.
10.
dwelling units
commercial buildings
dwelling units with services rated over 200 amperes
all of the above
The minimum height of headroom for the workspace in front of a 200 ampere service
panel in an office building is which of the following?
a.
b.
c.
d.
9.
30
36
48
60
60° C
75°C
90°C
40°C
Dissimilar metals shall not be intermixed within a connector unless the device is?
a.
b.
c.
d.
insulated for the purpose.
identified for the purpose.
encapsulated for the purpose.
isolated for the purpose.
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11. On a 4-wire, delta-connected secondary where the midpoint of one phase is grounded to
supply lighting and similar loads, the phase conductor having the higher voltage to ground
shall be identified by tagging or other effective means or by an outer finish that is which of the
following colors?
a. red
b. brown
c. white
d. orange
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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INTRODUCTION TO THE NATIONAL ELECTRIC CODE
ARTICLE 110
LEVEL I
ANSWER KEY
1. b
2. d
3. c
4. a
5. d
6. b
7. d
8. b
9. a
10. b
11. d
[110.3(B)]
[110.13(A)]
[110.14(A)]
[110.26(A)(2)]
[110.26(A)(2)]
Table [110.26(A)(1)]
[110.26(D)]
110.26(A)(3)
[110.14(C)(1)]
[110.14]
[110.15]
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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USE AND IDENTIFICATION OF GROUNDED CONDUCTORS
ARTICLE 200
LEVEL I
OBJECTIVES:
Each student should become familiar with:
1. The identification of grounded conductors.
2. The requirements for grounded conductors in premises wiring systems
3. The identification of terminals used for the connection of grounded conductors.
MATERIALS NEEDED:
Samples of white colored conductors, a three wire grounded receptacle, and a screw shell
lamp holder. (Optional)
INTRODUCTION:
When working in an electrical system, it is very important that the electrician know which
conductor is the grounded conductor. The grounded conductor is a system or circuit
conductor that is intentionally grounded. On some systems the grounded conductor is also
known as the “neutral” conductor. It has to be easily distinguished from the ungrounded
conductors. Article 200 gives the requirements of identifying grounded conductors and
terminals.
PRESENTING THE LESSON:
200.2
(A)With the few exceptions of section 200.2, all premises wiring systems shall have a
grounded conductor. 200.2 (B) The continuity of a grounded conductor shall not depend on a
connection to a metallic enclosure, raceway, or cable armor.
200.3
Premises wiring shall not be electrically connected to a supply system unless the latter
contains, for any grounded conductor of the interior system, a corresponding conductor
which is at the time of installation by a gray marking at its terminations grounded.
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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200.6
There are specific ways to identify grounded conductors of various sizes. Generally, an
insulated grounded conductor of No. 6 or smaller shall be identified by a Continuous white
or gray outer finish or by three continuous white or gray stripes on other than green
insulation along its entire length.
Insulated grounded conductors larger than No. 6 can be identified as the No. 6 and
smaller or, at the time of installation by a distinctive white marking at its terminations.
Cover the exceptions noted in Section 200.6 (B).
Note: 200.6(A) requires grounded conductors that included 6 AWG to be identified by a
continuous white, gray color, or by three continuous white stripes on other than green
insulation along its entire length. A black #12 AWG grounded conductor could not be marked
with tape at the terminations.
200.7
(A) A conductor identified as just described shall be used only for the grounded
conductor unless otherwise permitted in 200.7 (B) and (C).
200.7
(C) The use of insulation that is white or gray or that has three continuous white or gray
stripes for other than a grounded conductor for circuits of 50 volts or more shall be
permitted for an ungrounded conductor, switch loops and flexible cords for appliances
where re-identified.
200.9
The identification of terminals to which a grounded conductor is to be connected
shall be substantially white in color. The identification of other terminals shall be of a readily
distinguishable different color.
200.10
This section covers the identification of terminals for devices, receptacles, plugs and
appliances.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW UP:
If time allows, correct the worksheets and discuss the results.
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USE AND IDENTIFICATION OF GROUNDED CONDUCTORS
ARTICLE 200
LEVEL I
1. All premises wiring systems shall have a grounded conductor that is identified in
accordance with which of the following section(s)?
a.
b.
c.
d.
210.6
200.6
215.6
310.16
2. Without exception the insulated grounded conductor, in a multi conductor cable, shall be
identified by a continuous white or gray outer finish or by three continuous white stripes
on other than which color insulation along its entire length?
a.
b.
c.
d.
blue
red
green
white
3. An insulated grounded conductor larger than No. 6 may be identified at the time of
installation by all the following EXCEPT for which of the following?
a.
b.
c.
d.
by a continuous white finish.
by a continuous gray finish.
by a continuous green finish.
by making a distinctive white or gray marking at it’s terminations, with the
marking encircling the conductor’s insulation.
4. The grounded conductor in a flexible cord may be identified by which of the following means?
a.
b.
c.
d.
Tinned Conductors
Tracer in Braid.
both of the above
neither of the above
5. The continuity of a grounded conductor shall not depend on a connection to a ___________ .
a.
b.
c.
d.
metallic enclosure
raceway
cable armor
all of the above
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6. The identification of terminals to which a grounded conductor is to be connected
a shall be substantially white in color
b. shall be identified with the letter W
c. shall be identified with the word White.
d. shall be any of the above
7. A white wire, in a multiconductor, cable used as an ungrounded conductor, shall be
permanently re-identified by which of the following?
a. I. painting
b. II. other effective means at its terminations and other visible and accessible
locations.
c. Either I or II
d. Neither I nor II
8. For devices with screw shells, which of the following shall the grounded conductor be
connected to?
a.
b.
c.
d.
the screw shell
the base of the shell
the white switch terminal
the ungrounded terminal
9. No grounded conductors shall be attached to any terminal or lead so as to reverse which
of the following?
a.
b.
c.
d.
intrinsic connection
linear load
line voltage
designated polarity
10. Where grounded conductors of different systems are installed in the same
raceway, cable, box, auxiliary gutter, or other type of enclosure, the grounded
conductors may be marked in which of the following approved manners?
a.
b.
c.
d.
gray, white
white, gray with green stripes
green, white
white, white with green stripes
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USE AND IDENTIFICATION OF GROUNDED CONDUCTORS
ARTICLE 200
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
b. 200.6
c. green
c.
c.
d.
a.
c.
a.
d. polarity
a.
200.6
200.6 (E)
200.6b
200.6 (400.22(B)&(E)
200.2(B)
200.9
200.7 (C)(1)
200.10(C)
200.11
200.6 (D)
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BRANCH CIRCUITS
ARTICLE 210
LEVEL I
OBJECTIVES:
Each student should become familiar with the:
1. General provisions of branch circuits
2. Branch circuit rating provisions
3. Guidelines for required outlets of branched circuits
INTRODUCTION:
The branch circuit refers to the circuit conductors between the final overcurrent device
protecting the circuit and the outlets. For definitions of various types of branch circuits, see
Article 100.
210.1
This Article covers branch circuits except for branch circuits which supply only motor loads, which
are covered in Article 430. This Article applies to branch circuits with combination loads. Also,
branch circuits for electrolytic cells are covered in Section 668.3(C).
210.2
There are many applicable provisions of other articles of this code which apply to branch
circuits as well as this Article. Section 210.2 contains a list of these other articles.
210.3
The maximum permitted ampere rating or setting of the overcurrent device shall classify branch
circuits. If larger conductors are used for any reason, the overcurrent device shall determine the
circuit classification. The rating for other than individual branch circuits shall be 15, 20, 30, 40, and
50 amperes. Exception: Multioutlet branch circuits greater than 50 amperes permitted in industrial
premises under certain conditions. This was added in the 1984 Code so industries could have a
welder circuit, over 50 amperes at several locations, at one time.
210.4(A)
A multiwire branch circuit may be considered as multiple circuits and all conductors of a multiwire
circuit shall originate from the same panelboard or similar distribution equipment.
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210.4(B)
All multiwire branch circuits will be required to be provided with means that will
simultaneously disconnect all ungrounded conductors at the point where the branch circuit
originates.
210.4(C)
Multiwire branch circuits shall supply only line to neutral loads. Exception 1: Only one utilization
equipment. Exception 2: Where all ungrounded conductors of the multiwire branch circuit are
opened simultaneously.
210.4 (D)
All conductors of a multiwire circuit shall be grouped at least once within the
panelboard. As outlined in the exception this is not a requirement for cables or
raceways that are unique to the circuit and makes the grouping obvious or are
identified by numbers at the terminals with the appropriate circuit number.
210.5(A)
The color code for branch circuit grounded conductors shall be in accordance with 200.6
210.5(C)
Where the premises wiring system has branch circuits supplied from more than one
nominal voltage system, each ungrounded conductor of a branch circuit, where accessible,
shall be identified by phase or line and system at all terminations, connections, and splice
points.
210.8(A)
Dwelling Units – explain GFCI protection for 125 volt 15 and 20 ampere receptacles Go over
specific locations in 210.8(A)(1) – (10). Note: These requirements are only for dwelling units.
See definition of “dwelling unit” in Article 100. Note: 210.8(A)3 for NC Amendments.
210.8(B)
Note: Eight locations for “other than dwelling units” Other articles require GFCI protection:
555.19(B)(1), 511.12.
210.19
Branch circuit conductors shall have an ampacity of not less than the maximum load to be
served. See Section 210.19 for details on multi-outlet branch circuits, cooking appliances, etc.
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210.20
Overcurrent devices having a rating or setting within given specifications of the Code shall
protect branch circuit conductors and equipment.
210.21
Outlet devices shall have an ampere rating not less than the load to be served. See
Section 210.21 A and B. Show and discuss tables 210.21(B)(2) and (B)(3).
210.23
The maximum load shall not exceed the rating of the branch circuit or other specified
conditions of the code. Discuss permissible loads for specific branch circuits located in
sections 210.23(A), through 210.23(D). See Table 210.24 for a summary of branch circuit
requirements.
210 Part III
Whenever flexible cords are used, a receptacle shall be installed unless the cords are
permanently connected, as permitted in 400.7. Appliance outlets such as for a washing
machine shall be installed 6 feet from the intended location of the appliance. Receptacle
outlets shall be installed as specified in Sections 210.52 – 210.64. A cord connector that is
supplied by a permanently connected cord pendant shall be considered a receptacle outlet.
Discuss the general provisions for receptacle outlets for:
1.
2.
3.
4.
dwelling units
guest rooms
show rooms
rooftop heating, air conditioning and refrigeration equipment
Review required lighting outlets for dwelling units and guest rooms in Section
210.70.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results. Insure students
understand Article 210.
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BRANCH CIRCUITS
ARTICLE 210
LEVEL I
WORKSHEET
1.
Branch circuits shall be rated by which of the following?
A. Maximum permitted ampere rating.
B. Maximum setting of the overcurrent device.
C. Both of the above
D. Neither of the above
2.
Which of the following statements about the color codes for branch circuits is/are
correct?
A. The grounded conductor of a branch circuit shall be identified by a continuous white
or gray color.
B. The equipment grounding conductor of a branch circuit shall be a continuous
yellow color.
a.
b.
c.
d.
3.
A only
B only
Both A and B
Neither A or B
Under certain conditions, a receptacle may be mounted not more than which
of the following inches below a kitchen countertop.
a.
b.
c.
d.
4.
16 inches
10 inches
8 inches
12 inches
In places, other than dwelling units, GFCI protection shall be installed in all
the locations below with the exception of?
a.
b.
c.
d.
Bathrooms
Commercial and institutional kitchens
Outdoors in public places
At a convenience store behind the cash register
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5. In dwelling units all of the following require GFCI protection Except?
a. A single receptacle in the garage for a central vacuum
b. A garage door opener
c. A single receptacle in the basement for a permanently installed fire alarm or
burglar alarm
d. All of the above
6. Branch circuit conductors shall have an ampacity not less than which of the
following?
a.
b.
c.
d.
The minimum load to be served.
The maximum load to be served.
The total load to be served.
The expected load to be served.
7. The rating of a branch circuit supplying only store lighting shall not be less than which of the
following?
a.
b.
c.
d.
100 percent of the rating of the continuous load.
125 percent of the rating of the noncontinuous load.
300 percent of the starting load.
125 percent of the continuous load.
8. Branch circuit conductors and equipment shall be protected by an overcurrent protective
device having some noncontinuous load plus some continuous load shall have
overcurrent protection at which of the following?
a.
b.
c.
d.
100 percent of the continuous and 125 percent of the noncontinuous.
125 percent of the continuous and 100 percent of the noncontinuous.
150 percent of both loads.
250 percent of all loads.
9. Which of the following statements is/are permissible loads for branch circuits?
I- 15 or 20-ampere to supply to supply lighting units or other utilization
equipment
II- 40 and 50-ampere to supply cooking equipment and other utilization
equipment.
a. I only
c. both I and II
b. II only
d. neither I nor II
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10. Most rooms in dwelling units shall have receptacles installed so that no point along the
floor is more than which of the following?
a.
b.
c.
d.
12 feet from an outlet.
8 feet from an outlet.
3 feet from an outlet.
6 feet from an outlet.
11. At least one wall receptacle shall be installed in the bathroom of all dwellings at no more
than which of the following distance?
a.
b.
c.
d.
Within three feet of the basin.
Within three feet of the countertop.
Within three feet of the cabinet.
Within three feet of the GFCI.
12. A 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed at an
accessible location for the servicing of heating, air-conditioning, and refrigeration
equipment. The receptacle shall be located on the same level and within _____________ of the
heating, air-conditioning, and refrigeration equipment.
a. 25 feet.
b. In sight of
c.50 feet
d. none of the above
13. At the front and back of a two-family dwelling an outdoor outlet shall be
provided in which of the following manners?
a. At the point of exit, but not greater than 6 feet above grade.
b. Accessible from grade level and not more than 6 1/2 feet above grade level.
c. Accessible from the exit and not more than 3 feet above grade level.
d. Accessible from the HVAC system and not more than 6 feet away.
14. Appliance outlets installed in a dwelling unit for specific appliances, such as laundry
equipment, shall be installed within which of the following?
a.
b.
c.
d.
Within 3 feet of the intended location of the appliance.
Within 6 feet of the intended appliance.
Within 12 feet of the intended appliance.
Within 2 ft. 6 inches of the intended appliance.
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15. Balconies, decks and porches that are attached to the dwelling unit and are accessible from
inside the dwelling unit shall have at least one receptacle outlet installed within the
perimeter of the balcony, deck, or porch at not more than______ above the balcony, deck or
porch walking surface.
a.
b.
c.
d.
18ft
6.5ft
3ft
2ft
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BRANCH CIRCUITS
ARTICLE 210
Level 1
ANSWER KEY
1.
C
210.3
2.
a
210.5
3.
4.
5.
6. 3.
7.
8.
9.
10.
11.
12.
d
d
c
b, maximum
d, 125%
b
d
d, six
a, basin
a
13.
b
210.52(E)
14.
15.
b
b
210.50 (C)
210.52 (E)(3)
210.52 (C) (5) Ex to (5)
210.8(B) Ex.
210.8(A)(1-8)
210.19(A)(1)
210.19 (A)(1)
210.20(A)(1)
210.22
210.52(A)(1)
210.52(D)
210.63
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FEEDERS ARTICLE 215
LEVEL I
OBJECTIVE:
Each student should become acquainted with the installation requirements and minimum size and
ampacity of conductors for feeders supplying branch circuit loads.
INTRODUCTION:
The word “feeder” refers to all circuit conductors between the service equipment or the source of
a separately derived system and the final branch circuit overcurrent device.
The branch circuit loads are computed in accordance with Article 220.
PRESENTING THE LESSON:
Discuss and give examples of the following:
215.2 Minimum Rating and Size of Feeder Conductors.
(A) Ampacity for feeder conductors are computed by Part III, IV and V of Article 220. (A)(2) Feeder
conductors shall be sized to carry not be less than the load to be served:
215.3 Overcurrent Protection: See part I of Article 240
215.4 Feeders with Common Neutral Conductor.
(A) Up to 3 sets of 3-wire feeders or 2 sets of 4-wire or 5-wire feeders shall be permitted to contain
a common neutral.
(B) Feeders with a common neutral must be enclosed in the same raceway or enclosure
when the raceway or enclosure is metal.
215.6 Feeder and Grounding Means
215.9 Ground Fault Protection for Personnel: Explain the principle and emphasize why and where it is
most likely to be used.
APPLICATION:
If time will allow, let the class answer questions on the worksheet. CHECKING
AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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FEEDERS
ARTICLE 215
LEVEL I
WORKSHEET
1. Feeder conductors shall have an ampacity not lower than required to supply the load as
computed in which of the following parts of Article 220?
a.
b.
c.
d.
Part III, IV and V.
Part II, III and IV.
Part III and V.
Part V.
2. Feeders shall be protected against overcurrent in accordance with provisions of?
a.
b.
c.
d.
Part I of Article 240.
Part II of Article 220
Part III of Article 210
Part I of Article 310
3. Feeders containing a common neutral shall be permitted to supply which of the
following?
a.
b.
c.
d.
Two or three sets of 3 wire feeders.
Two sets of 4 wire feeders
Two sets of 5 wire feeders.
All of the above
4. A diagram showing feeder details shall be provided prior to the installation of the
feeders in which of the following circumstances?
a.
b.
c.
d.
If required by the authority having jurisdiction.
If required by the design professional.
If required by the Administration and Enforcement Code.
If required by the Department of Insurance.
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5. Where a feeder supplies branch circuits in which equipment grounding conductors are
required, the feeder shall provide a grounding means in accordance with which of the
following?
a. The provisions of 250.52
b. The provisions of 250.134
c. The provisions of 220.14
d. The provisions of 210.52
6. Feeders supplying 15 and 20 ampere receptacle branch circuits may be protected by which
of the following in lieu of regular GFCI outlets.
a.
b.
Ground fault circuit interrupter type 120/240 volt breakers.
Intrinsically safe systems breakers.
e. HID type circuit breakers.
f. SWD type circuit breakers.
7. The minimum size of the feeder circuit grounded conductor shall not be smaller than
the provisions given in which of the following?
a.
b.
c.
d.
Table 250.66 for the equipment grounding conductor.
Table 250.122 for the equipment ground.
Table 310.16 for the ungrounded conductor size.
Table 250.52 for the maximum size fused conductor.
8.Where a feeder supplies branch circuits in which equipment grounding conductors are
required, the feeder shall include or provide which of the following in accordance with the
provisions of 250.134, to which the equipment grounding conductors of the branch circuits
shall be connected.
a.
b.
c.
d.
a grounding electrode conductor
a neutral conductor
a common conductor
an equipment grounding conductor
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FEEDERS
ARTICLE 215
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
a. Parts III, IV and V
a.
d. all of the above
a.
b.
a.
b.
d.
Article 215.2 (A)(1)
215.3
215.4(A)
215.5
215.6
215.9
215.2 (A)(2)
215.6
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BRANCH CIRCUIT, FEEDER, AND SERVICE CALCULATIONS
ARTICLE 220
LEVEL I
OBJECTIVE:
Each student should become acquainted with the requirements for determining the number of
branch circuits required and for computing branch circuit, feeder, and service loads.
INTRODUCTION:
This lesson introduces the student to basic electrical formulas and methods used to determine
sizes of branch circuits, feeders, and services. Emphasis on the standard method and optional
method calculations will be used.
PRESENTING THE LESSON:
The relationship of amperes, ohms and volts can be expressed by the following formula
(known as Ohm’s Law).
I=E
R
I = the intensity of current flow in amperes
E = the electromotive force in volts R =
the resistance in ohms
Ohm’s Law can be modified to solve practical problems involving a house wiring circuit.
W=ExI
I = the intensity of current flow in amperes
E = the electromotive force in volts
W= the unit of power in watts
Thus, if we know that a lamp is 120 volts and 200 watts, the amperes flowing through it
can be found.
I = W/E = 200 watts = 1.66 amperes
120 volts
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When three-phase loads are calculated, the total wattage or volt-amperage is divided by phaseto-phase voltage times 1.732
The following values may be used:
For 208 volts x 1.732, use 360 volts For
230 volts x 1.732, use 398 volts
For 240 volts x 1.732, use 416 volts
For 480 volts x 1.732, use 831 volts
Lead the class through a calculation of a single-family dwelling using the standard method
and the optional method.
NEC references should be pointed out in each step of the calculation.
Example: Standard Method
(See examples - Annex D)
Given a 2,800 square foot dwelling with 120/240 volt single-phase service with the
following loads:
disposal @120 volts
compactor @120 volts
dishwasher @120 volts
attic fan @120 volts
clothes dryer @120/240 volts
range @120/240 volts
water heater @240 volts
electric space heater @240 volts
air conditioner @240 volts
The problem can be broken down into the following parts:
=
=
=
=
=
=
=
=
=
800 VA
600 VA
1,200 VA
1,080 VA
5,000 VA
12,000 VA
4,500 VA
15,000 VA
6,000 VA
1. Find the General Lighting Load. Use Table 220.12 to determine floor area. 220.12 says
that the floor area for each floor shall be computed from outside dimension of the
building but not including open porches, garages, or unused or unfinished spaces not
adaptable for future use.
2,800 sq. ft. x 3 VA = 8,400 VA
Section 210.11(C)(1)requires two or more 20-ampere small appliance branch circuits for
all receptacles in the kitchen, pantry, breakfast room, and dining room in a dwelling and
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Section 220.52 requires that each 2-wire small appliance branch circuit be computed at
1,500 VA. These loads may be included in the general lighting load.
Small Appliance Load:
2 @ 1,500 VA = 3,000 VA
Section 210.11(C)(2) requires at least one additional 20 ampere branch
circuit for the laundry and 220.52(B) requires each 2-wire laundry
branch circuit be computed at 1,500 VA. This may be included in the
general lighting load.
Laundry Load:
1 @ 1,500 VA = 1,500 V
gen. lighting 8,400VA, + small appl. 3,000VA + laundry 1,500VA =12,900VA
Minimum number of Branch Circuits Required General Lighting Load: I=E/R =
8,400VA/120VLTS = 70 AMPS
For 15 amp circuit: 70 ampere/15 amp circuit = 4.66 or 5 circuits
For 20 amp circuit: 70 ampere/20 amp circuit= 3.5 or 4 circuits
For General Lighting:
5.15 ampere 2 wire or
4.20 ampere 2 wire circuits
For small Appliances:
2.20 ampere 2 wire circuits
For Laundry:
1.20 ampere 2 wire circuits
For Bathroom Outlets:
1.20 ampere 2 wire circuit (no additional load)
Use Table 220.42 for demand factors,
3,000 VA @ 100% = 3,000 VA
3,001 to 120,000 @ 35%
12,900 to 3,000 = 9,900 @ 35% = 3,465 VA
General Lighting Load: 3,000 VA + 3,465 VA = 6,465 VA
2. Find the Cooking Equipment Load:
Review Table 220.55 explaining the use of columns A, B, and C and the notes to the
table.
Demand factor for one 12 KW range from Table
220.55 Column A: 12 KW = 8,000 VA Range Load = 8,000 VA
3. Find the Dryer Load:
Use Table 220.54
The load for household electric clothes dryers in a dwelling unit shall be 5,000 watts
(VA) or the nameplate rating whichever is greater.
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Demand factor for one 5KW dryer from Table
220.54 5,000 @ 100% = 5,000 VA Dryer Load = 5,000
VA
4. Find the Fixed Appliance Loads:
Section 220.53 allows a demand factor of 75% to the nameplate-rating load of four or
more appliances fastened in place or a feeder or service entrance for a residential dwelling.
Disposal
=
Compactor
=
Dishwasher
=
Attic Fan
=
Water Heater
=
TOTAL
=
Demand factor for 8,180 VA x 75% = 6,135 VA Fixed
appliance load = 6,135 VA
800 VA
600 VA
1,200 VA
1,080 VA
4,500 VA
8,180 VA
5. Find the Heating and/or Air Conditioning Load:
Section 220.60 allows omitting the smaller of two dissimilar loads where it is unlikely
they will be in use simultaneously.
Electric space heating @ 240 volts = 15 KW
Air conditioning @ 240 volts = 6 KW
Air conditioning load is smaller; therefore, it may be omitted
Section 220.51 requires that fixed electric space heating loads be computed at 100% of
the total connected load. Note and explain exception to Section 220.15.
Electric Space heating: 15,000 VA x 100% = 15,000 VA
6. Find Largest Motor Load:
Section 220.50 requires motor load to be computed in accordance with Sections
430.24, 430.25, and 430.26. Section 430.25 gives the requirement for motors and
combination loads (lighting and appliance loads). Sections 220.50 and 430.22 require
that 25% of the motor full load current be added to the total calculation for the
dwelling unit.
Largest motor is the attic fan @ 1,080 VA:
1,080 x 25% = 270 VA
7. Find the Service Load:
The service load is found by adding the loads found in the previous steps and dividing
by the applied voltage.
1. General Lighting Load =
6,465 VA
2. Range Load
=
8,000 VA
3. Dryer Load
=
5,000 VA
4. Fixed Appliance Load
=
6,135 VA
5. Heating Load
=
15,000 VA
6. Largest Motor Load
=
270 VA
TOTAL
=
40,870 VA
I = W/E = 40,870 VA = 170amps Service Load
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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240 Volts
8. Find the Neutral Load:
Section 220.61 requires that the feeder neutral load be the maximum unbalanced load
between the neutral and any one ungrounded conductor. A further demand factor of
70% is permitted for that portion of the unbalance load in excess of 200 amperes
except when that load consists of electric-discharge lighting data processing supplied
from a 4-wire, wye connected 3 phase system.
General Lighting Load from step 1
6,465 VA
Range Load from step 2
8,000 VA x 70% = 5,600 VA
5,600 VA
*Section 220.61 allows the maximum unbalanced load to be considered as 70% of the load
on the ungrounded conductors.
Dryer Load from step 3
5,000 VA x 70% = 3,500 VA
3,500 VA
*Section 220.54 allows the maximum unbalanced load to be considered as 70% of the
load on the ungrounded conductors. Fixed appliance load using only those that are
120 volt loads from step 4:
Disposal
Compactor
Dishwasher
Attic Fan
TOTAL:
Apply demand factors of Table 220.42:
3,680 VA x 75% Largest
Motor Load from step 6
Attic fan = 1,080 VA x 25% =
800 VA
600 VA
1,200 VA
1,080 VA
3,680 VA
2,760 VA
270 VA
18,595 VA
I = W/E = 18,595 VA = 77.48 amperes Neutral Load = 77 amps
240 Volts
Example #1: Optional Method
Section 220.82 permits the feeder and service load for a dwelling unit having the total
connected load served by a single 3-wire 120/240 volt or 208Y/120 volt set of serviceentrance or feeder conductor with an ampacity of 100 or greater computed in
2014 NEC Instructor Manual and Student Worksheets -- Level 1
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accordance with an optional method instead of the method specified in Part II of this
article.
There are two loads that are calculated when applying the optional method: Use
220.82. Other loads and remainder of other loads.
1,500 VA for each 20 ampere small appliance branch circuit:
1,500 VA x 2 = 3,000 VA
1,500 VA for each 20 ampere laundry branch circuit:
1,500 VA = 1,500 VA
Note: No load is added for bathroom outlets 3
VA per sq. ft x 2,800 sf = 8,400 VA
Nameplate rating of all fastened in place appliances, ranges, wall-mounted ovens, and
counter mounted cooking tops.
Disposal
Compactor
Dishwasher
Attic Fan
Clothes Dryer
Range
Water Heater
2 Small Appliance Circuits
1 Laundry Circuit
TOTAL:
Apply demand factors from 220.82(B)
Total Load
Less First: 10,000 VA @ 100%
800 VA
600 VA
1,200 VA
1,080 VA
5,000 VA
12,000 VA
4,500 VA
3,000 VA
1,500 VA
38,080 VA
38,080 VA
- 10,000 VA
28,080 VA
Next: 28,080 VA @ 40%
= 11,232 VA
Next: Add back first 10,000 VA + 10,000 VA
21,232 VA Heating
or Air Conditioning Load:
The smaller of the heating or air conditioning load is dropped after applying the demands as
specified in 220.82(C). Compare Heating and Air Conditioning
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Central Electric Space Heating:
15,000 VA x 65% = 9,750 VA Air
Conditioning:
6,000 x 100% = 6,000 VA
Electric Space Heating is largest: 9,750 VA
21,232 + 9,750 = 30,292 VA
I = W/E = 30,292 VA = 129.09 amperes Service Load
240 volts
Service Load = 129 amperes
The Neutral Load is permitted to be calculated as determined by Section 220.61;
therefore, the Neutral Load is the same as calculated in the standard method.
Example #2: Optional Method
Section 220.82 permits the feeder and service load for a dwelling unit having the total
connected load served by a single 3-wire 120/240 volt or 208Y/120 volt set of serviceentrance or feeder conductor with an ampacity of 100 or greater computed in
accordance with Section 220.82 instead of the method specified in Part II of this article.
There are two loads that are calculated when applying the optional method: Use
220.82. Other loads and remainder of other loads.
1,500 VA for each 20 ampere small appliance branch circuit:
1,500 VA x 2 = 3,000 VA
1,500 VA for each 20 ampere laundry branch circuit:
1,500 VA = 1,500 VA
Note: No load is added for bathroom outlets
3 VA per sq. ft x 2,800 sq. ft. = 8,400 VA
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Nameplate rating of all fastened in place appliances, ranges, wall-mounted ovens, and
counter mounted cooking tops.
Disposal
800 VA
Compactor
600 VA
Dishwasher
1,200 VA
Attic Fan
Clothes Dryer
Range
Water Heater
TOTAL:
1,080 VA
5,000 VA
12,000 VA
4,500 VA
25,180 VA
26,500 VA
38,080 VA
Apply demand factors from 220.30(B)
First: 10,000 VA @ 100% =
10,000 VA
Next: 29,400 VA @ 40% =
11,760 VA
21,760 VA
Heat Pump Compressor with supplemental heat operating at the same time:
See Section 220.82(C)
Compare Heating and Air Conditioning
Supplemental heat:
15,000 VA x 100% = 15,000 VA
Heat Pump Compressor:
6,000 x 65% = 3,900 VA
I = W/E = 40,660 VA = 169.4 amps
240 Volts
Service Load = 169 amperes
APPLICATION:
If time allows, let the class time to answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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BRANCH CIRCUIT, FEEDER, AND SERVICE CALCULATIONS
ARTICLE 220
LEVEL I
WORKSHEET
1.
Given a 3,200 sq. ft. dwelling with 120/240V, single phase. Find the minimum lighting
load demand for the General Lighting.
a.
b.
c.
d.
2.
What is the load for one 9-KW range?
a.
b.
c.
d.
3.
9 KW
8 KW
6.3 KW
12 KW
How many two wire branch-circuits are required in an 1,800 sq. ft. dwelling with three
bathrooms? The dwelling is supplied by a 120/240V, single phase service.
a.
b.
c.
d.
4.
14,100 VA
4,935 VA
9,600 VA
6,885 VA
3-15 ampere branch circuit and 4-20 ampere branch circuits
5-20 ampere branch circuit
4-15 ampere branch circuit and 2-20 ampere branch circuits
6-15 ampere branch circuits
Given a 2,800 sq. ft. dwelling with 120/240V, single phase service and the following
loads:
Range
= 12,000 VA
Dryer
=
5,000 VA
Water Heater
=
4,500 VA
Dishwasher
=
1,200 VA
15 KW Central Heating
= 15,000 VA
Air Conditioning
=
6,000 VA
Find the Service Load using the Standard Calculation. a. 200
amperes
b. 100 amperes
c. 167 amperes
d. 130 amperes
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5.
Given the same information as in problem #4, find the Neutral Load.
a.
100 amperes
b.
69.8 amperes
c.
116.9 amperes
d.
65 amperes
6.
Given the same information as in Problem 4, compute the service load using the
Optional Calculation.
a.
b.
c.
d.
7.
Using the optional method of calculation, determine the load that would be added to
the service for a 3 HP, 240, volt, single phase heat pump compressor with supplemental
heating rated at 15 KW. The control circuitry is not interlocked to prevent the heat
pump compressor and the supplemental heating from operating at the same time.
a.
b.
c.
d.
8.
189 amperes
150 amperes
125 amperes
169 amperes
17 amperes
19.6 amperes
57.63 amperes
62.5 amperes
Proper calculations for Electrified Truck Spaces are found in:
a.
b.
c.
d.
Article 220
Article 626
Article 511
Article 551
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BRANCH CIRCUIT, FEEDER, AND SERVICE CALCULATIONS
ARTICLE 220 LEVEL I
ANSWER KEY
1.
2.
3.
4.
d, 6,885 VA
({[(3200 x 3) + 3,000 + 1,500] - 3,000} x 35%) + 3,000 = 6,885
b, 8 KW
(Table 220.55)
a, 3-15 ampere branch circuit and 4.20 ampere branch circuits
([1,800 sq. ft. x 3 VA per sq. ft.]/120)/15 = 3.15 ampere branch circuit plus 4-20 amp
c, 167 amperes
2,800 x 3 = 8,400
4,500
12,900 - 3,000 = 9,900
9,900 x 35% = 3,465 + 3,000 = 6,465 General Lighting
8,000 Range
5,000 Dryer
4,500 Water Heater
1,200 Dishwasher
15,000 Heat
40,165 TOTAL
40,165/240 = 167 amps
5.
b, 69.8 amperes
6,465 General Lighting
8,000 x 70% = 5,600 Range
5,000 x 70% = 3,500 Dryer
1,200 Dishwasher
16,765
16,765/240 = 69.8 amps
6.
c, 125 amperes
HEAT 15,000 x .65 = 9750 VA (AC = 6,000 VA) HEAT is larger
Other Load
2800 x 3 = 8,400 VA Small Appliances
= 3,000
Laundry
= 1,500
Range
= 12,000
Dryer
= 5,000
Water Heater
= 4,500
Dishwasher
= 1,200
35,600
(35,600 . 10,000) x .40 = 10,240
10,240 + 10,000
= 20,240
20,240 + 9,750
= 29,990
29,990/240
= 124.95
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7. c
240 volts x 17 amperes = 4,080 VA @ (100%)
.65 x 15,000
= + 9,750 VA
13,830 VA
13,830/240
= 57.63 amperes
220.82 (C), Table 430.248
8. b. Article 626
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ARTICLE 225 LEVEL I
OBJECTIVE:
Each student should become familiar with electrical equipment and wiring located on the outside
of buildings, structures or poles on the premises served.
INTRODUCTION:
Circuits run on the exterior of buildings or between buildings and or other structures are
considered outside branch-circuits or feeder. For example, circuits supplying parking lot lighting are
cover by Article 225. There are many other Articles in the Code that deal with outside circuits and
they should also be consulted when the need arises. One such example is the wiring around a
swimming pool.
PRESENTING THE LESSON:
In order to determine the load on outdoor branch circuits you should consult with Article 220.
Also, the load on outdoor feeders shall comply with Part II of Article 220.
Where open wiring on insulators is within 10 feet of buildings it shall be covered or insulated.
See Section 225.4 for different types of coverings for various situations.
See Tables 310.16 through 310.31 for information on conductor sizes. Conductor minimum sizes
for overhead conductors 600 volts, nominal or less shall be No. 10 copper or No. 8 aluminum for spans
up to 50 feet in length and No. 8 copper or No. 6 aluminum for longer spans.
Festoon lighting is a string of outdoor lights suspended between two points. For such lighting
overhead conductors shall not be smaller than No. 12. unless supported by messenger wires. See
Section 225.14 for more information on festoon lights. (225.6)
When lighting equipment is installed outdoors, the branch-circuits shall comply with Article 210
and 225.7(B-D).
The disconnecting means for branch circuits and feeder fuse shall be in accordance with Section
240.40 and overcurrent protection shall be in accordance with Section 210.20 for branch circuits and
Part I of Article 240 for feeders.
Where more than one disconnecting means is provided at structures other than dwelling
units a plaque or directory must be installed at each disconnect location.
The restrictions on wiring for outside wiring surfaces of buildings are covered in Section 225.10.
When dealing with circuit entrances and exits, see the requirements listed in Section 230.52, and 54.
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See Table 230.51(C) for open conductor spacing. Open conductors of different circuits
shall be separated by not less than 4 inches. For information on the separation of conductors
on poles see Section 225.14(D).
Supports over buildings, points of attachment, and means of attachment are covered in
Section 230.29, 26, and 27 respectively. Ground clearances are outlined in Section 225.18.
Conductor clearances from buildings of not over 600 volts, nominal have several
requirements. Conductors that are not adequately insulated for normal operating voltage
shall have an 8 foot vertical or diagonal clearance from a roof surface unless they meet one of
the 4 exceptions listed in Section 225.19(A). Clearances from non-bridge or non-building
structures such as signs, chimneys, etc. shall not be less than 3 feet for conductors in vertical,
diagonal or horizontal positions.
Horizontal clearances shall not be less than 3 feet for conductors. Final spans of feeders
or branch circuits to a building shall be permitted to be attached to the building if kept 3 feet
from windows, doors, porches, fire escapes or similar locations; however, when conductors
run above a window it shall be permitted to be less than 3 feet. See Section 225.19(E) for
clearances in zones for fire ladders.
Other various Articles should be consulted concerning mechanical protection and
multiconductor cables and raceways on exterior surfaces of buildings. Underground circuits
shall comply with Section 300.5.
Outdoor lampholders when attached as pendants, the connection shall be
staggered. Also, if terminals that puncture the insulation of conductors are used to make
contact, they should only be used on stranded type conductors. See Section 225.25 for
location of outdoor lamps. (225.24)
Live vegetation, such as trees may not be used to support overhead conductor spans or
other electrical equipment, except when used in accordance with Article 590 concerning
temporary wiring. (225.26) See 410.16(H) for support of outdoor lighting fixtures in trees.
APPLICATION:
If time allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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OUTSIDE BRANCH CIRCUITS AND FEEDERS
ARTICLE 225
Level I
WORKSHEET
1. When without messenger wires, overhead conductors for festoon lighting shall not
be smaller than:
a.
b.
c.
d.
2.
#14
#12
#10
#8
Overhead conductors for 600 volts and less installations, up to 50 feet in length
and not supported by a messenger wire, shall be a minimum size in copper of:
a.
b.
c.
d.
#12
#8
#10
#6
3. Open conductors of a 480/277 volt overhead feeder shall have a minimum clearance
over a residential driveway of:
a.
b.
c.
d.
4.
10 feet
12 feet
15 feet
18 feet
Open conductors on insulators shall be insulated or covered, if they are installed
within how many feet of a building or other structure?
a.
b.
c.
d.
10 feet
12 feet
15 feet
18 feet
5. Festoon lighting shall be supported by a messenger wire if the span exceeds:
a.
b.
c.
d.
15 feet
18 feet
25 feet
40 feet
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6. When conductors run above a window they shall be permitted to be less than which of
the following distance from the window?
a.
b.
c.
d.
3 feet
6 feet
5 feet
10 feet
7. Which of the following may not be used to support overhead conductor spans?
a.
b.
c.
d.
brackets
live vegetation
poles
racks
8. More than one feeder or branch circuit is permitted, by the NEC, to supply a
building or structure, for all the reasons listed below with the exception of
power for which of the following?
a.
b.
c.
d.
convenience
fire pumps
enhanced reliability
optional standby systems
9. Raceways on the exterior of buildings shall be arranged to drain and shall be
raintight
in wet locations. Which of the following conduits may not be installed outside?
a.
b.
c.
d.
RMC
IMC
FM C
P VC
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OUTSIDE BRANCH CIRCUITS AND FEEDERS ARTICLE 225
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
b, #12
c, #10
b, 12 feet
a, 10 feet
d, 40 feet
a
b. live vegetation
a, convenience
c.
225.6(B)
225.6(A)(1)
225.18(2)
225.4
225.6(B)
225.19(D)(1) exception]
225.26
225.30(A)
225.22
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SERVICES
ARTICLE 230
LEVEL I
OBJECTIVES:
Each student should become familiar with the NEC requirements for electrical services.
INTRODUCTION:
This lesson will cover areas relating to services including service conductors and service
equipment.
PRESENTING THE LESSON:
230.1
Explain "service" definitions in Article 100.
230.2
The general rule on services is that only one service is allowed per building. There are six
exceptions to this rule.
(1)
(2)
(3)
(4)
(5)
(6)
Fire pumps
Emergency systems
Legally required standby systems
Optional standby systems
Parallel power production systems
Systems designed for connection to multiple sources of supply for the purpose of
enhanced reliability.
230.3
Service conductors shall not pass through the interior of another building or structure.
230.6
When applying the Code to service conductors, conductors shall be considered outside the
building if under 2 inches of concrete beneath the building, within a building in a conduit
encased with 2 inches of concrete or brick, in an approved transformer vault, installed in
conduit and under not less than 18 inches of earth beneath a building or other structure, and
when RMC or IMC passes directly through the eave, but not the wall of the building.
230.7
Conductors on the load side of the main overcurrent device shall not be run in the same
raceway with service conductors.
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230.9 (A)-(C)
Service conductors shall not be located within 3 feet of windows, doors, porches, fire escapes,
or similar locations. This applies only to open conductors and conductors emerging from
conduits and cable assemblies. If conductors are run above the top of a window, they will be
out of the 3 feet area. These conductors shall not be located below or obstruct the entrance.
230 Part II
Service overhead conductors to a building or other structure (such as a pole) on which a meter
or disconnecting means is installed shall be considered as a service drop and installed
accordingly. See definition of “service drop”.
230.22
Individual conductors shall be insulated or covered. (see exception)
230.23(A)-(C)
Conductors shall be a sufficient size to carry the load served and except in the case of limited
loads of a single branch circuit, not smaller than #8 copper or #6 aluminum. In the case of a
single branch circuit, the conductors shall not be smaller than #12 or equivalent. Grounded
conductors to be sized per 250.24(C).
230.24(A)
Service conductors that pass over a roof shall have a clearance of 8 feet from any point which it
crosses with four exceptions. See 230.24(A)(1)-(5).
Area above a roof subject to pedestrian or vehicular traffic shall meet the same requirements
for conductor clearance as any other.
230.24(B)(1)-(4)
Clearance of service conductors to final grade when the voltage is less than 600 volts shall
match the following:
1. 10 feet- clearance to drip loop from final grade above sidewalks and other areas
subject to pedestrians when limited 150 volts to ground.
2. 12 feet - same as 15 feet when limited to 300 volts to ground.
3. 15 feet - over residential property, driveways and commercial areas not subject to truck
traffic.
4. 18 feet - public streets, alleys, roads, parking areas subject to truck
traffic, driveways on other than residential property, and other areas
traversed by vehicles, such as those used for cultivation, grazing, etc.
230.26
The point of attachment shall be no less than 10 feet from grade.
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230.30,31,32 & 33
Underground service laterals shall meet the same requirements as overhead conductors for
insulation and size and shall be protected from physical damage.
230.40
The general rule for service entrance conductors is that each service drop shall supply only
one set. There are five exceptions. Review these exceptions.
230.41
Service entrance conductors shall be insulated. The grounded conductor may be uninsulated in
the following cases: (a) bare copper in a raceway or cable; (b) bare copper for underground
direct burial where judged suitable for soil conditions; (c) direct burial without regard to soil
conditions when part of an approved direct burial cable; and (d) aluminum or copper clad
aluminum when part of a cable assembly or identified for underground use or direct burial.
230.42b
In addition to the requirements of 230.42(A), the minimum ampacity for ungrounded
conductors for specific installations shall not be less than the rating of the service
disconnecting means specified in 230.79(A) through (D).
230.43
The wiring method for service entrance conductors shall comply with 230.43.
230.46
Unless otherwise approved by exceptions, you cannot splice service entrance conductors.
See exceptions to 230.46
230.50(B)(1)
Service entrance conductors above ground shall be protected against physical damage in
one of the following ways:
1. rigid metal conduit
2. Intermediate metal conduit
3. PVC schedule 80
4. EMT
5. Reinforced thermosetting resin conduit 6. Other approved means
230.50(B)(2)
Open conductors and cables other than service entrance cables shall not be installed within
10 feet of grade level with the exception of MI and MC cable.
230.51(A)
SE cables shall be supported every 30 inches and within 12 inches of a service head
gooseneck or raceway connection. Open conductors exposed to weather
shall be on insulating supports, racks, or brackets. If not exposed to weather on glass, on glass
or porcelain knobs. Both the above shall be spaced and maintain the clearances in Table
230.51(C).
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230.52
Open conductors must enter a building through open tubes slanted upward when
going through a wall. When entering through the roof, they must enter through
bushings, drip loops must be used.
230.53
Where subject to moisture, raceways shall be rain-tight and arranged to drain.
230.54
Service heads connecting to a raceway must be rain-tight. If run in cable, a service head
that is rain-tight or gooseneck must be used. In the case of a gooseneck, it must be
taped and sealed. Service heads must be located above the point of attachment or in
case this cannot be done, not more than 24 inches from service head. Conductors of
opposite polarity shall not be brought through the same hole. Drip loops shall be made
to prevent entrance of moisture.
230.56
The outer covering of the conductor in a high-leg system that has the highest voltage
to ground shall be colored orange. This high leg occurs when you have a delta
connected service and the mid-point of one phase is grounded.
230.62
Service equipment must have live parts protected from accidental contact by either
guarding or by meeting clearance requirements of Sections 110.18 and 110.27 and
have doors that can be locked.
230.66
Service equipment rated at 1000 volts or less shall be marked to identify it as
being suitable for use as service equipment.
230.70
Service disconnect means shall be located nearest the point of entrance at a readily
accessible location either inside or outside of the building. It must be marked and
identified as service equipment and must be approved for conditions. See and
handout DOI interpretation of 230.70(A).
230.71
There shall not be more than six disconnects per service or per set of service entrance
conductors. These disconnects shall be grouped in one enclosure or in up to six separate
enclosures. Two or three single pole switches or breakers capable of individual operation
used as a multiwire circuit, tied together with handle ties can be considered as one
disconnect.
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230.72(C)
In multiple occupancy buildings other than ones in which electric service and
maintenance are provided and accessible only to qualified persons, the service
equipment must be accessible to each occupants.
230.74 & 230.75
All ungrounded conductors must be disconnected at the same time. The neutral must
also be capable of being disconnected. The most common way is by a lug on the neutral
bar.
230.77
The disconnect shall be externally operable so as not to expose the operator to live
parts and shall plainly indicate whether it is open or closed.
230.79
Rating of service disconnects shall be determined by Article 220 but in no case less
than the following: (A) 15 amperes for limited loads of a single circuit, (B) 30 amperes
for two 2-wire branch circuits, (C) for single family dwelling 100 amperes 3 wire in (1)
computed loads of 10 KVA or more (2) six two wire circuits, (D) all others 60 amperes.
230.80
The combined rating of all disconnects shall not be less than that would be
required for a single disconnect.
230.82
Review this section thoroughly.
230.90
Each ungrounded service conductor shall be provided an overcurrent device in series
with that conductor for overload protection. The only exceptions to this rule would be as
provided elsewhere in the Code or for fire pumps which are capable of carrying locked
rotor current indefinitely. The neutral shall not be broken through an overcurrent device
unless, at the same time, breaking all ungrounded conductors.
230.91
Service overcurrent device shall be an integral part of the service disconnecting means
or adjacent to it.
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230.92
Where service overcurrent devices are locked or are not readily accessible, branch
circuit overcurrent devices shall be on the load side in an accessible location and
shall be of a lower ampere rating than the service overcurrent device.
230.95
Solidly grounded wye structures at more than 150 volts to ground and not over 600
volts phase-to-phase shall be required to have ground fault protection at each service
disconnect means rated 1,000 amperes or more. It shall open all ungrounded
conductors with a maximum setting of 1,200 amperes with a time delay of one second
for each fault current equal to or greater than 3,000 amperes. If a combination of switch
and fuse is used, the fuse shall be capable of interrupting any current higher than the
interrupting capacity of the switch during the time the ground fault system will not
cause the switch to open.
See two exceptions. Also note that Section 230.95(c) requires performance testing.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW UP :
If time allows, correct the worksheets and discuss the results.
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SERVICES
ARTICLE 230
LEVEL I
WORKSHEET
1. Without exception, what is the total number of services allowed on a building?
a. 1
b. 2
c. 3
d. 4
2. Conductors shall be considered outside of the building when installed by the following:
a. rigid conduit
b. in a service entrance cable inside the building encased in 2 inches of
concrete
c. in a transformer vault conforming to Article 450
d. where run under the building without conduit
3. Service conductors shall maintain a distance from a window of?
a.
b.
c.
d.
2 feet
3 feet
4 feet
5 feet
4. Minimum size of overhead service entrance conductors is:
a.
b.
c.
d.
#6 copper or #6 aluminum
#8 copper or #6 aluminum
#10 copper or #8 aluminum
#8 copper or #8 aluminum
5. Where conductors are rated at 120/208 volts and crosses only 3 feet of roof
overhang and terminates at rigid conduit, the clearance above the roof is:
a. 10 inches
b. 12 inches
c. 14 inches
d. 18 inches
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6. Service drop conductors must have a vertical clearance above a public street of:
a. 10 feet
b. 12 feet
b. 12 feet
d. 18 feet
7. The minimum size service disconnecting means to a single family dwelling is:
a. 100 amperes
b. 125 amperes
b. 125 amperes
d. 200 amperes
8. Service entrance conductors can be spliced in the following:
a. metering equipment
b. in a junction box going to a service disconnect
b. inside the service disconnect d. all of the above
9. Service entrances cables must be secure in accordance with which of the following?
a. 24 inches
c. 36 inches
b. 30 inches
d. 48 inches
10. What is the maximum number of service disconnects allowed for a service?
a. 4
c. 6
b. 5
d. 7
11. Ground fault protection is required on a solidly grounded wye system if over 150
volts to ground if the service disconnect is rated at greater than______ amperes.
a. 800
c. 2,000
b. 1,000
d. 3,000
12. More than one service is permitted on a building or structure for all the
reasons listed below with the exception of?
a. convenience
c. enhanced reliability
b. fire pumps
d. optional standby systems.
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SERVICES
ARTICLE 230
LEVEL I
ANSWER KEY
1. a, 1
230.2
2. c, in a transformer vault conforming to Article 450
230.6
3. b, 3 feet
230.9
4. b, #8 copper or #6 aluminum
230.23(B)
5. d, 18 inches
230.24(A) exc. #3
6. d, 18 feet
230.24(B)
7. a, 100 amperes
230.79(C)
8. d
230.46
9. b, 30 inches
230.51(A)
10.c,6
230.71(A)
11. b,1000
230.95
12. a, convenience
230.2
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OVERCURRENT PROTECTION
ARTICLE 240
LEVEL I
OBJECTIVES:
At the conclusion of this lesson each student should have gained:
1. an understanding that in electrical work every circuit must be provided with overcurrent
protection.
2. knowledge of the National Electrical Code 2014 standard ampere ratings.
3. knowledge about applications of overcurrent protection.
MATERIALS NEEDED:
1. Samples of different types of fuses and circuit breakers.
2. Handouts or pictures of the above.
INTRODUCTION:
In electrical work every circuit must be provided with overcurrent protection. It may be a 13,200
volt transmission line carrying 200 amperes, or it may be a 120 volt lighting circuit carrying a load of 10
amperes. Each must have some form of protective device for the possible overload of current for the
protection of both circuits and equipment.
We know that excessive current may seriously damage electrical equipment, motors, instruments,
radio receivers, etc. Fuses and circuit breakers are cheap compared with the equipment you are
protecting. When the fuse which is connected in series with equipment is blown, the circuit will open
before the excessive current damages the equipment.
It is important that you always use fuses or circuit breakers with proper current ratings. In
protecting equipment, to use fuses with too low current rating will result in unnecessary blowouts
while one with too high current rating may allow dangerously high currents to pass.
Fuses are used for protection so never jump out a fuse. Do not increase the size of a fuse unless
and until you are sure it would be in compliance with the NEC.
In this lesson we will be studying parts I through VII of Article 240 in which we are primarily
concerned with the simple circuits requiring the common types of overcurrent protective devices such
as, the plug fuse, circuit breakers and cartridge fuses.
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PRESENTING THE LESSON:
The list of Articles shown in Table 240.3 is the specific Articles that cover
protection of equipment. You can refer to this list to find what Article covers the
protection of a specific piece of equipment.
Emphasize that once the derating of any conductor occurs, that Section 240.4 (B) does
not apply. The derated wire must not be attached to the next higher rated overcurrent
device, but must be set back to the next LOWER OCPD.
In general, conductors other than flexible cords and fixture wires, shall be protected
against overcurrent in accordance with their ampacity as specified in Tables 310.16 through
310.19 and their notes.
Flexible cord shall be protected against overcurrent in accordance with their
ampacity listed in Table 400.5.
Fixture wire shall be protected against overcurrent in accordance with its
ampacity as shown in Table 402.5.
You should study and be familiar with the standard ampere ratings for fuses and
inverse time circuit breakers listed in Section 240.6.
Fuses or circuit breakers or combinations thereof shall not be connected in
parallel unless they are factory assembled and approved as a unit.
A thermal cutout, thermal relay, or other thermal device designed to protect motor
branch circuit conductors from overload and not designed to open short circuits shall not be
used to protect conductors against overcurrent due to short circuits or grounds.
Supplementary overcurrent protection shall not be used as a substitute for branch
circuit overcurrent devices. Supplementary overcurrent devices do not have to be readily
accessible.
Review the importance of electrical system coordination. (240.12)
In general, an overcurrent device shall be connected in series with each
ungrounded conductor. Circuit breakers shall open all ungrounded conductors of the circuit.
Listed devices providing equivalent protection in closed-loop power distribution
systems shall be permitted as a substitute for fuses or circuit breakers.
Read Section 240.21, in its entirety, to the class and discuss.
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No overcurrent device shall be connected in series with any conductor that is
intentionally grounded (neutral) unless it is so designed so that no pole can operate
independently and it opens all conductors of the circuit. There is also an exception for motor
overload protection.
Where a change occurs in the size of the ungrounded conductor, a similar change shall
be permitted to be made in the size of the grounded conductor.
Overcurrent devices shall be readily accessible with the exception of busways,
supplemental overcurrent devices, service equipment as covered in Section 230.92 and
overcurrent devices located adjacent to the equipment they supply.
Except for multiple occupancy building and guest rooms in hotels and motels under
continuous management supervision, overcurrent devices shall be readily accessible to
the occupants.
Overcurrent devices shall be located where they will not be exposed to physical
damage or located in the vicinity of easily ignitable material such as in clothes closets. Branch
circuit, Service and Feeder overcurrent devices are not allowed in bathrooms located in
dwelling units or guest rooms of hotels and motels.
Unless part of an assembly that provides equivalent protection or mounted on opentype switchboards, panelboards, or control boards, overcurrent devices shall be enclosed in
cabinets or cutout boxes.
If installed in damp or wet locations enclosures for overcurrent devices shall be
identified for use in such locations and shall be mounted at least 1/4 inch off its supporting
surface.
Enclosures for overcurrent devices shall be mounted in a vertical position unless it is
shown to be impracticable.
If accessible to other than qualified persons disconnecting means shall be provided on
the supply side of all fuses or thermal cutouts in circuits of over 150 volts to ground and
cartridge fuses in circuits of any voltage so that each individual circuit contains fuses or
thermal cutouts can be independently disconnected from the source of electric energy. Note
the two exceptions to this in Section 240.40.
Fuses and circuit breakers shall be so located or shielded that persons will not be
injured by their operation or movement of their handles or levers.
Plug fuses and fuseholders shall not be used in circuits exceeding 125 volts between
conductors except in circuits supplied by a system having a grounded neutral and having no
conductor at over 150 volts to ground.
Each fuse, fuseholder, and adapter shall be marked with its ampere rating.
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When the fuse is installed there shall be no live parts exposed.
Plug fuses of 15 ampere and lower rating shall be identified by a hexagonal
window or cap.
The screw shell of a plug-type fuseholder shall be connected to the load side of the
circuit.
Edison-base plug fuses shall be classified at not over 125 volts and 30 amperes and
below. They shall be used only for replacements in existing installations where there is no
evidence of overfusing or tampering. Emphasize this concept!
Edison-base fuseholders shall be installed only where they are made to accept Type S
fuses by the use of adapters. (240.52)
Type S fuses shall be classified at not over 125 volts and 0 to 15 amperes, 16 to 20
amperes, and 21 to 30 amperes. They shall not be interchangeable with a lower ampere
classification and so designed that they can not be used in any fuse holder other than Type S
fuseholders or adapters. [240.53 (A) (B)]
Type S fuseholders and adapters shall be designed so that no fuse other than a Type S
fuse can be used in them. Type S adapters shall fit Edison-base fuse holders and shall be so
designed that once inserted in a fuseholder, they cannot be removed. Type S fuse, fuseholders,
and adapters shall be so designed that tampering or shunting (bridging) would be difficult.
They shall be standardized to permit interchangeability regardless of manufacturer. [240.54 (AE)]
Cartridge fuses and fuseholders of the 300 volt type shall not be used in circuits of over
300 volts between conductors except in circuits supplied by a system having a grounded
neutral and having no conductor at over 300 volts. [240.60(A)]
0 - 6000 ampere fuseholders shall be so designed that it will be difficult to put a fuse of
any given class into a fuseholder that is designed for a current lower or voltage higher than
the class to which it belongs. Fuseholders for current limiting fuses shall not permit insertion
of fuses that are not current limiting. [240.60(B)]
Fuses shall be plainly marked showing the following:
1. ampere rating
2. voltage rating
3. interrupting rating where other than 10,000 amperes
4. "current limiting" where applicable
5. name or trademark of the manufacturer.
Cartridge fuses and fuseholders shall be classified according to voltage and amperage
ranges, fuses rated 600 volts, nominal or less, shall be permitted to be used for voltages at
or below their ratings.
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Circuit breakers shall be trip free and capable of being closed and opened by manual
operation. They can be operated by other means as electrical or pneumatic if manual
operation is also provided.
Circuit breakers shall clearly indicate whether they are open "off" or closed "on". If
operated vertically, the "up" position of the handle shall be the "on" position. Refer back to
Sections 240.33 and 240.81.
A circuit breaker shall be designed to require dismantling or breaking of a seal for any
alteration of its trip point or the time required for its operation for other than intended
adjustments.
Circuit breakers shall be marked with their ampere rating in a manner that will be
durable and visible after installation. If rated at 100 amperes or less and 600 volts or less they
shall be marked into their handle. When other than 5,000 amperes the interrupting rating shall
be shown on the circuit breaker.
When used as switches in l20-volt and 277-volt fluorescent lighting circuits, circuit
breakers shall be marked "SWD" or HID. High-intensity discharge lighting circuits shall be
listed and shall be marked HID. [240.83(D)]
It should be noted that circuit breakers with a slash voltage rating (for example
120/240V) should not be applied in circuits where the voltage to ground exceeds the lower
of two voltage ratings.
Temperature ratings of circuit breakers should be discussed at some point while on the
subject of circuit breakers.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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OVERCURRENT PROTECTION ARTICLE
240
LEVEL I
WORKSHEET
1. Which of the following is provided for conductors and equipment to open the circuit if
the current reaches a value that will cause an excessive or dangerous temperature in
conductors or conductor insulation.
a.
b.
c.
d.
Thermal overload devices.
Thermistors in wiring devices.
Overcurrent protection devices.
Heat detectors in line fuses.
2. Plug fuses shall be marked with which of the following?
a.
b.
c.
d.
Heat value
Ampere rating
Circular mils
Minimum circuit ampacity
3. When are fuses allowed to be connected in parallel.
a.
b.
c.
d.
When installed in the field.
When factory assembled
When required by the Electrical Inspector
When required by the Electrical provider.
4. Which of the following are two types of fuses.
a.
b.
c.
d.
Plug and Cartridge
Load and Thermal
Screwshell and Keyless
GFCI and GFI
5. Plug fuses shall not be rated over which of the following volts?
a.
b.
c.
d.
125 volts
600 volts
300 volts
400 volts
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6. Over current devices shall be readily accessible and shall be installed so that the center
of the grip of the operating handle of the switch or circuit breaker, when in its highest
position, is not more than which of the following above the floor or working platform
unless one of the following applies
a
b
c
d
.
.
.
.
6’7”
8’6”
6’
7’6”
7. The screw shell of a plug-type fuseholder shall be connected to which side of the
circuit?
a.
b.
c.
d.
The line side.
The other side.
The load side
The high side
8. An overcurrent device shall be connected with each grounded conductor in which of the
following manners.
a.
b.
c.
d.
parallel
sequentially
thermally
series
9. In general, overcurrent devices shall be located in accordance with which of the
following?
a.
b.
c.
d.
Where the conductors receive their supply.
Where the conductors are connected the appliance.
Where the service lateral originates.
Where the service lateral terminates.
10. A feeder consists of two 500 kcmil THW copper conductors connected in parallel. The
maximum rating of the overcurrent device protecting the feeder is:
a.
b.
c.
d.
800 amperes
600 amperes
750 amperes
400 amperes
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11. When overcurrent devices are installed, they shall be located in which of the
following type locations?
a.
b.
c.
d.
accessible
readily accessible
easily accessible
nearly accessible
12. When overcurrent devices are installed, they shall not be installed so as to be which of
the following?
a.
b.
c.
d.
Subject to physical damage.
Exposed to physical damage.
Exposed to sunlight.
Exposed to radiation.
13. Circuit breakers may be capable of being electrically opened if they are also
capable of being opened in which other manner?
a.
b.
c.
d.
Electronically
Normally
Separately
Manually
14. Which of the following four items of information are not required on each
cartridge fuse?
a.
b.
c.
d.
amperage rating
date of manufacture
voltage rating
interrupting rating
15. Which of the following is not a standard ampere rating for a circuit breaker?
a.
b.
c.
d.
25 amperes
110 amperes
45 amperes
55 amperes
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16. The ampacity of a conductor, 21 feet in length, that is tapped to a feeder protected by a
400 ampere fuse shall not be less than which of the following ampere ratings?
a. 40 amperes
b. 100 amperes
c. 133 amperes
d.. 400 amperes
17. Which of the following is the maximum size type S fuse in amperes?
a.
b.
c.
d.
20 amperes
30 amperes
50 amperes
60 amperes
18. A 120 volt or 277 volt circuit breaker used to switch fluorescent lighting circuits shall be
marked as which of the following?
a.
b.
c.
d.
SWD
HID
CO/ALR
Either a or b
19. Tap conductors permitted to be made without overcurrent protection that are
rated at 27 amperes would be provided with an OCPD at which of the following
ratings?
a.
b.
c.
d.
30 amperes
25 amperes
20 amperes
35 amperes
20. Flexible cord used in listed extension cord sets shall be considered to be
protected when?
a. the load is limited to the rating of the overcurrent device protecting the
branch circuit..
b. applied within the extension cord listing requirements.
c. GFCI devices are installed.
d. limited to use on lighting circuits and no greater than a 20 ampere
overcurrent is installed.
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OVERCURRENT PROTECTION ARTICLE 240
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
c, overcurrent protection
b, ampere rating
b, factory assembled
a, plug; cartridge
a, 125 volts
a, 6’7”
c, load
d, series
a, point of supply
a, 800 amperes
b, readily accessible
b, exposed
d, manually
b, date of manufacture
d, 55 amperes
c, 133 amperes
b, 30 amperes
d, "SWD" or HID
b, 25
b
240.1(FPN)
240.50(B)
240.8
240.(V&VI)
240.50(A)
240.24(A)
240.50(E)
240.20(A)
240.21
240.4(B)
240.24
240.24(C)
240.80
240.60(C)
240.6
240.21(B)(2)(1)
240.53(A)
240.83(D)
240.21(B)
240.5(B)(3)
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GROUNDING ARTICLE 250
LEVEL I
OBJECTIVE:
Each student should know the importance of grounding and the general requirements
for grounding and bonding electrical installations.
INTRODUCTION:
Using Soares book "Grounding Electrical Distribution System for Safety" go over the history of
grounding. Cover the reasons for grounding: (1) limit voltage due to lighting, line surges, or
unintentional contact with higher voltage line; (2) to stabilize the voltage to ground during normal
operations; and (3) to facilitate overcurrent device operations in case of ground faults.
PRESENTING THE LESSON:
Circuit and System Grounding
Discuss Sections 250.4 and 250.20 thoroughly.
Location of System Grounding Connections
When grounding electrical systems care must be taken that methods are used to prevent
objectionable flow of current over the grounding conductor. Temporary currents resulting from
accidental conditions such as ground-fault currents are not objectionable currents. This is the
purpose of grounding connections. 250.4 (A)
Once it has been determined that a premises system is required to be grounded there are
several places the grounded electrode conductor (GEC) may be connected to the grounded
(neutral) conductor.
Note: Go over definitions of grounded electrode conductor, grounded conductor, and grounding
electrode.
The grounded electrical conductor shall be connected at any accessible point from the load end of
the service drop or lateral to and including the terminal or bus to which the grounded service
conductor in the service disconnection means is connected.
Note: Some power suppliers by their conditions of service, require the GEC to be
attached at the service head or may prohibit it from being connected in their metering
equipment.
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A grounding connection shall not be made to any grounded circuit conductor on the load side
of the service disconnect mean except for the following conditions:
1.
for separately derived systems (250.30)
2.
at separate buildings (250.32)
3.
for ranges etc. (250.140)
These conditions will be covered in detail later in the lesson.
Another condition that allows the grounded electrical conductor to be connected to
something other than the grounded conductor or bus bar is when the main bonding jumper*
is a wire or busbar. The grounded electrical conductor may be connected to the equipment
grounding terminal bar or bus to which the main bonding jumper is connected. * See
definition of main bonding jumper.
The grounding conductor must be brought to the service equipment when an AC system
operates at less than 1000 volts and is grounded. The minimum size is based on Table 250.66
but is not required to be larger than the largest ungrounded conductor.
Note: Required to provide an effective path for ground fault currents to facilitate overcurrent
devices. [250.4(A)(5)]
Where one building or structure is fed from another building and there are no metallic paths
between them the second building shall have the AC system grounded circuit conductor and
the metal enclosure of the building disconnection means connected to a required grounding
electrode. Where there is only one branch circuit and there is nothing in the building that
requires grounding the grounding electrode is not required.
When an equipment grounding conductor (EGC) is run with the circuit conductors feeding
into the second building the grounded circuit conductor (neutral) need not be connected to a
grounding electrode at the second building where the equipment grounding conductor (EGC)
is brought to the second building it is used to ground any noncurrent-carrying equipment,
interior metal piping systems or structural frames and bonded to the building disconnecting
means. The equipment grounding conductor must be connected to any existing grounding
electrode and if none exist then one must be provided if there is more than one branch
circuit at the second building.
Note: 250.32(D) requires alternations if the disconnecting means is not located in the second
building.
If livestock is housed, that portion of the equipment grounding conductor run
underground shall be insulated in covered copper.
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Abbreviations:
UCC — ungrounded circuit conductors GCC — grounded circuit conductor EGC — equipment
grounding conductor GEC — grounding electrical conductor BJ — bonding jumper
Discuss the different AC systems. The conductor that is required to be grounded is
specified as follows: (250-26)
1. Single-phase, 2-wire, one conductor.
2. Single-phase, 3-wire, the neutral conductor.
3. Multiphase system having one wire common to all phases, the common
conductor.
4. Multiphase systems where one phase is grounded – one phase conductor
5. Multiphase system in which one phase is used as in (2) above the neutral
conductor.
A separately derived AC system that is required to be grounded shall be grounded as
follows: (250.30)
1. Main Bonding Jumper — A bonding jumper shall be used to connect the grounding
conductors to the grounded conductor. This shall be done at any point from the
source to the first disconnection means. The bonding jumper is sized based on the
derived phase conductor in accordance with 250.28.
2. Grounding Electrode Conductor — The GEC is used to connect the conductor required
to be grounded to the grounding electrode. This connection is to be made at any point
from the source to the first disconnection means. The GEC is sized based on the derived
phase conduction in accordance with Section 250.66.
3. Grounding Electrode — The GEC shall be the nearest available effectively grounded
structural metal member; or the nearest available effectively grounded metal water
pipe; or other electrode if the first two are not available. (250.50)
Enclosure Grounding
Metal enclosures are required to be bonded and grounded and continuity of metal
raceways assured. This is required to provide an effective path for ground fault current.
Short section of metal enclosures for support or protection of cable assemblies are not
required to be grounded. Example- short section of EMT run exposed down a wall to
protect a NM cable.
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Equipment Grounding
Exposed noncurrent carrying metal parts of fixed equipment likely to become
energized shall be grounded as follows: (See also Section 250.110)
1. Where within 8 feet vertically or 5 feet horizontally of ground or grounded metal
2.
3.
4.
5.
6.
objects and subject to contact by persons.
In wet or damp locations not isolated.
In electrical contact with metal
In hazardous locations
Where supplied by wiring methods which provides an equipment ground.
Where equipment operates at over 150 volts to ground.
Note: There are circumstances because of insulation or double insulation where
grounding is not required.
Methods of Grounding
Equipment grounding conductor connections — EGC at service equipment shall be
connected to the grounded services conductor and GEC. When replacing a nongrounding
type receptacle with grounding-type receptacle in existing installations the grounding
conductor of a grounding-type receptacle shall be permitted to be grounded to water
pipe where bonded according to Section 250.104(A). Note: GFCI type of receptacle also
permitted. (250.130; see also Section 250, Part VII) The grounding path shall be: (1) be
permanent and continuous; (2) have capacity to conduct safely the fault current; and (3)
have sufficiently low impedance to limit voltage to ground and to facilitate the operation
of overcurrent devices. Note that the earth is not to be relied upon as the sole equipment
grounding conductor.
(250.4(A)(5)
Example: Pole lighting circuits must contain an EGC to ground the noncurrent carrying
metal as the pole light a driven ground rod at the pole does not meet the requirement
of this Section, but can be installed as supplemental grounding.
The grounding electrode used to ground an AC system of a building shall be the same
electrode used to ground raceway and equipment in buildings as well as other services
in the building. Multiple electrodes effectively bonded together shall be considered as
one. (250.58)
Equipment requiring grounding shall be grounded by an equipment grounding conductor
run with the circuit conductors. This conductor may be bare, covered, or insulated. If
covered or insulated it shall be green or green with yellow stripes. Insulated or covered
conductor larger than No. 6 may be permanently identified by other means such as
striping, coloring, or marking type. (250.119)
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A grounded circuit conductor (neutral) may be used to ground noncurrent- carrying metal
parts of service equipment but may not be used to ground equipment on the load side of
service equipment, except as previously covered in Sections 250.32 and 250.60.
Bonding
Bonding is provided to assure electrical continuity and to conduct safely any fault
current.
Service raceways, service equipment enclosures, and raceway enclosing the GEC all
must be bonded together. An intersystem bonding termination for connecting
intersystem bonding and grounding conductors required for other systems shall be
provided external to enclosures at the service equipment and at the disconnecting
means for any additional buildings or structures. In existing buildings or structures, an
accessible means external to enclosures for connecting intersystem bonding and
grounding electrode conductors shall be permitted at the service equipment and at
the disconnecting means for any additional buildings or structures by at least one of
the following means: (250.94)
1.
2.
3.
Exposed metallic service raceways.
Exposed grounded electrical conductor.
Approved means for external connection: a 6 inch free end of a #6 copper
conductor connected to the service raceway of equipment is one example
Of an approved means. (250.94 FNP No.1)
Bonding of service equipment may be assured by one of the following methods:
[250.92(A)(B)]
1. Grounded service conductor.
2. Threaded couplings and threaded hubs.
3. Threadless coupling and connectors, regular locknuts or bushings do not meet the
requirement of bonding for services.
4. Bonding Jumpers.
5. Other approved devices.
The grounding terminal of a grounding-type receptacle must be grounded to the box
by an equipment bonding jumper. The exceptions covering direct metal-tometal
contact, cover-mounted receptacles, device listed for the purpose and special
receptacles used for reduction of electrical noise should be covered. (250.146)
Bonding of metal raceways containing circuits of over 250 volts to ground other than
service conductor shall be bonded the same as service raceways. When punched
knockouts (not oversized, concentric, or eccentric) the following shall be permitted:
1. Threadless coupling and connectors for cables with metal sheaths.
2. Two locknuts - one inside , one outside on rigid or IMC.
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3. Fitting with shoulders such as EMT connector. (250.97)
A main bonding jumper shall be a wire, bus, screw, or similar suitable conductor.
[250.28(A)]
The main bonding jumper is sized to be not smaller than the sizes given in Table 250.66
based on the size of the installed service conductors.
Example: A 200-amp service is installed with 4/0 THW Aluminum service
conductor. What size main bonding jumper is required?
Solution: Table 250-66. Use column for Aluminum conductor, find 4/0 size
conductor and read across to #4 copper on #2 aluminum conductor.
The equipment bonding jumper on the load side of service equipment is sized using
Table 250.122 based on the overcurrent device supplying circuit therein.
Example: A 200 amperes feeder supplies a panelboard. The metal conduit must
be bonded in the service equipment. What size equipment bonding jumper is
required to bond this conduit?
Solution: Using Table 250.122 go to column for overcurrent sizes- read down to 200
amp- go over to #6 copper or #4 aluminum.
The interior metal water piping system (this water piping system may not meet
requirements to be considered a grounding electrode) shall be bonded to the (1)
service equipment enclosure (2) grounded conducted at the service, or (3) the
grounding electrodes. The bonding jumper is sized using Table 250.66. The point of
attachment shall be accessible. (250.104)
In multiple occupancy building where the interior metal water piping system is "high and
dry" and isolated from other occupancies by use of nonmetallic water piping, the
interior metal water piping for each occupancy may be bonded to the subpanel with a
bonding jumper sized according to Table 250.122. (Use size of overcurrent feeding
subpanel) The equipment grounding conductor for the circuit servicing equipment that
may energize other metal piping shall be permitted to bond said piping.
Grounding Electrode System
A metal underground water pipe (in direct contact with earth for 10 feet or more) and
the effectively grounded metal frame of the building shall be bonded together
to form a grounding electrode system. The bonding conductor is sized based on 250.66.
All electrodes present must be used. (250.50)
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North Carolina Amendment 250.50
Delete NEC 250.50 and replace with:
250.50 Grounding Electrode System. If available on premises at each building or structure
served, each item in 250.52(A) (1) through (A)(6) shall be bonded together to form the
grounding electrode system. Where none of these electrodes are available, one or more
of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
A rod, pipe, or plate electrode must have a resistance to ground of 25 ohms or less or be
augmented by one additional electrode. Multiple rods, pipes, or plates must be at least 6
feet apart. (250.56)
Grounding Conductor
The electrical grounding conductor (EGC) shall be in one continuous length; solid or
stranded, insulated, covered or bare and of copper, aluminum, or copper-clad aluminum.
Equipment grounding conductors shall be as in 250.118:
1.
A copper or other corrosive- resistance conductor in the form of a wire or
busbar.
2.
Rigid metal conduit.
3.
IMC
4.
EMT
5.
Flexible metal conduit when listed for grounding.
6.
Armor of Type AC cable.
7.
Sheath of MI cable.
8.
Metallic sheath or the combined metallic sheath and grounding conductors
9.
10.
of Type MC cable.
Cable trays.
Other metal raceway listed for grounding.
Flexible metal conduit and Liquidtight flexible metal conduit may be used for grounding
when they meet requirements listed in Sections 250.118, 349 and 350.
The GEC or its enclosure shall be securely fastened to the surface on which it is carried. A
#6 or larger GEC, when free from physical damage may be installed without protection
when securely fastened. GEC smaller than #6 shall be
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installed in rigid metal conduit, IMC, EMT, rigid nonmetallic conduit, or cable
armor. (250.62)
Metal enclosure for GEC shall be electrically continuous from the cabinet or
equipment to the grounding electrode. If not they shall be made electrically
continuous by bonding each end to the GEC. [250.62(E)]
GEC's are sized as per Table 250.66 unless it is the sole connection to such made
electrode as discussed in 250.66 (A). Where the grounding electrode conductor is
connected to rod, pipe, or plate electrodes as permitted in 250.52(A)(5) or (A)(6),
that portion of the conductor that is the sole connection to the grounding
electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG
aluminum wire.
The EGC is sized based on Table 250.122. Show these tables and explain.
Grounding Conductor Connections
The connection of the GEC to the grounding electrode shall be accessible. The
connection shall be by one of the following methods: (250.70)
1.
2.
3.
4.
5.
Exothermic welding
Listed lugs
Listed pressure connectors
Listed clamps
Other listed means
EGC shall be spliced or joined in accordance with Section 110-14(B) except for
insulation, when more than one EGC enter a box. The removal of a receptacle,
fixture or other device shall not interrupt the grounding continuity.
APPLICATION:
If time allows, let the class answer the questions on the
worksheet. CHECKING AND FOLLOW UP :
If time allows, correct worksheets and discuss the results.
GROUNDIN
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G
ARTICLE 250
LEVEL I
WORKSHEET
1. A “system bonding jumper” is which of the following?
a. the connection between the grounded circuit conductor and the equipment
grounding conductor at a separately derived system
b. the connection between the grounded circuit conductor and the equipment
grounding conductor at the service.
c. the connection between two or more portions of the equipment
grounding conductor.
d. the permanent joining of metallic parts to form an electrically conductive
path that ensures electrical continuity and the capacity to conduct safely any
current likely to be imposed.
2. Which of the following statements is/are true?
I.
A bare aluminum grounding electrode conductor that is physically
protected can be connected to an outside buried ground rod.
II.
An insulated aluminum grounding electrode conductor can be connected
to an outside buried ground rod if physically protected.
a.
b.
c.
d.
I only
II only
both I and II
neither I nor II
3. A main disconnect circuit breaker is installed outside in a weatherproof
enclosure below the meter feeding a distribution panel in the basement of a
residence. Which of the following statements conforms to NEC requirement?
I.
II.
a.
b.
c.
d.
Service grounding must be done at the service disconnecting means.
The distribution panel neutral bar must be bonded to the cabinet.
I only
II only
both I and II
neither I nor II
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4.
It is permissible to connect the grounding electrode conductor:
I.
at the service disconnect means
II.
on the load side of the service disconnect
a. I only
b. II only
c. both I and II
d. neither I nor
5. The maximum required size copper grounding electrode conductor to a ground rod
with paralleled 4/0 TW service conductors is:
I.
II.
a.
b.
c.
d.
1/0 copper
6 copper
I only
II only
both I and II
neither I nor II
6. The minimum size copper equipment grounding conductor required for
equipment connected to a 40 ampere circuit is:
a.
b.
c.
d.
#12
#14
#10
#8
7. A main bonding jumper is which of the following?
a. the connection from the equipment ground to all non current carrying
metal parts.
b. the grounding conductor on the load side of the service disconnecting
means.
c. the connection between the grounded circuit conductor and the equipment
grounding conductor at the service.
d. the conductor from the grounded conductor to the grounding electrode.
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8. If separate grounding electrodes are used on the CATV, telephone and electrical service;
what is the minimum size conductor required to bond these systems together?
a.
b.
c.
d.
#6
#8
#10
#14
9. Which of the following shall not be used to connect grounding conductors or connection
devices to enclosures?
a.
b.
c.
d.
Pressure connectors
Sheet metal screws
Exothermic welding
Listed clamps
10. Electrical continuity for bonding service equipment shall be assured by the following
method(s):
a.
b.
c.
d.
e.
grounded service conductor
threaded couplings
bonding jumpers
approved bonding devices
all of the above
11. Connecting the receptacle grounding terminal to a metal box may be
accomplished by the use of:
I.
II.
Bonding jumper
Neutral conductor
(a) I only
(b) II only
(c) both I and II
(d) neither I nor II
12. The following may be included in the grounding electrode system:
I.
metal underground water pipe
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II.
a.
b.
c.
d.
metal frame of building
I only
II only
both I and II
neither I nor II
13. Air Terminals conductors, driven rods, pipes or plate electrodes used for grounding air
terminals shall not be used in lieu of which of the following?
a.
b.
c.
d.
A grounding electrode system.
A single grounded electrode system.
An exothermic welded system.
A building bonding system.
14. Which of the following grounding electrodes as described in 250.52(A)(1)
through (A)(6) shall be bonded together to form the grounding electrode
system.
a.
b.
c.
d.
That is specified by the AHJ.
That is available at each building.
That is specified by the Electrical Engineer.
That is present at each building.
15. The equipment bonding jumper on the load side of the service overcurrent devices
shall be sized, as a minimum, in accordance with the sizes listed in Table 250.122,
but shall not be required to be larger than the largest ungrounded circuit conductors
supplying the equipment and shall not be smaller than which AWG?
a.
b.
c.
d.
14
12
10
none of the above
16. Which of the following shall not be permitted to be used as an effective faultcurrent path.
a.
b.
c.
d.
The plate electrode.
The grounded conductor.
The grounding conductor.
The earth.
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17. What size copper conductor is required for the grounding electrode conductor on a
service with 2/0 copper conductors:
a.
b.
c.
d.
#8
#6
#4
#2
18. All metal enclosures for service conductors and equipment must be properly?
a.
b.
c.
d.
painted
bonded
sealed
grounded
19. A means must be provided for disconnection of the grounded conductor of a
service from the premises wiring. This may be which of the following?
a. A terminal or bus with pressure connectors.
b. A wire binding screw and a pressure connector.
c. A wire nut connector.
d. None of the above
20. A grounded circuit conductor may be used to ground the frame of a range under
which of the following conditions?
a.
b.
c.
d.
In new installations.
In existing installations.
In new multi-family dwellings.
In new apartments and townhouses.
21. A metal underground water pipe may serve as a grounding electrode under which of
the following conditions.
a.
b.
c.
d.
If it is in direct contact with the earth and 10 feet in length.
If it is electrically continuous.
If it has no insulated joints.
All of the above
22. The grounded conductor for a service shall not be smaller than the size of the:
a.
b.
c.
d.
grounding electrode conductor
equipment grounding conductor
ungrounded service conductor
any of the above
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23. The main bonding jumper must not be smaller than the size of:
a.
b.
c.
d.
The grounding electrode conductor.
The equipment grounding conductor.
The equipment bonding jumper.
None of the above.
24. Rod and pipe electrodes must not be less than how many feet in length?
a.
b.
c.
d.
4
6
8
10
25. For a grounded system, a main bonding jumper is required to connect which of the
following?
a. equipment grounding conductors
b. service equipment enclosure
c. grounded service conductor
d. all of the above
26. Which of the following may not be used for attaching grounding conductors to
circuits or equipment?
a.
b.
c.
d.
Exothermic welded connections.
Listed pressure connectors.
Soldered lugs.
Other listed means.
27. Which of the following may be used as a grounding conductor?
a.
b.
c.
d.
copper conductor
aluminum conductor
copper-clad aluminum
all of the above
28. In an existing branch circuit installation where a grounding conductor is not present in
the junction box, it is permissible to utilize a neutral conductor as an equipment
grounding conductor. The minimum size is not to be less than?
a. # 10 copper or # 8 aluminum
b.# 8 copper or # 10 aluminum c.#
6 copper or # 4 aluminum d.This is
not allowed.
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29. Electrical systems that are grounded shall be connected to earth in manner that will
limit the voltage imposed by which of the following except for?
a.
b.
c.
d.
Lightning
Line surges
Unintentional contact with higher voltages
Ungrounded circuits
30. System grounding electrode conductors of the following size(s) are required to be
installed in a metallic raceway for mechanical protection.
a.
b.
c.
d.
4
6
8
all of the above
31. Bonding jumper(s) from grounding electrode(s) and grounding electrode
conductor(s) shall be installed in one continuous length without splice or joint
and shall be permitted to be connected to an aluminum or copper busbar not
less than which of the following in size?
a
b
c
d
.
.
.
.
1/2 x 1
1/2 x 2
1/4 x 2
1/4 x 3
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GROUNDING
ARTICLE 250
LEVEL I
ANSWER KEY
1. a
2. d, neither I nor II
3. a, I only
4. a, I only
5. b, II only
6. c, #10
7. c
8. a, #6 250.94, 820-100(D)
9. b
10. e, all of the above
11. a, I only
12. c, both I and II
13. a
14. d
15. a, #14
16. d, the earth
17. c, # 4
18. d.
19. a.
20. b.
21. d.
22. a, grounding electrode conductor
23. a, grounding electrode conductor
24. c, 8 250.52
25. d, all of the above
26. c.
27. d.
28. a.
29. d.
30. c, 8 250.64(B)
31. c
Article 250.2, Definitions
250.64(A)
250.142
250.24, 250.142
250.66(A)
250.122
Article 100, Definitions
250.8
250.94
250.146
250.50
250.60
250.50
250.102(D)
250.2, 250.54
250.66
250.80
230.75
250.142
250.52(A)(1)
250.24(C)(1)
250.28(D)
250.28
250.8
250.118
250.140 exception 2
250.2(A)
250.64(D)(1)(3)
D)(3)
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SURGE ARRESTOR ARTICLE 280
LEVEL I
OBJECTIVE:
Each student should become familiarized with the general installation
requirements of surge arrestors on premises wiring systems.
INTRODUCTION:
Explain to the class that you will cover Article 280 parts I, II, and III. Types and sizes of
conductors utilized depend on KV of Circuit.
PRESENTING THE LESSON:
Cover Article 280 in NEC, where arrestors are to be connected, one to each ungrounded
conductor, to the grounded service conductor, or grounding electrode conductor. Conductor size
will differ in circuits of 1 KV and over. Arrestors may be located inside or outside. The selection of
surge arrestors depends on voltage.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results. Insure students understand
Article 280.
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SURGE ARRESTOR
ARTICLE 280 LEVEL I
WORKSHEET
1. Which of the following is/are correct concerning the installation of surge
arrestors?
I. In general, surge arrestors shall be made inaccessible to unqualified persons.
II. Surge arrestors shall be installed outdoors only.
a.
b.
c.
d.
I only
II only
Both I and II
Neither I nor II
2. For circuits of 1 KV and over, The conductor between the surge arrestor and the line and
surge arrestor and the grounding connection shall not be smaller than:
(a) #8 Copper
(b) #6 Copper
(c) #4 Copper
(d) #3 Copper
3.
Surge arresters shall comply with all the following with the exception of
a. The rating of the surge arrester shall be equal to or greater than the maximum
continuous operating voltage available at the point of application
b. The maximum continuous pertaining voltage shall be the phase-to-ground
voltage of the system
c. The maximum continuous operating voltage shall be the phase-to-phase voltage of
the system.
d. Surge arresters shall be permitted to be installed on ungrounded systems only.
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SURGE ARRESTOR
ARTICLE 280 LEVEL I
ANSWER KEY
1. a,
2. b,
3. d
280.11
280.23
280.4(A)
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WIRING METHODS
ARTICLE 300
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with various wiring
methods for all types of wiring installations.
INTRODUCTION:
In the USA, cable wiring is probably the most recognized wiring method, especially for
residential-type construction. The general requirements for wiring methods are listed
in the National Electrical Code, Article 300.
This assignment contains information about overcurrent protective devices and fuses,
sizes of conductors, types of conduit, installing boxes, grounding conductors, and
various raceways. This information will be very useful to the students in their daily
work on the job.
The students may not realize the fact, but it requires a skilled craftsman to make a
concealed electrical installation in an old building. It is essential that they leave the
building in good repair when they are finished.
PRESENTING THE LESSON:
The instructor should lead a class discussion of the material found in the assignment.
The students should have read the assignment and have questions for discussion ready
to present.
300.1 & 2 Scope and Limitations
Note that this Article covers all wiring installations unless modified by other Articles.
This Article does not pertain to conductors which are an integral part of equipment such
as motors and controllers Also, note voltage and temperature limitations in this Article.
300.3 Conductors
Various single conductors must comply with wiring methods in Chapter 3 of the Code.
Discuss the housing or enclosure requirements of conductors of the same and
different circuits.
300.4 Protection Against Physical Damage
Pay close attention to specifications for placing cables and raceways through wood
members, metal framing members and behind access panels. Review Section 300.4(E)
regarding cable- or raceway-type wiring method, installed in exposed or concealed
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locations under metal-corrugated sheet roof decking and Section G that requires
protection of conductors 4 AWG or larger in raceways where entering an enclosure,
cabinet, box or raceway.
300.5 Underground Installations.
Cable, conduit, and raceways when buried underground have minimum cover
requirements detailed in Table 300.5. Review Section 300.5 (B) regarding the interior of
enclosures or raceways, splices and connections installed underground shall be
considered to be a wet location and shall comply with Section 310.10(C).
Show transparency of Table 300.5 and discuss.
Underground installations shall be grounded and bonded in accordance with Article
250. Also, note specifications for cables under buildings and the burying of cables.
300.6 Protection Against Corrosion
Guidelines for protection against corrosion of cable enclosures are explained in terms
of concrete, direct contact with earth, and wet indoor locations. Note 300.6 (B)
regarding Aluminum Metal Equipment.
300.7, 8 Raceways
Raceways should not be exposed to a wide range of different temperatures, particularly
the circulation of warmer air to a colder area through the raceway. This could cause
condensation and create damp conditions in the raceway. In addition, raceways should
allow for thermal contraction and expansion by having adequate expansion joints. No
electrical conductor shall be installed in a raceway with other service pipes or tubes
other than electrical.
300.9 Raceways in Wet Locations Above Grade.
Where raceways are installed in wet locations above grade, the interior of these
raceways shall be considered to be a wet location. Insulated conductors and cables
installed in raceways in wet locations above grade shall comply with 310.10(C).
300.11 Securing and Supporting
Enclosures and raceways for electrical conductors shall be securely supported with
rigid supports and may not be used as supports for other raceways or other nonelectrical equipment unless otherwise stated in exceptions. [See section 300.11 (B)]
Discuss the supporting of wiring above fire-rated and non-fire-rated floor/ceiling or
roof/ceiling assemblies and attachment thereto.
300.12, 13 Mechanical and Electrical Continuity
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Raceways and cables shall be continuous and electrical conductors within them shall
not be spliced or tapped unless otherwise noted in exceptions of the Code.
300.14 Length of Free Conductors
Discuss the length of free conductors at outlets, junctions, and switch points.
300.15 Boxes; Where Required
Discuss where boxes are required for electrical conductors.
300.16 Raceway or Cable to Open or Concealed Wirings
Explain requirements for raceway or cable to open or concealed wirings.
300.17 Number and Size of Conductors in Raceway
The number and size of conductors in a raceway shall not be more than will permit
dissipation of heat and ready installation or withdrawal of the conductors without
damage to the conductors or to their insulation. For more information see Section
300.17 of the Code.
300.18 Raceway Installations
Installation of raceways, other than busways or exposed raceways having hinged or
removable covers are to be complete from outlet, junction, or splicing points prior to
the installation of conductors. Metal raceways are not to be supported, terminated, or
connected by welding unless designed to be or otherwise specifically permitted in the
code.
300.19 Supporting Conductors in Vertical Raceways
Supporting conductors in vertical raceways is covered in terms of maximum spacing
intervals and support methods in Section 300.19 accompanied by a Table for spacing
requirements. Review Section 300.19 (B) support methods and spacing intervals for firerated cables and conductors.
Show transparency of Table 300.19(A) and discuss.
300.20 Induced Currents in Ferrous Metal Enclosures and Ferrous Metal Raceways. Explain
methods of controlling induced currents in metal enclosures with individual
conductors and grouped conductors.
300.22 Ducts, Plenums, and Other Air-Handling Spaces
Discuss the rules of wiring in ducts, plenums and other air handling spaces.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheet and discuss the results.
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WIRING METHODS
ARTICLE 300
LEVEL I
WORKSHEET
1. The provisions of this Article are not intended to apply to which of the following?
a.
b.
c.
d.
the conductors which form an integral part of equipment.
The conductors for motors and motor control centers.
The conductors for motor controllers.
All of the above.
2. All conductors of the same circuit and where used, the grounded conductor and which of the
following shall be contained in the same raceway, cable tray, trench, cable or cord.
a.
b.
c.
d.
3.
equipment grounding conductors, bonding conductors
bonding jumpers, grounded circuits
grounding electrodes, electrode conductors
ground rings, grounding clamps
Cables and insulated conductors installed in enclosures or raceways in
underground installations shall considered to be what type of location?
a.
b.
c.
d.
damp
dry
wet
hazardous
4. Where cables or wires are installed through bored holes in wood members, the holes shall be
bored so that the edge of the hole is not less than how many inches from the nearest edge
of the wood member.
a.
b.
c.
d.
3 inches
2 inches
1 5/8 inches
1 1/4 inches
5. The minimum cover requirement for direct buried cable of 1000 volts or less not
protected by concrete is:
a.
b.
c.
d.
18 inches
16 inches
24 inches
none of the above
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6. A residential branch circuit rated 120 volts or less and provided with GFCI protection
and maximum overcurrent protection of not more than 20 amperes will be directly
buried in soil. Minimum cover requirement shall be not less than which of the
following?
a.
b.
c.
d.
24 inches
12 inches
6 inches
18 inches
7. Where raceways containing ungrounded conductors are entering a box or
enclosure, a substantial fitting providing a smoothly rounded insulating surface
should be used when the conductors are of which of the following sizes?
a.
b.
c.
d.
3 AWG or larger
2 AWG or larger
1 AWG or smaller
4 AWG or larger
8. Where an enclosure or raceway is subject to physical damage and conductors
are installed in a non-metallic raceway, the raceway shall be which of the
following?
a.
b.
c.
d.
9.
Schedule 40 rigid
Schedule 80 rigid
Schedule 120 rigid
Schedule 60 rigid
Conduits or raceways that contain live parts shall be sealed or plugged at
either or both ends if they may contact which of the following?
a.
b.
c.
d.
moisture
hazardous gases
hazardous vapors
all of the above
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10.
Where portions of a cable raceway or sleeve is subjected to different
temperatures, to prevent the circulation of warm air to a colder section of
the raceway or sleeve, which of the following shall be provided?
a.
b.
c.
d.
11.
an insulated bushing
approved fill material
a non-explosionproof seal
an explosionproof seal
Raceways or cable trays containing electrical conductors shall not contain other
services such as the following?
a.
b.
c.
d.
Water lines
Air lines
Gas pipes
all of the above
12. Conductors shall be continuous between outlets, devices, etc., and there shall be no
splice or tap within a raceway itself, unless permitted by which of the following?
a.
b.
c.
d.
13.
300.15 (A)
368.56(A)
376.56
All of the above
A box or conduit body shall not be required for each splice, junction, switch, pull,
termination, or outlet points in wiring methods, such as wireways, multioutlet
assemblies, auxiliary gutters, and surface raceways if they are equipped with
which of the following?
a.
b.
c.
d.
a cover
an accessible removable cover
a readily accessible removable cover
an accessible cover
14. Regulating the number and size of conductors in any raceway is important to allow for
which of the following?
a.
b.
c.
d.
Permit dissipation of heat.
Allow for ready installation or withdrawal.
Removal of wiring without damage to the insulation.
All of the above
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15. Conductors in vertical raceways shall be supported. In accordance with which of the
following?
a.
b.
c.
d.
Table 300.5
Table 300.19(A)
Table 310.16
Table C.11
16. Phase conductors carrying alternating current that are installed in metal raceways shall be
arranged to avoid heating the surrounding metal by which of the following?
a.
b.
c.
d.
induction
convection
radiation
thermal expansion
17. Openings around electrical penetrations through fire-resistance rated walls,
partitions, floors or ceilings shall be fire-stopped using approved methods to
maintain which of the following?
a.
b.
c.
d.
the fire-resistance rating
the proper clearance
the thermal resistance
the reduction of harmonics
18. Which of the following wiring systems may be installed in ducts used for
environmental air?
a.
b.
c.
d.
19.
MI Cable
MC Cable
EMT
All of the above
Where nonmetallic-sheathed cables pass through either factory or field punched,
cut, or drilled slots or holes in metal members, the cable shall be protected by
which of the following?
a.
b.
c.
d.
listed bushings
listed grommets
Either A or B
Neither A nor B
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20. In both exposed and concealed locations, where a cable or raceway-type wiring method is
installed parallel to framing members, such as joists, rafters, or studs, or is installed parallel to
furring strips, the cable or raceway shall be installed and supported so that the nearest outside
surface of the cable or raceway is not less than which of the following from the nearest edge of
the framing member or furring strips where nails or screws are likely to penetrate.
a.
b.
c.
d.
1 1/4 inches
1 inch
3/4 inch
1 3/4 inch
21. A cable- or raceway-type wiring method, installed in exposed or concealed
locations under metal-corrugated sheet roof decking, shall be installed and supported
so the nearest outside surface of the cable or raceway is not less than which of the
following distances from the nearest surface of the raceway?
a.
b.
c.
d.
5/8 inch
1 1/2 inches
2 inches
3/4 inch
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WIRING METHODS
ARTICLE 300 LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
d, all of the above
a, equipment grounding conductors, bonding conductors
c.
d, 1 1/4 inches
c, 24 inches
b, 12 inches
d.
b.
d.
b.
d.
d.
d.
d.
b.
a.
a.
d. all of the above
c.
a
b 1 1/2 inches
300.1(B)
300.3(B)
300.5(B)
300.4(A)(1)
Table 300.5
Table 300.5
300.4(G)
300.5(D)(4)
300.5(G) & note
300.7(A)
300.8
300.13(A)
300.15(A)
300.17
Table 300.19(A)
300.20
300.21
300.22(B)
300.4(B)(1)
300.4(D)
300.4(e);
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CONDUCTORS FOR GENERAL WIRING
ARTICLE 310
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
requirements for conductors for general wiring.
INTRODUCTION:
Conductors for general wiring come in different sizes as well as having different insulation on
the conductor. It can come in single conductors or in a cable assembly. The conductors can be
solid or stranded also copper, aluminum, or copper clad aluminum. As voltages change, so can
the requirements for conductors. In this lesson we will take a look at these different
requirements.
MATERIALS NEEDED :
Samples of different kinds of conductors (i.e. single conductor, cables, conductors with
different types of insulation.
PRESENTING THE LESSON:
Conductors and cables used in wet locations must be (1) moisture impervious metal
sheathed, (2) type MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW,
XHHW-2, ZW or (3) listed for wet locations. (310.10[C])
Conductors used for direct burial shall be of a type identified for such use. (310.10[F])
Conductors exposed to direct sunlight must be listed as sunlight resistant or covered with a
material listed and marked as sunlight resistant. (310.10[D])
Conductors used in corrosive conditions must be of a suitable type. (310.10[G])
Read carefully about conductors installed in parallel in section 310.10 (H), paying close
attention to the exceptions and Conductor and Installation characteristics.
Conductor must not exceed the temperature for which it is rated. ( 310.15 [A] 3)
Review ampacities for general conductors and Tables 310.15. Show the students how to interpret
the Tables. Note changes to numbering (e.g. 310.16 is now 310.15[B] 16)
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 Note that each Table is based on a certain ambient air temperature. If the conductor
installation exceeds this ambient, then the ampacity in the Table must be multiplied by the
correction factor based on the temperature the conductor is to encounter. (see table
310.15 [B] 2.a or b.)
 There is also a temperature adder for conductors exposed to sunlight on rooftops. (310.15
[B] 3.c, see exception for XHHW-2)
 Note that 310.15(B)(3)(a) has further reductions for more than 3 current-carrying
conductors in a raceway or cable or where spacing is not maintained. The neutral shall not
be counted when making these demand calculations except per 310 15 (B) 5.
 Note 310.15 (B) 7 which deletes the table and replaces it with a reduction to 83% of required
ampacity. (see example D-7 in Annex D)
The minimum size of conductors for various voltages are found in Table 310. 106(A).
Conductors in this article shall be of aluminum, copper-clad aluminum, or copper unless otherwise
specified. (310.106[B])
When installed in raceways, conductors #8 and larger shall be stranded unless specifically permitted
or required elsewhere in this code. (310.106[C])
Conductors shall be insulated unless specifically permitted elsewhere in the code. (310.106[D])
Ungrounded conductors shall be distinguishable from grounded and grounding conductors.
(310.110[C])
Conductors must be marked with maximum voltage, conductor or cable type, manufacturer's name or
trademark, and wire size at intervals not to exceed 24” or 40”. (310.120[A&B])
Metal-covered multi-conductor cable shall have a marker tape within the cable along its entire length.
Exceptions would be MI cable, AC cable, MC, ITC or PLTC cable.(310.120 [B]2)
APPLICATION:
If time allows, let the class answer questions on the worksheet.
CHECKING AND FOLLOW UP :
If time allows, correct the worksheets and discuss the results.
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CONDUCTORS FOR GENERAL WIRING
ARTICLE 310
LEVEL I
WORKSHEET
1. The largest solid conductor that can be pulled in a raceway unless specifically permitted
or required elsewhere in the code:
a.
b.
c.
d.
#14
#12
#10
#8
2. in general, conductors must be at least what size and larger to be paralleled?
a.
b.
c.
d.
1/0
2/0
3/0
4/0
3. Cables and conductors marked THW with maximum voltage of 600 volts
manufacture southwire must have this marking not exceeding
a.
b.
c.
d.
40 inches
36 inches
30 inches
24 inches
4. The minimum size copper conductor for 0 to 2000 volts is:
a.
b.
c.
d.
16
14
12
10
5. The ampacity of a #4 copper THW conductor run in ambient temperature of 40 degrees
Celsius in a conduit with 3 current carrying conductors are:
a.
b.
c.
d.
75
74.8
85
65
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6. The minimum size of the service conductors to a single family dwelling with a 125 amperes
service using THW aluminum is:
a.
b.
c.
d.
#4
#2
#1/0
#2/0
7. Six 1/0 THW copper conductors are run in parallel, in the same raceway, two conductors
per phase, on a three phase system. The conductors must be derated to what percent
of their normal ampacity.
a.
b.
c.
d.
8.
20 percent
30 percent
60 percent
80 percent
Insulated conductors or cables used where exposed to direct rays of
the sun shall comply with all of the following with the exception of?
a. Cables must be listed, or listed and marked, as being sunlight resistant
b. Conductors must be listed, or listed and marked, as being sunlight resistant.
c. Covered with insulating material, such as tape or sleeving, that is listed, or listed
and marked, as being sunlight resistant
d. Conductors exposed to direct sunlight must be terminated to an over current
device rated at no more than 60 amperes.
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CONDUCTORS FOR GENERAL WIRING
ARTICLE 310
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
c, #10
a, 1/0
a, 40 inches
b
b, 74.8
c, #1/0
d, 80
d,
310.106 (C)
310.15 (H) 1
310.120(B)(1)
Table 310.106 (A)
310.15(B)16, 310.15(B)(2)(a)
Table 310.15(B)(7)
Table 310.15(B)(3)(a)
310.10(D)
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CABINETS , CUTOUT BOXES AND METER SOCKET ENCLOSURES
ARTICLE 312
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the requirements applying
to installation and construction specifications of cabinets, cutout boxes, and meter socket
enclosures.
MATERIALS:
Samples of the enclosures for use in a damp or wet location. Handouts
or pictures showing the above.
PRESENTING THE LESSON:
Present requirements included in Section 312.2 as applies to installations in damp and wet
locations.
Cover the requirements included in section 312.3 as they apply to cabinets that are placed in
walls of the various types of materials. The requirements for unused openings are covered
elsewhere in the Code 110.12(A) and need to be touched on lightly. Cover Section 312.4 for
repairing noncombustible surfaces.
The requirements included in Tables 312.6(A) and 312.6(B) are very important and should
be covered in detail. Show these Tables on overhead and explain.. Panelboards and other
types of overcurrent equipment are listed. The space requirements in these tables is
necessary to determine intended use of the equipment.
The requirements in Section 312.6(C) are important and emphasis should be placed on
protection of the cable sheath.
Briefly review required clearances to live parts.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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CABINETS, CUTOUT BOXES, AND METER SOCKET ENCLOSURES
ARTICLE 312
LEVEL I
WORKSHEET
1. The cabinet for a flush panelboard installed in a non-combustible wall shall be installed
no farther than which of the following from the wall surface?
a.
b.
c.
d.
1/8 inch
1/2inch
3/8 inch
1/4inch
2. Non-metallic cable (Type NM) is used for both the feeder and branch circuits for
a
panelboard installation. Each cable is required by Code to be:
a.
b.
c.
d.
secured to the cabinet
secured within 12 inches of the cabinet
both a and b
none of the above
3. Three 250 KCmil copper conductors enter a panelboard enclosure opposite their
termination point on the terminal of a circuit breaker. The minimum amount of
wire bending space required for this panelboard is which of the following?
a. 2 1/2 inches
b. 4 1/2 inches
c. 5 inches
d. 9 inches
4. Three 250 KCmil conductors enter a panelboard enclosure at right angles to their
termination point on the terminal of a circuit breaker. The minimum amount of
wire bending space required for this panelboard is which of the following?
a.
b.
c.
d.
4 1/2 inches
5 inches
8 inches
10 inches
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5. Noncombustible surfaces that are broken or incomplete shall be repaired so that there
are no gaps at the edge of a cabinet employing a flush type cover exceeding which
distance?
a.
b.
c.
d.
4 mm
6 mm
1/8”
1/16”
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CABINETS, CUTOUT BOXES, AND METER SOCKET ENCLOSURES ARTICLE 312
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
d, 1/4 inch
c, both a and b
d
c
c, 1/8”
312.3
312.5(C) and 334.30
Table 312.6(B)
Table 312.6(A)
312.4
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OUTLET, DEVICE, PULL AND JUNCTION BOXES, CONDUIT BODIES, FITTINGS, AND
HANDHOLES
ARTICLE 314
LEVEL I
OBJECTIVE After completing this section the code official should be able to:
a. Identify the various types of boxes encountered in typical level 1 residential
and small commercial installations,
b. Calculate minimum size for outlet boxes and conduit bodies based on the
number of conductors and devices installed
c. Evaluate installations for code compliant mounting of boxes and conduit
bodies
Samples of various boxes and conduit bodies (if available)
INTRODUCTION
Review the scope of Article 314 and identify the type of boxes typically used in residential
and small commercial installations. Identification of the various types of boxes and conduit
bodies and as well as proper sizing of outlet and junction boxes including minimum
dimensions of pull and junction boxes for conductors size #4 and larger will be discussed.
This article also covers fittings used to connect raceways and cables to boxes and conduit
bodies.
PRESENTING THE LESSON
Emphasize that the ability to apply the requirements of Article 314 for boxes and conduit
bodies is an essential skill for a Level 1 code official. Article 314 covers the installation and
use of all boxes and conduit bodies. Refer back to Section 300.15 as covered in a previous
lesson for information on where boxes are required. If available provide samples of
different types of boxes and conduit bodies. Remind course participants that requirements
in other articles are also applicable to the installation of boxes and conduit bodies including
Article 250 Grounding and Bonding. Cover the topics from the course outline as thoroughly
as possible within the time allowed. Use in-class exercises to reinforce covered topics if
time allows or provide exercises as handouts for home study.
In Class exercise
1) Assuming a 0.5 cubic inch plaster ring is installed, what is the minimum standard
size metal switch box required to accommodate the conductors and devices in
the diagram #1? Note: Standard NM cable connectors are installed with the
clamping means outside of the box.
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Solution: Refer to Table 314.16(A)
Begin with 314.16(B)(5): All equipment grounding conductors are connected together and
counted as a single conductor based on the largest equipment grounding conductor in the
group. In this case a #12 conductor. The required volume allowance for a #12 conductor is
2.25 cubic inches (Table 314.16(B). The required allowance for the equipment grounding
conductors is 2.25 cubic inches.
Section 314.16(B)(4) requires a double volume allowance for each device yoke containing
one or more devices. In this case we have two devices, a single pole switch and a duplex
receptacle. Each will require a double volume allowance based on the largest conductor
connected to the device. For the switch connected to the #14 conductors this would be 2 X
2 cubic inches for a total of 4.0 Cubic inches. The receptacle is connected to #12
conductors so the volume allowance for the receptacle is 2 X 2.25 cubic inches for a total of
4.5 cubic inches. Adding the 4.0 cubic inches required for the switch to the 4.5 cubic inches
for the receptacle gives a total volume allowance for the installed devices of 8.5 cubic
inches.
Section 314.16(B)(3): There are no luminaire studs or hickeys installed in this box.
Section 314.16(B)(2): There are 3 cable clamps installed, but the clamping means is located
outside of the box. No volume allowance is required.
NOTE: Review 2014 Code Change
Section 314.16(B)(1): There are three cables entering the box (one 14/2 with ground one
14/3 with ground and one 12/2 with ground). The equipment grounding conductors have
already been accounted for in step 1. The 14/2 cable counts as 2 conductors (2 X 2 cubic
inches equals 4 cubic inches). The 14/3 cable counts as 3 conductors (3 X 2 cubic inches
equals 6 cubic inches). The 12/2 cable counts as 2 conductors (2 X 2.25 cubic inches equals
4.5 cubic inches). There is also a short # 14 pigtail connected to the switch. This conductor
does not have to be counted since no part of the conductor leaves the box. The total
conductor fill for this box is then 4 + 6 + 4.5 = 14.5 cubic inches.
The total volume required for the box is the sum of 2.25 (eq. grounds) + 8.5 (devices) +
14.5 = 25.25 cubic inches. The plaster ring provides 0.5 cubic inches of the total required
which leaves 24.75 cubic inches required for the box.
A 4 inch square by 2-1/8 deep metal box (30.3 cu. in.) is sufficient per Table 314.16(A).
Discuss other possible box/plaster ring combinations that could meet the minimum
required volume.
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OUTLET, DEVICE, PULL AND JUNCTION BOXES, CONDUIT
BODIES, FITTINGS AND HANDHOLES
ARTICLE 314
LEVEL I
WORKSHEET
1. Under which of the following conditions does the code permit an 8 inch x 8 inch nonmetallic box to be used with electrical metallic tubing.
a.
b.
c.
d.
with an internal equipment bonding jumper between all entries
with a proper seal around the conduit
with a round opening type box
with a rectangular type box with threaded openings
2. Which of the following boxes are considered conduit bodies?
a.
b.
c.
d.
FD boxes
FS boxes
Type LB conduit fittings
All of the above
3. The maximum number of #14 conductors in a 4 inch x 1 1/2 inch square is?
a.
b.
c.
d.
6
8
10
12
4. What is the minimum size standard metal device box for 2 #14/2 AWG non-metallic
sheathed cables, 2 cable clamps and two (2) devices on one strap?
a.
b.
c.
d.
3 x 2 x 2 3/4
3 x 2 x 2 1/2
3 x 2 x 1 1/2
3x2x3½
5. What is the minimum distance the sheath of a non-metallic sheathed cable shall
extend into a box?
a.
b.
c.
d.
1 inch
1/2 inch
1/4 inch
1/8 inch
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6.
What is the maximum opening permitted around boxes in drywall?
a.
b.
c.
d.
7.
Boxes mounted in non-combustible walls shall be installed so that the front edge
will be flush or set back no more than:
a.
b.
c.
d.
8.
1 inch
1/ 2 inch
1/4 inch
1/8 inch
1 inch
1/2 inch
1/4 inch
1/8 inch
Screws, used for the support of a device box, shall not be permitted to pass
through the box unless which of the following occurs?
a.
b.
c.
d.
9.
The minimum depth of a box when a flush device is supplied by #12
conductors is:
a.
b.
c.
d.
10.
They pass through the interior of the box 1/2 inch from the back.
The exposed threads in the box are covered by approved means.
The box is a non-metallic box with a rectangular opening.
The box is a metallic box with a rectangular opening.
1 inch
15/16 inch
1/2 inch
3/4 inch
A looped, unbroken conductor not less than twice the minimum length
required for free conductors in 300.14 shall count as which of the following
number of conductors when passing through a box.
a.
b.
c.
d.
1
2
3
0
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OUTLET, DEVICE, PULL AND JUNCTION BOXES, CONDUIT BODIES, FITTINGS, AND
HANDHOLES
ARTICLE 314
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
a.
c
c, 10
d, 3 x 2 x 3 1/2
c, 1/4 inch
d, 1/8 inch
c, 1/4 inch
b
b, 15/16 inch
b, 2
314.3 Exception 1
314.1
Table 314.16(A)
Table 314.16(A)
314.17(C)
314.21
314.20
314.23(B)(1)
314.24(B)(4)
314.16(B)(1)
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ARMORED CABLE
ARTICLE 320
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
requirements for the installation of Type AC cable.
MATERIALS NEEDED:
Sample of different types of Armored Cable.
INTRODUCTION:
This Article covers the use and installation requirements for a fabricated assembly of
insulated conductors in a flexible metallic enclosure. Note the differences between Type
AC and Type MC cable assemblies.
PRESENTING THE LESSON:
Cover the permitted uses and uses not permitted for Type AC cable. Note the
requirements for supporting, bending, terminating and installation in accessible attics
and through studs, joists and rafters. Type AC cable shall provide an adequate path for
fault current as required by 250.4(A)(5) or (B)(4) to act as an equipment grounding
conductor. Note the bond wire in Type AC cable is in constant contact with metal
armor. The bond wire and the cable armor together constitute a single equipment
grounding conductor.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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ARMORED CABLE
ARTICLE 320
LEVEL I
WORKSHEET
1. In general, type AC Cable shall be supported at intervals not exceeding which of the
following?
a.
b.
c.
d.
3 feet
4 -1/2 feet
6 feet
5 feet
2. Where in accessible attics Type AC cable is run across the top of floor joists or within
7 feet of the floor on the face of a studded rafter the cable shall be protected by
substantial guard strips which are at least:
a.
b.
c.
d.
As high as the box the cable is attached to.
As high as the cable.
At least 1-1/2 inches high.
At least 3 inches high.
3. Type AC cable is not permitted to be used in which of the following?
a.
b.
c.
d.
in damp or wet locations
both exposed and concealed work
dry locations
in cable trays
4. The ampacity of Type AC cable installed in thermal insulation shall be that of
which of the following?
a.
b.
c.
d.
40º C
60º C
90º C
110º C
5. A 12/3 copper Type AC cable with individual conductors rated 90C is run through
thermal insulation. The allowable ampacity of the conductors is:
a.
b.
c.
d.
15 Amperes
20 Amperes
25 Amperes
30 Amperes
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ARTICLE 320
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
b
b
a
b
b
320.30
320.23(A)
320.12
320.80
320.80/310.15(B)16
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FLAT CABLE ASSEMBLIES: TYPE FC
ARTICLE 322
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
requirements for the installation of Type FC cable.
MATERIALS NEEDED:
Show samples of different types of Flat Cable Assemblies, (if available).
INTRODUCTION:
This article covers the use, installation, and construction specifications for flat cable
assemblies, Type FC.
PRESENTING THE LESSON:
Cover the permitted uses and uses not permitted for Type FC cable. Note the
requirements for securing and supporting. Type FC cable shall be formed to provide a
suitable insulation covering all the conductors and using one of the materials recognized
in Table 310.13(A) for general branch-circuit wiring. Type FC cable shall have the
temperature rating durably marked on the surface at intervals not exceeding 24 in. Note
that the grounded conductor shall be identified throughout its length by means of a
distinctive and durable white or gray marking. Point out the informational note
following Section 322.120(B). The color gray may have been used as an ungrounded
conductor in the past.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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FLAT CABLE ASSEMBLIES: TYPE FC
ARTICLE 322
LEVEL I
WORKSHEET
1.
Flat cable assemblies shall have conductors of
a.
b.
c.
d.
# 16 AWG spiral stranded copper conductors.
# 12 AWG single stranded copper wires.
# 14 AWG special stranded conductors.
# 10 AWG special stranded copper wires.
2. Flat cable assemblies shall consist of which of the following?
a.
b.
c.
d.
Two conductors.
Three or four conductors.
Four or five conductors.
Two, three, four, or five conductors.
3. Type FC cable shall have the temperature rating durably marked on the surface at intervals
not exceeding
a.
b.
c.
d.
24 inches
36 inches
48 inches
18 inches
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FLAT CABLE ASSEMBLIES: TYPE FC
ARTICLE 322
LEVEL I
ANSWER KEY
1. d, # 10 AWG special stranded copper wires
322.104
2. d, Two, three, four, or five conductors
322.100
3. a, 24 inches
322.120(A)
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FLAT CONDUCTOR CABLE: TYPE FCC
ARTICLE 324
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar
with the requirements for the installation of Type FCC systems.
MATERIALS NEEDED:
Sample of Flat Conductor Cable (if
available). INTRODUCTION:
This article covers the use, installation, and construction specifications
for flat conductor cable Type FCC.
PRESENTING THE LESSON:
Cover the permitted uses and uses not permitted for Type FCC systems.
Note the requirements for securing and supporting. Type FCC cable shall be
listed. Type FCC systems shall be permitted both for general-purpose and
appliance branch circuits and for individual branch circuits. General-purpose
and appliance branch circuits shall have ratings not exceeding 20 amperes.
Individual branch circuits shall have ratings not exceeding 30 amperes. FCC
systems shall be permitted on hard, sound, smooth, continuous floor
surfaces made of concrete, ceramic, or composition flooring, wood, and
similar materials as well as wall surfaces in surface metal raceways. All
receptacles and connections shall be constructed and installed so as to
maintain proper polarization of the system.
APPLICATION:
If time will allow, let the class answer the questions on the
worksheet. CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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FLAT CONDUCTOR CABLE: TYPE
FCC ARTICLE 324
LEVEL I
WORKSHEET
1. FCC general-purpose and appliance branch circuits shall have ratings not
exceeding which of the following?
a.
b.
c.
d.
15 amperes.
30 amperes
20 amperes
25 amperes
2. FCC systems may be used in which of the following locations:
a.
b.
c.
d.
Outdoors or in wet locations
Damp locations
In any hazardous (classified) location
In residential, school, and hospital buildings
3. Floor-mounted Type FCC cable, cable connectors, and insulating ends shall be
covered with carpet squares not larger than
a.
b.
c.
d.
39.37 inches square.
24 inches square
36 square inches
48 square inches
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FLAT CONDUCTOR CABLE: TYPE FCC ARTICLE 324
LEVEL I
ANSWER KEY
1. c, 20 amperes
324.10(2)
2. b, damp locations
324.10(E)
3. a, 39.37 inches square
324.41
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METAL-CLAD CABLE: TYPE MC
ARTICLE 330
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
requirements for the installation of type MC cable.
MATERIALS NEEDED:
Samples of different types of MC Cable
INTRODUCTION:
This article covers the use and installation of MC cable. The cable is a fabricated
assembly of insulated conductors in a flexible metallic enclosure.
PRESENTING THE LESSON:
Cover the uses permitted and the uses not permitted for MC cable. MC cable is widely
used without many limitations. Cover support requirements with exceptions. Fittings for
MC cable should be listed and identified for use with MC cable. In wet locations note the
requirement for a corrosion-resistant jacket to be provided over the metallic sheath.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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METAL-CLAD CABLE: TYPE MC
ARTICLE 330
LEVEL I
WORKSHEET
1.
Type MC cable shall be supported and secured at intervals not exceeding ___?
a.
b.
c.
d.
3’
4’
4 1/2’
6’
2.
MC installed through joist, studs, rafters must be spaced _______ from face of
structural member.
a.
b.
c.
d.
3.
Type MC cable shall not be used in which of the following?
a.
b.
c.
d.
4.
in concrete
outdoors
direct buried where identified for such use
on services
Minimum copper conductor size shall be?
a.
b.
c.
d.
5.
1”
1 1/4”
1 1/2”
1 3/4”
14 Al
18 Cu
10 Al
16 Cu
Type MC Cable shall be permitted to be unsupported where the cable is not
greater in length from a fixture connection than which of the following?
a.
b.
c.
d.
2 feet
4 feet
6 feet
8 feet
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METAL-CLAD CABLE: TYPE MC
ARTICLE 330
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
d, 6’
b, 1 1/4”
a, in concrete
b, 18 Cu
c, 6 feet
330.30
330.17
330.12
330.104
330.30
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NONMETALLIC-SHEATHED CABLE: TYPES NM, NMC AND NMS
ARTICLE 334
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be acquainted with the use,
installation and construction specifications of non-metallic sheathed cable.
MATERIALS:
Sample of NM cable, NMC cable.
Handouts and/or pictures of the above.
INTRODUCTION:
Nonmetallic-sheathed cable is a factory assembly of two or more insulated conductors having
an outer sheath of moisture-resistant material. There are three types of nonmetallic-sheathed
cables: NM, NMC and type NMS. In addition to the provisions of Article 334, non-metallic
sheathed cable shall be installed to comply with other applicable provisions of the Code
especially Articles 300 and 310.
PRESENTING THE LESSON:
Both types NM and NMC cables can be used in one, two, and multi-family dwellings
and other structures. NM cable can be used for both exposed and concealed work in
dry locations. It can be installed or fished in air voids in masonry walls that are not
subject to excessive moisture or dampness.
NMC cables can be used for both exposed and concealed work in dry, moist, damp, or
corrosive locations. It can be used in outside and inside masonry walls. It can be used in a
shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar
finish.
Both types NM, NMC and NMS shall not be used:
1. In any dwelling or structure not specifically permitted in 334.10(1), (2), and (3)
Exception: Type NM, NMC, and NMS cable shall be permitted in Type I and II construction
when installed within raceways permitted to be installed in Type I and II construction.
2. Exposed in dropped or suspended ceilings in other than one- and two-family and
multifamily dwellings
3. As service-entrance cable
4. In commercial garages having hazardous (classified) locations as defined in 511.3
5. In theaters and similar locations, except where permitted in 518.4(B)
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6. In motion picture studios
7. In storage battery rooms
8. In hoistways or on elevators or escalators
9. Embedded in poured cement, concrete, or aggregate
10. In hazardous (classified) locations, except where permitted by the following:
a .
501.10(B)(3)
b .
502.10(B)(3)
c .
504.20
In exposed work non-metallic sheathed cable shall closely follow the surface of
the building finish or of running boards. It shall be protected from physical
damage when necessary. When passing through a floor the cable shall be
enclosed in a metal pipe extending at least 6 inches above the floor. Where run at
angles with joists in unfinished basement cable can be secured directly to the
lower edges of the joists when not smaller than two #6 or three #8. Smaller cables
shall either be run through bored holes in joists or on running boards. In
accessible attics cables run across the top of floor joists or within 7 feet of floor
joists run across the face of rafters on studs shall be protected by guard strips at
least as high as the cable. Where run along the sides of rafters, studs, or floor
joists, neither guard strips nor running boards are required. Where attic space is
not accessible by permanent stairs or ladders protection is only required within 6
feet of the nearest edge of the scuttle hole. The cable shall be protected as
required in Section 300.4 where installed through studs, joists, rafters, and similar
members.
Wiring devices with integral enclosures identified for such use shall be permitted
as provided in 300.15(E).
The insulated conductors shall be rated at 90 degrees Celsius and be one of the
types listed in Table 310.13 which is suitable for branch-circuit wiring or one
which is identified for use in NM, NMC or NMS cables. The size conductors shall
be sized #14 through 2 copper or sizes #12 through 2 aluminum or copper-clad
aluminum. In addition to the insulated conductors, the cable can have an insulated
or bare equipment grounded conductor sized in accordance with Article 250. As
stated before, the conductors shall be rated 90 degrees Celsius but the cable itself
ampacity shall be that of 60 degrees Celsius conductors.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW UP :
If time will allow, correct the worksheets and discuss the results.
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NONMETALLIC-SHEATHED CABLE: TYPES NM, NMC AND NMS
ARTICLE 334
LEVEL I
WORKSHEET
1. NM cable shall be permitted to be used in which of the following?
a.
b.
c.
d.
one-and-two family dwellings
multi-family dwellings
other structures
all of the above
2. Type NMC cable shall not be permitted for which of the following?
a. In any dwelling or structure not specifically permitted
b. Exposed in dropped or suspended ceilings in other than one- and twofamily and multifamily dwellings
c. As service-entrance cable
d. All of the above
3. Where passing through a floor in exposed work, NM cable shall be enclosed in
metal pipe extending at least which of the following distances above the floor?
a.
b.
c.
d.
2 inches
4 inches
8 inches
6 inches
4. Which of the following statements about NM cable in unfinished basements is/are
correct?
(A) two No. 6 cable can be secured directly to the lower edge of a joist.
(B) two No. 8 cable can be secured directly to the lower edge of a joist.
a.
b.
c.
d.
A only
both A and B
B only
neither A nor B
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5. Which of the following statements about bends in NM cable is/are correct?
(A) A run of cable between outlet and outlet, fitting and fitting, or outlet and
fitting shall not contain more than the equivalent of four quarter bends (360
degrees total).
(B) No bend shall have a radius less than six times the diameter of the cable.
a.
b.
c.
d.
A only
B only
both A and B
neither A nor B
6. Unless fished, NM cable shall be supported at intervals not exceeding which of the
following?
a.
b.
c.
d.
4 feet
4 1/2 feet
6 feet
3 feet
7. The maximum size 600 Volt NM cable is not greater than which of the following?
a.
b.
c.
d.
# 14 AWG
# 4 AWG
# 3 AWG
# 2 AWG
8. The overall covering of NM cable shall be which of the following?
a.
b.
c.
d.
flame-retardant
weather-resistant
fungus-resistant
corrosion-resistant
9. The ampacity of the insulated conductors in NM cable shall be which of the
following?
a.
b.
c.
d.
60º C
90º C
75º C
40º C
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10. Where more than 2 NM cables containing 2 or more currentcarryingconductors are bundled together and pass through wood framing
that is to be fire- or draft-stopped using thermal insulation or sealing foam,
the allowable ampacity of each conductor shall be adjusted in accordance
with which of the following?
a.
b.
c.
d.
Table 310.15 (B)(2)(a)
Table 310.16
Table 310.15 (B)
Table 310.15 (C)(3)
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NONMETALLIC-SHEATHED
CABLE: TYPES NM, NMC AND
NMS ARTICLE 334
LEVEL I
ANSWER KEY
1.
2.
d, all of the above
d. all of the above
334.12(A)
3. d
334.15(B)
4. a, A only
334.15(C)
5. d, neither A nor B
6. b, 4 1/2 feet
7. 2
8. a, flame-resistant
334.116(A)
9. a, 60º C
10. c.
1
334.10
334.24
334.30
334.104
334.80
334.80
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SERVICE-ENTRANCE CABLE: TYPES SE AND USE
ARTICLE 338
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
construction and restrictions in the use of service-entrance cables Type SE and Type
USE.
MATERIALS NEEDED:
Samples of types SE and USE cables.
PRESENTING THE LESSON:
A service-entrance cable is a conductor assembly provided with a suitable overall
covering, primarily used for service of the following types:
a.
b.
Type SE service-entrance cables shall be permitted in wiring systems
where all of the circuit conductors of the cable are of the thermoset or
thermoplastic type.
Type USE, having a moisture-resistant covering and recognized for
underground use.
Certain constructions do not require an outer overall covering.
a. Cabled single-conductor Type USE that has a bare copper conductor cabled with
the assembly.
b. Type USE single, parallel, or cabled conductor assemblies that have a bare
copper concentric conductor applied.
If you have two or more of either SE or USE cables, one shall be permitted to be
uninsulated. Review Article 230 for uses of service-entrance cable for conductors.
Where all circuit conductors of Type SE cable are of rubber-covered or
thermoplastic type, then the cable may be used in interior wiring systems.
Type SE cables without individual insulation on the grounded circuit conductor
shall not be used as a branch circuit or as a feeder in a building unless certain
specifications are met.
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Type SE cable shall not be subject to temperatures in excess of the specified
temperature requirement for a particular type of insulation.
If Type SE cable is used for interior wiring it must comply with provisions of Article 338
and cables must comply with provisions of Part II of Article 334 excluding 334.80.
If cables are installed through studs, rafter, joists, etc. they are subject to provisions of
Section 300.4.
Sections 310.15 (A) 3 and338.120 contain information on temperature limitations
of conductors and marking procedures for service-entrance cables.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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SERVICE ENTRANCE CABLE: TYPES SE AND USE
ARTICLE 338
LEVEL I
WORKSHEET
1. Type SE cable has which of the following type cable coverings?
a.
b.
c.
d.
flame-retardant
moisture-resistant
Both of the Above
Neither of the above
2. Which of the following type cables is identified for underground use?
a.
b.
c.
d.
3.
Type SE service-entrance cable shall be permitted for use where the insulated
conductors are used for circuit wiring and the uninsulated conductor is used only
for which of the following?
a.
b.
c.
d.
4.
SER
SE
RHW
USE
Equipment grounding purposes.
Grounding electrode conductor.
Grounded electrode conductor.
Ungrounded conductor.
Bends in Types USE and SE cable shall be so made that the cable will not be
damaged. The radius of the curve of the inner edge of any bend, during or after
installation, shall not be less than which of the following?
a.
b.
c.
d.
6 times the diameter of the cable.
5 times the diameter of the cable.
4 times the diameter of the cable.
3 times the diameter of the cable.
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SERVICE ENTRANCE CABLE: TYPES SE AND USE ARTICLE 338
LEVEL I
ANSWER KEY
1.
2.
3.
4.
c, both of the above
d, USE
a, equipment grounding purposes
b. five times the diameter
338.2
338.2
338.10 (B)(2)
338.24
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UNDERGROUND FEEDER AND
BRANCH-CIRCUIT CABLE: TYPE UF
ARTICLE 340
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the use and application
of type UF cable.
MATERIALS NEEDED: Sample
of UF cable.
INTRODUCTION:
As the title of Article 340 (Underground Feeder and Branch Circuit Cable) implies, UF
cable has been tested and approved for direct burial application. UF cable is a factory
assembled cable of one or more moisture resistant cables with a flame-retardant,
moisture-, fungus-, and corrosion-resistant covering. See Table 310.15 (A) 3 for
temperature limitations.
This cable is similar in construction to NM cable and can be installed as NM cable
subject to the provisions of Article 334. UF cable is primarily utilized as feeders or
branch circuits to small detached structures or branch circuits for landscape lighting and
similar equipment.
PRESENTING THE LESSON:
The students should be instructed to review Article 340 in its entirety. The instructor
should review the Article with particular emphasis to allowable uses and prohibited uses of
UF cable. After the course presentation, the students should complete the following test.
Questions repeatedly missed should alert the instructor to material warranting additional
instruction.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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UNDERGROUND FEEDER AND
BRANCH-CIRCUIT CABLE: TYPE UF
ARTICLE 340
LEVEL I
WORKSHEET
1.
UF cable shall utilize conductors of size:
a.
b.
c.
d.
#14 AWG through #10 AWG, aluminum, copper, or copper-clad
#14 AWG copper, #12 AWG aluminum or copper-clad through #4/0 AWG
recognized by Table 310-16
not larger than #4 AWG
2. UF cable shall not be permitted in all the following except:
a.
b.
c.
d.
as service entrance cable to detached structures
in agricultural buildings
in residential dwellings not exceeding five floors above grade
in commercial garages
3. The ampacity of UF cable shall be that of:
a.
b.
c.
d.
90 degree Celsius conductors per Section 310.16
60 degree Celsius conductors per Section 310.16
60 degree Celsius conductors per Section 310.15
90 degree Celsius conductors per Section 310.15
4. UF cable embedded in concrete shall:
a.
b.
c.
d.
5.
be concrete-tight type
be listed for type application
not be permitted except per Article 424.43
be encased in not less than 2 inches
UF cable sheath shall be:
a.
b.
c.
d.
fungus resistant
UV resistant
heat resistant
flame proof
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6. The insulation of Type UF cable when used as NM cable shall be that of:
a)
b)
c)
d)
60 degrees Celsius
90 degrees Celsius
60 degrees Fahrenheit
140 degrees Hahrenheit
UNDERGROUND FEEDER AND BRANCHCIRCUIT CABLE: TYPE UF ARTICLE 340
LEVEL I
ANSWER KEY
1.
b, #14 AWG copper, #12 AWG aluminum or
copper-clad through #4/0 AWG
340.104
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2.
3.
4.
5.
6.
b, in agricultural buildings
c, 60 degrees Celsius conductors
per Section 310-15
c, not be utilized
a, fungus resistant
b
340.12, 547.5
340.80
340.12(8)
340.116
340.112
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INTERMEDIATE METAL CONDUIT: TYPE IMC
ARTICLE 342
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be acquainted with the use,
installation, and construction specifications of intermediate metal conduit.
INTRODUCTION:
The instructor may want to integrate Articles 342, 344, and 358 into one unit for teaching
purposes. Intermediate metal conduit is a conduit in which the walls are thinner than rigid
metal but thicker than electrical metallic tubing (EMT). It has a circular cross section and
when used with proper fittings and couplings can be used for the installation of
conductors.
MATERIALS NEEDED:
Samples of intermediate metal conduit, various fittings and couplings, and
different types of straps.
PRESENTING THE LESSON:
Intermediate metal conduit can be used in all atmospheric conditions. To prevent
galvanic action all use of dissimilar metals shall be avoided except aluminum couplings
can be used. Intermediate metal conduit can be used as an equipment grounding
conductor. (342.10, 342.14 and 342.60)
When subject to severe corrosive installations, it must be protected or suitable for the
condition. (342.10 (B))
When used in cinder fill, it must be either by a layer of non-cinder fill concrete or all
sides at least 2 inches thick or be not less than 18 inches deep, or be suitably protected
against corrosion. (342.10 (C))
When used in wet locations, all bolts, straps, screws, etc. must be corrosionresistance or suitably protected. (342.10 (D))
The minimum size that can be used in 1/2 trade size and the maximum is 4 inches trade
size. (342.20)
When the conduit has to be field cut, the ends must be reamed to remove the rough edges.
When field threading is required, a standard cutting die of 3/4 inches per taper foot shall
be used. (342.28)
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IMC shall be installed as a complete system in accordance with 300.18 and shall
be securely fastened in place and supported in accordance with 342.30(A) and
(B).
Running threads shall not be used to connect couplings. Couplings shall be made
up tight and must be approved for conditions. (342.42)
When bends are needed, they must be made so as not to damage the wire to be
pulled inside the conduit by reducing the size or causing crimps. The radius must
meet the same requirements as rigid metal conduit. (342.24) Bends in one run of
intermediate conduit must not exceed 360 degrees. (342.26)
Supports must be installed within 3 feet of each box or fitting and at least every
10 feet. Where straight runs are used with threaded couplings and supports
prevent stress, then supports can meet requirements for rigid metal conduit.
Where in industrial uses from machinery, and vertical risers with threaded
couplings are used firmly supported at top and bottom and no other means of
support is available the distance can be increased to 20 feet. (342.30 (B) 3)
Intermediate metal conduit shall be installed as a complete system as provided in
Article 300.18 and shall be securely fastened in place. Conduit shall be supported
at least every 10 feet (3.05m). In addition, conduit shall be securely fastened
within 3 feet (914 mm) of each outlet box, junction box, device box, cabinet,
conduit body, or other conduit termination. Fastening shall be permitted to be
increased to a distance 5 feet (1.52 m) where structural members do not readily
permit fastening within 3 feet (914 mm). (342.30 (A&B))
Splices shall only be made in accordance with 300.15. (342.56)
A bushing shall be used when entering a box unless the design of the box
provides equal protection. (342.46) Remind them to look at footnote
under 300.4(G)
Intermediate metal conduit shall be in standard lengths of 10 feet with one
coupling provided with each length. The letters IMC shall be durably marked
every five feet. (342.Part III)
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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INTERMEDIATE METAL CONDUIT: TYPE IMC
ARTICLE 342
LEVEL I
WORKSHEET
1. Minimum size of intermediate metal conduit is:
a.
b.
c.
d.
l/2 inches
3/4 inches
l l/2 inches
2 inches
2. Maximum size of intermediate metal conduit is:
a.
b.
c.
d.
1 1/2 inches
2 inches
3 inches
4 inches
3. When field threading intermediate metal conduit standard die with which of
following inches taper per foot must be used.
a.
b.
c.
d.
l/2
3/4
l
1 1/4
4. The number of bends shall not exceed:
a.
b.
c.
d.
90
180
360
200
5. Each run must be supported within what distance of the box.
a.
b.
c.
d.
2 feet
2 l/2 feet
3 feet
4 feet
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6. Each 10 feet joint of intermediate metal conduit must be marked "IMC" at not less
than which of the following?
a. 2 feet
b. 5 feet
c. 3 feet
d. 4 feet
7. Cables shall be permitted to be installed in IMC in which of the following?
a.
b.
c.
d.
as long as a 20% fill is not exceeded.
only on industrial projects.
only if the cables do not exceed three conductors.
where such use is not prohibited by the respective cable articles
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INTERMEDIATE METAL CONDUIT: TYPE IMC
ARTICLE 342
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
a, 1/2 inches
d, 4 inches
b, 3/4 inches
c, 360 degrees
c, 3 feet
b, 5 feet
d
342.20(A)
342.20(B)
342.28
342.26
342.30(A)
342.120
342.22
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RIGID METAL CONDUIT: TYPE RMC
ARTICLE 344
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be acquainted with the use,
installation, and construction code requirements of rigid metal conduit.
MATERIALS:
Sample of rigid metal conduit and fittings.
INTRODUCTION:
Single family dwellings are seldom wired completely with rigid metal conduit because of
the high cost of such an installation; however, it is widely used in industrial plants.
Electrical metallic tubing is sometimes employed because the cost of labor for installation
is much less than for rigid conduit. The cost is still higher than for a cable type
installation. Sometimes rigid metal conduit is used for service raceway even though the
bulk of the installation is some other wiring method.
Industrial installations of rigid metal conduit have routinely presented electricians with jobs
of great proportions; however, with the hydraulic equipment in use today, this work is
easily accomplished. Various attributes of fluid or hydraulic power equipment recommend
it to the electrical industry. Hydraulic tools readily increase 100 pounds of applied effort to
200,000 pounds of output. This makes rigid metal conduit a lot easier to bend than the old
railroad track method.
PRESENTING THE LESSON:
Rigid metal conduit shall be permitted under all atmospheric conditions and occupancies. If
protected solely by enamel it is permitted only indoors where not subject to sever
conditions.
Where practicable, dissimilar metals on contact anywhere in the system shall be avoided
to eliminate the possibility of galvanic action. Aluminum and steel fittings and enclosures
shall be permitted to be used either steel or aluminum conduit. Rigid metal conduit and
associated fittings can be used in severe corrosive areas if protected by corrosion
protection and judged suitable for the condition.
Rigid metal conduit shall not be used in or under cinder fill where subject to
permanent moisture, unless suitable for the purpose, enclosed in a two inch
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concrete envelope, or at least 18 inches under cinder fill. If
installed in a wet locations all support material shall be
protected against corrosion.
The minimum size conduit to be used shall be 1/2 inch
electrical trade size with the exception of 3/8 inch for enclosing
motor leads.
The number of conductors permitted in a single conduit shall
not exceed the percentage fill specified in Table 1 of Chapter 9.
The instructor should show an overhead of Table 9 and explain
how to interpret it.
All cut ends of rigid metal conduit shall be reamed to remove
rough edges. Where threaded, a standard cutting die with a
3/4 inch taper per inch shall be used. Where a conduit enters
a box or other fitting it shall be bushed with a bushing or
other approved means.
Running threads shall not be used at couplings. If threadless
couplings or connectors are used they shall be made tight and, if
used in masonry or concrete they shall be concrete tight type.
A run of conduit shall not contain more than the equivalent of 4
quarter bends total of 360 degrees. The radius of bends shall not
be less than shown in Tables Table 1, Chapter 9 for one shot
and full shoe benders or other bends.
Rigid metal conduit shall be supported within three feet of each
outlet box, junction box, cabinet, or fitting and no more than 10
feet apart. If threaded couplings are used, Table 344.30(B)(2),may
be used. Splices or taps shall be made only in junction boxes,
outlet boxes, or conduit bodies that comply with the applicable
provisions of Article 314.
Uses Permitted. Note the changes in 344.10 for the different
types of RMC such as Galvanized Steel and Stainless Steel
RMC, Red Brass RMC and Aluminum RMC.
Rigid metal conduit shall be installed as a complete system as
provided in Article 300 and shall be securely fastened in place
and supported in accordance with Article 344.30 (A) and (B).
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Standard lengths of rigid metal conduit shall be ten feet including
one coupling. Other lengths can be shipped for specific applications
or uses. If made of corrosive resistant material the rigid metal
conduit shall have suitable markings. Each length shall be clearly
and durably identified in each ten feet.
APPLICATION:
If time will allow, let the class answer the questions on the
worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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RIGID METAL CONDUIT: TYPE RMC
ARTICLE 344
LEVEL I
WORKSHEET
1.
The use of dissimilar metals in contact in a rigid metal conduit system shall be
avoided to eliminate the possibility of which of the following?
a.
b.
c.
d.
2.
Galvanic action.
Corrosion.
Electrolysis
Harmonics.
RMC shall be permitted to be installed in or under cinder fill where subject to
permanent moisture where protected on all sides by a layer of noncinder concrete
not less than which of the following?
a.
b.
c.
d.
3.
18 inches thick
12 inches thick
8 inches thick
2 inches thick
Which of the two following statements is/are correct?
A. All screws holding supports for rigid metal conduit in a wet location
shall be made of corrosion-resistant materials.
B. In general, the minimum size conduit shall be 1/2 inch.
a.
b.
c.
d.
A only
B only
both A and B
neither A nor B
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4. Which of the following is a condition which allows an exception to the minimum
size rigid metal conduit?
a.
b.
c.
d.
5.
Underplaster extensions.
Motor lead enclosures.
Junction box connectors
Conduit connectors.
Conduit ends shall be reamed to remove which of the following?
a.
b.
c.
d.
paint
cutting oil
threads
rough edges
6. Where conduit is threaded in the field a standard cutting die with which of the
following requirements shall be used?
a.
b.
c.
d.
7.
Bushings are required on conduit at junction boxes where design of box does not
offer equipment protection in order to provide for which of the following?
a.
b.
c.
d.
8.
To prevent water infiltration.
To prevent corrosion of the wire.
To prevent abrasion of the wiring.
To strengthen the box-to-conduit connection.
Threadless couplings where buried in masonry shall be of which type?
a.
b.
c.
d.
9.
a 3/4 inch taper per foot
a 1/2 inch taper per foot
a 1/4 inch taper per foot
a 1 inch taper per foot
watertight
airtight
sealed
concrete tight
Running threads shall not be used on conduit for which of the following reasons?
a.
b.
c.
d.
For connection at couplings.
For connections at junction boxes.
For bonding connectors to boxes.
For grounding conductors.
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10. The minimum radius bend of a one inch rigid metal conduit for the installation of
THW conductors bent in the field with a one shot bender is which of the
following?
a.
b.
c.
d.
5 1/2 inches
5 3/4 inches
6 inches
11 inches
11. Which of the following statements about rigid metal conduit is correct?
A. The maximum number of bends permitted in one conduit run is four
quarter bends or total of 360 degrees.
B. Standard length shall be 5 feet.
a.
b.
c.
d.
A only
B only
both A and B
neither A nor B
12. The percentage fill of a 1/2 inch rigid metal conduit with 3 THW conductors will
be which of the following?
a.
b.
c.
d.
60 percent
40 percent
75 percent
80 percent
13. If structural members do not allow closer fastening, RMC shall be securely
fastened at junction boxes within which of the following?
a.
b.
c.
d.
4 feet
3 feet
6 feet
5 feet
14. RMC shall be permitted to be used as which of the following?
a.
b.
c.
d.
A grounded conductor.
An equipment grounding conductor.
A junction box.
An auxiliary gutter.
15. Red brass RMC shall be permitted to be installed for which of the following
types of applications?
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I. swimming pools
II. direct burial
a.
b.
c.
d.
I only
II only
Neither I or II
Both I and II
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Student Worksheets -- Level 1
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RIGID METAL CONDUIT: TYPE RMC
ARTICLE 344
LEVEL I
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
ANSWER KEY
a, galvanic action
d, 2 inches thick
c, both A and B
b, motor lead enclosures
d, rough edges
a, 3/4 inch taper per foot
c, to prevent abrasion of the wiring
d. concrete tight
a
b, 5 3/4 inches
a, A only
b, 40%
d, 5 feet
b, an equipment grounding conductor
d, both I and II
344.14
344.10(C)
344.10(D), 344.20(A)
344.20 Exception
344.28
344.28
344.46
344.42(A)
344.42(B)
Table 2, Chapter 9
344.26
Table 1 Ch. 9, 344.22
344.30(A)
344.60
344.10(2)
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FLEXIBLE METAL CONDUIT: TYPE FMC
ARTICLE 348
LEVEL I
OBJECTIVE:
After completing this lesson, the students should be acquainted with the
construction and restrictions in the uses of Flexible Metal Conduit.
INTRODUCTION:
Flexible metal conduit is used in places requiring irregular bends or where flexibility is
required during or after installation. Trade sizes l/2" and larger may be installed in any
length, although supporting and grounding requirements vary depending on lengths
installed. Sizes of 3/8" have restricted uses in lengths not exceeding 6'.
PRESENTING THE LESSON:
The students should be instructed to review Article 348 in its entirety. The instructor
should review the Article with particular emphasis on usages, sizes, and grounding.
Samples can be utilized to familiarize the student with the construction and application
of flexible metal conduit. Show Table 348.22 and explain.
Flexible metal conduit shall be supported at intervals not exceeding 4 1/2" and within
12" of each outlet box unless fished, or length does not exceed 3' or being used in
lengths not exceeding 6' for a fixture tap.
Flexible metal conduit can be used as a grounding means according to 250.118 and
250.102(E). It shall be limited to lengths of 6' or less and overcurrent protection of 20
amps or less. Note the uses permitted in wet locations.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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FLEXIBLE METAL CONDUIT: TYPE FMC
ARTICLE 348
LEVEL I
WORKSHEET
1. Flexible metal conduit of 3/8" trade size may be used for all of the following
except:
a.
b.
c.
d.
In lengths not exceeding 6' located in hoistways
In lengths not exceeding 6' for the connections to lighting fixtures.
Encased in concrete not over 4' in length
Manufactured wiring systems
2. The maximum number of #14 AWG type THHN conductors in 3/8" flexible metal
conduit with outside fittings is:
a.
b.
c.
d.
3.
7
3
2
4
Flexible Metal Conduit is installed in accordance with 250.118(5) it shall be
allowed to be used an equipment grounding conductor when which of the
following occurs?
a.
b.
c.
d.
When flexibility is required.
When flexibility is not required.
When approved by the AHJ
Not allowed
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FLEXIBLE METAL CONDUIT: TYPE FMC
ARTICLE 348
LEVEL I
ANSWER KEY
1. c, Encased in concrete not over 4' in length
2. d, 4
3. b, Where flexibility is not required
348.20
Table 348.22
348.60
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156
LIQUIDTIGHT FLEXIBLE METAL CONDUIT: TYPE LFMC
ARTICLE 350 and
LIQUIDTIGHT FLEXIBLE NON-METALLIC CONDUIT: TYPE LFNC
ARTICLE 356
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the use and
construction of liquid tight flexible metal conduit and also with liquid-tight flexible
non-metallic conduit.
INTRODUCTION:
Before we can look at the use and application of liquid-tight, as it is referred to in the
trade, let's look at what it is. Liquidtight is a flexible conduit that is circular in cross
section with an outer covering that is non-metallic but an interior flexible metal core.
When used with proper couplings and fittings. It can be used for the installation of
conductors.
MATERIALS NEEDED:
This material is used extensively and should be covered thoroughly. Articles 348, 350
and 356 could be taught at the same time or in consecutive order. For this lesson, you
need samples of both liquid-tight flexible metal conduit and liquid-tight flexible nonmetallic conduit and their respective fittings and couplings.
PRESENTING THE LESSON:
Liquidtight flexible metal conduit, when listed and marked, can be used for both
concealed and exposed work, and for direct burial in earth where required for flexibility
or protection from liquids, vapors or solids. It can also be used for hazardous locations
where approved both by listing and by provisions of Article 500. It cannot be used
where subject to physical damage or to temperatures higher than what it has been tested
and approved for. (350.10, 350.12)
The minimum size of liquid-tight flexible metal conduit is 1/2" trade size unless 3/8"
meets the requirements for flexible metal conduit of 3/8" size. The maximum size is 4"
trade size.
The maximum number of conductors that can be installed must meet the
requirements for conduits in Table 1 of Chapter 9. Size 3/8" shall meet the
requirements of flexible metal conduit. (350.22)
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When being used as a fixed raceway, liquid-tight flexible metal conduit shall be
supported every 4 1/2 feet and within 12" of each box, cabinet or fitting. The
exceptions to this is for fixture taps, lengths not exceeding 3 feet and at
terminations where flexibility is needed. Note the changes to the exceptions to in
350.30(A) (350.30)
When using liquid-tight flexible metal conduit as a grounding means, both the
conduit and fittings must be approved for grounding. If the conduit is 1 1/4" and
smaller and less than 6 feet in length, terminated in fittings approved for
grounding, and 1/2" and 3/8" is protected by 20 amp and 3/4" to 1 1/4" by 60
amps, then the conduit does not have to be approved for grounding. Where
connecting equipment, and flexibility is needed, a grounding conductor shall be
used. (350.60, 250.118)
Bends shall not exceed 360 degrees and angle connectors shall not be used in
concealed spaces. (350.26)
Liquidtight flexible non-metallic conduit differs from the metallic kind by having
an interior that is reinforced but non-metallic. It can be used in places where
liquid-tight flexible metal conduit can be used. If used outside it must be
approved for outside use. It is not approved for hazardous locations, and cannot
be used for conductors in excess of 600 volt nominal. (356.10, 356.12). Note
356.10 (4) Direct Burial.
Except for 3/8" motor leads, the minimum size of 1/2" trade size and the
maximum is 4" trade size. (356.20)
Discuss maximum supporting lengths. (356.30)
The equipment grounding conductor can be run inside or outside the raceway if
run outside the grounding conductor is limited to 6 feet in length. (356.60,
250.102)
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW UP:
If time will allow, correct the worksheets and discuss the results.
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LIQUIDTIGHT FLEXIBLE METAL CONDUIT: TYPE LFMC
ARTICLE 350
and
LIQUIDTIGHT FLEXIBLE NON-METALLIC CONDUIT: TYPE LFNC
ARTICLE 356
LEVEL I
WORKSHEET
1.
The smallest size of liquid-tight flexible metal conduit that can be used without
exception in normal circumstances is?
a.
b.
c.
d.
3/8 inch
1/2 inch
3/4 inch
1 inch
2. Maximum size of liquid-tight flexible non-metallic conduit that can be used is?
a.
b.
c.
d.
1 1/4 inches
1 1/2 inches
2 inches
4 inches
3. Liquidtight must be supported within which of the following distances of each
fitting?
a.
b.
c.
d.
12 inches
24 inches
36 inches
48 inches
4. Where flexibility is not required, LFMC shall be permitted in which of the
following?
a. shall be permitted to be used in all sizes if conductors therein
are protected at no greater than 70 amperes.
b. shall be permitted to be used in any location.
c. may be used in any location with an ambient temperature below
110 degrees F.
d. shall be permitted to be used as an equipment grounding conductor
when installed in accordance with 250.118(6).
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5. Liquidtight flexible non-metal conduit cannot be used in lengths of more than?
a .3 feet
b. 4 feet
c. 5 feet
d. any length
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LIQUIDTIGHT FLEXIBLE METAL CONDUIT
ARTICLE 350 and
LIQUIDTIGHT FLEXIBLE NON-METALLIC CONDUIT
ARTICLE 356
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
b, 1/2 inch
d, 4 inches
a, 12 inches
d, 60
d
350.20
356.20(B)
350.30(A)
250.118(6), 350
350.60 (356.12 (3)
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RIGID POLYVINYL CHLORIDE CONDUIT: TYPE PVC
ARTICLE 352
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be acquainted with the use, installation,
and construction specifications of rigid polyvinyl chloride conduit.
MATERIALS NEEDED:
Samples of various types of rigid polyvinyl chloride conduit.
Handouts and/or pictures of the above.
INTRODUCTION:
For use above ground, the material shall be resistant to moisture and chemical
atmospheres, it shall be flame-retardant, resistant to impact and crushing, resistant to
distortion from heat under conditions likely to be encountered in service and resistant to
low temperature and sunlight effects.
For use underground, the material shall be acceptably resistant to moisture and corrosive
agents and be of sufficient strength to withstand abase, such as by impact and crushing, in
handling and during installation. Where intended for direct burial without encasement in
concrete, the material shall also be capable of withstanding continued loading that is likely
to be encountered after installation.
PRESENTING THE LESSON:
Rigid polyvinyl chloride conduit shall be permitted to be used under the following
conditions:
1.
2.
3.
4.
5.
6.
7.
concealed
in locations subject to severe corrosive influences as cited in Section 300.6
in cinder fill
in wet locations
in dry and damp locations
for exposed work
for underground installations
Rigid polyvinyl chloride conduit shall not be used:
1. in hazardous locations except as covered in Sections 503.3(A), 504.20, 514.8, 515.8,
and the exception to Section 501.4(B)
2. for support for fixtures or other equipment not described in 352.10(H)
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3. where subject to physical damage
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4. where subject to ambient temperatures exceeding those the conduit was
approved.
5. For conductors whose insulation temperature limitations would exceed those
for which the conduit is approved.
6. in theaters and similar locations except as provided in Article 518 and 520.
In addition to the requirements of Article 352, rigid polyvinyl chloride conduit
shall comply with the applicable provisions of Article 300. Where equipment
grounding is required by Article 250, a separate equipment grounding conductor
shall be installed in the conduit.
All cut ends of rigid polyvinyl chloride conduit shall be trimmed inside and
outside to remove the rough edges. All joints shall be made by an approved
method.
Rigid polyvinyl chloride conduit shall be securely fastened within 3 feet of each
box, cabinet, or other conduit termination and the maximum spacing between
supports shall be as shown in Table 352.30(B).
The minimum size rigid polyvinyl chloride conduit that can be used is 1/2 inch
electrical trade size. The number of conductors permitted in a conduit shall not
exceed the percentage fill as allowed in Table 1, Chapter 9.
Unless the design of the box or fitting is such to provide equivalent protection, a
bushing or adapter shall be used to protect conductors from abrasion where a
conduit enters a box or fitting.
Field bends in rigid polyvinyl chloride conduit shall be made only with bending
equipment identified for the purpose and the bend itself shall meet the
specifications of Table 2, Chapter 9.
The number of bends in one run of conduit shall not exceed the equivalent of four
quarter bends (360 degrees, total).
Each length of polyvinyl chloride conduit shall be clearly and durable marked
every 10 feet as required in Section 110.21.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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RIGID POLYVINYL CHLORIDE CONDUIT: TYPE PVC
ARTICLE 352
LEVEL I
WORKSHEET
1. Which of the following statements about rigid polyvinyl chloride conduit is correct?
A. it shall be made from rigid polyvinyl chloride (PVC) material only.
B. it may be used in continuous lengths from a reel when listed for this
purpose.
a.
b.
c.
d.
A only
b only
both A and B
neither A nor B
2. All cut ends of PVC shall be required to meet the following?
a.
b.
c.
d.
trimmed inside
trimmed outside
have rough edges removed.
All of the above
3. Rigid polyvinyl chloride conduit may be used in locations subject to severe corrosive
influences as covered in which of the following sections?
a.
b.
c.
d.
Section 300.6.
Section 342
Section 352
Section 310.5
4. Which of the following statements about the permitted uses of rigid polyvinyl chloride
conduit is correct?
A. it may support fixtures and other equipment.
B. it may be run in cinder fill.
a.
b.
c.
d.
A only
B only
both A and B
neither A nor B
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5. A 1 1/2 inch PVC conduit may have a radius bend not greater than which of the following if
other than a one-shot bend is used?
a.
b.
c.
d.
6.
8 3/4 inches
10 inches
6 inches
4 inches
Rigid polyvinyl chloride conduit shall be securely fastened within what distance
of each box, cabinet, or other conduit termination?
a.
b.
c.
d.
4 feet
5 feet
6 feet
3 feet
7. The percentage fill for a 3/4 rigid nonmetallic conduit containing three conductors is which
of the following?
a
b
c
d
.
.
.
.
3
31
8
40
8. The total number of bends permitted in one run of polyvinyl chloride conduit is
equivalent to:
a.
b.
c.
d.
four 45 degree bends
180 degrees total
four quarter bends
three quarter bends
9. The maximum spacing between supports for rigid polyvinyl chloride conduit 6 inches in
size is:
a.
b.
c.
d.
3 feet
6 feet
8 feet
10 feet
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10. Rigid polyvinyl chloride conduit may be used in trade sizes not smaller than which of
the following?
a.
b.
c.
d.
11.
Where equipment grounding is required, which of the following is used?
a.
b.
c.
d.
12.
trade size 3/8 inch
trade size 3/4 inch
trade size 1/2 inch
trade size 5/8 inch
A separate grounded conductor shall be installed.
A separate grounding conductor shall be installed.
A separate bonding jumper shall be installed.
A separate equipment grounding conductor shall be installed.
Rigid polyvinyl chloride conduit shall be permitted to support polyvinyl chloride
conduit bodies not larger than which of the following?
a. nonmetallic conduit bodies not larger than the largest trade size of an
entering raceway
b. nonmetallic conduit bodies not larger than 3/4 inch.
c. nonmetallic conduit bodies in corrosive circumstances.
d. Shall never be used to support conduit bodies.
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RIGID POLYVINYL CHLORIDE CONDUIT: TYPE PVC
ARTICLE 352
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
c, Both A&B
d. all of the above
a.
b, B only
b
d, 3 feet
d, 40
c, 360 degrees total
c, 8 feet
c
d,
a
352.100
352.28
352.10(B)
352.10(C), 352.12(B)
Table 2, Chapter 9
352.30(A)
352.22, Chap 9 Table 1
352.26
Table 352.30(B)
352.20(A)
352.60
352.10(H)
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NONMETALLIC UNDERGROUND CONDUIT
WITH CONDUCTORS: TYPE NUCC
ARTICLE 354
LEVEL I
OBJECTIVE: After completing this lesson, each student should be acquainted
with the use, installation, and construction specifications of Nonmetallic
Underground Conduit with Conductors: Type NUCC
MATERIALS NEEDED:
Samples of various types of Nonmetallic Underground Conduit with Conductors:
Type NUCC conduit or if unavailable, handouts and/or pictures of the above.
INTRODUCTION:
NUCC is an assembly that is provided in continuous lengths shipped in a coil,
reel, or carton. The nonmetallic underground conduit shall be listed and
composed of a material that is resistant to moisture and corrosive agents. It shall
also be capable of being supplied on reels without damage or distortion and shall
be of sufficient strength to withstand abuse, such as impact or crushing, in
handling and during installation without damage to conduit or conductors. NUCC
shall be clearly and durably marked at least every 10 ft. as required by 110.21.
The type of conduit material shall also be included in the marking. Identification
of conductors or cables used in the assembly shall be provided on a tag attached
to each end of the assembly or to the side of a reel. Cover uses permitted as well
as uses not permitted.
PRESENTING THE LESSON:
NUCC is a factory assembly of conductors or cables inside a nonmetallic, smooth
wall conduit with a circular cross section. NUCC and associated fittings shall be
listed. NUCC and fittings shall be permitted for direct burial underground type
installation, encased or embedded in concrete or cinder fill, in underground
locations subject to severe corrosive influences where specifically approved for
this type of installation and aboveground, except as prohibited in 354.12, where
encased in not less than 2 inches of concrete. NUCC shall not be used in exposed
locations, inside buildings, or in any hazardous (classified) location, except as
permitted by other articles of this Code. Note the Exception for inside buildings to
the students.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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NONMETALLIC UNDERGROUND CONDUIT WITH
CONDUCTORS: TYPE NUCC
ARTICLE 354
LEVEL I
WORKSHEET
1. NUCC shall be clearly and durably marked in accordance with which of the
following?
a.
b.
c.
d.
at least every 2 feet
at least every 30 inches
at least every 5 feet
at least every 10 feet
2. The radius of the curve of the centerline of a bend in a 1 inch NUCC conduit shall
not be less than which of the following?
a.
b.
c.
d.
10 inches
8 inches
14 inches
12 inches
3. When using NUCC where equipment grounding is required, which of the
following is to be used?
a.
b.
c.
d.
an assembly with a separate enclosure with a green or bare
wire
an assembly containing a separate equipment grounding
conductor.
a gutter assembly containing a separate grounding
conductor.
an equipment grounding conductor.
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NONMETALLIC UNDERGROUND CONDUIT
WITH CONDUCTORS: TYPE NUCC
ARTICLE 354
LEVEL I
ANSWER KEY
1.
d, 10 feet
354.10
2.
c, 14 inches
Table 354.24
3.
b, an assem bl y cont ai ni ng sep arat e equi pm ent
grou ndi n g conduct o r .
354.60
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171
ELECTRICAL METALLIC TUBING: TYPE EMT
ARTICLE 358
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be acquainted with the
construction and restriction in the uses of electrical metallic tubing.
MATERIALS:
Samples of electrical metallic tubing.
INTRODUCTION:
Electrical metallic tubing (EMT) sometimes called "thin-wall conduit" has a wall
thickness less than that of rigid conduit, and it bends more easily. It is connected with
compression or indentation-type fittings, since it is too thin to thread. A special tool is
used to install indentation fittings.
PRESENTING THE LESSON:
Electrical metallic tubing is installed and has the same use for both exposed and
concealed work as rigid conduit except it cannot be used where subject to severe physical
damage, or in hazardous locations. When used in wet locations or poured over in
concrete, fittings of the type to prevent water entering the conduit shall be used.
Tubing and fittings may be obtained, made of an alloy having corrosion-resisting
characteristics. This makes them especially suitable for use in many locations where
there are corrosive fumes, or excessive moisture.
No tubing shall be used smaller than 1/2 inch in diameter, electrical trade size, except for
under plastic extensions. The maximum size tubing shall be the 4-inch electrical trade
size. Bends in the tubing shall be made so that the tubing will not be injured and that the
internal diameter of the tubing will not be effectively reduced. One run of conduit shall
include not more than four "quarter" bends.
APPLICATION:
If time allows, let the class answer questions on the worksheet.
CHECKING AND FOLLOW UP :
If time allows, correct the worksheets and discuss the results.
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ELECTRICAL METALLIC TUBING: TYPE EMT
ARTICLE 358
LEVEL I
WORKSHEET
1. Which of the following is a permitted use for Electrical Metallic Tubing?
a. Where, during installation or afterward, it will be subject to severe
physical damage.
b. Where protected from corrosion solely by enamel.
c. For the support of luminaires (fixtures) or other equipment except
conduit bodies no larger than the largest trade size of the tubing.
d. For both exposed and concealed work.
2. Electrical trade size tubing shall not be used smaller than which of the following?
a.
b.
c.
d.
3.
Electrical trade size tubing shall not be used larger than which of the following?
a.
b.
c.
d.
4.
1 inch
3/4 inch
3/8 inch
1/2 inch
4 inch
3 inch
2 inch
6 inch
The radius of the curve of any field bend to the centerline of 2 inch tubing using a
One Shot bender shall not be less than which of the following?
a.
b.
c.
d.
10 inches
9 1/2 inches
8 1/4 inches
7 1/4 inches
5. One run of conduit shall not include more than which of the following "quarter"
bends.
a.
b.
c.
d.
6
4
3
2
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ELECTRICAL METALLIC TUBING: TYPE EMT
ARTICLE 358
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
d
d, 1/2 inch
a
b,91/2 inches
b, 4
358.10 (A)
358.20(A)
358.20(B)
Table 2, Chapter 9 pg. 625
358.26
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174
AUXILIARY GUTTERS
ARTICLE 366
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
more important requirements related to auxiliary gutters.
INTRODUCTION:
Auxiliary gutters are permitted to supplement wiring spaces at meter
centers, distribution centers, switchboards, and similar points of wiring
systems and may enclose conductors or busbars, but shall not be used to
enclose switches, overcurrent devices, appliances, or other similar
equipment.
PRESENTING THE LESSON:
1. Metallic Auxiliary Gutter. A sheet metal enclosure used to supplement
wiring spaces at meter centers, distribution centers, switchboards, and
similar points of wiring systems.
2. The enclosure has hinged or removable covers for housing and
protecting electrical wires, cable, and busbars.
3. The enclosure is designed for conductors to be laid or set in place
after the enclosures have been installed as a complete system.
4. It is very important that the number and ampacity of conductors
contained within the gutters be understood.
5. Each installation of the subject equipment involves splices and taps.
Therefore the requirements in Section 366.56 are important.
6. Section 366.100 dealing with construction is primarily used by testing
labs to evaluate equipment for testing.
APPLICATION:
If time allows, let the class answer the questions on the
worksheet. CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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AUXILIARY GUTTERS
ARTICLE 366
LEVEL I
WORKSHEET
1.
Auxiliary gutters shall not extend beyond the equipment that it supplements a
distance greater than which of the following?
a.
b.
c.
d.
10 feet
20 feet
30 feet
15 feet
2. What is the maximum distance between the supports of auxiliary metal gutters?
a.
b.
c.
d.
2 feet
3 feet
4 feet.
5 feet
3. As a general rule, what is the maximum number of conductors permitted at any
cross section of an auxiliary gutter?
a.
b.
c.
d.
15
20
25
30
4. The sum of the cross-sectional areas of all contained conductors at any cross
section of a sheet metal auxiliary gutter shall not exceed what percent of the
interior cross-sectional area of the sheet metal auxiliary gutter?
a.
b.
c.
d.
15
20
30
40
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AUXILIARY GUTTERS
ARTICLE 366
LEVEL I
ANSWER KEY
1.
2.
3.
4.
c. 30 feet
d. 5 feet
d. 30
a. 20%
366.12
366.30
366.22
366.22
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177
MULTIOUTLET
ASSEMBLY ARTICLE
380
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be acquainted with the
requirements concerning the installations of multioutlet assembly.
MATERIALS NEEDED:
Samples of multioutlet assembly and fittings. Handouts of pictures of the
above.
INTRODUCTION:
This subject is not often common in level one jobs, so a limited amounted of
time should be spent on this subject. Multioutlet assembly is a type of
surface or flush raceway designed to hold conductors and receptacles. It can
be assembled in the field or at the factory.
PRESENTING THE LESSON: Discuss ultioutlet assembly.
Discuss where multioutlet assembly shall not be installed. [380.2(B)]
1. Where concealed, except that it shall be permissible to surround the back
and sides of a metal multioutlet assembly by the building finish or recess a
nonmetallic multioutlet assembly in a baseboard.
2. Where subject to severe physical damage.
3. Where the voltage is 300 volts or more between conductors unless the
assembly is of metal having a thickness of not less than .040 inch.
4. Where subject to corrosive vapors.
5. In hoistways.
6. In any hazardous (classified) location, except as permitted by other
articles of this Code.
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APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP.
If time allows, correct the worksheets and discuss the results.
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MULTIOUTLET ASSEMBLY
ARTICLE 380
LEVEL I
WORKSHEET
1. Which of the following statements about multioutlet assembly is/are correct?
A. It can be installed in dry locations.
B. It can be installed in wet locations.
a.
b.
c.
d.
2.
A only
B only
both A and B
neither A nor B
It shall be permissible to extend a metal multioutlet assembly through which of
the following?
a.
b.
c.
d.
walls
ceilings
floors
dry partitions
3. Multioutlet assembly can not be used where subject to which of the
following?
a.
b.
c.
d.
4.
severe physical damage
hoistways
corrosive atmospheres
all of the above
Multi-outlet assembly shall not be used where the voltage is 300 volts or more
between conductors unless the assembly is of a metal having a thickness of not
less than which of the following?
a.
b.
c.
d.
.40 inches
.040 inches
.0040 inches
.04 inches
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MULTIOUTLET ASSEMBLY
ARTICLE 380
LEVEL I
ANSWER KEY
1.
2.
3.
4.
a, A only
d. dry partitions
d. all of the above
b. .040
380.2(A)
380.3
380.2(B)
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SURFACE METAL RACEWAYS
ARTICLE 386 and
SURFACE NONMETALLIC RACEWAYS
ARTICLE 388
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
use, installation, and construction specifications of surface raceways.
MATERIALS NEEDED:
Samples of surface metal raceways.
INTRODUCTION:
In surface metal or aluminum raceway wiring, the wires are supported in a
thin metal casing. The raceway is installed exposed, being mounted on dry
walls, ceilings, and if approved, on floors. The sheet-steel casing called metal
raceway or metal molding is made with a flattened oval or rectangular cross
section. Most types of molding are made in two parts, a trough or base which
is snapped on the base. One type of metal surface raceway is manufactured
with the capping crimped on the base at the factory. With this type, the wires
must be pulled through the raceway from outlet to outlet as in the conduitwiring method. Provisions for outlets or switches are made by means of
special fittings inserted in the runs of molding. Surface nonmetallic raceways
are made of a suitable nonmetallic material that is resistant to moisture and
chemical atmospheres. It shall also be flame retardant resistant to impact and
crushing, resistant to distortion from heat under conditions likely to be
encountered in service and resistant to low-temperature effects.
PRESENTING THE LESSON:
Surface metal raceways shall be permitted in dry locations.
They shall not be used:
1. where subject to severe physical damage unless otherwise approved;
2. where the voltage is 300 volts or more between conductors unless the
metal has a thickness of not less than .040 inch;
3. where subject to corrosive vapors;
4. in hoistways;
5. concealed as permitted under raised floors.
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The number and size conductors in both surface metal and nonmetallic raceways
shall be determined by what the raceways are designed for. Unbroken lengths of
surface metal and nonmetallic raceways shall be permitted to extend through dry
walls, dry partitions, and dry floors.
Where combination surface metal or nonmetallic raceways are used for signaling
and for lighting and power circuits, the different systems shall be run in separate
compartments identified by sharply contrasting colors of the interior finish or in
nonmetallic an identified printed legend. The same relative position of
compartments shall be maintained throughout the premises.
Splices and taps shall be permitted in surface metal and nonmetallic raceways
having a removable cover that is accessible after installation. The conductors,
including splices and taps shall not fill the raceway to more than 75 percent of its
area at that point. In raceways without removable covers, splices and taps shall be
made only in junction boxes. The use of surface nonmetallic raceways shall be
permitted in dry locations.
They shall not be used: (388.12)
1. where concealed [except 388.10(2)];
2. where subject to severe physical damage;
3. where the voltage is 300 volts of more between conductors, unless listed for
higher voltage;
4. in hoistways;
5. in any hazardous (classified) location except as permitted by this Code.
6. where subject to ambient temperature exceeding those for which it is listed;
7. for conductors whose insulation temperature exceeds the limitations for which
the raceway is listed.
Surface metal and nonmetallic raceways shall be of such construction as will
distinguish them from other raceways. The surface raceways and their elbows,
couplings, and similar fittings shall be designed that the sections can be
mechanically, and in surface metal raceway, electrically coupled together without
subjecting the wires to abrasion.
Where covers and accessories of nonmetallic materials are used on surface metal
raceways, they shall be identified for such use.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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SURFACE METAL RACEWAYS
ARTICLE 386
and
SURFACE NONMETALLIC RACEWAYS
ARTICLE 388
LEVEL I
WORKSHEET
1.
Surface metal raceways shall be supported at intervals?
a.
b.
c.
d.
not exceeding 2 ft.
not exceeding 4 ft.
not exceeding 5 ft.
in accordance with the manufacturer's installation instructions.
2. When combination surface nonmetallic raceways are used both for signaling
and for lighting and power circuits, the different systems shall be run in
separate compartments identified by which of the following?
a.
b.
c.
d.
stamping, imprinting, or color coding of the interior finish.
stamping of the outer surface..
coloring of the outer surface.
imprinting of the outer surface.
3. The number of current carrying conductors permitted in a single surface metal
raceway shall not exceed which of the following?
a
b
c
d
4.
.
.
.
.
20
30
25
40
The sum of the cross-sectional areas of all contained conductors does not exceed
which of the following percentage of the interior cross-sectional area of the
surface metal raceway?
a.
b.
c.
d.
30 percent
20 percent
40 percent
10 percent
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5.
Splices and taps shall be permitted in surface metal raceways having which of the
following?
a.
b.
c.
d.
6.
A readily accessible removable cover after installation.
An accessible removable cover after installation.
A removable cover.
A listed readily removable cover.
When combination surface metallic raceways are used for both signaling and for
lighting and power circuits, the different systems shall be run in separate
compartments identified by which of the following?
a.
b.
c.
d.
stamping
imprinting
color coding
all of the above
7. Surface metal raceways and their elbows, couplings, and similar fittings shall be
so designed that the sections can be electrically and mechanically coupled together
without subjecting the wires to which of the following?
a.
b.
c.
d.
moisture
fumes
static electricity
abrasion
8. Which if the following statements about surface nonmetallic raceways is correct?
A. They shall not be used where concealed.
B. They shall not be used where the voltage exceeds listing of
equipment.
a.
b.
c.
d.
9.
A only
B only
both A and B
neither A nor B
The number of conductors or cables installed in surface metal raceway shall
not be greater than which of the following?
a.
b.
c.
d.
The number determined by Table 1, Chapter 9.
The number determined by Table 310.16
The number for which the raceway is designed.
The number determined by percentage of free space.
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10. Surface nonmetallic raceways shall be of such construction as will distinguish
them from which of the following?
a.
b.
c.
d.
11.
other conduits
other wiring methods
other designs
other raceways
Surface nonmetallic raceways shall not be used in the following:
a. Where concealed, except as permitted in 388.10(2)
b. Where subject to severe physical damage
c. Where the voltage is 300 volts or more between conductors,
unless listed for higher voltage
d. all of the above
12.
Surface nonmetallic raceway shall be permitted to pass transversely through
dry walls, dry partitions, and dry floors if which of the following occurs?
I.
If the length passing through is unbroken.
II.
Access to the conductors shall be maintained on both sides
of the wall, partition, or floor.
a.
b.
c.
d.
I only
II only
Both I and II
Neither I or II
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SURFACE METAL RACEWAYS
ARTICLE 386
and
SURFACE NONMETALLIC RACEWAYS
ARTICLE 388
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
d
a
b. 30
b. 20 percent
b.
d. all of the above
d. abrasion
c, both A and B
c
d
d
c
386.30
388.70
386.22(2)
386.22(3)
386.56
386.70
386.100
388.12
386.22
388.100
388.12
388.10
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CONCEALED KNOB-AND-TUBE WIRING
ARTICLE 394
LEVEL I
OBJECTIVES:
After completing this lesson, each student should be familiar with the:
1.
2.
The definition and use of knob-and-tube wiring.
The construction and restrictions in the use of knob-and-tube wiring.
MATERIALS NEEDED:
Sample of knobs, tubes, and flexible nonmetallic tubing. Handouts or pictures of the
above.
INTRODUCTION:
Concealed knob-and-tube wiring is a wiring method using knobs, tubes, and flexible
nonmetallic tubing for the protection and support of single insulated conductors
concealed in hollow spaces of walls and ceilings of buildings.
It shall be permitted to be used only for extensions of existing installations and
elsewhere only by special permission.
It shall not be used in (1) commercial garages, (2) theaters, (3) motion picture studios,
(4) hazardous locations, and (5) in the hollow spaces of walls, ceilings, and attics when
such spaces contain loose or rolled insulation material.
In this lesson we will learn the Code requirements for running extensions of existing
installations of concealed knob-and-tube wiring and if allowed by special permission.
Not much time should be spent on this because it is hardly ever used in practice.
PRESENTING THE LESSON:
Conductors shall be supported within 6 inches of each side of each tap or splice and at
intervals not exceeding 4 1/2 feet.
Where solid knobs are used, conductors shall be tied with tie wires having
insulation equal to that of the conductors.
Where it is impracticable to provide supports, conductors shall be permitted to be fished
through hollow spaces in dry locations, provided each conductor is individually enclosed
in flexible nonmetallic tubing that is in continuous lengths between supports, between
boxes, or between a support and a box.
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Conductors shall be kept apart at least 3 inches and at least 1 inch from the
surface over which they pass. They shall be separated at least 2 inches from metal
conduit piping or other conducting material.
In unfinished attics and roof spaces, conductors shall be installed along the sides of or
through bored holes in floor joist studs and rafters. When run through bored holes in
spaces that are accessible by stairway or permanent ladder they shall be protected by
running boards to a height up to 7 feet.
Splices shall be soldered unless approved splicing devices are used.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW UP:
If time allows, correct the worksheets and discuss the results.
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CONCEALED KNOB-AND-TUBE WIRING
ARTICLE 394
LEVEL I
WORKSHEET
1. Concealed knob-and-tube wiring can be installed in a new single family residence by
which of the following?
a.
b.
c.
d.
Special permission.
Special application.
Special requirements.
Special needs.
2. Concealed knob-and-tube wiring can be used in which of the following?
a.
b.
c.
d.
3.
commercial garages
theaters
motion picture studios
extension of existing installations
Where not accessible by stairway or permanent ladder, conductors shall be
installed along the sides of or through all of the following except?
a.
b.
c.
d.
Bored holes in floor joists.
Bored holes in masonry.
Bored holes in studs.
Bored holes in rafters.
4. The maximum support for conductors in knob-and-tube wiring is at intervals not to
exceed which of the following?
a.
b.
c.
d.
2 feet
4 feet
4 1/2 feet
5 feet
5. Where solid knobs are used, conductors shall be securely tied thereto by wires
having insulation of which of the following types?
a.
b.
c.
d.
Insulation with a greater value than the conductor.
Insulation with a lesser value than the conductor.
Insulation with a value of not less than 60º C.
Insulation with a value equivalent to the conductor.
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6.
When Knob and Tube wiring is installed, a clearance of not less than which of
the following shall be maintained between conductors?
a.
b.
c.
d.
6 inches
5 inches
4 inches
3 inches
7. Conductors passing through wood cross members in plastered partitions shall be
protected at least 3 inches beyond the wood member by which of the following?
a.
b.
c.
d.
noncombustible tubes
nonabsorbent tubes
insulating tubes
noncombustible, nonabsorbent, insulating tubes
8. Concealed knob-and-tube conductors shall be separated at least which of the
following distances from metal conduit?
a.
b.
c.
d.
9.
Where run through bored holes, conductors in the joists and in studs or rafters
to a height of not less than 2.1 m (7 ft) above the floor or floor joists shall be
protected by which of the following?
a.
b.
c.
d.
10.
2 inches
3 inches
4 inches
5 inches
Running boards extending 2 inches on each side of the wiring.
Running boards extending 3 inches on each side of the wiring.
Substantial covers of wood.
Running boards extending 1 inch on each side of the wiring.
Unless approved splicing devices are used, which of the following shall be done
to splices in knob and tube wiring?
a.
b.
c.
d.
Welding of all splices.
Soldering of all splices.
Supporting of all splices.
Sealing of all splices.
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CONCEALED KNOB-AND-TUBE WIRING ARTICLE
394
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
a. special permission
d
b.
c. 4 1/2 feet
d.
d.
d. noncombustible, nonabsorbent, insulating tubes
a. 2 inches
d. 1 inch running boards
b. soldering
394.10
394.12
394.23(A)
394.30 (A)(2)
394.30(B)
394.19(A)
394.17
394.19(C), 398.19
394.23(A)
394.56
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FLEXIBLE CORDS AND CABLES
ARTICLE 400
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the trade names,
construction and restrictions in the uses of flexible cords and fixture wires.
INTRODUCTION:
Flexible cords and cables have many uses, most of which are for temporary purposes.
There are certain times they can be utilized for special equipment. In discussing this
article, we will see when and where they can be used and how.
PRESENTING THE LESSON:
Review Table 400.4.
Briefly discuss the Table pointing out the different types and their construction.
Ampacity of flexible cables shall be according to Table 400.5(A)(1)-Ampacity of
Flexible Cords and Cables with More Than Three Current-Carrying Conductors shall be
according to Table 400.5(A)(2). Be sure to discuss the Notes to Tables since they
explain how to use each table.
Cords and cables rated 105°C shall use correction factors in the 90°C column of Table
310.15(B)(2)(a) for temperature correction
Cords and cables shall be marked by a tag on the carton or reel with information in
310.11(A). If of the type listed in Section 400.6, it shall be marked with type, size, and
number of conductors in intervals not to exceed 24 inches.
Reference 110.3(B)
Flexible cords shall be permitted to be used as: (400.7)
(1) Pendants.
(2) Wiring of luminaires.
(3) Connection of portable luminaires, portable and mobile signs, or appliances.
(4) Elevator cables.
(5) Wiring of cranes and hoists.
(6) Connection of utilization equipment to facilitate frequent interchange.
(7) Prevention of the transmission of noise or vibration.
(8) Appliances where the fastening means and mechanical connections are specifically
designed to permit ready removal for maintenance and repair, and the appliance is
intended or identified for flexible cord connection.
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(9) Connection of moving parts.
(10) Where specifically permitted elsewhere in this Code.
(11) Between an existing receptacle outlet and an inlet, where the inlet provides power to
an additional single receptacle outlet. The wiring interconnecting the inlet to the single
receptacle outlet shall be a Chapter 3 wiring method. The inlet, receptacle outlet, and
Chapter 3 wiring method, including the flexible cord and fittings, shall be a listed
assembly specific for this application.
Flexible cords and cables shall not be used:
(1) As a substitute for the fixed wiring of a structure
(2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped
ceilings, or floors
(3) Where run through doorways, windows, or similar openings
(4) Where attached to building surfaces
Exception to (4): Flexible cord and cable shall be permitted
to be attached to building surfaces in accordance with the
provisions of 368.56(B)
(5) Where concealed by walls, floors, or ceilings or located above suspended or
dropped ceilings
(6) Where installed in raceways, except as otherwise permitted in this Code
(7) Where subject to physical damage
Splices may be made only in hard service cord No. 14 and larger. The splice must
maintain the insulation and outer sheath properties. Cords must be connected in a way so
as not to put tension on the terminal. Show windows must use a type insulation listed in
400.11.
Where passing through holes in covers, outlet boxes, or similar enclosures, the cord
must be protected by bushings or fittings.
Construction Specifications
The manufacturer uses the specifications in Section 400.20 through 400.24 in their
construction of flexible cords. Briefly discuss the types of identification of grounded and
grounding conductors in flexible cords.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results. Be sure the
students understand Article 400.
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FLEXIBLE CORDS AND CABLES
ARTICLE 400
LEVEL I
WORKSHEET
1. What would be the ampacity of a No. 18 two conductor type SO cord?
a.
b.
c.
d.
2.
6 amperes
8 amperes
10 amperes
12 amperes
A splice made in junior hard-service cord shall be permitted if conductors are
spliced in accordance with 110.14(B) and the completed splice retains which of
the following except?
a.
b.
c.
d.
The same insulation quality.
The same outer sheath properties.
The same usage characteristics.
The same length.
3. SJO cord is to be marked on the cord at intervals not to exceed which of the
following?
a.
b.
c.
d.
36 inches
24 inches
48 inches
60 inches
4. Which of the following is required for appliances designed to permit ready
removal when using flexible cord?
a.
b.
c.
d.
A listed NM connector
A locking-type attachment plug.
An attachment plug.
A safety strap and lockable cover.
5. A three conductor, No. 12, 105 degree C rated STOOW cord, is being used in an
ambient temperature of 113 degrees F. These conductors shall have an ampacity of
which of the following amperes?
a.
b.
c.
d.
12 amperes
17.4 amperes
16.9 amperes
18 amperes
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FLEXIBLE CORDS AND CABLES
ARTICLE 400
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
c. 10 amps
d. length
b. 24 inches
a
b, 17.4
Table 400.5(A)
400.9
400.6
400.7(B)
400.5, Table 310.15(B)(2)(a)
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FIXTURE WIRES
ARTICLE 402
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
requirements involving fixture wires.
MATERIALS NEEDED:
Samples of fixture wires (Table 402.3)
INTRODUCTION:
Review other articles that need to be cross referenced so as to understand permitted uses
of these conductors other than for fixture application. See Articles 410 (fixtures), Section
725.16 (class I circuits), and Section 310.15 (temperature limitations).
PRESENTING THE LESSON:
Sections 402.3 through 402.7 include types, ampacities, minimum sizes and
number of conductors permitted in conduit. Review these briefly.
Give handouts of Table 2 from Chapter 9 and Table 402.3 and discuss each or have
students turn to these pages in NEC during discussion.
When reviewing permitted uses in Sections 402.10 and 402.11, it is important that the
students understand required marking of Section 402.9 so that misapplications can be
avoided.
It is imperative that the student know when conductors in question are tapped to the
branch-circuit conductor of a branch circuit, Article 240.5 (B)(2) specifies
overcurrent protection for fixture wires.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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FIXTURE WIRES
ARTICLE 402
LEVEL I
WORKSHEET
1. The ampacity of a #16 fixture wire is?
a.
b.
c.
d.
10 amperes
8 amperes
6 amperes
12 amperes
2. What is the minimum size of fixture wires permitted by the Code?
a.
b.
c.
d.
# 12 AWG
# 14 AWG
# 16 AWG
# 18 AWG
3. Fixture wires shall not be used as which of the following?
a.
b.
c.
d.
as branch circuit conductors
as lamp cord circuits
as flexible cords
all of the above
4. What is the maximum operating temperature of type HFF fixture wire?
a.
b.
c.
d.
150º F/302º C
302º F/150º C
165º F/340º C
340º C/165º F
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FIXTURE WIRES
ARTICLE 402
LEVEL I
ANSWER KEY
1.
2.
3.
4.
b. 8 amperes
d. #18
a.
b. 302º F / 150º C
Table 402.5
402.6
402.11
Table 402.3
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SWITCHES
ARTICLE 404
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the requirements
concerning the installation and construction specifications of switches.
MATERIALS NEEDED:
Sample of different snap switches. Sample
of a safety switch.
INTRODUCTION:
Any switch should open all ungrounded conductors of the circuit. In no case may a singlepole switch be placed in the grounded conductor. Number of poles required for switches
to control three common types of circuits: (1) two-wire single phase or DC circuit with
one conductor grounded; (2) three-wire single phase or DC circuit with grounded neutral;
and (3) four-wire three-phase circuit with grounded neutral.
Opening only the grounded wire of a two-wire circuit would leave all devices that are
connected to the circuit alive. The voltage to the ground would equal the voltage between
the wires on the mains. In case of accidental ground on the grounded wire, the circuit
would not be controlled by the single-pole switch.
Lamps that are connected between the neutral and the two or three outer wires of the threewire and four-wire circuits are not balanced. If the neutral is the opened, it would cause the
voltages to become unbalanced and might burn out all lamps on the more lightly loaded
side. In any case, a switch may be arranged to open the grounded conductor if it
simultaneously opens all the other conductors of the circuit. Since three-way and four-way
switches are actually single-pole switches, they must not be used to disconnect the ground
circuit wire because this would be a violation. See 404.2.
A metal switch plate, if not grounded, may become "alive" by reason of contact of the
ungrounded circuit wire with the plate or switch box. A hazard is thus created.
Rating of Snap Switches:
For an AC General Use Switch resistive and inductive load, not including any tungstenfilament lamps, a snap switch is merely required to have an ampere rating at least equal
to the ampere rating of the load it controls. Electrically heated appliances are common
examples of such loads.
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For an AC or DC General Use Switch controlling of loads consisting of tungsten
lamps alone, and for combined tungsten-filament with any other non-inductive
load, snap switches should be "T" rated.
Inductive loads which are commonly controlled by snap switches are fluorescent
lamps, mercury-vapor lamps, and gas-tube signs and lighting. The term "snap
switch" as used here and elsewhere in the Code is the common type of flush and
surface-mounted switches. They are used for the control of lighting equipment
and small appliances and are generally of the tumbler or toggle type switch.
PRESENTING THE LESSON:
The provision of Article 404 shall apply to all switches, switching devices, and
circuit breakers where used as switches.
Three- and four-way switches shall be wired so that all switching is done only in
the ungrounded conductors.
Exception: Switches or circuit breakers shall not disconnect the grounded
conductor unless they disconnect all conductors of the circuit simultaneously or
are arranged so that the grounded conductor cannot be disconnected until the
ungrounded conductors of the circuit have been disconnected.
Switches and circuit breakers shall be of the externally operable type mounted in
an enclosure listed for the intended use. The enclosure shall have wire bending
space to comply with Section 312.6. If installed in a wet location, they shall be in
a weatherproof enclosure. Time switches and similar devices do not need to be
externally operable.
Single-throw knife switches shall be installed so that gravity will not tend to close
the blades. They shall be so connected so that the blades are de-energized when the
switch is open.
Double-throw knife switches mounted where the throw is vertical shall be
provided with a locking device to hold the blade in the open position.
General use and motor-circuit switches mounted in enclosures listed for the
intended use shall clearly indicate whether they are in the open, off or closed "on"
position, all except the double-throw switches.
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All switches and circuit breakers used as switches shall be so
located that they may be operated from a readily accessible place.
The center of the grip of the operating handle when in its highest
position shall not be more than 6’ 7” above the floor or working
platform. There are three exceptions to this listed in 404.8.
Voltage between snap switches cannot exceed 300 volts unless
permanently installed barriers are installed between adjacent
switches.
Face plates shall be installed so as to completely cover the wall
opening and seat against the wall surface.
A handle-operated circuit breaker can be used as a switch if it has
the required number of poles.
Enclosures for switches or circuit breakers shall be grounded. Where
nonmetallic enclosures are used with metal-sheathed cables or
metallic conduits, provisions shall be made for grounding continuity.
Knife switches rated at over 1200 amperes at 250 volts or less, and at
over 1000 amperes at 251 to 1000 volts, shall be used only as
isolating switches and shall not be opened under load. To interrupt
currents above these ratings a circuit breaker or a switch of special
design listed for such use shall be used. Knife switches less than these
ratings shall be considered general-use switches.
AC general-use snap switches can be used for resistive and inductive
loads not exceeding the ampere rating of the switch at the voltage
involved on tungsten-filament lamp load not exceeding the ampere
rating of the switch at 120 volts, and motor loads not exceeding 80
percent of the ampere rating of the switch at its rated voltage.
AC-DC general-use snap switches can be used for resistive loads not
exceeding the ampere rating of the switch at the applied voltage,
inductive loads not exceeding 50 percent of the ampere rating of the
switch at the applied voltage, and tungsten-filament lamp loads not
exceeding the ampere rating of the switch at the applied voltage if "T"
rated. Switches rated in horsepower are suitable for controlling motor
loads within their rating at voltage applied.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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SWITCHES
ARTICLE 404
LEVEL I
WORKSHEET
1. When used in a branch circuit, switches shall not disconnect which of the
following?
a.
b.
c.
d.
The ungrounded conductor.
The grounding conductor.
The grounded conductor.
The motor circuit.
2. Without exception, switches shall be externally operable and mounted in which of the
following?
a.
b.
c.
d.
A disconnecting means listed for electrical service.
An enclosure listed for the intended use.
A switch-type enclosure.
A cabinet or cut-out box.
3. Switches mounted outdoors shall be in which of the following type enclosure?
a.
b.
c.
d.
Waterproof
Weatherproof
Raintight
Moisture resistant
4. Time switches not of the enclosed-type, need to be mounted in which of the
following type enclosure?
a.
b.
c.
d.
e.
5.
Cabinet
Box
Equipment enclosure
All of the above
Double-throw knife switches shall be permitted to be mounted so that the throw
is which of the following?
a.
b.
c.
d.
vertical
horizontal
both of the Above
neither of the above
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6.
Single-throw knife switches shall be connected so that when the switch is open
the blades are which of the following?
a.
b.
c.
d.
7.
energized when the switch is in the open position
de-energized when the switch is in the open position
de-energized when the switch is in the closed position
locked when the switch is in the open position
Face plates for flush mounted snap switches shall be installed in which of the
following methods?
a.
b.
c.
d.
8.
So as to completely cover the wall opening.
So as to be rigidly mounted and grounded.
So as to be straight and level.
So as to be easily changed.
A snap switch shall not be grouped or ganged in enclosures with other snap
switches, receptacles, or similar devices, unless they are arranged so that the
voltage between adjacent devices does not exceed which of the following?
a.
b.
c.
d.
9.
150 volts to ground.
300 volts
120/240 volts
277/480 volts
A snap switch, without grounding provisions, being used for replacement
purposes only, and located within reach of earth, grade, conducting floors,
or other conducting surfaces shall be provided with a faceplate of
nonconducting, noncombustible material or:
a.
b.
c.
d.
shall be protected by a ground-fault circuit interrupter.
shall be rated at no more than 120 volts to ground.
shall be used only in residential applications.
shall be used in dry locations only.
10. Motor-circuit switches shall be permitted to be of which of the following types?
a.
b.
c.
d.
HACR Circuit-breaker type
Industrial rated type
Commercial rated type
Knife-switch type
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11.
Knife switches rated at over 1200 amperes at 250 volts or less, and at over 1000
amperes at 251 to 1000 volts, shall be used only as isolating switches and shall not
be opened if in which of the following conditions?
a.
b.
c.
d.
When under load.
When used as a motor-controller.
When used as a disconnecting means for a motor.
When used as a thermal overload for a motor.
12. Which of the following type switches simultaneously breaks the connection in
two conductors of a circuit?
a.
b.
c.
d.
A two-way switch.
A single-pole switch.
A double-pole switch
A four-way switch.
13. Which of the following type switches will make a closed circuit when thrown in
either of two positions?
a.
b.
c.
d.
A single-throw switch.
A double-throw switch.
A double-gang switch.
A single-gang switch.
14. What two items of information appear on all switches?
I.
II.
a.
b.
c.
d.
Current rating
Voltage rating
I onl y
II only
Both I and II
Neither I or II
15. Except as permitted in 240.8, a fused switch shall not have which of the
following?
a.
b.
c.
d.
Fuses in series.
Fuses in parallel.
Fuses in grounded conductors.
Fuses in motor-controllers.
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SWITCHES
ARTICLE 404
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
c. grounded conductor
b. an enclosure listed for the intended use
b. weatherproof
d. all of the above
c. either or both of the above
b. de-energized when in the open position
a. completely cover the wall opening
b. 300 volts
a. ground fault circuit interrupter
d. knife-switch type
a. when under load
c. double-pole (refer to 410.48 to clarify)
b. double-throw
c. both current rating and voltage rating
b. parallel.
404.2(B)
404.3(A)
404.4(A)
404.5
404.6(B)
404.6(C)
404.9(A)
404.8(B)
404.9(B)
404.13(D)
404.13(A)
404.11; 110.3 (B)
404.6(B)
404.15
404.17
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RECEPTACLES, CORD CONNECTORS, AND
ATTACHMENT PLUGS (CAPS)
ARTICLE 406
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the requirements
concerning the rating, type, and of receptacles, cord connectors, and attachment plugs
(cord caps).
MATERIALS NEEDED:
Sample of different types of receptacles, cord connectors and attachment plugs.
INTRODUCTION:
Receptacles for portable cords shall not be rated less than 15 Amps for 125 volts or 250
volts. [406.3(B)] Those rated 20 Amps or less for aluminum wire must be marked
CO/ALR. [406.3(C)] Attachment plugs rated 15 or 20 amps must be dead-front
construction. Receptacles and plugs must not interchange with those of different
voltages. Receptacles that are non-grounding must not accept a grounded plug.
Receptacles installed in a damp or wet location must be approved for such location.
Floor receptacles must allow for cleaning without damage to the receptacle.
[406.9(D)]
Receptacles and plugs having grounding means must also have a grounding pole that
will not fit any other connection identified by: [406.10(B)]
1.
2.
3.
4.
Green hex-head screw or nut
Green pressure connector
Green adapter
An invisible hole must be marked green or have the word "Green"
PRESENTING THE LESSON:
Article 406 covers the rating, type, installation or receptacles, cord connectors, and
attachment plugs. Receptacles shall be listed and marked with the manufacturer’s name
or identification and voltage and ampere ratings. Receptacles installed on 15- and 20ampere branch circuits shall be of the grounding type. Grounding-type receptacles shall
be installed only on circuits of the voltage class and current for which they are rated,
except as provided in Table 210.21(B)(2) and Table 210.21(B)(3). For replacements
where attachment to an equipment
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grounding conductor does not exist in the receptacle enclosure, the installation
shall be permitted to be replaced with another non–grounding-type receptacle.
They may also be permitted to be replaced with a ground-fault circuit interruptertype of receptacle marked “No Equipment Ground.” 406.4(D)(1)(2) and (3).
Replacements also have to be GFCI rated, AFCI rated, TP rated, and WR rated
when required elsewhere in the code per 406 (D).
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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RECEPTACLES, CORD CONNECTORS, AND ATTACHMENT PLUGS
(CAPS)
ARTICLE 406
LEVEL I
WORKSHEET
1. Receptacles rated 20 amperes or less and designed for the
direct connection of aluminum conductors shall be
marked...,
a.
b.
c.
d.
CO/ALR
SWD
HID/SWD
GFCI
2. Receptacles incorporating an isolated grounding conductor
connection intended for the reduction of electrical noise
shall be identified by which of the following?
a.
b.
c.
d.
a white slash marking
a green dot marking
a red circle marking
an orange triangle marking
3. Non–grounding-type receptacles and connectors shall not
accept which of the following?
a.
b.
c.
d.
4.
cord connectors of the pin type
grounding-type attachment plugs
grounded type attachment plugs
plugs for appliances
Receptacles shall not be installed in what position in countertops or similar work
surfaces?
a.
b.
c.
d.
in the face-up position
in a cabinet space
in an appliance garage
in the island sink area
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RECEPTACLES, CORD CONNECTORS, AND
ATTACHMENT PLUGS (CAPS)
ARTICLE 406
LEVEL I
ANSWER KEY
1.
a, CO/ALR
406.3(C)
2.
d, an orange triangle marking
406.3(D)
3.
b, grounding-type attachment plugs
406.8
4.
a, in the face-up position
406.5(E)
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SWITCHBOARDS, SWITCHGEAR, AND PANELBOARDS
ARTICLE 408
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the
construction and use of switchboards, switchgear, and panelboards.
INTRODUCTION:
When using switchboards, switchgear, and panelboards certain rules need to be applied
to make a safe installation. Such things as location of installation, clearances required to
service equipment, maximum number of overcurrent devices, and overcurrent protection
for the switchboard or panelboard. These things and more will be discussed in this
lesson. This article only applies to equipment of 1000 volts and less.
PRESENTING THE LESSON:
Article 408 should be used in conjunction with other articles to make the job Code
compliant. Some of these Articles are 240, 250, 312, 314, and 404. Specific
requirements of hazardous locations will be found in Articles 500.517.
Care needs to be taken when checking a switchboard to insure that barriers are in place to
isolate the service busbars and terminals from the rest of the switchboard. Only for
required interconnections can conductors travel from one vertical section to another
unless separated by horizontal barriers. Conductors need to be arranged so as not to cause
over heating.
Each switchboard, switchgear, or panelboard used as service equipment shall be
provided with main bonding jumpers sized according to Article 250.28(D). Each section
of a switchboard or switchgear, shall be bonded together.
On a high leg system, the high leg will have to be the center leg from front to back,
side to side or top to bottom. This leg shall be marked orange in color. Equipment
within the same single section or multi-section switchboard, switchgear or
panelboard as the meter on 3-phase, 4-wire delta-connected systems shall be
permitted to have the same phase configuration as the metering equipment.
Panelboards are required to have a room or dedicated space for servicing or inspection.
This space should include the space specified in Article 110.26, and will include a space
with the width and depth of the equipment from the floor to a height of 6ft. or the
structural ceiling. Nothing foreign to this equipment is to be allowed in this space. See
FPN and exceptions.
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Switchboards shall maintain 3 foot clearance from the top of a combustible
ceiling unless totally enclosed or a noncombustible shield is placed on top of the
switchboard.
Panelboards shall have overcurrent protection not exceeding their rating. A panel
protected by an overcurrent device in another panelboard is considered protected
without additional protection in the subpanel. Service panels when complying
with 230.71(2-6 mains) do not need main overcurrent protection. A panel with
two mains is allowed but is limited to 42 breakers and 2 or 3 pole units count as 2
or 3 breakers respectfully. Another exception is allowed for existing residential
service panels of the split bus type.
Panelboards with 30 ampere "snap switches" cannot have overcurrent protection
above 200 amperes.
Overcurrent devices used for continuous load shall not exceed 80% of its rating
unless approved for 100% of its rating.
Where a panelboard is supplied through a transformer, the overcurrent protection
must have the protection on the secondary side (has 1 except.).
Delta breakers are not to be installed in any panelboard.
Panelboards shall be provided with an equipment grounding terminal and shall
not be tied to the neutral bar except in service equipment. Isolated equipment
grounds as provided for in Section 250.146(D) do not have to be tied to the
panelboard. (408.40)
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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SWITCHBOARDS AND PANELBOARDS
ARTICLE 408
LEVEL I
WORKSHEET
1.
As viewed from the front of the switchboard or panelboard the phase
arrangement on 3-phase buses shall have that phase having the higher voltage to
ground on 3-phase, 4-wire, delta-connected systems marked as which of the
following?
a.
b.
c.
d.
Orange, C phase
Orange, B phase
Orange, A Phase
Brown, B phase
2. Unused openings for circuit breakers and switches shall be closed using
identified closures, or other approved means that provide protection
substantially equivalent to which of the following?
a.
b.
c.
d.
The thermal rating of the wire.
The circular mils rating of the wire.
The wall of the enclosure.
The length of the wire penetration.
3. Minimum distances between the top of a switchboard to a combustible ceiling is:
a.
b.
c.
d.
0 clearance
1 foot
2 feet
3 feet
4. Plug-in-type overcurrent protection devices or plug-in type main lug assemblies
that are backfed and used to terminate field-installed ungrounded supply
conductors
a.
b.
c.
d.
shall not be used in service panels.
may be used with engineering supervision.
shall be secured in place by an additional fastener.
may be used if rated no higher than 30 amperes.
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5. Which of the following is the minimum spacing between busbars of opposite
polarity mounted on the same surface in a 1000 volt panelboard?
a.
b.
c.
d.
1 1/4 inches
2 inches
3 inches
1/2 inch
6. Maximum number of main breakers allowed on non-service panelboard is which of
the following?:
a
b
c
d
7.
.
.
.
.
2
4
6
8
Where the panelboard is used with nonmetallic raceway or cable or where
separate grounding conductors are provided, which of the following shall be
provided for and properly secured inside the cabinet for the grounding
conductors?
a.
b.
c.
d.
A bonding jumper.
A grounding jumper.
A terminal bar.
A grounding electrode conductor.
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SWITCHBOARDS AND PANELBOARDS
ARTICLE 408
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
b. orange, B phase
c. the wall of the enclosure
d, 3 feet
c,
b. 2 inches
a, 2
d. terminal bar
408.3(E) (1) and 110.15
408.7
408.18
408.36 (D)
Table 408.56
408.36
408.40
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LIGHTING SYSTEMS OPERATING AT 30
VOLTS OR LESS
ARTICLE 411
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with requirements in
regard to lighting systems operating at 30 volts or less and their associated
components.
INTRODUCTION:
This article covers lighting systems at 30 volts or less and their associated
components.
PRESENTING THE LESSON:
Review Scope of 411.1 and review new change to note the article now covers
lighting equipment connected to a Class 2 power source.
Review 411.3 (A-B)
Lighting systems operating at 30 volts or less each are limited to 25 amperes
maximum
Specification location requirements are found in Section 411. 5.
Secondary circuits shall not be grounded. Bare conductors shall not be installed less than
7 feet. (2.1 m) above the finished floor, unless specifically listed for a lower installation
height. 411.6 (A_D)
Lighting systems covered by Article 411 shall be supplied from a maximum 20-ampere
branch circuit. 411.7
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheet and discuss the results.
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LIGHTING FIXTURES, LAMPHOLDERS,
LAMPS, AND RECEPTACLES
ARTICLE 410
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with the specifications and
requirements for construction and installation of luminaires and lamps and lampholders.
MATERIALS NEEDED:
Samples of ceiling incandescent light, recessed light, fluorescent light and chain hung
lights.
INTRODUCTION:
When dealing with luminaires, we are covering a broad range of things, such as
incandescent, arc lamps, and electric discharge lamps. This Section also includes wiring
and construction of luminaires.
PRESENTING THE LESSON:
All live parts of luminaires shall not be exposed such as luminaires with open bases or
metal canopies. Cleat type lampholders must be located at least 8 feet above the floor
in order to be allowed to have exposed terminals. (410.5) Exception
Luminaires used for specific location shall be suitable for said location and marked to
indicate such approval. For example, luminaires used in a wet location must be
approved for a wet location and marked "Suitable for wet locations". Any area which
the luminaire is likely to be saturated with water or a similar liquid shall be considered
a wet location. Areas subject to moderate degrees of moisture shall be considered as a
damp location. Luminaires used with cooking hoods in non-residential occupancies
shall meet the following requirements: [410.10(C)]
1. The luminaire shall be listed for such use and the temperature limit of the
luminaires shall not be exceeded.
2. The luminaire shall be constructed so that exhaust vapors, grease, oil or
cooking
vapors are excluded from the lamp and wiring compartment. Diffusers shall be
resistant to thermal shock.
3. Parts of the luminaire exposed within the hood shall be corrosion resistant or
protected against corrosion, and the surface shall be smooth so as not to collect
deposits and to facilitate cleaning.
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4. Wiring methods and materials supplying the luminaire(s) shall not be exposed within
the cooking hood..
No hanging luminaires shall be within 3 feet horizontally and 8 feet vertically of the top
rim of a bathtub or shower threshold. [410.10(D)]
410.10 (F) review this new section related to installations in or under roof decking.
Luminaires must be installed so as combustible material will not be subjected to
temperatures in excess of 90 degrees Celsius. (410.11)
When luminaires are installed over combustible material, unless each luminaire has a
switch provided, shall be unswitched and located at least 8 feet above the floor and
located so as the lamps cannot be readily removed or damaged. (410.12)
Unless chain supported show-window shall not be externally wired.
(410.14)
The types of luminaires permitted in clothes closets are restricted and the definition of
storage space safety clearly defined. Cover these requirements in depth as installation
in clothes closets are frequently encountered. (410.16(C)
Luminaires shall be made so as not to subject conductors to temperatures higher than the
rating of the conductor. Boxes that are integral parts of luminaires shall not be used as
through wiring for branch circuits unless the luminaire is identified for through wiring.
(410.21)
Unless the luminaire covers the box, a cover shall be provided to cover all
connections. (410.22)
Electric discharge luminaires supported independent of the outlet box shall be connected
to the branch circuit through metal raceway, nonmetallic raceway, Type ML cable, Type
AL cable, Type MI cable, nonmetallic sheathed cable or by flexible cord as permitted in
Section 410.24(A). (410.62)(B) 410.62(C)
When a luminaire exceeds 6 lbs. or l6 inches in dimension, it shall not be supported to
shell of lampholder. 410.30(A) Cover requirements for metal pole supporting
luminaires 410.30(B)(1)
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Luminaires supported solely by an outlet box shall be installed by 314.27. Where a
suspended ceiling is used to support a luminaire, the framing members must be securely
fastened to each other and to the building structure. The luminaire shall then be securely
fastened to ceiling framing member by bolts, screws, rivets, or approved clips approved
for such use. Luminaire studs not a part of outlet boxes or approved accessories shall be
made of malleable iron. Insulating joints that are not designed to be mounted with screws
or bolts shall have an exterior metal casing insulated from both screw connections.
Raceway fittings used to support a luminaire shall be capable of supporting the weight of
the complete luminaire assembly including lamps. (410.36)(E)
Exposed metal parts shall be grounded or insulated from ground and other conducting
surfaces or inaccessible to unqualified persons. Lamp tie wires, mounting screws, clips,
and decorative bands on glass spaced at least 1 1/2 in. from lamp terminals shall not be
required to be grounded. (410.42)
Luminaires shall be considered grounded if connected to a grounding conductor
described in 250.118 and sized by Table 250.122. (410.46)
Excess wiring to a luminaire shall be avoided to prevent physical damage.
(410.48)
Cover polarization of luminaires as is required in Section 410.50.
The requirements included in Sections 410.48 through 410.52 are generally used by the
testing laboratory. Compliance is primarily accomplished by requiring listed or labeled
luminaires.
410-59 (A-C) Showcases that are portable shall be permitted to connected by flexible
cord up to six (6) different showcases. Where more than one case is hooked together
locking type connectors shall be used. These cords shall ampacity equal to the branch
circuit wiring and overcurrent device. Receptacles and plugs shall be rated at 15 or 20
Amps. Cables shall be supported to the underside of the showcase so as to:
1. Protect it from mechanical damage.
2. Assure a space of no more than 2 inches between cases nor more than l2
inches between the fixed outlet and the first case.
3. The free lead end of the last case has a female end not extending beyond
the case.
4. No other equipment shall be connected to these cases and electric
discharge lighting shall not extend beyond the case. (410.59)(D)
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Where lampholders are attached to the cord, they shall be protected by a bushing. If using
a threaded nipple then it must be at least 3/8 pipe size. Bushed holes 9/32 in size where
used with plain cord and 13/32 with reinforced cord. Adjustable luminaires shall not be
required to have an attachment plug where extra-hard or hard usage cords and no long
than required for adjustment. (410.62(A)
Fluorescent-type lights can be wired with cord as long as no strain is put on the cord
and it is attached by plug. A listed luminaire or a listed feature assembly with a cord
and canopy is not required to be connected by an attachment plug. (410-62 (B)
Electric discharge lights equipped with mogul-base, screw-shell shall be permitted to be
protected by Section 240.4 if 50 Amps or less. Outlets and plugs must be rated at least
125% of the rating of the luminaire load. (410.62)(C)(2)
Luminaires shall not be used as a raceway unless listed and marked for such use
(410.64).
Conductors within 3 inches of a ballast must be rated at least 90 degrees Celsius.
(410.68)
410-82 (A_B) review
Portable luminaires shall comply with the following:
1. Metal-shelled, paperlined lampholders shall not be used.
2. Shall be equipped with handle that is insulated.
3. Must have a guard attached to handle or lampholder.
4. Metallic guards must be grounded.
5. Portable handlamps shall not be required to be grounded where supplied through an
isolating transformer with an ungrounded secondary of not over 50 volts.
Exposed live parts must have 1/2 inch clearance between exposed parts and
mounting plane. (410.46)
Lampholders having a switch must disconnect both ungrounded conductors.
(410.93)
Incandescent lamps shall have medium base up to 300 watts, mogul-base up to 1500
watts and special base for over 1500 watts. (410.103)
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Luminaires shall not subject combustible material to a temperature in excess of 90
degrees Celsius unless construction is fire resistant material then the luminaire, if properly
marked, can be rated up to 150 degrees Celsius. Unless a luminaire by design offers
equivalent protection or is listed and approved for use in poured concrete, recessed
luminaires must be thermally protected and so identified. (410.115 (A-C)
Recessed lights must have 1/2 clearance to combustibles, and thermal insulation must not
be installed within 3 inches of recessed enclosure or ballast and over top so as to entrap
heat unless they are type I.C. (410.116)(B)
Tap conductors of a type suitable for the temperature encountered shall be permitted to
run from the luminaire terminal connection to an outlet box placed at least one foot from
the luminaire. Such tap conductors shall be in suitable raceways or type AC or MC cable
of at least 18 inches (450 mm) but not over 6 feet in length. [410.117(C)]
Maximum wattage of lamps in recessed lamps shall be marked in letters at least l/4
inches high where visible when relamping. Solder shall not be used in construction of
the luminaire box. (410.120) (410.121)
[410.130(E)]
(1) The ballast of a fluorescent luminaire installed indoors shall have integral thermal
protection. Replacement ballasts shall also have thermal protection.
(2) A simple reactance ballast, used in fluorescent luminaires with straight tubular lamps
shall not be required to be thermally protected.
(3) A ballast in a fluorescent exit luminaire shall not have thermal protection.
(4) A ballast in a fluorescent luminaire that is used for egress lighting energized only
during an emergency shall not have thermal protection.
[410.73(F)]
(1) Recessed high-intensity luminaires designed to be installed in wall or ceiling cavities
shall have thermal protection and be identified as thermally protected.
(2)
Thermal protection shall not be required in a recessed high-intensity
luminaire whose design, construction, and thermal performance characteristics are
equivalent to a thermally protected luminaire and are identified as inherently protected.
(3)
Thermal protection shall not be required in a recessed, high-intensity
discharge luminaire identified for use and installed in poured concrete.
(4)
A recessed remote ballast for a high-intensity discharge luminaire shall
have thermal protection that is integral with the ballast and be identified as thermally
protected.
Open circuit voltage in excess of 300 volts shall not be used in dwellings unless such
equipment is designed so that there will be no exposed live parts when lamps are being
inserted, are in place, or are being removed. (410.135)
Luminaires on low-density combustible cellulose fiberboard shall be approved for this use
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or be spaced at least 1 1/2 inches from surface. [410.136(B)]
Review 410.151 (B) and explain the new language regarding load calucaltions.Lighting
track shall only have fittings approved for lighting track installed. No general purpose
receptacles shall be connected to lighting track. Lighting track shall not be used in the
following locations: 410.151(C)
1. Where subject to physical damage
2. Damp or wet location
3. Where subject to corrosive vapors
4. Storage battery rooms
5. Hazardous location
6. Concealed
7. Through walls or partitions
8. Less than 5 feet above finished floor except where protected
9. Within the zone measured 3’ horizontally and 8 ’ vertically from the top of the
bathtub rim. Track for use in excess of 20 amps shall be considered heavy duty.
(410.153)
Single sections of Track 4 feet or less shall have 2 supports. Where in one
continuous length each 4 feet section shall have one additional support. (410.154)
Track conductors shall be a minimum of #12 or equal. (410.155)(A)
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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LUMINAIRES, LAMPHOLDERS, AND LAMPS
ARTICLE 410
LEVEL I
WORKSHEET
1. Hanging luminaires shall not be installed within what distance vertically of a bath tub
rim?
a.
b.
c.
d.
4 feet
6 feet
8 feet
10 feet
2. Which of the following is the proper clearance that surface mounted incandescent
luminaires mounted on the ceiling of clothes closets must have?
a.
b.
c.
d.
6 inches
12 inches
18 inches
24 inches
3. Any luminaires weighing more than which of the following shall not be supported by
the screw shell.
a.
b.
c.
d.
6 pounds
8 pounds
10 pounds
12 pounds
4. Luminaires with open or partially enclosed lamps and pendant luminaires or
lampholders of which of the following type shall not be permitted in clothes
closets?
a.
b.
c.
d.
Luminescent
Intumescent
Fluorescent
Incandescent
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5. Where no equipment grounding conductor exists at the outlet, replacement
luminaires shall not be required to be connected to an equipment grounding
conductor when installed in which of the following manners?
a.
b.
c.
d.
6.
With wiring rated less than 20 amperes.
With wiring rated more than 20 amperes.
When directly fastened to a grounded mounting bracket.
When GFCI protected.
In general, luminaires shall not be used as a raceway for circuit conductors unless
which of the following applies?
I. Unless they are listed for raceways.
II. Unless they are marked for use as a raceway.
a.
b.
c.
d.
7.
I only
II only
Both I and II
Neither I or II
A luminaire requiring supply wire rated higher than 60°C (140°F) shall be marked
in letters not smaller than which of the following?
a.
b.
c.
d.
1/2 inch high
3/4 inch high
5/8 inch high
1/4 inch high
8.
When installing a luminaire to the bottom side of metal corrugated roof decking
which of the following are true
a. The fixture shall be not less than 1” unless approved
b. The fixture shall be 1 ½ “ from the top of the deck
c. The fixture shall be not less than 1” from the lowest portion of the
deck unless approved
d. The fixture shall be not less than 1 ½” from the lowest potion of the
deck
9.
Thermal insulation shall not be installed within what distance of the sides of a
recessed luminaire enclosure, wiring compartment or ballast unless it is identified
for contact with insulation, Type IC.
a.
b.
c.
d.
3 inches
6 inches
10 inches
l2 inches
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10.
Lighting track shall be considered heavy duty when in excess of?
a.
b.
c.
d.
15 amperes
20 amperes
30 amperes
40 amperes
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LIGHTING FIXTURES, LAMPHOLDERS, LAMPS, AND
RECEPTACLES
ARTICLE 410
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
9.
10.
c, 8
b. 12 inches
a. 6 lbs.
d. incandescent.
d, GFCI protected
c. Both I and II
d. 1/4 inch high
d 1 1/2 “ from lowest
b. 20 amps
410.10(D)
410.16(C)(1)
410..30(A)
410.16(B)
410.44 Ex 3
410.64
410.74(A)
410. 10 (F)a. 3 inches
410.153
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410.116(B)
226
LIGHTING SYSTEMS OPERATING
AT 30 VOLTS OR LESS
ARTICLE 411
LEVEL I
WORKSHEET
1.
Low voltage lighting systems shall operate at a maximum voltage of?
a.
b.
c.
d.
2.
120 volts
50 volts
30 volts
12 volts
Lighting systems circuits operating at 30 volts or less shall not be installed where
concealed or extended through a building wall unless
(1)
installed using any of the wiring methods specified in Chapter 3
(2)
installed using wiring supplied by a listed Class 2 power source
and installed in accordance with 725.130
a.
b.
c.
d.
3.
On secondary circuits, bare conductors shall not be installed less than which of
The following distances above the finished floor?
a.
b.
c.
d.
4.
1 only
2 only
neither 1 or 2
either 1 and 2
6 1/2 ft.
7 ft.
7 1/2 ft.
8 ft.
Lighting systems operating at 30 volts or less shall be supplied from a branch
circuit with a maximum ampere rating of which of the following?
a.
b.
c.
d.
15
20
25
30
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LIGHTING SYSTEMS OPERATING
AT 30 VOLTS OR LESS
ARTICLE 411
LEVEL I
ANSWER KEY
1.
2.
3.
4.
c, 30 volts
d
b. 7 ft.
b. 20
411.3 (A)
411.5(A)
411.6C
411.7
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APPLIANCES
ARTICLE 422
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with appliances and the
requirements for branch-circuit sizing, their installations, control, and protection.
MATERIALS NEEDED:
Samples of appliances. Handout with pictures of appliances.
INTRODUCTION:
The definition of an appliance is "utilization equipment, generally other than industrial,
normally built in standardized sizes or types which is installed or connected as a unit to
perform one or more functions such as clothes washing, air conditioning, food mixing,
deep frying, etc.".
With as much contact as we have with appliances at home, work, and play, it is very
important that they be installed and wired in a safe manner. In this lesson, we will
study the following National Electrical Code requirements:
1.
2.
3.
4.
5.
The general requirements of appliances.
Branch-circuit requirements.
Installation of appliances.
Control and protection of appliances.
Marking of appliances.
PRESENTING THE LESSON:
Article 422 covers electrical appliances used in any occupancy with the exception of
appliances in which the current-carrying parts at high temperature are necessarily
exposed, such as toasters and grills. Appliances shall have no live parts normally
exposed.
Review new section 422.5 GFCI- protection
Where applicable, all requirements of the Code shall apply. If used in hazardous
locations, appliances shall comply with Articles 500 and 517. An appliance containing
hermetic refrigerant motor-compressors shall comply with Article 440.
The rating of an individual branch-circuit shall not be less than the marked rating of the
appliance with the following exceptions. (422.10 (A)
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Motor operated appliances not having a marked rating shall be in accordance with Part
II of Article 430.
An appliance other than motor-operated that is continuously loaded shall
have a branch circuit rated not less than 125% of the marked rating or 100% if listed
Branch circuits for household cooking appliances shall be permitted to be
in accordance with Table 220.55 and sized in accordance with 210.19(A)3
422.10(B) circuits supplying 2 or more loads branch circuit supplying appliances and
other loads. shall be protected in accordance with 210.23.
If an appliance is marked with a protective device rating, the overcurrent device rating
shall not exceed this marking. [422.11(A)]
Review new requirements for Water Heaters in 422.11(F)3
Central heating equipment, other than fixed electric space heating equipment, shall be
supplied by an individual branch circuit. (422.12)
All fixed storage-type water heaters having a capacity of 120 gallons or less shall have a
branch-circuit rating no less than 125% of the name plate rating of the water heater.
(422.13)
In industrial occupancies, infrared heating appliance lampholders shall be permitted to
be operated in series on circuits of over 150 volts to ground, provided the voltage rating
of the lampholders is not less than the circuit voltage.. (422.14)
The types of cords and how they are installed on an appliance is shown in Section
422.16.
Review new sections 422-19 Space for Conductors; 422.20 Outlet Boxes to be
Covered; 422.21 Covering of Combustible Material at Outlet and 422.23 Tire
Inflation and Automotive Vacuum Machines

Make note of new GFCI requirement
Each electrically heated appliance that is located in a fixed position shall be placed
as to provide ample protection between the appliance and adjacent combustible
material.(422.17)
Wall-mounted ovens and counter-mounted cooking units complete with provision for
mounting and or making electrical connections shall be permitted to be permanently
connected or, only for ease of serving or installation, cord-and-plug connected. When a
separable connection or a plug and receptacle is used it shall be approved for the
temperature of the space. [422.16(B)(3)]
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A means shall be provided to disconnect each appliance from all grounded conductors. If
supplied from more than one source, the disconnecting means shall be grouped and
identified. (422.30)
Permanently connected appliance rated at not over 300 volt amperes or 1/8 Hp may
use branch-circuit overcurrent devices as the disconnecting means. [422.31(A)]
For permanently connected appliances of greater rating, the branch-switch or circuit
breaker shall be permitted to serve as the disconnecting mean where readily accessible to
the user of the appliance. See Section 422.32 for motor drive appliance of more than 1/8
horsepower. [422.31(B)]
When unit switches are used as disconnecting means they shall meet all requirements
for disconnecting means. All switches and circuit breakers used as disconnecting means
shall meet all requirements for disconnecting means.(422.34)
Electric heaters of the cord-and-plug connected immersion type shall be so constructed
and installed that current carrying parts are effectively insulated from electrical contact
with the substance in which they are immersed. (422.44)
Each electrical heated appliance intended to be applied to combustible material such as
and iron, shall be equipped with an approved stand. These appliances in other than
dwelling type occupancies shall be provided with a signal unless it is provided with an
integral temperature-limiting device. (422.45)
Electrically heated smoothing irons shall be equipped with an identified
temperature-limiting means. (422.46)
Storage and instantaneous-type water heaters shall be equipped with a temperature
limiting means in addition to its control thermostat to disconnect all ungrounded
conductors. (422.47)
Unless identified as suitable for use with infrared heating lamps within their rated
wattage, screw-shell lampholders shall not be used with infrared lamps over 300 watts. If
300 watts or less, they shall be permitted with lampholders of medium-base unswitched
porcelain type. (422.48)
All switches and circuit breakers used as disconnecting means shall be of the
indicating type. (422.35)
The disconnecting means for a motor operated appliance of more than 1/8
horsepower shall comply with 430.109 & 431.110.. (422.32(C)
If the branch circuit supplies a single non-motor-operated appliance rated at more than
13.3 amperes, the overcurrent device shall not exceed 150% of the appliance rating. If
the appliance is rated at 13.3 amperes or less, the largest overcurrent device allowed is
20 amperes. [422.11(E)]
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Review 422.51 (B) Vending Machines Other than Cord and Plug Connected
Each electric appliance shall be provided with a nameplate marking that is located so as
to be visible or easily accessible after installation. Information that is to be on the
nameplate can be found in 422.60.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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APPLIANCES
ARTICLE 422
LEVEL I
WORKSHEET
1. Article 422 covers electric appliances used in which of the following
occupancies?
a.
b.
c.
d.
single family dwellings
multi-family dwellings
commercial and industrial
all occupancies
2. The installation of motor-operated appliances is governed by which of the
following?
a.
b.
c.
d.
Article 440
Article 430
Article 300
Article 250
3. When the branch circuit switch or circuit breaker is being used as the
disconnecting means for appliances rated higher than which of the following,
the provision for locking or adding a lock to this disconnecting means shall be
installed on or at the switch or circuit breaker used as the disconnecting means
and shall remain in place with or without the lock installed.
a.
b.
c.
d.
1/2 horsepower, 300 volt-amperes
1/8 horsepower, 300 volt-amperes
1/3 horsepower, 300 volt-amperes
1/4 horsepower, 300 volt-amperes
4. For branch circuits supplying appliance and other loads, the rating shall be
determined in accordance with which of the following?
a
b
c
d
.
.
.
.
210.23
422.12
310.16
310.15(B)
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5.
If a protective device rating is marked on an appliance, the branch-circuit
overcurrent device rating shall not exceed which of the following?
a.
b.
c.
d.
6.
Under which of the following conditions are cord-and-plug connected range
hoods permitted to be terminated without the use of a grounding-type
attachment plug?
a.
b.
c.
d.
7.
The protective device rating marked on the breaker.
The protective device rating marked on the appliance.
The protective device rating marked in the Code.
The protective device rating of the branch circuit.
If the receptacle is accessible.
If the receptacle is located to prevent damage to the cord.
If the receptacle is supplied by an individual branch circuit.
If the range hood is double-insulated.
Which of the following statements about cord-and-plug connected appliances in
dwelling unit kitchens is/are correct?
A. The length of cord for waste disposers shall be three to four feet long.
B. A trash compactor protected by a system of double insulation shall not
be required to be grounded.
a.
b.
c.
d.
8.
A only
B only
Both A and B
Neither A nor B
Where the separable connector or plug and receptacle are not accessible, cordand-plug-connected appliances shall be provided with disconnecting means in
accordance with 422.31. Which of the following is acceptable for an appliance
rated at 1/8 horsepower and 300 volt-amperes?
a.
b.
c.
d.
The branch circuit switch.
The circuit breaker.
Both A and B.
Neither A or B.
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9. Which of the following statements about when heated appliances are required to be
provided with a signal is not correct?
a. If in any occupancy but dwelling types.
b. If applied to combustible material
c. If not provided with an integral temperature-limiting device.
d. If it is in reach of a grounded object.
10. Cord-and-plug-connected vending machines manufactured or remanufactured on or after January 1, 2005, shall include a ground-fault circuitinterrupter as an integral part of the attachment plug or be located within what
distance of the attachment plug.
a.
b.
c.
d.
18 inches
12 inches
24 inches
36 inches
11. A branch circuit supplying a fixed storage-type water heater having a capacity of
120 gallons or less shall have a rating not less than which of the following?
a.
b.
c.
d.
100 percent of the marked rating of the appliance.
125 percent of the marked rating of the appliance.
80 percent of the marked rating of the appliance.
250 percent of the marked rating of the appliance.
12. Screw-shell lampholders shall not be used with infrared lamps rated over 300
watts, unless the lampholders are identified as being suitable for use with which of
the following?
a.
b.
c.
d.
Infrared heating lamps rated under 300 watts.
Infrared heating lamps rated over 300 watts.
Infrared heating lamps rated for non-commercial use.
Infrared heating lamps rated for industrial use.
13. Permanently connected air-conditioning equipment shall be permitted to be
connected to the same branch circuit as which of the following?
a.
b.
c.
d.
Fixed electric space-heating equipment.
Central heating equipment.
Unitary heating systems.
Proprietary heating systems.
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14. If a switch or circuit breaker serves as the disconnecting means for a
permanently connected motor-driven appliance of more than 1⁄8 hp, it shall
be located at which of the following?
a. At the switch serving the motor using a lockout device.
b. At the motor-controller panel in an adjacent area.
c. At the motor location enclosure within 6 feet.
d. Within sight of of the appliance according to 110.25.
15.
A unit switch with a marked-off position that is part of an appliance shall be
permitted as the disconnecting means if it disconnects which of the following?
a.
b.
c.
d.
16.
If a protective device rating is marked on an appliance, the branch-circuit
overcurrent device rating shall not exceed which of the following?
a.
b.
c.
d.
17.
All of the conductors.
All of the ungrounded conductors.
All of the grounded conductors.
All of the conductors including the grounding conductor.
The protective device rating marked on the appliance.
The feeder circuit rating for the branch.
The protective device rating marked on the circuit breaker.
The full load amperes of the circuit plus 25 percent.
Marking shall be located so as to be which of the following?
I. Visible
II. Easily accessible after installation.
a.
b.
c.
d.
I only
II only
Either I or II
Neither I or II
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APPLIANCES
ARTICLE 422
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
d. all occupancies
b. Article 430
b. 1/8 horsepower, 300 VA
a. 210-23
b. rating marked on the appliance
d. if the range hood is double-insulated
b, 2 only
a. ample, appliance, adjacent
d, If it is not in reach of a grounded object
b. 12 inches
b. 125 percent of the marked nameplate rating
b. rated over 300 watts
b. Central heating equipment
d. within sight
b. ungrounded
a.
c. visible or easily accessible
422.1
422.3
422.31(B))
422.11
422.11(A)
422.16(B)(4) Exception
422.16(B) Exception
422.31 (A)
422.42
422.51 (A)
422.13
422.48(B)
422.12
422.32 (C) 2
422.34
422.11(A)
422.60(B)
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FIXED ELECTRIC SPACE HEATING EQUIPMENT
ARTICLE 424
LEVEL I
OBJECTIVE:
After completing this lesson, each student should be familiar with enforcement of code
requirements for fixed electric space heating equipment.
Article 424 includes requirements for several different types of heating systems some
of which will only be encountered occasionally such as heating cable, unit heaters,
boilers, central systems, etc. This Article does not apply to process heating or room air
conditioners.
PRESENTING THE LESSON:
Branch Circuit Requirements
Branch circuits supplying more than one outlet for fixed electric heaters (baseboard
heaters) shall be rated 15, 20, 25 or 30 amperes. Fixed infrared equipment located in
other than residential occupancies can be supplied from branch circuits rated not over
50 amperes. [424.3(A)] Branch circuits supplying only one piece of equipment must be
rated 125% of the total load including motors and resistance heaters, except for relays
and contactors which are approved for continuous operation at 100% ampacity
[424.3(B)]. Heat pump compressors are covered under Article 440.34 and 35.
Installation
If heating equipment requires more than 60 degrees Celsius insulation on supply wiring,
it must be clearly marked and the marking must be visible after installation. (424.11)
Locations
Units subject to physical damage shall be protected in an approved manner. Units in wet
or damp areas shall be approved for such location and installed so liquid cannot enter.
(424.12)
Spacing from Combustible Material
Equipment shall be installed to provide manufacture’s requirements for clearance to
combustible materials. (424.13)
Control and Protection
A disconnecting means must be provided to disconnect all ungrounded
conductors where supplied from more than one source, feeder, or branch circuit,
disconnects shall be grouped. (424.19)
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A disconnecting means for units equipped with supplementary overcurrent
devices shall be within sight from and on the supply side of supplementary
overcurrent protection, and comply with numbers 1 or 2 below.
1.
For motors not over 1/8 horsepower, a disconnecting means shall be
permitted to serve both the motor controller and heater if located within
sight of both or the disconnecting means must be lockable in accordance
with 110.25. Where unit switches meet the requirements of 424.19(C)
they may be used as the required disconnecting means.
2.
Units containing motors rated over 1/8 horsepower, disconnect described
in number 1 above may be used, if within sight of the motor controller and
heater.
Disconnecting means not within sight from the heater requires either a separate
disconnect be installed or a disconnect capable of being locked open or unit
switches complying with 424.19(C)
A branch circuit switch or circuit breaker may serve as a disconnecting means for
units without supplementary overcurrent protection containing motors not more
than 1/8 horsepower where readily accessible for servicing. Similar units more
than 1/8 horsepower will require a disconnect within sight of motor controller.
Unit switches may be used as disconnecting means where provided with a marked
"off" position and when meeting requirements of 424.19(C) for the type of
occupancy involved.
Thermostatically controlled switching devices may be used as both a controller
and a disconnecting means under ALL the following conditions. (424.20)
Example: thermostats for basement heat
1.
2.
3.
4.
Marked "off" position
Must open all ungrounded conductors when in "off" position (manually)
Must not be capable of being automatically energized when in the manual
"off" position.
Must be located as per Section 424.19.
Switches must be of the type indicating the "on" and "off" positions.
Overcurrent Protection
Space heating equipment supplied by branch circuits in Article 210 shall be
permitted where not supplying motor operated equipment as in Articles 430 and
440. [424.22(A)]
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Resistance-type heating elements may not be protected at more than 60 amperes.
Where rated more than 48 amperes, it shall be subdivided not to exceed 48
amperes within each subdivided load. [424.22(B)]
Overcurrent protective devices for subdivided loads shall be factory installed or
factory provided, accessible and suitable for branch circuit protection. (see
Article 240.10). [424.22(C)]
Conductors supplying supplementary overcurrent protective devices shall be
considered branch circuit conductors. [424.22(D)]
Field installed conductors between supplementary protective devices and heater
shall be sized not less than 125% of load. Overcurrent protective devices shall
comply with Article 240.3. [424.22(E)].
Marking of Heating Equipment
Each unit must have manufacturer's nameplate installed and visible after
installation. [424.28(A & B)]
Space Heating Cables
Area heating cables shall not extend beyond the room in which they originate.
They shall not be installed in closets, over walls or over cabinets. [424.38]
Heating cables must be at least 8 inches from the edge of outlet boxes and
junction boxes, and at least 2 inches from recessed fixtures. [424.39]
Adjacent runs of cable not less than 1 1/2 inch on center and secured at intervals
not exceeding 16 inches. [424.41(B)]
Splices in the cable should be made only where necessary and in no case to alter
length of cable. Cables shall cross joists only at ends of room. [424.41(D)]
[424.41(J)]
Heating cables shall not exceed 16 1/2 watts per linear foot in concrete or
masonry floors.
[424.44(A)]
All cable installations must be inspected before being covered. Review typical
installation procedures. [424.45]
Duct Heaters
All duct heaters must first be identified as suitable for installation. [424.58]
If duct heater is located within 4 feet of a heat pump or air conditioner it must be
identified as suitable for such installation. [424.61]
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The fan circuit must be interlocked to insure fan is running when heater
is on. [424.63]
Each heater must be provided with limit devices. [424.64]
A disconnecting means must be at or within sight from the controller.
[424.65] Installation must meet manufacturer's instructions. [424.66]
Electrode-type Boilers
Branch circuit conductors and protective devices shall be calculated at
125% of total load except for contactors, relay, or other devices approved
for continuous operation at 100% of rating. [424.82]
Over temperature and over pressure limiting controls are required and
must meet the same requirements as for resistance-type boilers. [424.83]
and [424.84]
All boilers must be marked with manufacturer's name, rating, and
electrical supply required. In addition a warning: "ALL POWER
SUPPLIES SHALL BE DISCONNECTED BEFORE SERVICING
INCLUDING SERVICING THE PRESSURE VESSEL." must appear.
[424.86]
Electric Radiant Heating Panels and Heating Panel Sets
This section of Article 424 applies to wall heaters, baseboard heaters and
other heating units which may be exposed or concealed when installation
is complete. Heating panels and heating panel sets must be installed to
meet manufacturer's installation instructions, and the conditions of
Section 424.93(A)(2):
1. Must not be installed subject to physical damage
2. Must not run through or above walls, partitions, or other
structures that extend to ceilings.
3. Must not run through or in thermal insulation.
Excess non-heating leads of heating panels and heating panel sets may be
cut to desired length. [424.97]
Heating panels or panel sets installed in concrete or poured masonry must
meet the requirements of Section 424.98. (Review requirement).
Heating panels installed under floor covering must be installed in
accordance with instructions and identified for such use and provided with
fault protection in accordance with Section 424.99. It is important for the
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inspector to have access to installation instructions for the specific panel
installed. Inspection must be made prior to applying floor covering. Heating
panels installed under floor covering shall not exceed 15 watts per square
foot. [424.99]
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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FIXED ELECTRIC SPACE HEATING EQUIPMENT
ARTICLE 424
LEVEL I
WORKSHEET
1. Branch circuits supplying two or more outlets for fixed electric heat shall be rated
which of the following?
a.
b.
c.
d.
For fixed electric heating at 50 or more amperes.
15, 20, 25 or 30 amperes.
40 or 50 amperes.
Rated for not more than 80% of the circuit ampacity.
2. Branch circuit conductors supplying fixed electric space heating equipment shall be
considered which of the following?
a.
b.
c.
d.
Nonlinear loads.
Appliance circuits.
Nonlighting loads.
Continuous loads.
3. In heating equipment with supplementary overcurrent protection and a motor not
over 1/8 horsepower, the supplementary overcurrent protection shall be
permitted to serve as the required disconnecting means for both the motor
controller(s) and heater under which of the following conditions?
(I) The disconnecting means provided is also within sight from the
motor controller(s) and the heater.
(II) The disconnecting means provided is capable of being locked in
the open position.
a.
b.
c.
d.
I only
II only
Both I and II
Neither I or II
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4. Readily accessible thermostatically controlled switching devices may be used
as both the controller and disconnecting means under which of the following
conditions?
a. Provided with a marked “off” position
b. Directly open all ungrounded conductors when manually
placed in the “off” position
c. Designed so that the circuit cannot be energized automatically
after the device has been manually placed in the “off” position
d. All of the above
5. Heating equipment requiring supply conductors shall be clearly marked when
rated more than which of the following?
a.
b.
c.
d.
75º C
60º C
75º F
60º F
6. Resistance-type heating elements in electric space heating equipment rated at 48
amperes, shall have these elements protected at not more than which of the
following ampacities?
a.
b.
c.
d.
50 amperes
70 amperes
100 amperes
60 amperes
7. All heating elements that are replaceable in the field and are part of an electric heater
shall have the element ratings legibly marked with which of the following?
a.
b.
c.
d.
Volts and watts.
Volts and amperes.
Neither of a or b
Either of a or b
8. Which of the following would be the minimum wire size in THW for 5 KW
resistance heater with a 3 amperes fan motor rated 240V/1ø.
a
b
c
d
.
.
.
.
#
#
#
#
8
10
12
1/0
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9. Which of the following circumstances will allow an embedded electric space
heating cable to be spliced?
I.
II.
a.
b.
c.
d.
only where necessary to lengthen the cable
only by an approved means
I only
II only
Both I and II
Neither I nor II
10. How close can a duct heater be to a heat-pump air conditioner without having to be
identified for air conditioner use?
a.
b.
c.
d.
4 feet
6 feet
Within sight
5 feet
11. Disconnecting means for duct heaters must be located in accordance with which of
the following?
I.
be either readily accessible with the disconnecting means installed
at or within sight from the controller
II.
or as permitted by 424.19(A).
a.
b.
c.
d.
I only
II only
Both I and II
Either I or II
12. A non-ASME boiler employing resistance type heating elements must be
subdivided when the elements are rated more than which of the following
amperes?
a.
b.
c.
d.
50 amperes
48 amperes
30 amperes
60 amperes
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13. When cables are installed in heated floors of bathrooms and in hydromassage
bathtub locations which of the flowing shall be installed for protection for
personnel in these locations?
a.
b.
c.
d.
Grounding and Bonding grids.
Groundfault circuit-interrupter.
Ground bars in all panels.
Intrinsically Safe systems.
14. A complete assembly provided with a junction box or a length of flexible conduit
for connection to a branch circuit is describing which of the following?
a.
b.
c.
d.
Heating Panel Set.
Heating Panel.
Ceiling Heat Grid.
Floor Heating Element.
15. Heating panels or panel sets installed under floor covering shall not exceed which of
the following wattages per square foot of heated area?
a.
b.
c.
d.
20 watts per square foot.
18 watts per square foot.
12 watts per square foot.
15 watts per square foot.
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FIXED ELECTRIC SPACE HEATING EQUIPMENT
ARTICLE 424
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
b. 15, 20, 25 or 30 amperes
d. 125%
c. Both I and II
d. All of the above
b. 60 oC
d. 60 amperes
d. either of a or b
b. # 10 THW copper wire
b. Only by an approved means
a. 4 feet
b. II only
d. 60 amperes
b. Ground Fault Circuit Interrupter
b. A heating panel
d. 15 Watts per square foot
424.3(A)
424.3(B)
424.19(A)(1)
424.20(A)
424.11
424.22(B)
424.29
424.3(B)
424.40
424.61
424.65
424.72(B)
424.44(G)
424.91
424.99(B)
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MOTORS, MOTOR CIRCUITS, AND CONTROLLERS
ARTICLE 430
LEVEL I
OBJECTIVES:
After completing this lesson, each student should be familiar with:
1.
2.
3.
4.
5.
6.
7.
8.
the general requirements of motors, motor circuits, and controllers.
specific sizes of motor controllers.
overload devices intended to protect motors, motor-controllers and
branch-circuit conductors.
specific devices used to protect motor branch-circuit conductors, motor
controllers, and motors against overcurrent due to short circuits or grounds.
specific protective devices for feeder conductors supplying motors against
overcurrent due to short circuits and grounds.
modifications of the general requirements of motor control circuits.
suitable controllers for all motors, and means of disconnecting motors and
controllers from the circuit.
how live parts should be protected in an adequate manner relative to the
hazard involved.
MATERIALS NEEDED:
National Electric Code
Samples of motors, motor circuits and controllers.
Handouts and/or pictures showing the above.
INTRODUCTION:
Article 430, dealing with motors, is somewhat unique from other articles because electric
motors come in so many different kinds and sizes. Also, motors are generally rated by
size and voltage, and general principles that apply to motors may hold true over a wide
array of motor sizes. Motor circuits are quite different from other circuits, in that, they
have different overcurrent protection for starting and have different fuse systems. As far
as motor controllers are concerned, there are many ways to control motors. One way is by
means of automatic controllers, which tend to complicate matters somewhat. Hence, a
working knowledge of motors and the like would be very helpful in understanding this
article.
Article 430 encompasses guidelines for motors, motor circuits and controllers for all
levels of inspection. Since a Level I inspector will only see certain areas governed by
this Article, cover only those sections that are typical of what a Level I inspector would
most likely experience on the job. This lesson plan will
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only cover those appropriate areas. The remaining sections of this Article should
be picked up in Levels II and III.
There are many problems related to motors which require some calculations. It is
very important that one become familiar with tables 430.247 through
430.251(A)because they will be used and referred to extensively in solving
problems. Explain how to read these tables and discuss each.
Knowledge and understanding of various terms and definitions would be
extremely helpful when studying Article 430. In order to review and provide a
background for studying motors, etc., a list of definitions is included as a handout
to be distributed to the students. See handout entitled “Key Terms.”
Given the fact that this Article is rather lengthy, the instructor may want to break
down the lesson and teach only a couple of objectives at a time. It would also be
advisable to teach Article 440 along with or after Article 430.
PRESENTING THE LESSON:
In order to present the class with a general overview or outline of this Article, the
instructor may want to show a transparency of Figure 430.1 and explain the
relationship of the Article parts.
Part I covers provisions for motors, circuits, and controllers that are not covered
in other parts of this Article. For example, air conditioning and refrigerator
equipment are covered in Article 440. (430.1)
Some important definitions are given in this section (430.2)
Motors and controllers shall also comply with the provisions of other articles in
the Code. See the list in Section 430.5 .
All equipment covered by this Article shall be supplied by conductors selected
from allowable ampacity tables in accordance with 310.15(B) or calculated
(under engineering supervision) in accordance with 310.15(C). For general
motor applications, required ampacity and motor ratings shall be determined
as follows:
If the current rating of a motor is used to determine the ampacity
of conductors or ampere ratings of switches, branch-circuit shortcircuit and ground-fault protection, etc., then values in Tables
430.247 through 430.250 shall be consulted instead of the actual
current rating on the motor nameplate.
Separate motor overload protection shall be based on the motor
nameplate current rating.
If the motor is not marked by horsepower, but by amperes, the
horsepower rating shall be assumed to be that corresponding to
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the value given in Tables 430.247 through 430.250; however, they may
need to be interpolated.
Three exceptions occur which are noted in Section 430.6(A)(1).
Motors shall be marked as indicated in Section 430.7. A discussion of markings and an
example nameplate would be helpful.
A handout of a photocopied nameplate may be helpful. [430.7(A)]
For locked rotors, code letters shall be used to mark them as illustrated in Table
430.7(B).
Controllers shall be marked with the marker’s name or identification, voltage, current or
horsepower rating, short-circuit current rating and other data necessary to properly
indicate suitable motors. If the controller includes overload protection suitable for group
motor application it shall be marked with the motor overload protection and maximum
branch-circuit short-circuit and ground-fault protection for such applications. If
combination controllers have adjustable instantaneous trip circuit breakers they shall be
marked to indicate ampere settings of the adjustable trip element. (430.8)
If the necessary data is on the nameplate then it is not required to mark individual
controllers when they are an integral part of a motor as a motor generator set. If the
controller is an integral part of equipment approved as a unit, then the markings shall be
on the equipment nameplate. (430.8)
Terminal torque requirements for control circuit devices with screw type pressure
terminals used with less than or equal to No. 14 AWG copper conductors shall be torqued
to a minimum of 7 inch-pounds unless identified for a different torque value. [430.9I,
Tables 430.12(B), 430.12(C)(1), and 430.12(C)(2)]
Motors shall be located in a manner that will permit adequate ventilation and access for
maintenance. Open motors having commutator or collector rings shall be protected so
sparks will not reach nearby combustible materials. This does not
limit the location of these motors on wooden floors or supports.
(430.14)
In order to determine the largest motor, select the motor with the highest rated full-load
current, which shall be the equivalent value corresponding to the motor
horsepower rating in Tables 430-247 through 430-250.
(430.17)
Branch-circuit conductors that supply a single motor shall have an ampacity not less than
125% of the motor full-load current rating. If a multi-speed motor is used, then the
branch-circuit conductors on the line side of the controller shall be based on the highest of
the full-load current ratings shown on the motor nameplate. The branch-circuit conductors
between the controller and the motor shall be based on the particular speed at which that
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circuit is energized. Exceptions apply to motors used for a short time and for d-c motors
operating from a rectified single phase power supply. [430.22(A)]
When conductors supply several motors, the ampacity shall be equal to the sum of the
full-load current rating of all of the motors plus 25% of the highest rated motor in the
group. (430.24)
If one or more of the motors is short-time or periodic etc., compute the ampacity of the
conductors as follows:
1. Use Table 430.22(E) and find the needed ampere rating for each other than
continuous duty motor.
Show Table 430-22(E) and review how to interpret.
2. Find the needed ampere rating for each continuous duty motor based on
100% motor full-load current rating.
10. Take the largest single motor ampere rating from part (1) or (2) and
multiply by 1.25. Then, add all other motor ampere rating from (1) and
(2) and select the conductor ampacity for the total ampere rating.
The conductor size shall be determined from the larger motor or a group of motors
that is/are operated at a given time, if the circuitry prevents the starting and running
of a second motor or group of motors. (430.24)
If you run into conductors that supply motor loads and a lighting or appliance load, then
the ampacity shall be sufficient for the particular load and computed in accordance with
the appropriate Article as follows: (430.25)
Lighting or appliance load
Article 220
Motor loads
Section 430.24
Single motor load
Section 430.22
Motor-operated fixed electric
space heating equipment
Section 424.3(B)
Multi-motor and combination
load equipment
Section 430.7(D)
Feeder tap conductors have several guidelines noted below: (430.28)
Ampacity not less than that required in part II. Terminate in a
branch-circuit protective device.
Shall meet one of the following:
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1. Be enclosed by a controller or raceway and not more than 10 feet in
length, and for field installation, be protected by an overcurrent protective
device on the side of the tap conductor, the rating or setting of which shall
not exceed 1000 percent of the tap conductor ampacity.
2. Ampacity at least 1/3 that of the feeder conductors, be protected from
physical damage, not more than 25 feet in length.
3.
Have same ampacity as the feeder conductors.
There is an exception to feeder taps over 25 feet long noted in 430.28. Review
conditions of the exceptions.
Those exceptions may apply as feeder taps. (240.21)
11. Motor and Branch-Circuit Overload Protection. There
are several ways to protect against overload for a continuous duty motor rated greater
than 1 horsepower. [430.32I] Asterisk percent values allow for incremental increase
in overload rating where the initial device selected in accordance with 430.32 is
insufficient to start the motor or to carry the load.
For example: The use of a separate overload device that is
responsive to motor current and will trip at no more
than the following percent of the motor nameplate
full-load current rating.
Motors with a marked service
factor not less than 1.15
125% *140%
Motors with a marked temperature
rise not over 40 degrees Celsius.
125% *140%
All other motors
115% *130%
Thermally protected motors shall have ultimate trip currents of the following
percentages of motor full-load current as stated in Tables 430.248 through 430.150.
Motor Full-Load Current
Percentage
Not exceeding 9 amperes
9.1 to and including 20 amperes
Greater than 20 amperes
170
156
140
Motors greater than 1500 horsepower shall have a protective device that has
temperature detectors that cause current to the motor to be interrupted when the
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motor attains a temperature rise greater than what is marked on the nameplate in
an ambient of 40 degrees Celsius. [430.32(A)(4)]
Other specifications in this Section apply for one horsepower or less motors that start
automatically and non-automatically. [430.32(B)]
If the overload relay selected in Section 430.32(A) (1) is not sufficient to start and carry
the load of the motor, then the next higher size overload relay shall be permitted to be
used if the trip current of the overload relay does not exceed the following percentages of
the motor full-load current rating. See 430.32(A)(1) figure. Show transparency Table
430.32. (Section 430.32(C))
See 430.36 concerning fuse locations.
If devices other than fuses are used as motor overload devices see Table 430.37. Show
transparency of Table 430.37 and discuss.
Overload devices other than fuses, thermal cutouts, or thermal protectors shall
simultaneously open a sufficient number of ungrounded conductors to interrupt current
flow to the motor. (Section 430.38)
For more information on thermal cutouts and overload relays, see 430.40 and note
exceptions.
The overload protection for motors used on general purpose branch-circuits shall be
specified in 430.42 as permitted in Article 210 concerning branch-circuits. Areas
specifically addressed include: less than 1 horsepower motors, greater than 1 horsepower
motors, cord and plug-connected, and time delay.
(430.42)
12. Motor Branch-Circuit Short-Circuit and Ground-Fault
Protection
The motor branch-circuit short-circuit and ground-fault protective device shall be capable
of carrying the starting current of the motor; however, the protective device shall not have
a setting exceeding the calculated value given in Table 430.52. Exception No. 1 and 2
may be considered as the general rule because they occur more often than not. (430.52)
Several motors or loads on one branch-circuit shall be permitted to be connected to the
same branch-circuit under certain conditions.
If the motors do not exceed 1 horsepower in rating they shall be permitted on a nominal
120 volt branch-circuit protected at not over 20 amperes or as a branch circuit of 1000
volts, nominal, or less, protected at not over 15 amperes, if certain conditions are meet:
1. The full-load rating of each motor does not exceed 6 amperes.
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2. The rating of the branch-circuit short-circuit and ground-fault
protective device marked on any of the controllers is not exceeded.
3. Individual overload protection conforms to Section 430.32. (430.53)
Branch-circuit protective devices shall comply with the provisions of Section 240.15.
(430.56)
Fuseholders shall not be of a smaller size than required to accommodate the fuses
specified in Table 430.52. Show transparency of this Table.
Smaller fuseholders than specified in the Table shall be permitted if the fuses have
time delay appropriate for the starting characteristics of the motor used. (430.57)
V. Motor Feeder Short Circuit and Ground Fault Protection
Any feeder supplying a specific motor load using conductors based on Section 430.24
shall have a protective device with a rating not greater than the largest rating of the
branch-circuit short-circuit and ground-fault protective device for any motor of the
group plus the sum of the full-load currents of the other motors of the group. Table 430.
52 shall be used to determine maximum settings for branch-circuit short-circuit and
ground-fault protective devices.
Section 440.22(A) shall be reviewed for hermetic refrigerant motor-compressors.
When feeder conductors have an ampacity greater than required by 430.24, the rating
of the feeder protective devices shall be permitted to be based on the ampacity of the
feeder conductors. [430.62(A)]
Where a feeder supplies a motor load and a lighting and or appliance, the feeder
protective device shall be permitted to have a sufficient rating to carry the lighting or
appliance load as outlined in Article 210 and 220, plus for a single motor, the rating
outlined in Section 430.52 and for two or more motors, the rating permitted by Section
430.62. (430.63)
VI. Motor Control Circuits
Motor Control Circuit: The circuit of a control apparatus or system that carries the
electrical signals directing the performance of the controller, but does not carry the
main power current. (430.71)
If a motor control circuit is tapped from the load side of a motor branch-circuit shortcircuit ground-fault protective device(s) and its function is to control the motor(s)
connected to that branch-circuit, then it shall be protected against overcurrent in
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accordance with Section 430.72. This tapped control circuit is not considered to be a
branch-circuit and should be permitted to be protected by a supplementary or branchcircuit overcurrent protective device. (430.72)
Show transparency of Table 430.72(B) and explain that overcurrent protection for
conductors shall not exceed the values specified in Column A of the Table.
Review the exceptions 1-4 to this rule.
(430.72)
Where damage to a motor control circuit would create a hazard, then all conductors of the
control circuit that are outside the control device shall be installed in a raceway or
protected from physical damage in other ways. (430.73) If one side of the motor control
circuit is grounded, then the motor control circuit shall be arranged so that an accidental
ground in the remote-control device will (1) not start the motor and (2) not bypass
manually operated shutdown devices or automatic safety shutdown devices. (430.74)
When the disconnecting means is in the open position, motor control circuits shall be
disconnected from all sources of supply. [430.75(A)]
The disconnecting means may consist of two or more separate devices; one that
disconnects the motor and controller from the power source and the other(s), the motor
control circuit(s) from its power supply. [430.75(A)]
When separate devices are used, they should be located immediately adjacent to one
another. Note the two exceptions to this rule. (430.75(A))
VII. Motor Controllers
In respect to this Article, a controller is any switch or device normally used to start
and stop a motor by making and breaking the motor circuit locked-rotor current.
[430.82A)]
A branch-circuit protective device shall be permitted to serve as the controller for a
stationary motor rated at less than or equal to 1/8 horsepower which is normally left
running such as a clock motor. Also, the motor must be constructed so that it cannot be
damaged by overload or failure to start. [430.81(A)
The controller may be an attachment plug and receptacle for a portable motor
rated at less than or equal to 1/3 horsepower.
[430.81(B)]
The horsepower rating of the controller shall not be lower than the horsepower rating
of the motor. Pay particular attention to 430.83(A)(1) and (2).
The controller shall not be required to open all conductors to the motor, unless the
controller serves also as a disconnecting means, then it shall open all ungrounded
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conductors to the motor. (430.84)
If a controller is so designed that the pole in the grounded conductors cannot be opened
without simultaneously opening all conductors of the circuit, then one pole of the
controller shall be permitted to be placed in a permanently grounded
conductor.
(430.85)
Each motor shall be provided with an individual controller; however, there is an
exception. See 430.87.
A combination fuseholder and switch may be used as a motor controller if the rating of
the fuseholder will accommodate the size of the fuse recommended in Part III of this
Article for motor overload protection, unless the fuse having time delay appropriate for
the starting characteristics of the motor used, then smaller size fuseholders may be used.
(430.90)
VIII. Motor Control Centers
All requirements for motor control centers are now grouped in Part VIII. These
requirements cover design and construction of these centers except for 430.94 on
overcurrent protection.
IX. Disconnecting Means
A disconnecting means shall be located “in sight from” the controller location: The Code
specifies that one equipment shall be in “sight from” another equipment, one of the
equipment specified is to be visible and not more than 50 feet distant from the other.
Note the exceptions to this rule. [430.102(A)]
A disconnecting means shall be located “in sight from” the motor location and the driven
machinery location, except where the disconnecting means provided in accordance with
430.102(A) is capable of being locked in the open position. [430.102(B)]
The disconnecting means for both motor and controller shall be permitted in the same
enclosure with the controller. Also, it shall disconnect the motor and controller from all
ungrounded supply conductors and be designed so that no pole can be operated
independently. (430.103)
The disconnecting means shall indicate clearly whether it is in the open (off) or
closed(on) position. (430.104)
See 430.105 concerning grounded conductors. For information concerning the service
switches as a disconnecting means, see 430. One of the disconnecting means shall be
“readily accessible.”
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Readily accessible: Capable of being reached quickly for operation, renewal, or
inspections, without requiring those to whom readily access is a requisite to climb over or
remove obstacles or to resort to portable ladders, chairs, etc. (Article 110, 430.107)
Generally speaking, the type of disconnecting means shall be a motor-circuit switch
rated in horsepower, a circuit breaker, or a molded case switch (nonautomatic
circuit interrupter
The ampere rating of the disconnecting means for motor circuits rated 1000
volts, nominal, or less, shall be at least 115% of the full-load current rating of the motor.
[430.110(A)]
See 430.110IC] for the ampere rating and interrupting capacity for combination
loads.
Certain types of switch and breakers may be used as both the controller and
disconnecting means. See 430.111 for details.
Each motor shall be provided with an individual disconnecting means, but a single
disconnecting means shall be permitted to serve a group of motors under any one of the
following conditions. (430.112)
Where a group of motors:
a. drive several different parts of a single machine.
b. is under the protection of one set of branch-circuit protective devices.
[See 430.53(A)].
c. is in a single room within sight from the location of the disconnecting means.
Motors receiving electrical energy from more than one source shall have disconnecting
means from each source located immediately adjacent to the equipment served, unless
the disconnecting means is capable of being locked in the open position. Also, a separate
disconnecting means shall not be required for a Class 2 remote-control circuit
conforming with Article 725, rated not over 30 volts, and is isolated and ungrounded.
Explain how motors may be fed from more than one source. (430.113)
K. Protection of Live Parts
Basically, all live parts shall be protected in a manner judged adequate to the hazard
involved.
Exposed live parts of motors and controllers operating at 50 volts or more between
terminals shall be guarded against accidental contact by enclosure or various other
ways noted below: (430.232)
1. By installation in a room or enclosure that is accessible only to qualified
persons.
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2. By installation on a suitable balcony, gallery, or platform, so elevated and
arranged as to exclude unqualified persons.
3. By elevation 8 feet or more above the floor.
See 430.232 for the exception to the rule.
See 430.233 for guidelines on guards for attendants.
It may be helpful to go over sample problems with the class to illustrate the
procedures for solving typical motor problems.
The following example may not be a typical problem for a Level I inspector;
however, it requires that one know how to look up data in the tables and apply it
to solve the problems. Also, this particular example involves many of the
essential calculations required for other problems. Generally, if the student can
work out the correct answers to this problem he/she should not have much
difficulty doing other types of motor problems.
See Sample Problem.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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Sample Problem
Using various sections and tables from Article 430, determine the following for one 25
horsepower squirrel-cage induction motor and two 30 horsepower wound- rotor induction
motors on a 460-volt, 3 phase, 60 Hertz supply. Assume dual-element fusing for short
circuit protection.
25 Hp
Squirrel cage
Induction motor
Full volt starting
25 Hp
1. Full-load Current
(Table 430.250)
34
30 Hp
30 Hp
Wound-rotor
Induction motors
40oC rise
Service factor 1.15
Code letter F
30 Hp
Amperes
40
30 Hp
40
2. Conductor Size
a. Each Motor (125% FLA)
50
(430.22)
b. All Motors 34 + 40 + (40 times
(430.24)
3. Motor Overload Protection
43
50
432(A)(1)]
*If not sufficient to
start or carry load. 48
[430.32(C)]
43
50
1.25) = 124
50
56
56
60
70
90
90
4. Branch-circuit Short-circuit
Ground-fault Protection
70
(Table 430.52) exception 1
*If not sufficient for starting
may use fuses rated: 70
[430.52 Exceptions (2)(B)]
5. Feeder Protection
70 + 34 + 40 = 144
[430.62(A)]
(Use 125 standard fuse)
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MOTORS, CIRCUITS, AND CONTROLLERS
ARTICLE 430
LEVEL I
WORKSHEET
1. The full-load rating of a motor found on the nameplate is 30.4 amperes and that found
in Table 430.250 is 31.8 amperes. Which value is required to be used when determining
the minimum size branch-circuit conductor permitted?
a.
b.
c.
d.
The nameplate rating of the motor.
The ampacity found in Table 430.250
The ampacity found in 430.52.
The ampacity multiplied by the difference in amperes calculated.
2. The circuit of a control apparatus or system that carries the electric signals directing
the performance of the controller but does not carry the main power current is known as
which of the following?
a.
b.
c.
d.
The Control Circuit
The Motor Controller.
The Motor Control Circuit.
The Control Center.
3. Motors shall be located so that adequate ventilation is provided. Open motors that
have commutators or collector rings shall be located or protected so that sparks
cannot reach adjacent combustible material. Which of the following floor types is
prohibited for these type motors?
a.
b.
c.
d.
Concrete.
Metal covered
Wood
None of the above
4. When referring to the largest motor in a group of motors, which of the following is
the intent of the Code regarding this statement?
a. The Code is referring to the motor requiring the most amperes.
b. The Code is referring to the motor requiring the largest wire size.
c. The Code is referring to the motor requiring the most Full Load
Current.
d. The Code is referring to the motor requiring the most Full Load Ohms.
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5. A 10 ft. motor feeder tap conductor must be enclosed either by an enclosed controller
or by a raceway, be not more than 10 feet in length, and, for field installation, be
protected by an overcurrent device on the line side of the tap conductor, the rating
or setting of which shall not exceed which of the following?
a.
b.
c.
d.
100 percent.
150 percent.
500 percent.
1,000 percent.
6. Conductors that supply a single motor used in a continuous duty application shall
have an ampacity of not less than which of the following?
a.
b.
c.
d.
125 percent of the motor’s full-load current rating.
250 percent of the motor’s full-load current rating.
100 percent of the motor’s full-load current rating.
300 percent of the motor’ full-load current rating.
7. Each motor used in a continuous duty application and rated more than 1 hp shall be
protected against overload by one of the following except for?
a.
b.
c.
d.
A separate Overload Device.
A Thermal Protector.
An Integral Protector.
An Interior Overcurrent Device.
8. A motor with a marked service factor of 1.15 shall have its overload heater
calculated at what percentage?
a.
b.
c.
d.
100 percent
250 percent
300 percent
125 percent
9. Thermally protected motors shall have ultimate trip currents of what percentage
when full-load currents are greater than 20 amperes?
a.
b.
c.
d.
100 percent
250 percent
140 percent
125 percent
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10. Where fuses are used for motor overload protection, a fuse shall be inserted in
each of the following?
a. Branch circuit feeder conductors.
b. Main Circuit breaker bus bars.
c. Ungrounded Conductors.
d. Motor Control Conductors.
11. A three phase motor shall have an overload protection inserted in how many of
it’s phase conductors?
a.
b.
c.
d.
All three phase conductors.
All four phase conductors.
Both of it’s phase conductors
All non-current carrying phase conductors.
12. One pole of the disconnecting means shall be permitted to disconnect a permanently
grounded conductor, provided the disconnecting means is designed so that the
pole in the grounded conductor cannot be opened without which of the following
occurring?
a.
b.
c.
d.
Simultaneous disconnecting of all conductors of the circuit.
Simultaneous notification by alarm signal to the control circuit.
Simultaneous shut-down of the control circuit by electronic signal.
Simultaneous alert to a supervised system of the shut-down.
13. Where damage to a motor control circuit would create a hazard, then all
conductors of the control circuit that are outside the control device shall be
installed in accordance with which of the following?
I.
II.
a.
b.
c.
d.
In a raceway.
Protected from physical damage in other ways.
I only
II only
Either I or II
Neither I or II
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14. For a portable motor rated at 1/3 horsepower or less, the controller for the motor
shall be permitted to be which of the following?
a.
b.
c.
d.
A detachable cord connector.
An attachment plug and receptacle.
A lockable plug and receptacle.
An SJO cord with locking attachment.
15. Find the feeder conductor ampacity for the three, single phase
(alternating current) motors listed below.
Two – 1 Hp, 230 volt, motors. One –
1 1/2 Hp, 230 volt, motor.
(Use Table 430-248)
16. Find the conductor ampacity for a 3/4 Hp, continuous duty, 120 volt, single
phase motor.
17. Complete the following requirements for a 15 Hp, 230 volt, 3-phase, induction
type, a-c motor with a service factor of 1.15, nameplate thermal protection at
125% of FLC and no code letter.
Full Load Current
Branch-Circuit Ampacity
Disconnecting Means
Overcurrent Protection
(Time delay fuse)
Heater Size
(From Motor Nameplate)
(Not FLC of Motor/NEC)
(Table-430-150)
(430-22)
(430-110)
(Table-430-152)
(430-32)
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MOTORS, CIRCUITS, AND CONTROLLERS
ARTICLE 430
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
b.
c. the motor control circuit
d. none of the above
c. Full-load current
d. 1,000 percent
a. 125 percent
d. an Interior Protective Device.
d. 125 percent
c. 140 percent
c. Ungrounded conductor
a. In all three phase conductors
a. simultaneous opening of all conductors
c. Either I or II
b. an attachment plug and receptacle
28.5 [ 8 + 8 + ( 10 times 1.25 ) = 28.5 ]
17.25 ( 13.8 times 1.25 = 17.25 )
17.
(see following)
430.6(A)(1)
100
430.14(B) Exception
430.24
430.28
430.22
430.32(A)(1)(2)(3)
430.32(A)(1)
430.32 (A)(2)
430.36
Table 430.37
430.105
430.73
430.81(B)
430.24
430.22(A)
Full Load Current
42 amp (Table 430.250
Branch-Circuit Size
52.5 amp
(430.22)
(42 times 125% = 52.5)
Disconnecting Means
48 amp [430.110(A)]
(42 times 115% = 48.3)
Overcurrent Protection
70 amp
(Table 430.52)
(42 times 175% = 73.5 ; Go up to 80 ampere)
(Time delay fuse) 80 amp
Heater Size
52.5 amp
(430.32)
(42 times 125% = 52.5)
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AIR CONDITIONING AND REFRIGERATING EQUIPMENT
ARTICLE 440
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar with requirements
regarding air conditioning and refrigeration equipment.
INTRODUCTION:
This Article will identify areas of concern regarding ampacity requirements for air
conditioning equipment, branch circuit selection current, location and ground fault
protection including room air conditioners.
Hermetic Refrigerant Motor Compressor: A combination consisting of a
compressor and motor, both of which are enclosed in the same housing, with no
external shaft or shaft seals, the motor operating in the refrigerant.
In discussing this lesson, you may need to refer back to other articles such as:
430, 422, and 424.
PRESENTING THE LESSON:
Section 440.4 covers the nameplate requirements and should be studied carefully.
Single phase, 115 volt motor compressors rated in excess of 9 amperes locked
rotor or 4.5 amperes at 230 volts and all polyphase systems shall have nameplates
giving load currents.
If a motor is thermally protected, or in a thermally protected system, it shall be so
marked. Branch circuit short circuit and ground fault protective devices shall be
calculated by Part III.
The inspector should be able to locate, read and properly apply the nameplate
information given by the manufacturer. In studying Section 440.7, it may be
helpful to review Sections 430.24 and 430.53 Review the single machine concept
in Section 440.8.
The disconnecting means of a hermetic refrigerant motor compressor shall be
selected in a number of ways. See Section 440.12(A) for details. Combination
loads are covered in 440.12(B). All switches in circuits must comply with 440.12.
A cord and plug is permitted as disconnect means for equipment such as room air
conditioners , refrigerators, freezers, etc.
The location of disconnecting means shall be located within sight from and
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readily accessible from the air conditioning or refrigerating. (440.14)
Rating or settings for individual motor compressors are not to exceed 175% of
rated load current or branch circuit selector current whichever is greater. It may
be increased to 225% if necessary for starting current. [440.22(A)]
Protective devices must meet manufacturer’s values for overload. [440.22(C)]
Branch circuit conductor ampacity must be at least 125% of rated load current or
branch selection current whichever is greater. (440.32)
Feeder ampacity of multimotor installations must be the sum of all motor
ampacities plus 25% of the largest. See exceptions. (440.33)
For combinations loads see 440.34.
Motor compressors and branch circuit overload protection shall be according to
one of the following[440.52(A)]:
1.
Overload relay 140% of load.
2.
Integral thermal protection.
3.
Fuse or inverse time circuit breaker 125% of load.
4.
Protective system furnished for use with specific motor compressor.
Briefly review overload relays and motor compressors in Sections 440.53 and
440.54, respectively. Attachment plug ratings are not to exceed 20 amperes at
125 volts, or 15 amperes at 250 volts. [440.55(B)]
Room air conditioners rated not over 250 volts, single phase are covered under
part VII and over 250 volts or 3 phase shall be directly connected. (440.60)
Consider single motor unit when all four conditions are meet. See 440.62(A & B).
440.62(B) states that a plug-connected room air conditioner shall not exceed 80%
of the branch circuit.
Attachment plugs may be permitted as disconnecting means if meeting conditions
of Section 440.63. Briefly mention supply cords in Section 440.64.
APPLICATION:
If time allows, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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AIR CONDITIONING AND REFRIGERATING EQUIPMENT
ARTICLE 440
LEVEL I
WORKSHEET
1.
A room air conditioner shall be permitted to be cord and plug connected
if not rated over which of the following?
a.
b.
c.
d.
2.
40 amperes and 250 volts, single phase.
30 amperes and 240 volts, single phase.
20 amperes and 230 volts, single phase
15 amperes and 220 volts, single phase.
An attachment plug and receptacle shall be permitted to serve as the
disconnecting means for a single-phase room air conditioner rated 250 volts
or less if which of the following is applied?
I.
II.
The manual controls on the room air conditioner are readily
accessible and located within 1.8 m (6 ft) of the floor
An approved manually operable disconnecting means is installed in a
readily accessible location within sight from the room air conditioner.
a.
b.
c.
d.
3.
I only
II only
Either I or II
Neither I or II
What is the maximum length flexible cord permitted for a nominal 240
volt room air conditioner?
a.
b.
c.
d.
6 feet
8 feet
10 feet
12 feet
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4.
Which of the following situations would require a nameplate on a 115
volt motor compressor?
a. When the locked-rotor current of each single-phase motor-compressor
has a rated-load current of more than 9 amperes at 115 volts.
b. When the locked-rotor current of each single-phase motor-compressor
has a rated-load current of less than 9 amperes at 115 volts.
c. When the locked-rotor current of each single phase motor-compressor
exceeds a rated load-current of 6 amperes or greater at 115 volts.
d. When the locked-rotor current of each single-phase motor-compressor
has a rated-load current of more than 10 amperes at any voltage.
5.
For a wye-start, delta-run connected motor-compressor, the selection of
branch-circuit conductors between the controller and the motorcompressor shall be permitted to be based on what percentage of either
the motor-compressor rated-load current or the branch-circuit selection
current, whichever is greater?
1.
2.
3.
4.
6.
Rating or settings for individual motor compressors are not to exceed
175% of
rated load current or branch circuit selector current
whichever is greater. It may
be increased to which of the
following if necessary for starting current?
a.
b.
c.
d.
7.
125 percent
75 percent
72 percent
80 percent
150 percent
250 percent
300 percent
225 percent
Motor compressors and branch circuit overload protection shall be
according to which of the following?
a. Overload relay 140% of load.
b. Integral thermal protection.
c. Fuse or inverse time circuit breaker 125% of load.
d. Protective system furnished for use with specific motor compressor.
E. Any of the above.
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8.
The motor-compressor branch-circuit short-circuit and ground-fault
protective device shall be capable of carrying which of the following?
a.
b.
c.
d.
9.
The starting current of the motor.
The starting surge of the compressor.
The ampacity of the motor-controller center.
The total load of the compressor, fans and controls.
A controller shall be marked with data as may be needed to properly
Indicate the motor-compressor for which it is suitable to include
which of the following?
a. The manufacturer’s name, trademark, or symbol.
b. Identifying designation.
c. Voltage; phase; full-load and locked-rotor current (or horsepower)
rating;
d. All of the above
10.
The provisions of Part III specify devices intended to protect the branchcircuit conductors, control apparatus, and motors in circuits supplying hermetic
refrigerant motor-compressors against overcurrent due to short circuits and
grounds. They are in addition to or amendatory of the provisions of which of the
following?
a.
b.
c.
d.
11.
12.
Article 240.
Article 300.
Article 250.
Article 440.
Conductors supplying a motor-compressor load as a combination load
shall have an ampacity sufficient for the appliance load plus the
required ampacity for the additional lighting or appliance load as
calculated from which of the following?
a. Article 210 and other applicable articles.
b. Article 220 and other applicable articles.
c. Article 300 and other applicable articles.
d. Article 422 and other applicable articles.
The ampere rating of a disconnecting means for a Hermetic Refrigerant
Motor-Compressor shall be at least which of the following
percentages of the rated-load current or branch-circuit selection
current which ever is greater.
a. 250%
b. 150%
c. 125%
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d. 115%
13.
AC disconnecting means must be located within which of following
distances from the equipment. (Without Exceptions)
a.
b.
c.
d.
14.
A motor-compressor is protected by a separate overload relay protective
Device that is responsive to motor-compressor current. This type
protection is allowed if the device is set to trip at a percentage not to
exceed which of the following?
a.
b.
c.
d.
15.
140%
175%
125%
225%
A motor-compressor is also allowed to be protected by a fuse or inverse
time circuit breaker responsive to motor current, which shall also be
permitted to serve as the branch-circuit short-circuit and ground-fault
protective device. This device shall be rated at not more than which of the
following?
a.
b.
c.
d.
16.
within 35 feet
within sight
within 40 feet
within 25 feet
125% of the motor-compressor rated-load current.
175% of the motor-compressor rated-load current
225% of the motor-compressor rated-load current
250% of the motor-compressor rated-load current
Branch circuit conductors supplying a single motor-compressor shall
have an ampacity of which of the following?
a.
b.
c.
d.
125%
150%
115%
d. 175%
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17.
Overload relays and other devices for motor overload protection that are
not capable of opening short circuits shall be protected by which of the
following?
a.
b.
c.
d.
18.
A room air conditioner that is rated as follows shall be directly
connected to wiring?
a.
b.
c.
d.
19.
single phase and 250 volts
3 phase and 250 volts
single phase and 120/240 volts
It is not required to be directly connected to wiring.
Where lighting units are also supplied along with a room air conditioner
the rating shall not exceed what percentage of the circuit.
a.
b.
c.
d.
20.
I.
Fuses
II.
Inverse time circuit breakers
I only
II only
Either I or II
Neither I or II
25%
75%
50%
100%
Where no other loads are supplied, the total marked rating of a cord-andattachment-plug-connected room air conditioner shall not exceed which of the
following percentage of the rating of a branch circuit?
a
b
c
d
.
.
.
.
50
70
80
25
%
%
%
%
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AIR CONDITIONING AND REFRIGERATING EQUIPMENT
ARTICLE 440
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
a. 40 amperes and 250 volts single phase
c. Either I or II
a, 6 feet
a. Locked rotor current in excess of 9 amperes.
c. 72 percent
d. 225 percent
e, Any of the above.
a. The starting current of the motor
d. all of the above
a. Article 240
b. Article 220 and other applicable articles
d. 115%
b. within sight
a. 140%
a. 125%
a. 125%
c. Either I or II
b. 3 phase and 250 volts
c. 50%
c. 80 %
440.62(A)
440.63
440.64
440.4(A)
440.32
440.22
440.52
440.22(A)
440.5
440.21
440.34
440.12(A)(1)
440.14
440.52(A)(1)
440.52(A)(3)
440.32
440.53
440.60
440.62(C)
440.62(B)
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INTRINSICALLY SAFE SYSTEMS
ARTICLE 504
LEVEL I
OBJECTIVES:
After completing this lesson each student should be acquainted with the
requirements covering the installation of intrinsically safe apparatus and
wiring for class I, II, and III locations.
INTRODUCTION:
Wiring methods in hazardous locations can be extremely expensive. For
economical reasons, more I.S. wiring was being used which brought about
the need for specific regulations covering such installations.
PRESENTING THE LESSON:
1. Thoroughly cover the requirements included in scope, equipment
approval, and the definitions included within the Article.
2.
Point out the importance of complying with installation
limitations that
may be in the instructions included with the equipment listing and/or
included with Section 504.10(A) as to location.
3. Cover the remaining material included in the article which proved
installation specifics.
r.
Use manufacture’s literature, pictures, and samples to more thoroughly
illustrate the intended application and installation methods.
APPLICATION:
If time allows, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time allows, correct the worksheets and discuss the results.
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INTRINSICALLY SAFE SYSTEMS
ARTICLE 504
LEVEL I
WORKSHEET
1.
All of the following terms are included in the definitions in Section 504.2 except:
a. Control Drawing
b. Associated Apparatus b.
Intrinsically Safe System d.
Cold Arc Circuit
2.
Conductors and cables of intrinsically safe circuits run in other than raceway
or cable tray systems shall be separated by at least which of the following
distances and secured from conductors and cables of any non-intrinsically safe
circuits?
a.
b.
c.
d.
3.
The maximum spacing between labels used to identify “Intrinsic Safety Wiring”
is:
a.
b.
c.
d.
4.
2 inches
4 inches
6 inches
8 inches
6 inches
24 inches
6 feet
25 feet
The clearance between two terminals for connection of field wiring of
different intrinsically safe circuits shall be at least what distances apart unless
this clearance is permitted to be reduced by the control drawing?
a.
b.
c.
d.
1.25 inches
1.00 inches
.75 inch
.25 inch
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INTRINSICALLY SAFE SYSTEMS
ARTICLE 504
LEVEL I
ANSWER KEY
1. D, Cold Arc Circuit
504.2
2. A, 2 inches
504.30(A)(3)
3. D, 25 feet
504.80(B)
4. A .25 (1/4 inch)
504.30(B)
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MOTOR FUEL DISPENSING FACILITIES
ARTICLE 514
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar with wiring
requirements of service stations and other gasoline dispensing establishments.
MATERIALS NEEDED:
Samples of explosion proof fittings and seal-offs.
INTRODUCTION:
Service stations include any place where volatile flammable liquid is transferred
to fuel tanks of self-propelled vehicles. Special care is taken in around these areas
because a spark could set off an explosion.
PRESENTING THE LESSON:
Look at the Table 514.3(B)(1) and go over the different areas as to their
classification.
All wiring in the class I location as determined in Table 514.3(B)(1) shall meet the
requirements set forth in Article 501. (514.4)
All wiring above the hazardous locations shall have the wiring meet the same
requirements as commercial garages described in 511.7. (514.7)
All conductors going to the gas pump including the neutral shall be disconnected at the
same time. (514.5)
Discuss emergency controls as outlined in 514.11(B & C).
Provisions for maintenance and service of dispensing equipment are outlined in
514.13.
Seal-off fittings shall be provided as the first fitting out of the ground at the dispenser
or cavity or enclosure also at the boundary of the hazardous location.
The sealing compound shall be approved for the application used. (514.9)
All metal parts of pumps, raceways, and any non-current carrying parts shall be
grounded per Article 250. (514.16)
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Underground wiring shall be installed in rigid metal conduit, threaded steel
intermediate conduit. Any wiring below a Class I Division II location shall be
considered a Class I Division I location. Rigid non-metal conduit shall be
permitted were under 2 feet of cover and terminates in a trench with rigid or
intermediate conduit for the last 2 feet of the conduit and run. Where rigid nonmetallic is used care is to be taken in that the junction box at the pump must have
built in grounding terminals. (514.8)
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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MOTOR FUEL DISPENSING FACILITIES
ARTICLE 514
LEVEL I
WORKSHEET
1.
An underground tank vent opening is classified as a class I division I
where it discharges upward for which of the following?.
a.
b.
c.
d.
2.
A motor fuel dispenser shall have a class I division II location for a
distance of up to 18 inches above grade and horizontally for which of the
following?
a.
b.
c.
d.
3.
10 feet
20 feet
15 feet
5 feet
Disconnecting means for the gas pumps must disconnect?
a.
b.
c.
d.
5.
20 feet
10 feet
5 feet
3 feet
A remote outdoor pump has a class I division I location underground for
a
distance of how far from the pump.
a.
b.
c.
d.
4.
10 feet
12 feet
6 feet
5 feet
only one of the ungrounded conductor
both of the ungrounded conductors
both ungrounded conductors and the grounded
the ungrounded conductors and the grounding conductors
Seal-offs shall be provided at which of the following in Class I
locations?
a.
b.
c.
d.
only at the pump
at the first fitting emerging from the earth and at the boundary
at the location where the conduit leaves the hazardous location
in any accessible location in the run to the pump
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6. Type PVC conduit can be used if buried below grade at a minimum depth of__?
a.
b.
c.
d.
12 inches
18 inches
20 inches
24 inches
7. Each dispensing device shall be provided with a means to remove all external voltage
sources, including feedback, during periods of maintenance and service of the
dispensing equipment. The location of this means shall be permitted to be other than
inside or adjacent to the dispensing device. The means to remove all voltage sources
shall also meet which of the following?
a.
b.
c.
d.
Shall be capable of being locked in the open position.
Shall be rated at least 100 amperes.
Shall be within sight of the grounding electrode.
Shall cut off all the power, internal and external to the building.
8. Underground wiring shall be installed in threaded rigid metal conduit or
threaded steel intermediate metal conduit. Any portion of electrical wiring
that is below the surface of a Class I, Division 1, or a Class I, Division 2,
location [as classified in Table 514.3(B)(1) and Table 514.3(B)(2)] shall be
sealed within what distance of the point of emergence above grade.
a.
b.
c.
d.
2 feet
4 feet
6 feet
10 feet
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MOTOR FUEL DISPENSING FACILITIES ARTICLE
514
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
d, 5 feet
Table 514.3(B)(1)
a, 20 feet
Table 514.3(B)(1)
a, 10 feet
Table 514.3(B)(1)
c, both ungrounded conductors and grounded conductors 514.11(A)
b, as first fitting at pump and at
514.9(A & B)
hazardous location boundary.
d, 24 inches
514.8 Ex. No. 2
a, shall be capable of being locked in the open
514.13
position.
d, 10 ft.
514.8
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HEALTH CARE FACILITIES ARTICLE
517
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar with electrical construction
and installation criteria for general health care facilities such as doctor’s offices, dental
offices and emergency medical facilities.
MATERIALS NEEDED:
Examples of approved wiring methods.
INTRODUCTION:
Part A:
517.1, Scope
517.2, Definitions
Part B:
517.10(A), Applicability
517.11, General Installation/Construction Criteria
517.12, Wiring Methods
517.13, Grounding of Receptacles and Fixed Electrical Equipment
517.14, Panelboard Bonding
PRESENTING THE LESSON:
Wiring in patient care areas shall be installed in metal raceways or cable assemblies
approved for that purpose. [517.13(B)]
APPLICATION:
Allow the class time to answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
Correct the worksheets and discuss the results.
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HEALTH CARE FACILITIES
ARTICLE 517
LEVEL I
WORKSHEET
1.
517.10 Part II does not apply to:
a.
b.
c.
d.
2.
Exam Rooms
Surgical Suites
Waiting Rooms
All of the above
In an area used for patient care operating at over 100 volts the grounding
conductor shall be:
a.
b.
c.
d.
3.
An insulated copper conductor
An insulated aluminum conductor
An uninsulated copper conductor
An uninsulated aluminum conductor
Following the energizing of the Emergency System all the following
equipment, with the exception of which of the following shall be arranged for
delayed automatic connection to the alternate power source:
a. Central suction systems serving medical and surgical functions,
including controls. Such suction systems shall be permitted on the critical
branch.
b. Sump pumps and other equipment required to operate for the safety of
major apparatus, including associated control systems and alarms.
c. Closed circuit TV systems used for educational purposes.
d. Smoke control and stair pressurization systems, or both.
4. A system of circuits and equipment intended to supply alternate power to a limited
number of prescribed functions vital to the protection of life and safety is a(n);
a.
b.
c.
d.
life safety branch
essential electrical system
isolated power system
emergency system
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HEALTH CARE FACILITIES
ARTICLE 517
LEVEL I
ANSWER KEY
1.
c., Waiting Rooms
517.10 (B)(1)
2.
a., An insulated copper conductor
517.13(B)
3.
c. closed circuit TV systems used for educational purposes
517.34(A).
4.
d. emergency system
517.2 Def.
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PLACES OF ASSEMBLY
ARTICLE 518
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar special wiring
requirements in places of assembly as provided in Article 518.
MATERIALS NEEDED:
Handout of sections of the North Carolina State Building Code pertaining to places
of assembly.
INTRODUCTION:
A place of assembly is a building or portion of a building intended for the assembly
of 100 or more persons. If a room or space for assembly purposes is designed or
intended to be occupied by less than 100 persons it shall not be classified as a place of
assembly. For determining the area required per person consult the North Carolina
State Building Code.
PRESENTING THE LESSON:
Discuss wiring methods as covered in 518.4 for non-rated construction, rated
construction, and spaces with finish rating.
If any part of the place of assembly is classified as a hazardous area the wiring within
the hazardous location shall comply with the provisions of Article 500.
With the exception that approved flexible cables and cords shall be permitted to be laid
on floors where protected from contact by the general public, temporary wiring in
exhibition halls used for display booths, as in trade shows shall be installed in
accordance with Article 590.
The control of emergency systems shall comply with Article 700. Give the class some
time to review Article 590.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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PLACES OF ASSEMBLY
ARTICLE 518
LEVEL I
WORKSHEET
1.
Article 518 covers all building or portions of buildings or structures
designed or intended for the assembly of which of the following
number of persons?
a.
b.
c.
d.
2.
Occupancy of any room or space for assembly purposes by less than 100
persons in a building of other occupancy, and incidental to such other
occupancy, shall be classified as which of the following?
a.
b.
c.
d.
3.
Assembly occupancy.
Part of the other occupancy.
Coincidental Occupancy.
Non-incidental Occupancy.
Occupancy of any room for assembly purposes by 100 persons or more,
that contains a portable stage platform for the presentation of a musical
production shall comply with the applicable provisions of which of the
following?
a.
b.
c.
d.
4.
50 or more
100 or more
75 or more
300 or more
Article 590
Article 518
Article 520
Article 511
Hazardous areas located in any assembly occupancy shall be installed in
accordance with which of the following?
a.
b.
c.
d.
Article 500
Article 590
Article 520
Article 518
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5.
Which of the following statements about temporary wiring in exhibition
halls used for display booths, as in trade shows is correct?
I.
II.
a.
b.
c.
d.
6.
It shall be installed in accordance with Article 590.
Approved flexible cords shall be permitted to be laid on
floors where protected from contact by the general public.
I only
II only
Both I and II
Neither I or II
Which of the stipulations listed below must be met to permit electrical
nonmetallic tubing and rigid nonmetallic conduit to be installed in
club rooms, conference and meeting rooms in hotels or motels, courtrooms,
dining facilities, restaurants, mortuary chapels, museums,
libraries, and places of
religious worship where the following
apply:
I.
II.
a.
b.
c.
d.
The electrical nonmetallic tubing or rigid nonmetallic
conduit is installed concealed within walls, floors, and
ceilings where the walls, floors, and ceilings provide a
thermal barrier of material that has at least a 15-minute
finish rating as identified in listings of fire-rated
assemblies.
The electrical nonmetallic tubing or rigid nonmetallic
conduit is installed above suspended ceilings where the
suspended ceilings provide a thermal barrier of material
that has at least a 15-minute finish rating as identified in
listings of fire-rated assemblies.
I only
II only
Neither I or II
Both I and II
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PLACES OF ASSEMBLY
ARTICLE 518
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
b. 100
b. Incidental to whatever the occupancy is
c. Article 520
a. Article 500
c. Both I and II
d. Both 1 and 2
518.1
518.2(B)
518.2(C)
518.3(A)
518.3(B)
518.4(C)(1)(2)
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MANUFACTURED BUILDINGS
ARTICLE 545
LEVEL I
OBJECTIVE:
After this lesson each student should be familiar with procedures for inspecting
concealed wiring installed at the factory.
MATERIALS NEEDED:
Pictures, slides, and plans for typical applications likely to be encountered.
INTRODUCTION:
Discuss the difference between manufactured buildings and manufactured homes
(mobile homes) – Article 550.
PRESENTING THE LESSON
1. When presenting the requirements included in this Article, be sure the students
have a clear understanding of the scope, Section 545.1 and the definitions included in
Section 545.2. *NOTE: North Carolina recognizes a third party testing agency label
which exempts the unit from local inspection. Regulations are available from NC
Department of Insurance Manufactured Building Division.
2. As a general rule requirements found in other Articles will be applicable
unless there is a different requirement included in Article 545 on the same
subject. When there is a difference, Article 545 will apply.
3. The requirements covered in Sections 545.4 through 545.9 are for the most part
the same as included in other code sections governing same subject, such as wiring
methods as recognized in Chapter 3, service entrance conductor and service
equipment as in Article 230, and boxes as included in Article 370.
NOTE: The requirements for the securing of cables and box dimensions permitted
in Section 545.4(B) and 545.9(A) differ slightly and these exceptions should be
pointed out.
4. Bonding and grounding requirements covered in Section 545.11 and 545.12
should be covered by making reference to Article 250.
5. The subject of component inter-connection is important and emphasis should be
placed on this subject both in the classroom and in the field. (545.13).
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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MANUFACTURED BUILDING
ARTICLE 545
LEVEL I
WORKSHEET
1.
A Manufactured Building is a building that is of closed construction and is
made or assembled in manufacturing facilities on or off the building site
for installation, or for assembly and installation on the building site, other than
which of the following?
a.
b.
c.
d.
2.
In closed construction, cables shall be permitted to be secured only at
cabinets, boxes, or fittings where which of the following size conductors are
used and protection against physical damage is provided?
a.
b.
c.
d.
3.
manufactured homes or recreational vehicles
mobile homes or park trailers
I only
Both I and II
# 12 AWG and smaller
# 10 AWG and larger
# 12 AWG and larger
# 10 AWG and smaller
Pre-wired panels and building components shall provide for the bonding, or
bonding and grounding, of all exposed metals likely to become energized,
a. to the frame of the building and the ground rod.
b. in accordance with article 250, parts V, VI, and VII.
c. to the first means of disconnect.
d. to the grounding electrode.
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MANUFACTURED BUILDING
ARTICLE 545
LEVEL I
ANSWER KEY
1.
2.
3.
d. see definition of manufactured building
545.2
d. # 10 AWG and smaller
545.4(B)
b. in accordance with article 250, parts V, VI, and VII. (545.11)
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AGRICULTURAL BUILDINGS
ARTICLE 547
LEVEL I
OBJECTIVE:
After this lesson each student should be familiar with special applications and
provisions of agricultural buildings as related to the Code.
MATERIALS NEEDED:
Pictures or slides of fixtures and enclosures suitable for dust, water, and corrosive
atmospheres and an equipotential plane being installed.
INTRODUCTION:
Agricultural buildings are places where excessive dust and water may accumulate such
as poultry or livestock confinements and grain elevators or storage barns. Many of these
areas may have a corrosive atmosphere due to different kinds of vapors emitted. Also,
some of these buildings are washed and sanitized with water and cleansing agents. These
conditions present a potentially dangerous environment for the use of electricity, so
precautions must be taken.
PRESENTING THE LESSON:
Section 547.3 clearly indicates that there are agricultural buildings or farm buildings not
of the types covered in Section 547.1(A & B) and they are intended to be wired
according to other applicable articles in the Code.
Sections 547.5 and 547.6 cover wiring methods, flexible connections and enclosures for
devices, relays, overcurrent devices and similar equipment required for agricultural
buildings governed by this Article.
Electrical motors and lighting fixtures should be designed for protection against
moisture, dust, etc. Guards should be used on lights to protect them from physical
damage and in some cases watertight guards should be used.
Section 547.9(B)(3) covers the important grounding requirements for agriculture
buildings. These requirements, and the equipotential plane requirements in 547.10 are
necessary as livestock within such facilities are generally highly vulnerable when
exposed to different voltage potentials. See Section 547.2 for the definition and an
explanation of an equipotential plane.
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APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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AGRICULTURAL BUILDINGS
ARTICLE 547
LEVEL I
WORKSHEET
1.
The provisions of this article shall apply to the following agricultural buildings or
that part of a building or adjacent areas of similar or like nature where excessive
dust and dust with water may accumulate, including all areas of which of the
following except?
a.
b.
c.
d.
Poultry buildings.
Livestock buildings
Fish confinement systems.
Pet shops.
2. Which of the following wiring methods is not allowed in agricultural
buildings?
a.
b.
c.
d.
UF cable
NMC cable
SE (copper)
NM cable
3. What is the minimum size of the bonding conductor required to connect the wire mesh
in a concrete floor of an animal confinement room to the building grounding
electrode system?
a
b
c
d
.
.
.
.
#
#
#
#
6
4
8
10
4. All 125-volt, single-phase, 15- and 20-ampere general-purpose receptacles installed
in the following locations, with the exception of which of the following, shall have
ground-fault circuit-interrupter protection for personnel?
a.
b.
c.
d.
Areas having an equipotential plane and a receptacle
Outdoor receptacles with weatherproof covers
A receptacle in an adjacent office area
Dirt confinement areas for livestock
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AGRICULTURAL BUILDINGS
ARTICLE 547
LEVEL I
ANSWER KEY
1.
2.
3.
4.
d. Pet shops
d, NM cable
c. # 8
c.
547.1 (A)
547.5 (A)
547.10(B)
547.5(G)
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MOBILE HOMES, MANUFACTURED HOMES, AND MOBILE HOME
PARKS
ARTICLE 550
LEVEL I
OBJECTIVE:
After this lesson each student should be familiar with the requirements regarding
electrical installations within or on a mobile home or manufactured home and the wiring
in a mobile home park.
INTRODUCTION:
Discuss the definitions in Section 550.2 with emphasis on “Mobile Home”,
“Manufactured Home”, “Mobile Home Lot” and “Mobile Home Park”.
Discuss the requirements pertaining to the location of “Service Equipment for mobile
or manufactured homes. Refer to Part III.
PRESENTING THE LESSON:
Cover sample calculation for computing load for service and/or feeder assembly size.
[550.18]
Electrical distribution systems within the mobile home park must be 120/240 V, single
phase, 3 wire. The feeder to the mobile home park is calculated based on a lot demand of
the larger of (1) 16,000 VA or (2) the calculated load of the largest mobile home the lot
will accept. Load diversity among the lots can be accommodated by the application of
demand factors given in Table 550.31.
The students should review Article 550 with particular emphasis to exterior wiring systems
(i.e. feeders within the mobile home park, to the mobile home lot, and to the mobile home;
mobile home service equipment). New mobile homes, including the internal electrical
distribution systems, are inspected by a third party agent at the point of manufacture and
are not subject to local inspection. After the students have reviewed this Article to
familiarize themselves with the organization and information contained in this Article, the
instructor should review the Section in its entirety. Insure they understand how to do
calculations for MH for sizing feeder assemblies. Discuss example D11 in Annex D.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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MOBILE HOMES AND MOBILE HOME PARKS
ARTICLE 550
LEVEL I
WORKSHEET
1. The power supply to a mobile home shall be a feeder assembly of:
a.
b.
c.
d.
Not less than 250-amp listed mobile home cords
A permanently installed feeder with 3 insulated conductors
a or b
Neither a nor b
2. When supplied with a feeder assembly consisting of a cord and cap:
a.
b.
c.
d.
The cap shall be listed for damp locations
The cord shall not be more than 21 feet long
The cord and cap shall have a minimum rating of 60A
The point of entrance may be in the roof
3. The mobile home disconnecting means shall:
a.
b.
c.
d.
Contain not more than 6 disconnects
Be located in the mobile home
Have provisions to accommodate accessory buildings
Not be mounted closer than 4 feet above finish grade or platform
4. Grounding of electrical and non-electrical metal parts shall be by means of:
a. Grounding the neutral bus in the distribution panel to made
electrodes: as per 250.83
b. Bonding the neutral bus to the ground bus and grounding either bus in
the distribution panel to "made electrodes: as per 250.83
c. Either a or b
d. Neither a nor b
5. Where a laundry area is provided, a branch circuit of what ampere rating shall be
provided?
a.
b.
c.
d.
15 ampere
20 ampere
30 ampere
not required
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6. In other than mobile home parks, secondary electrical distribution to the mobile
home lots may be:
a.120/208 V, 3 wire, derived from a 120/208, 34, 4 wire service
b. 120/240V, 34-4 wire taped from an auto transformer of 600 volts or less
c. 120/240/ 1 Phase, 3 wire
d. b or c
7. Mobile home service equipment may be located:
a. On the mobile home not more than 18 inches above grade
b. Up to 30 feet from the mobile home in a conspicuous location
c. Adjacent to and within 30 feet of the mobile home in a non-conspicuous
location
d. At the point of entrance of the feeder cable to the mobile home
8. Where outdoor or under-chassis line-voltage (120 volts, nominal, or higher)
wiring is exposed to moisture or physical damage, it shall be protected by any
of the following with the exception of which of the following?
a. rigid metal conduit.
b. intermediate metal conduit.
c. type MI cable, electrical metallic tubing, or rigid nonmetallic conduit
shall be permitted where closely routed against frames and equipment
enclosures.
d. EMT raceways.
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MOBILE HOMES AND MOBILE HOME PARKS
ARTICLE 550
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
d, Neither a nor b
d, The point of entrance may be in the roof
b, Be located in the mobile home
d, Neither a nor b
b, 20 ampere
c, 120/240/ 1 Phase, 3W
b,
d, EMT raceways
550.10(A)
550.10(F)
550.11(A)
550.16
550.12(C)
550.4(B)
550.32(A)
550.15(H)
ARTICLE 550 EXAMPLE
A mobile home floor is 70 feet x 10 feet and has two small appliance circuits, a 100volt-ampere, 240-volt heater, 120-volt exhaust fan, 120-volt dishwasher, and a 7000volt-ampere electric range.
LIGHTING AND SMALL APPLIANCE LOAD
Lighting 70 x 10 x 3 x VA/sq. ft.
=
2100 volt-amperes
Small appliance 1500 x 2
=
3000 volt-amperes
Laundry 1500 x 1
=
1500 volt-amperes
6600 volt-amperes
1st 3000 volt-amperes at 100%
Remainder (6600-3000) at 35%
4260 volt-amperes =
240 volts
=
=
3000 volt-amperes
1260 volt-amperes
4260 volt-amperes
17.75 amperes per leg
Lighting and Appliances
Heater, 100 VA/240 Volt =
Fan, 200 VA x 125%/120 Volt =
Dishwasher, 400 VA/120 Volt =
Range, 7,000 VA x .8/240 Volts =
Totals:
AMPERES PER LEG
A
B
17.75
17.75
4.2
4.2
2.08
3.3
23.3
23.3
47.33
48.55
Based on the higher circuit calculated for either leg, a minimum 50-ampere supply cord is
required.
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RECREATIONAL VEHICLES AND RECREATIONAL VEHICLE PARKS
ARTICLE 551
LEVEL I
OBJECTIVE:
After this lesson each student should be familiar with the requirements of the
wiring and equipment used in recreational vehicle parks.
MATERIALS NEEDED:
Information from dealers
INTRODUCTION:
Recreational vehicles are those used for temporary living for things such as
camping. These include motor homes, travel trailers, and truck campers. To get a
better idea of certain definitions in this Section, have students spend a few minutes
looking over the definitions in 551.2.
PRESENTING THE LESSON:
RV's are factory wired and due to their mobile nature are not available for
inspecting by AHJ therefore much of the material in part A need not be covered
in detail.
Have student look over definitions for recreational vehicle parks. (551.2)(A) All
125-volt, single-phase, 15- and 20-ampere receptacles shall have listed ground-fault
circuit-interrupter protection for personnel. A minimum of 70% of the sites shall be
equipped with a 30 amp 125 volt outlet with configuration per 550.15(C). All 125volt, single-phase, 15- and 20-ampere receptacles shall have listed ground-fault
circuit-interrupter protection for personnel. (551.71)
Calculations per site shall be based on the following:
Sites with both 20 and 30 amp supply, 3600 volts amps per site.
Sites with only 20 amps supply, 2400 volt amps per site.
The demand factors in Table 551.73 shall be applied for figuring the service and
feeders. Where park services exceed 240 volts the secondary panelboards shall be
treated as services. Site feeders shall be large enough for the load but not less
than 30 amps. [551.73(d)]
Where provided on back-in sites, the recreational vehicle site electrical supply
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equipment shall be located on the left (road) side of the parked vehicle, on a line
that is 1.5 m to 2.1 m (5 ft to 7 ft) from the left edge (driver’s side of the parked
RV) of the stand and shall be located at any point on this line from the rear of the
stand to 4.5 m (15 ft) forward of the rear of the stand. [551.77(A)]
Equipment grounding shall be based on Table 250.122. Neutral shall not be used
for grounding on a recreational vehicle or vehicle site. (551.54)
Overhead open conductors shall have overhead vertical clearance of 18 feet and
horizontal clearance of 3 feet to all areas subject to recreational vehicle movement
(551.79). Underground conductors shall be protected from 18 inches below grade
up to termination . (551.80)
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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RECREATIONAL VEHICLES AND RECREATIONAL PARKS
ARTICLE 551
LEVEL I
WORKSHEET
1.
The demand factor on 50 recreational vehicle sites to be applied to the
total load is which of the following?
a
b
c
d
2.
47%
45%
40%
41%
In an RV Park, what percentage of all sites with electric supply must be
equipped with 30 ampere, 125 V receptacles?
a
b
c
d
3.
.
.
.
.
.
.
.
.
25%
50%
70%
100%
All 125-volt, single phase, 15 and 20 ampere receptacles provided for the
RV site are required to have which of the following?
a.
b.
c.
d.
4.
GFCI protection for personnel.
Arc-fault circuit protection for personnel.
Arc-flash protection for personnel.
Grounding switches for personnel.
Where outdoor or under-chassis wiring is 120 volts, nominal, or over
and is exposed to moisture or physical damage, the wiring shall be
protected by rigid metal conduit, by intermediate metal conduit, or by
electrical metallic tubing, rigid nonmetallic conduit, - OR which of
the following type of cable, that is closely routed against frames and
equipment enclosures or other raceway or cable identified for the
application?
a.
b.
c.
d.
Type MI
Type NM
Type UF
Type NMC
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RECREATIONAL VEHICLES AND RECREATIONAL PARKS
ARTICLE 551
LEVEL I
ANSWER KEY
1.
2.
3.
4.
d,
c, a, a, -
Table 551.73
551.71
551.71
551.47 (G)
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PARK TRAILERS
ARTICLE 552
LEVEL I
OBJECTIVE:
After this lesson the students should be familiar with the requirement of park
trailers.
INTRODUCTION:
Cover general rules for installations in article 552.
PRESENTING THE LESSON:
Discuss the scope and definitions in sections 552.1 and 552.2.
Cover requirements for power supply and feeders in sections 552.43 and 552.44(A).
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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PARK TRAILERS
ARTICLE 552
LEVEL I
WORKSHEET
1.
The cord-exposed usable length shall be measured from the point of entrance to
the park trailer or the face of the flanged surface inlet (motor-base attachment
plug) to the face of the attachment plug at the supply end. What is the maximum
length of the power supply cord?
a.
b.
c.
d.
2.
23 feet
28 feet
40 feet
36.5 feet
Dual-Voltage fixtures including luminaires or appliances having both 120-volt
and low-voltage connections shall be listed for dual voltage. Which of the
following shall not be used to supply the voltage?
I.
II.
a.
b.
c.
d.
3.
I only
II only
Both I and II
Neither I or II
Feeder supply cords shall have a minimum ampere rating of which of the
following?
a.
b.
c.
d.
4.
Autotransformer
Voltage Converter
50 amperes
100 amperes
60 amperes
30 amperes
Each 125-volt, single-phase, 15- or 20-ampere receptacle shall have groundfault circuit-interrupter protection for personnel in which of the following
locations?
a. Where the receptacles are installed to serve kitchen countertop
surfaces
b. Receptacles installed within 5 ft. of a metal water pipe.
c. Receptacles serving dining room circuits
d. Receptacles for interior holiday lighting.
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PARK TRAILERS
ARTICLE 552
LEVEL I
ANSWER KEY
1.
2.
3.
4.
d. 36.5 feet
a. I only
d. 30 amp.
a.
552.44(B)
552.20 (E)
552.43 (A)
552.41 (C)(1)
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FLOATING BUILDINGS
ARTICLE 553
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar with the
requirements of floating buildings.
INTRODUCTION:
The general rules and requirements for installations are covered by Article 553.
PRESENTING THE LESSON:
Cover scope and definition of section 553.1 and 553.2.
Discuss the location of service equipment in section 553.4.
Discuss the installation of services and feeders in section 553.7.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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FLOATING BUILDINGS
ARTICLE 553
LEVEL I
WORKSHEET
1.
The service to a floating building shall be located?
a.
b.
c.
d.
2.
on the floating building
adjacent to but not in or on the floating building or structure.
both a and b
neither a nor b
Which of the following wiring methods shall not be used as a feeder when
flexibility is required?
a.
b.
c.
d.
liquidtight flexible metal conduit
liquidtight flexible nonmetal conduit
liquidtight nonmetallic conduit
extra-hard usage portable power cable
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FLOATING BUILDINGS
ARTICLE 553
LEVEL I
ANSWER KEY
1.
b, -.
2.
c, -
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553.4
553.7(A & B)
308
MARINAS AND BOATYARDS
ARTICLE 555
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar with the general
requirements of electrical installation in Marinas and Boatyards.
INTRODUCTION:
The number of installations covered by Article 555 is increasing rapidly and the
importance of proper understanding and application of these safety regulations cannot
be over emphasized. There have been a number of electrocutions on such installations
in North Carolina that could have been avoided provided applicable safety requirements
had been incorporated in the original installation. Maintenance of these installations is
also a very important part of the "safety package."
Many of the recreational facilities covered in the scope of Article 555 will be found
in locations where corrosion is a very difficult problem. Samples of outdoor
equipment which has been designed and listed for such use will be helpful when
evaluating proper application of the necessary components.
PRESENTING THE LESSON:
The scope and application of other Articles in Section 555.1 and 555.2 need to be
reviewed with the students.
The requirements in Section 555.19 cover receptacles which are divided into two classes
of use; (1) Those which provide shore power to the boats and (2) Those which are for use
in maintenance and other purposes. The safety requirements for each are different and
consequently must be thoroughly understood.
Permitted wiring methods are given in Section 555.13 and should be thoroughly
discussed.
A great deal of emphasis should be placed on covering the grounding requirements
included in Section 555.15. Applicable requirements in Article 250 should also be
reviewed.
Wiring over and under navigable water is subject to the approval of governmental
agencies, such as the Coast Guard and Army Corps of Engineers.
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The requirements included in Sections 555.21 pertain to Gasoline Dispensing and should
be reviewed carefully.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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MARINAS AND BOATYARDS
ARTICLE 555
LEVEL I
WORKSHEET
1.
Shore power for boats shall be provided by single receptacles rated not less
than which of the following?
a.
b.
c.
d.
15 amperes
30 amperes
40 amperes
50 amperes
2. Disconnecting means shall be provided to isolate each boat from its supply
connection(s). The disconnecting means shall be readily accessible and mounted
not more than which of the following from the receptacle it controls?
a.
b.
c.
d.
Not greater than 6’7” above the deck surface
24 inches
Not less than 12 inches above the deck surface
30 inches
3. Twenty shore power receptacles rated 20 amperes and 120 volts will be supplied
from one panel. The minimum ampacity for the 120/240 volt feeder is which of
the following?
a.
b.
c.
d.
70 amperes
140 amperes
200 amperes
280 amperes
4. When grounding metal boxes and cabinets at a marina which of the following is the
minimum size and type of equipment grounding conductor permitted?
a.
b.
c.
d.
#12 insulated copper
# 12 insulated aluminum
# 12 insulated conductor
# 12 bare copper
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5.
All electrical connections shall be located at least 12 inches above the deck of
a floating pier. All electrical connections shall be located above the electrical
datum plane and at least what height above the deck of a fixed pier?
a.
b.
c.
d.
6.
30 inches
24 inches
36 inches
12 inches
Electrical wiring and equipment located at facilities for the repair of marine
craft containing flammable or combustible liquids or gases shall comply with
which of the following in addition to the requirements of this article?
a.
b.
c.
d.
Article 511
NFPA 110
The Local fuel distributor’s regulations.
NFPA 101
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MARINAS AND BOATYARDS
ARTICLES 555
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
b. 30 ampere
d. 30 inches
a. 140 amps;
20 x 20 = 400 x 70% = 280 amps
280 amps x 120 volts = 33,600 VA
33,600 VA / 240 volt = 140 amps
c. #12 insulated conductor
d. 12 inches
a. Article 511
555.19(A)(4)
555.17(B)
555.12 and Table 555.12
555.15(C)
555.9
555.22
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TEMPORARY INSTALLATIONS
ARTICLE 590
LEVEL I
OBJECTIVE:
After completing this lesson, each student should understand the purpose of
temporary wiring, when and where it is permitted, and the difference between
temporary and permanent wiring.
INTRODUCTION:
The contents of this lesson will deal with temporary electrical power and lighting wiring
methods which may be of a class less than would be required for a permanent
installation.
PRESENTING THE LESSON:
Time periods in which temporary wiring may be used include: (1) during the period of
construction, (2) 90 days for certain temporary wiring, (3) emergencies and tests, and (4)
during the removal of temporary wiring.
Discuss Section 590.3 in detail.
Highlight the prohibition within Section 590.4 against installing directly on the
floor or ground those cable assemblies and flexible cords used as temporary
branch circuits or feeders; note the exception for extension cords.
Discuss Section 590.6 concerning ground-fault protection for personnel.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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TEMPORARY INSTALLATIONS
ARTICLE 590
LEVEL I
WORKSHEET
1.
Temporary electrical power and lighting installations shall be permitted for a
period not to exceed which of the following for holiday decorative lighting and
similar purposes?
a.
b.
c.
d.
2.
Whatever is set by the AHJ.
120 days
30 days
90 days
Conductors shall be permitted within cable assemblies or within multiconductor
cords or cables used in temporary installations shall be of a type identified for
which of the following?
a.
b.
c.
d.
Hard usage or extra-hard usage.
Junior hard usage.
RHSJO
USE
3. Receptacles on construction sites shall not be on branch circuits which supply
which of the following?
a.
b.
c.
d.
4.
Temporary branch circuits.
Temporary heat or ventilation.
Temporary battery charging units.
Temporary lighting.
Under which of the following conditions can vegetation be used for support
of branch circuit conductors or cables for holiday lighting?
I.
II.
a.
b.
c.
d.
The use of proper strain-relief devices.
The use of tension take-up devices.
I only
II only
Both I and II
Neither I or II
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TEMPORARY INSTALLATIONS
ARTICLE 590
LEVEL I
ANSWER KEY
1.
2.
3.
4.
d. 90 days
a. hard usage or extra hard usage
d. temporary lighting
c. both I and II
590.3(B)
590.4(C)
590.4(D)
590.4(J) Exception
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ELECTRIC SIGNS AND OUTLINE LIGHTING
ARTICLE 600
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar with the special
wiring requirements of electric signs and outline lighting.
MATERIALS NEEDED:
Pictures of electric signs.
INTRODUCTION:
Cover appropriate definitions from article 100.
(1) Electric sign: a fixed, stationary, or portable self-contained, electrically
illuminated utilization equipment with words or symbols designed to convey
information or attract attention.
(2) Electric-discharge Lighting: systems of illumination utilizing fluorescent
lamps, high-intensity discharge (HID) lamps, or neon tubing.
(3) Outline lighting: an arrangement of incandescent lamps, electric discharge
tubing or other electrically powered light sources to outline or call attention to
certain features such as the shape of a building or the decoration of a window.
This lesson covers special wiring needed for special types of equipment.
Remember that Chapter 6 supplements or modify the general rules. Chapters 1
through 4 apply except as amended by Chapter 6 for the particular conditions.
This lesson is concerned with 1000 volts and less.
PRESENTING THE LESSON:
Article 600 covers the installation of conductors and equipment for electrical signs
and outline lighting.
Discuss definitions of; neon-tubing; section sign; sign body; skeleton tubing
(600.2).
Signs, unless approved by special permission, must be listed, provided with
installation instructions and installed according to that listing (600.3).
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Each commercial building and each commercial occupancy accessible to pedestrians
shall be provided at an accessible location outside the entrance to each occupancy with
at least one outlet for sign or outline lighting use. This outlet shall be supplied by a
branch circuit which supplies no other loads.
The branch circuit must be rated at least 20 amperes. Circuits that supply neon tubing
shall not be rated in excess 30 amps. Circuits that supply all other signs and outline
lighting shall not exceed 20 amps. (600.5)
Wiring methods used to supply signs and outline lighting shall terminate within a sign or
system enclosure. Signs and transformer enclosures shall be permitted as pull or junction
boxes to supply adjacent signs or outline lighting system. Metal poles used to support
signs shall be permitted to enclose conductors provided poles and conductors are
installed per 410.30(B).
Each outline lighting installation and each sign shall be controlled by an externally
operable switch or circuit breaker that will open all ungrounded conductors. Emphasize
that this disconnecting means shall be located at the point where the feeder circuit or
branch circuit(s) supplying a sign or outline lighting enters a sign enclosure or pole and
must disconnect all wiring. (600.6)
Switches, flashers, and similar devices controlling transformers shall either be rated for
controlling inductive loads or have an ampere rating not less than twice the ampere
rating of the transformer. AC general use snap switches shall be permitted to be used on
AC circuits to control inductive loads not exceeding the ampere and voltage rating of
the switch. [600.6(B)] (See 404.14)
Metal equipment of signs, outline lighting, and skeleton tubing must be grounded. Listed
flexible metal conduit or listed liquidtight flexible metal conduit that encloses secondary
conductors of a transformer or power supply for use with neon tubing shall be permitted
as the bonding means if the total length does not exceed 100 feet. Where flexible
nonmetallic conduit or tubing is used a bonding conductor is required and shall meet the
following: (1) be spaced at least 1-1/2 inches from the conduit when the circuit is
operated at < 100 Hz or 1-3/4 inches if > 100 Hz (2) installed separate from the flexible
non-metallic conduit (3) Copper not smaller than #14 and protected from physical
damage if installed external to sign or raceway. (600.7)
Enclosures shall have ample strength and rigidity made of metal or be listed. The
minimum thickness for sheet copper or aluminum shall be 0.020 inches and 0.016 inches
for sheet steel. Metal parts must be protected against corrosion. (600.8)
A sign or outline lighting system shall be located at least 14’ above areas accessible to
vehicles unless protected from physical damage. Neon tubing readily accessible to
pedestrians shall be protected from physical damage. Adjacent combustible materials
shall not be subject to temperatures in excess of 90 degrees Celsius. The spacing between
wood and other combustible material in incandescent or HID lamp or lamp holder shall
not be less than 2”. [600.9]
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Sign and outline lighting systems in wet location shall be weather proof and have a drain
hole in the low point or isolated section no larger than 1/2 “ or smaller than 1/4” and be
positioned so there can be no external obstructions. [600.9(D)]
Portable or mobile signs shall be adequately supported and readily removable without
tools. Attachment plugs shall be provided for each sign. In wet or damp locations cords
shall be for hard service or hard service types and have an equipment grounding
conductor. The cord shall be one designated in table 400-4. The cord shall not exceed
15’. [600.10(D)]
Ballasts, transformers, electronic power supplies and Class 2 power sources shall be
securely fastened in place as near to the lamps or neon tubing as practicable. If in a wet
location then they must be weather proof or be listed for outdoor use. A work space of
3’ high 3’ wide and 3’ deep shall be provided at each ballast, transformer, electronic
power supply and Class 2 power source where not installed in a sign. Ballasts,
transformers, electronic power supplies and Class 2 power sources shall be permitted in
attic spaces where there is an access door and passageway to the ballast of at least 3’ X
2’ and a 12” suitable permanent walkway extending from the point of entry. Ballasts,
transformers, electronic power supplies and Class 2 power sources in suspended ceiling
are not to be supported by ceiling grid and are not connected to the branch circuit by
flexible cord. (600.21)
Ballast shall be listed for use. Transformers and electronic power supplies shall have
secondary ground-fault protection except for (1) transformers with isolated ungrounded
secondaries and maximum open circuit voltage < 7500 volts (2) transformers with
integral porcelain or glass secondary housing for neon tubing requiring no field wiring.
Secondary voltage shall not exceed 15,000 volts and the voltage to ground of any output
terminal shall not exceed 7500 volts. The secondary current rating shall have a
secondary current rating of not more than 300 milliamperes. Secondary circuits shall not
be connected in paralleled or in series. (600.23)
Neon secondary circuit conductors, 1000 volts or less shall use wiring in chapter
3. Conductors shall be insulated not smaller than # 18. The number of conductors in
a raceway shall be in accordance with Table 1 of Chapter 9. (600.31)
Neon secondary conductors over 1000 volts must be installed per 600.32(A). Conductors
shall be separated from each other and from other objects by spacing not less than 1 1/2”.
The insulation on all conductors shall extend beyond the conduit not less than 2 1/2”.
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Terminals of electrodes shall not be accessible to unqualified persons. The neon tubing
shall be supported not more than 6” from the electrode connection.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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ELECTRIC SIGNS AND OUTLINE LIGHTING
ARTICLE 600
LEVEL I
WORKSHEET
1. Which of the following statements about sign disconnects is correct?
I. Without exception each outline lighting installation and each sign shall
be controlled by a switch that is in sight of the sign.
II. If not rated for controlling inductive load(s) flashers controlling
transformers shall have an ampere rating not less than twice the ampere
rating of the transformer.
a.
b.
c.
d.
2.
I only
Both I and II
II only
Neither I or II
All of the following are true of wiring methods for outdoor electric signs
EXCEPT for which of the following?
a. The wiring method shall terminate within the sign or in a suitable
enclosure.
b. Signs shall not be permitted to be used as pull or junction boxes when
they contain both branch and secondary circuit conductors, which
supply the light.
c. Metal poles that support the sign may be permitted to enclose supply
conductors.
d. Wiring methods for electric signs and outline lighting must comply
with 600.5 (C) 1, (C) 2, and (C) 3 and Article 410.30(B).
3.
Which of the following statement is correct regarding outdoor signs?
I. Each commercial building shall be provided at an accessible location outside
the occupancy with at least one outlet for sign and or outlet lighting use.
II. The required sign outlet for commercial buildings and commercial occupancy
shall be supplied by a 20 ampere branch circuit, which supplies no other load.
a.
b.
c.
d.
Both I and II
I only
II only
Neither I or II
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4. Which of the following statements about branch circuits for signs or outline
lighting is correct?
I. Circuits which supply other than neon tubing installations shall be rated
not to exceed 20 amperes.
II.Circuits supplying neon tubing installations shall not be rated in excess
of 30 amperes.
a.I
b.
Both I and II
c . II only
d.
Neither I or II
5.
Signs and outline lighting systems shall be marked with the manufacturer’s
name, trademark, or other means of identification as well as which of the
following?
a.
b.
c.
d.
6.
A section sign is a sign or outline lighting system is which of the following?
a.
b.
c.
d.
7.
Input voltage and current rating.
Ampacity and Hertz.
Resistance and Cycles per Second.
Point of purchase.
A sign that is engineered in the field.
A sign that is assembled by sheet metal craftsmen in the field.
A sign that operates at 50 volts or less.
A sign that is shipped as sub-assemblies and requires field installed
wiring between the sub-assemblies to complete the overall sign.
Which of the following statements about sign enclosures is correct?
I. Minimum thickness for sheet copper shall be NO. 26 MSG if ribbed,
corrugated, or embossed.
II. Minimum thickness for sheet steel is .028 inch.
a.
b.
c.
d.
I only
II only
Both I and II
Neither I or II
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8.
Signs and outline lighting system equipment for wet location use, other than
listed watertight type, shall be weatherproof and have drain holes, as
necessary, in accordance with the following EXCEPT?
a. Drain holes shall not be larger than 1⁄2 inch or smaller than 1⁄4 inch.
b. Every low point or isolated section of the equipment shall have at least
one drain hole.
c. Drain holes shall be positioned such that there will be no external
obstructions.
d. Drain holes shall be placed no more than 6” apart.
9.
Portable or mobile signs shall have a factory installed ground-fault interrupter
as an integral part of the attachment plug, or shall be located in the power-supply
cord within what distance of the attachment plug.
a.
b.
c.
d.
5 inches
5 feet
12 feet
12 inches
10.
Secondary circuit conductors 1000 volts or less shall be listed, insulated, and not
smaller than.
a.
b.
c.
d.
18 AWG
16 AWG
14 AWG
12 AWG
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ELECTRIC SIGNS AND OUTLINE LIGHTING
ARTICLE 600
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
c. II only
b.
c. II only
b. Both I and II
a. Input voltage and current rating
d
d.
d.
c, 12 inches
a. 18 AWG
600.6(B)
600.5(C)(2)
600.5(A)
600.5(B)(1 & 2)
600.4a
600.2
600.8(C)
600.9(D)
600.10(C)(2)
600.31(B)
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OFFICE FURNISHINGS
ARTICLE 605
LEVEL I
OBJECTIVE:
After completing this lesson each student should be familiar with the
requirements related to office furnishings including lighting accessories and wired
partitions.
MATERIALS NEEDED:
Handouts or pictures showing office partitions and of wiring methods used in
connecting partitions.
PRESENTING THE LESSON:
It is important that the scope included in Section 605.1 be understood. Sections
605.2 through 605.4 covers general wiring methods, conductor and permitted
materials for the wiring system and their interconnection.
Section 605.2 has a new definition: Office furnishings. Emphasis needs to be given for
the new definition. Section 605.5 covers the types of Office furnishing interconnections
and the use of flexible cords. Section 605.6 covers the lighting equipment permitted for
the partition and requires such to be listed. Note that receptacles in fixtures are not
permitted.
Sections 605.7 through 605.8 covers the different types of partitions and the
permitted methods of providing power to the same.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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OFFICE FURNISHINGS
ARTICLE 605
LEVEL I
WORKSHEET
1. Under which of the following circumstances does the N.C. Electrical
Code allow relocatable wired partitions to extend from floor to
ceiling?
a.
b.
c.
d.
Where permitted by the manufacturer of the panels.
Where permitted by the appropriate referenced standard.
Where permitted by express request in writing.
Where permitted by the authority having jurisdiction
(AHJ).
2. Which of the following is not allowed in lighting equipment
accessories for cord and plug connected wired partitions?
I.
II.
a.
b.
c.
d.
Convenience receptacles.
18 AWG wiring.
I only
II only
Both I and II
Neither I nor II
3.
Individual office furnishings of the freestanding type, or groups of
office furnishings that are electrically connected, are mechanically
contiguous, and do not exceed 30 feet when assembled, shall be permitted
to be connected to the building electrical system by which of the
following?
a.
b.
c.
d.
A single flexible cord and plug.
A multi-wire branch circuit.
A non-metallic sheathed cable assembly.
A flexible cord with # 14 AWG conductors.
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4. Which of the following is not correct of partition
interconnections for office furnishings?
a. The cord is extra-hard usage type 14 AWG or larger
conductors, with an insulated grounding conductor.
b. The partitions are mechanically contiguous.
c. The cord is not longer than necessary for maximum
positioning of the partitions but is in no case to exceed
2 feet.
d. The cord is terminated at an attachment plug and cord
connector with strain relief.
5. Multiwire branch circuits supplying power to permanently connected
freestanding partitions shall be provided with a means to disconnect
simultaneously all ungrounded conductors at which of the following
locations?
a.
b.
c.
d.
Shall not contain multiwire circuits.
The panelboard where the branch circuit originates.
The main distribution panelboard.
The first means of disconnect for the sub-fed panel.
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OFFICE FURNISHINGS
ARTICLE 605
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
d. 605.2 Exception
a. I only
a. a single flexible cord and plug
a
a. Not permitted
605.2
605.5(C)
605.8 605.9
605.4 605.5
605.9 (D)
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328
SWIMMING POOLS, FOUNTAINS, AND SIMILAR INSTALLATIONS
ARTICLE 680
LEVEL I
OBJECTIVES:
After completing this lesson each student should be familiar with:
1.
2.
the requirements that apply to the construction and installation of electric
wiring for various types of pools and fountains.
the specific wiring requirements for auxiliary equipment such as pumps
and filters.
INTRODUCTION:
In this Article, the term "pool" includes: swimming, wading, and permanently installed
therapeutic pools. "Fountains" refer to fountains, ornamental pools, reflection pools, and
display pools. Those sections covered in this lesson plan are the most important for a
level one class.
PRESENTING THE LESSON:
Review definitions in Section 680.2. Make sure the students have a good idea of the
terms in this Section.
Discuss section 680.5 on ground – fault circuit – interrupters.
Review the requirement on grounding in section 680.6.
Many restrictions exist on the location of overhead conductors. Note these
requirements and their exceptions. See Section 680.8 for underground wiring
locations.
Study carefully the requirements for underwater lighting fixtures installed below the
normal water level of the pool. Explain the wiring methods and materials for Wet-Niche,
Dry-Niche, and No-Niche fixtures. (680.23)
Review the requirements for junction boxes and enclosures for transformers or
ground fault circuit interrupters in Section 680.24.
Explain the bonding requirements for all pool associated equipment. Also cover the
minimum size and type of bonding conductors required in Section 680.26.
Briefly discuss storable pools. (680.30)
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Cover Section IV in detail because indoor installations of spas and hot tubs are
very popular areas of wiring.
Briefly discuss the rest of this Article and have the class read it. The use of
handouts and materials may be very helpful in this Article.
APPLICATION:
If time will allow, let the class answer the questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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SWIMMING POOLS, FOUNTAINS, AND SIMILAR INSTALLATIONS
ARTICLE 680
LEVEL I
WORKSHEET
1.
A permanently installed bathtub equipped with a re-circulating piping system,
pump, and associated equipment. It is designed so it can accept, circulate, and
discharge water upon each use is which of the following?
a.
b.
c.
d.
A fountain.
A packaged spa.
A therapeutic tub.
A hydromassage tub.
2. A permanently installed swimming pool shall no fewer than one 125 volt, 15-or
20-ampere receptacle on a general-purpose branch circuit shall be located at
what distance from the inside wall of the pool?
a.
b.
c.
d.
not less than 5 feet, not more than 20 feet
not less than 5 feet, not more than 10 feet
not less than 6 feet, not more than 20 feet
not less than 6 feet, not more than 10 feet
3. Lighting fixtures are permitted to be installed no less than which of the following
above the maximum water level of an outdoor pool?
a.
b.
c.
d.
5 feet
10 feet
15 feet
12 feet
4. Underground wiring is to be used to supply a lighting standard located 20 feet
from a swimming pool. What is the minimum horizontal clearance required
from the inside wall of the pool for this direct burial cable?
a.
b.
c.
d.
5 feet
10 feet
15 feet
20 feet
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5.
Unless listed and identified otherwise, an underwater lighting fixture installed in a
side wall of a pool shall be located a minimum of which of the following below
the normal water line?
a.
b.
c.
d.
2 feet
2 feet 6 inches
1 foot 6 inches
3 feet
6. A conductor used to connect two pieces of metal pool equipment is required to be
sized a minimum of # 8. This conductor is which of the following?
a.
b.
c.
d.
An equipment grounding conductor
A bonding conductor
A grounding electrode conductor.
A grounding conductor.
7. The minimum size of an equipment grounding conductor permitted to ground a wet
niche lighting fixture is:
a.
b.
c.
d.
# 12 insulated copper conductor
# 12 bare copper conductor
# 14 insulated copper conductor
# 14 insulated copper conductor
8. A panelboard at a swimming pool not part of the service equipment shall have an
equipment grounding conductor installed between its grounding terminal and the
grounding terminal of the service equipment, sized according to Table 250-95, but
not smaller than which of the following?
a.
b.
c.
d.
9.
# 6 copper conductor
# 8 copper conductor
# 10 copper conductor
# 12 copper conductor
Receptacles located indoors where a spa or hot tub is installed shall be at least
which of the following distance from the inside walls of the spa or hot tub?
a.
b.
c.
d.
20 feet
15 feet
6 feet
10 feet
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10. Lighting fixtures or lighting outlets that are located near a spa or hot tub located
inside and within five feet from the inside walls of the spa or hot tub and
protected by a ground-fault circuit-interrupter shall be what minimum height
above the maximum water level?
a. 8 feet
b. 7 feet 6 inches
c. 10 feet
d. not allowed
11. Each maintenance disconnecting means for pool equipment shall be
which of the following?
a.
b.
c.
d.
readily accessible
located at least 5 ft from wall of pool unless separated by barrier
either a or b
both a and b
12. Any wiring method for a pool associated pump motor shall include an
equipment grounding conductor which is?
a.
b.
c.
d.
insulated
not smaller than a # 14
uninsulated
directly connected to a grounding electrode
13. Where reinforcing steel of the pool shell is encapsulated with a nonconductive
compound, which of the following statements describes the required grid?
a. a minimum #8 solid copper conductor following the contour of the
pool
b. be arranged in 12 in. by 12 in. grid pattern
c. be secured within or under the pool no more than 6 in. from the pool
shell
d. all of the above
14. All 15- or 20-ampere, single-phase 125-volt through 250-volt receptacles located
within which of the following distances of a fountain edge shall be provided with GFCI
protection.
a.
b.
c.
d.
2 feet
4 feet
10 feet
20 feet
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15. Which of the following statements is true concerning outlets supplying pool pump
motors?
a. cord and plug connected motors shall be GFCI protected
b. direct connected motor shall not require GFCI protection
c. both cord and plug as well as direct connected motors shall have GFCI
protection
d. GFCI protection is not required for residential pools
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SWIMMING POOLS, FOUNTAINS, AND SIMILAR INSTALLATIONS
ARTICLE 680
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
d. hydromassage tubs
c. not less than 6 feet, not more than 20 feet
d. 12 feet
a. 5 feet
c. (18 inches) 1 foot 6 inches
b, a bonding conductor
a. #12 insulated copper conductor
d. # 12 copper conductor
c. 6 feet
b. 7 feet and 6 inches
d. both a and b
a. insulated
d. all of the above
d. 20
c. both cord and plug as well as direct connected
680.2
680.22(A)(1)
680.22(B)(1)
680.10
680.23(A)(5)
680.26(B)
680.23(F)(2)
680.25(B)(1)
680.43(A)(1)
680.43(B)(1)(b)
680.12
680.21
680.26(B) (1)(a)
680.58
680.22(A)(2)(3)
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SOLAR PHOTOVOLTAIC SYSTEMS
ARTICLE 690
LEVEL I
OBJECTIVE:
At the conclusion of this lesson each student should know about alternate sources of
power to power companies and some of the rules in installing these types of systems.
MATERIALS NEEDED:
Pictures from a local source of certain types of solar systems. Wiring
schematics showing how this system generates power.
INTRODUCTION:
When talking about photovoltaic systems let us first look at what it means. The definition
is: The total components and subsystems which in combination convert solar energy into
electrical energy suitable for connection to a utilization load. This means this is electrical
power for a load or loads in either conjunction with a local utility or totally on its own. In
this Article we will cover regulations we need to be looking for in these types of
installations.
PRESENTING THE LESSON:
Have the students read the definitions then go over certain key definitions such as:
Panel, Module, Power Source, Source Circuit, and Solar Cell (690.2). Where other
articles differ from this Article, Article 690 shall apply. (690.3).
Explain 690.1.
Photovoltaic system conductors shall be kept separate from all other raceways, cable
trays, cables, boxes, and anything similar containing branch circuits of other systems. The
grounded conductor shall be so installed at the panel or module so as to assure that the
removal would not interrupt the circuit. [690.31(B)]
In DC circuits the voltage considered shall be the rated open-circuit voltage. Source and
output circuits which do not included lampholders, fixtures, or receptacles shall be
permitted up to 600 volts. If over 150 volts to ground at a single family or two family
dwelling the output and source circuits shall be inaccessible to other than qualified
persons while energized. [690.7 (A, C, & D)]
Ampacity of conductors and overcurrent devices shall be based on 125% of the
current ratings of source circuits, output circuits and conditioning unit output
circuits. [690.8(B)(1)]
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Circuits and equipment shall be protected according to Article 240. Power
transformers shall be protected according to Article 450. Overcurrent devices
shall be accessible but not required to be readily accessible. (690.9)
(D)Disconnecting shall means be provided to disconnect all conductors.
(690.13)
All equipment shall have disconnecting means. If equipment is energized from
more than one source all disconnects shall be grouped. (690.15)
Where fuses are separate from the disconnecting means a disconnect shall be
provided to disconnect the fuse, if energized from both directions and accessible
to other than qualified persons. Source circuit fuses shall be disconnected
separately from other circuit fuses. (690.16)
A switch or circuit breaker used as a disconnecting means shall:
1.
2.
3.
4.
Be located readily accessible
Be externally operable without exposing operator to live parts
Be indicating whether open or closed
Have ratings not less than the load served
When the DC circuit switch is designed so it cannot be opened under load the
disconnect can be lower than the load rating. (690.17) Means shall be provided to
disable an array or portions of an array. (690.18)
Connectors intended to be concealed shall be listed and meet the following:
(690.33)
a. Must be polarized and not interchangeable with receptacles of other circuits b
Guarded against accidental contact
c. Be latching or locking type
d. Grounding contact must be the first to make contact and the last to break
contact
e. Must be capable of interrupting circuit without hazard to operator
For a photovoltaic power source, one conductor of a 2-wire system rated over 50
volts and a neutral conductor of a 3-wire system shall be solidly grounded.
(690.41) The DC circuit shall be grounded at any point on the output circuit.
(690.42)
Where the power source short-circuit current is less than twice the current rating of
the overcurrent device or where overcurrent devices are not required according to
690.9(A) the grounding conductor shall be no smaller than the circuit conductors.
All others to be sized according to 250.134. (690.43)
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All metal parts of equipment and conductor enclosures shall be bonded to the DC
circuit grounding electrode. Where more than one electrode is installed and they
are all bonded together it shall meet this requirement. (690.47)
Modules shall be marked with (1) open-circuit voltage, (2) operative voltage, (3)
maximum voltage, (4) operating current, (5) short circuit current, and (6)
maximum power. (690.51)
Power source must be marked with (1) operating current, (2) operating voltage,
(3) open-circuit voltage, (4) short-circuit current. (690.53)
If a power-conditioning unit is interactive with other systems it shall
automatically disconnect the ungrounded conductors in such other systems upon
loss of voltage and shall not be reconnected until voltage is restored. (690.61)
The maximum load connected between the neutral and any one ungrounded
conductor of single-phase or 3 phase circuits shall not exceed the ampacity of the
neutral conductor. (690.63)
Output of single-phase power conditioning units must not be derived from a deltaconnected transformer. Three phase power conditioning units shall automatically
disconnect all conductors when any one is lost. [605.64]
Output power productive source shall be permitted to be connected as follows:
(705.12)
1. On the supply side of service disconnecting means
2. On the load side of service disconnecting means if the following conditions are
met:
a. Each source interconnection shall be made as a dedicated circuit
b. Ampere rating of overcurrent devices shall not exceed rating of busbar.
(Can go up to 120% in a dwelling.)
c. Line side of GFI
d. Equipment containing overcurrent devices supplying power to busbars
shall be marked to indicate the presence of all sources.
Storage batteries must meet requirements of Article 480. If used in dwelling units
must operate at less than 50 volts, and be insulated to guard against accidental
contact. [690.71(B)(1)(2)]
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results.
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SOLAR PHOTOVOLTAIC SYSTEMS
ARTICLE 690
LEVEL I
WORKSHEET
1. Live parts of DC output circuits connected at a single family
dwelling rated at which of the following shall be accessible
only to qualified persons?
a.
b.
c.
d.
2.
Under 150 volts ground
Over 150 volts ground
Over 150 volts line to line
Under 150 volts line to line
A switch or circuit breaker used as a disconnect shall:
a.
b.
c.
d.
Be located readily accessible
Accessible to qualified persons
Not required to be accessible
Located as to owner specifications
3. Wiring systems shall be permitted to be:
a.
b.
c.
d.
Rigid metal conduit
NM cable
AC cable
Any of the above
4.
Lead-acid storage batteries for dwellings shall have no more
than which of the following number of 2-volt cells connected in series
(48-volts nominal).
a.
b.
c.
d.
12
16
20
24
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5.
Where the removal of equipment disconnects between the
bonding connection between the grounding electrode conductor
and exposed conducting surfaces in the photovoltaic source or
output circuit equipment which of the following is required?
a. A bonding jumper shall be installed while the equipment is removed.
b. The area must be roped off in a manner that no one may enter.
c. The power company must be notified.
d. A sign must be placed in this area specifying exactly what has been
done and how long the jumper will not be in place.
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SOLAR PHOTOVOLTAIC SYSTEMS
ARTICLE 690
LEVEL I
ANSWER KEY
1.
2.
3.
4.
5.
b, Over 150 volts ground
a, Be located readily accessible
d, Any of the above
d, 24
a, a bonding jumper shall be installed.
690.7(D)
690.13 (A)
690.31
690.71(B)(1)
690.48
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ARTICLE 702
OPTIONAL STANDBY SYSTEMS
ARTICLE 702
LEVEL I
OBJECTIVE:
To inform the student that the provisions of this article apply to the installation
and operation of optional standby systems.
The systems covered by this article consist of those that are permanently installed
in their entirety, including prime movers, and those that are arranged for a
connection to a premises wiring system from a portable alternate power supply.
MATERIALS NEEDED:
Provide an example of an Optional Standby Generator (Photo, slide or overhead if
available)
INTRODUCTION:
Inform the student that this system is intended to supply power to public or
private facilities or property where life safety does not depend on the performance
of the system. Optional standby systems are intended to supply on-site generated
power to selected loads either automatically or manually. This system is often
used when situations occur that make it necessary for owners to perform
equipment maintenance or when breakdowns occur or when there is an extended
power outage. In such instances, a portable generator can be brought to a facility
and connected to the existing distribution system. The supervision by qualified
personnel is critical to ensuring that a dangerous backfeed condition is not created
by connecting the generator to the system without the benefit of transfer
equipment.
PRESENTING THE LESSON:
Explain that optional standby systems are typically installed to provide an
alternate source of electric power for such facilities as industrial and commercial
buildings, farms, and residences and to serve loads such as heating and
refrigeration systems, data processing and communications systems, and
industrial processes that, when stopped during any power outage, could cause
discomfort, serious interruption of the process, damage to the product or process,
or the like.
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APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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OPTIONAL STANDBY SYSTEMS
ARTICLE 702
WORKSHEET
LEVEL I
1. Where manual transfer equipment is used with adequate capacity and rating for
all of the equipment to be operated at one time, the user of the optional standby
system shall be permitted to do which of the following?
a.
b.
c.
d.
2.
Select the load connected to the system.
Select the connection point to the system.
Select the grounded conductor location.
Select the optional fusing connection.
Audible and visual signal devices shall be provided, where practicable, for which
of the following purposes?
I. To indicate that the optional standby system is carrying load.
II. To indicate the derangement of the optional standby source.
a.
b.
c.
d.
3.
I o nl y
II only
Neither I or II
Both I and II
Where a portable optional standby source is used as a nonseparately derived
system, the equipment grounding conductor shall be bonded to which of the
following?
a.
b.
c.
d.
A grounded conductor
The grounding electrode conductor
The earth
The system grounding electrode
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OPTIONAL STANDBY SYSTEMS
ARTICLE 702
LEVEL I
ANSWER KEY
1.
a, Select the load connected to the system
702.4(B) (1)
2.
d, Both I and II
702.6 (1) and (2)
3.
d, The system grounding electrode
702.11(B)
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INTERCONNECTED ELECTRIC POWER PRODUCTION SOURCES
ARTICLE 705
LEVEL I
OBJECTIVE:
Each student should be acquainted with the requirements for interconnected electric power
production sources and their installation(s).
INTRODUCTION:
This article applies to interconnected electric power production sources. This article covers
the installation of one or more electric power production sources operating in parallel.
PRESENTING THE LESSON:
Cover the definitions outlined in 705.2. Explain in detail that other articles; such as 445
Generators, 690 Solar Photovoltaic (PV) Systems, and 692 Fuel Cell Systems, apply to the
use of this article.
Cover in detail 705.12 Point of connection, inverters and overcurrent.
705.20 through 705.22 for disconnecting means of sources and equipment and their
prospective locations.
705.30 Overcurrent protection of solar photovoltaic systems, transformers, fuel cell
systems, utility-interactive inverters, and generators.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheets and discuss the results. Ensure the students
understand Article 705.
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INTERCONNECTED ELECTRIC POWER PRODUCTION SOURCES
ARTICLE 705
LEVEL I
WORK SHEET
1. The output of a generator or other electric power production source operating in
parallel with an electrical supply system shall be compatible with the;
a. voltage
c. frequency
b. wave shape
d. all the above
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INTERCONNECTED ELECTRIC POWER PRODUCTION
SOURCES
ARTICLE 705
LEVEL I
ANSWER SHEET
1. d, all the above
705.14
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COMMUNICATION CIRCUITS
ARTICLE 800
LEVEL I
OBJECTIVE:
This article covers voice, audio, video, data, interactive services, telephone, telegraph
(except radio), outside wiring for fire alarm and burglar alarm, and similar central station
systems; and telephone systems not connected to a central station system but using similar
types of equipment, methods of installation, and maintenance. Cover Article 810 for
Radio and Television Equipment, Article 820 for Community Antenna Television and
Radio Distribution Systems, and Article 830 for Network-Powered Broadband
Communications Systems.
MATERIALS NEEDED:
Provide examples of communications cables, (CATV, telephone wire, RG-8, etc.),
pictures and or plans of towers, and communications wiring diagrams.
INTRODUCTION:
When talking about communications systems, let us first look at what it means. The
definition is: The electronic equipment that performs the telecommunications operations
for the transmission of audio, video, and data, and includes power equipment (e.g., dc
converters, inverters and batteries) and technical support equipment (e.g., computers).
PRESENTING THE LESSON:
Have the students read the definitions then go over certain key definitions such as:
Abandoned Communications Cable, Cable, Point of Entrance, Premises, and Wire. Cover
articles 800.100, 800.154 (including the tables), and additional Sections in
communications such as article 810, article 820, and article 830. Be sure to cover in detail
the bonding and grounding of communication systems.
APPLICATION:
If time will allow, let the class answer questions on the worksheet.
CHECKING AND FOLLOW-UP:
If time will allow, correct the worksheet and discuss the results.
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COMMUNICATIONS CIRCUITS
ARTICLE 800
LEVEL I
WORKSHEETS
1.
Communication circuit cables installed in ducts, plenums and other spaces
used for environmental air can be which of the following?
a.
b.
c.
d.
2.
A bonding jumper not smaller than which of the following (or equivalent) shall
be connected between the communications grounding electrode and power
grounding electrode system at the building or structure served where separate
electrodes are used?
a.
b.
c.
d.
3.
#
#
#
#
4
3
8
6
AWG
AWG
AWG
AWG
Where practicable, a separation of at least which of the following shall be
maintained between communications wires and cables on buildings and
lightning conductors?
a.
b.
c.
d.
4.
C MP
CMR
C MG
CMX
10 feet
8 feet
5 feet
6 feet
Cable and primary protector grounding conductors shall be insulated
and shall be listed as suitable for the purpose. The grounding conductor shall
be copper or other corrosion-resistant conductive material, stranded or solid
and the grounding conductor shall not be smaller than which of the
following?
a.
b.
c.
d.
#
#
#
#
14 AWG.
6 AWG.
4 AWG
8 AWG
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5. Communications wires and cables from the protector to the equipment or,
where no protector is required, communications wires and cables attached
to the outside or inside of the building shall be permitted in the same raceway or
enclosure with cables of any of the following except?
a. Class 2 and Class 3 remote-control, signaling, and power-limited
circuits.
b. Power-limited fire alarm systems.
c. Nonconductive and conductive optical fiber cables.
d. High-power network-powered broadband communications circuits.
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COMMUNICATIONS CIRCUITS
ARTICLE 800
LEVEL I
ANSWER SHEET
1.
2.
3.
4.
5.
a, CMP
d, # 6 AWG
d, 6 feet
a, # 14 AWG
d, High-power network is not listed
800.154 (a)
800.100(D)
800.53
800.100(A)(3)
800.133(A)(1)(a)(b)
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