Wiring Methods and Materials

Wiring Methods and Materials
Conductors
are substances or materials

used to convey or allow the
flow of electric current
Conductors shall be insulated
Conductors
Wires
o are those electrical conductors

8mm2 (AWG No. 8) and smaller
in sizes.
Cables
o are those larger than wires
Wires and Cables are either:

o Stranded Wire
o Solid Wire
Conductors
Stranded Wires
oconsist of a group of wires twisted to

form a metallic
string
o the circular mil area of a stranded
wire is found by multiplying the
circular mil area of each strand by the
total number of the strand
Mil- the word mil is equal to
1/1000 of an inch was used to
describe or measure a round wire
diameter
conductors of size 8mm2 and larger shall
be stranded
Different Types of Cables

o Armored Cable: Type AC
is a fabricated assembly of insulated
conductors enclosed in flexible metal
sheath.
used on
oBoth exposed and concealed work
oCable trays
oDry locations
oEmbedded in plaster finish on brick or
other masonry, except in damp or wet
locations
o run or fished in the air voids of masonry
block or tile walls where such walls are not
exposed to excessive moisture or
dampness.

oFlat Conductor Cable: Type FCC
consist of three or more flat copper
conductor placed edge to edge separated
and enclosed within an insulating
assembly
used in
o Branch circuits
o hard smooth continuous floor surfaces

o Integrated Gas Spacer Cable: Type IGS
A factory of one or more conductors, each
individually insulated and enclosed in a loose fit, nonmetallic flexible conduit as an integrated gas spacer
cable rated through 0 to 600V.
Use in
o Service entrance conductors
o Feeder or branch circuit conductor

o Metal-Clad
Cable: Type MC
A factory assembly of one or more

insulated circuit conductors with or without
optical fiber members enclosed in an armor of
interlocking metal tape , or a smooth or
corrugated metallic sheath.
used for
o services, feeders, and branch circuits
o power, lighting control, and signal circuits
oIndoors or outdoors
oExposed or concealed
o any raceway
o as aerial cable on a messenger
o in hazardous locations as permitted

o Medium Voltage Cable: Type MV
A single or multi-conductor solid dielectric insulated
cable rated 2001V or higher.
used in
o wet or dry locations
o Raceways
o In messenger supported wiring

oMineral Insulated Cable: Type MI
Is a factory assembly of one or more
conductors insulated with a highly
compressed refractory mineral insulation
enclosed in a liquid and gas tight
continuous copper sheath.
used in
o dry, wet, or continuously moist location
o As service feeders or branch circuits

oNon-metallic Sheathed Cable: Type NM
is also a factory assembly of two or

more insulated conductors having
moisture resistant, flame retardant,
and non-metallic material outer
sheath.
Used for
o one or two family dwellings not exceeding 3 storey
buildings

oShielded Non-metallic Sheathed Cable: Type SNM
This type of cable is a factory assembly of two or more
insulated conductors in an extruded core of moisture resistant
and flame retardant material covered within an overlapping
spiral metal tape.
used in
o hazardous locations
o Cable trays
o raceways

o Underground Feeder and Branch Circuit Cable: Type
(UF)
Is a moisture resistant cable used for underground connections including direct burial in
the ground as feeder or branch circuit.
o Service Entrance Cables: Type SE and USE

A single or multi-conductor assembly provided with or
without an overall covering primarily used for service
wire.
Table 3.10.1.5 Minimum Size of Conductors

Minimum Conductor Size mm2 (mm dia.)
Conductor
Voltage Rating
(Volts)
0-2000
2001-8000
8001-15000
15001-28000
28001-35000
Copper
2.0(1.6)
8.0(3.2)
30
38
50
Aluminum ore
Copper- Clad
Aluminum
3.5(2.0)
8.0(3.2)
30
38
50
Insulated Conductors and Cables

oLocations
Dry and Damp Locations
FEP
RHW
THHW
XHH
FEPB RHW-2
THHW-2 XHHW-2
MTW SA
THWN
Z
PFA
THHN
THWN-2 ZW
RHH
THW-2
TW

oLocations
Wet Locations
- Moisture impervious metal-sheated
- types MTW, RHW, RHW-2, TW,THW, THW2, THHW, THHW-2,
THWN, THWN-2,
XHHW, XHHW-2, ZW
- Of a type listed for use in wet locations

oLocations
Exposed to Direct Sunlight
- sunlight resistant cables
- sunlight resistant conductors
- covered with insulating materials such as tape
or sleeving, that is
listed, or listed or marked as
being sunlight resistant.
Conductors of the same circuit

shall be contained in the same:
o raceway
oAuxiliary gutter
oCable tray
ocable bus assembly
oTrench
o cable or cord
Marking
All conductors
and Cables shall be marked to indicate the

following information:
oThe maximum rated voltage
oThe proper type letter or letters for the type of wire or cable
oThe manufacturers name, trademark, or other distinctive
marking by which the organization responsible for the
product can be readily identified
oThe size in millimeter square or millimeter diameter
oCable assemblies where the neutral conductor is smaller than
the ungrounded shall be so marked.
Protection Against Corrosion and

Deterioration
oRaceways
ocable trays
oCable bus
oauxiliary gutters
ocable armor
oBoxes
o
o
o
o
o
o
o
Cabinets
Elbows
Couplings
Fittings
Support
Support hardware
Cable sheathing
Shall be materials suitable for the environment in which they are

to be installed.

Deterioration
oFerrous Metal Equipment
shall be protected by a coating of
corrosion resistant material.
listed
EXEPTION:
stainless steel shall not be required to have
protective coatings
Protection Against Corrosion and Deterioration

oProtected from Corrosion Solely by Enamel
shall not be used outdoors or in wet locations
oOrganic Coatings on Boxes or Cabinets

marked with Raintight, Rainproof,
Type shall be permitted outdoors
or Outdoor

Deterioration
o Non-Ferrous Metal Equipment
shall be provided with supplementary

protection.
o Nonmetallic Equipment
Exposed to Sunlight
shall be listed as sunlight resistant
Chemical Exposure
shall either be inherently resistant to
chemicals
corrosion
Protection Against Corrosion and Deterioration

oIndoor Wet Locations
the entire wiring system, where installed exposed, including
all boxes fittings, raceways, and cable used therewith shall be
mounted so that there is at least a 6 mm airspace between it and
the wall or
supporting surface
Raceways
-------are channels or wiring accessories so
designed for holding
wires, cables, or
busbars that are either made of metal,
plastic, or any insulating mediums.
Common Types of Raceways
o Conduits
o Connectors and Other Accessories
Other Types of Raceways

oConduit coupling, elbows, and other fittings
oConduit supports, such as clamps, hanger, etc.
oCable trays, cable bus, etc.
oMetal Raceways
oNonmetal Raceways and other
Raceways To a Different Temperatures

oSealing
shall be filled with an approved material to prevent the circulation of

warm air to a colder section of the raceway or sleeve
An explosion proof seal shall not be required for this purpose.
Raceways To a Different Temperatures

oExpansion Fittings
Raceways shall be provided with expansion
fittings where necessary to compensate for thermal
expansion and contraction .
Raceway Installations
oComplete Runs
exposed raceways having hinged or removable
covers, shall be installed complete between
outlet,
Junction
Splicing points
Prior to the installation of conductors
Raceway Installations
oWelding
Metal Raceways shall not be
supported,
terminated, or
connected by welding
to
the raceway unless specifically designed to be
or otherwise permitted to be in this code.
Installations of Conductors with Other

Systems
oRaceways
or cable trays containing electric
conductors shall not contain any pipe, tube, or equal
for steam, water, air, gas, drainage, or any other
services other than electrical.
Induced currents in Metal Enclosures or Metal

Raceways
oConductors Grouped Together
--to avoid heating the surrounding
metal by induction
oIndividual Conductors
inductive effect shall be minimized by
cutting slots in the metal between the individual
holes through which the individual conductors
pass
Passing all conductors in a circuit through an
insulating wall sufficiently large for all the
conductors of the circuit.
Underground Installations
oMinimum Cover Requirements
shall meet the minimum cover
of
table 3.0.1.5
requirements
table 3.0.1.5 Minimum Cover Requirements, 0 to 600V,

Nominal, Burial in Millimeters
LEGEND
Column 1- Direct Burial Cables or Conductors
Column 2- Rigid Metal Conduit or Intermediate Metal Conduit
Column 3- Nonmetallic Raceways Listed for Direct Burial w/o
Concrete Encasement or other Approved Raceways
Column 4- Residential Branch Circuits Rated 230 Volts or Less
with GFCI Protection and Maximum Overcurrent Protection
of 20 Amperes
Column 5- Circuits for Control of Irrigation and Landscape
Lighting Limited to not more than 30 Volts and Installed w/
Type UF or in other Identified Cable or Raceway
TYPES OF WIRING METHODS OR CIRCUIT

Location of Wiring Method or
Circuit
Column 1
Column 2
Column 3
Column 4
Column 5
All Locations not

specified below
600
150
450
300
150
In trench below 50mm

thick concrete or
equivalent
450
150
300
150
150
Under a building
0 (In
0 (In
0 (In
raceway
only)
raceway
only)
150
150
raceway
only)
Under minimum of 100

mm thick concrete
exterior slab with no
vehicular traffic and the
slab extending not less
than 150 mm beyond the
underground installation
450
100
100
(direct
burial)
100
(In
raceway)
TYPES OF WIRING METHODS OR CIRCUIT

Location of Wiring Method or Circuit
Column 1
Column 2
Column 3
Column 4
Column 5
Under streets, highways,

roads, alleys, driveways,
and parking lots
600
600
600
600
600
One and two family

dwelling driveway and
outdoor parking areas, and
used only for dwelling
related purposes
450
450
450
300
450
In or under airport runways,

including adjacent areas
where trespassing
prohibited
450
450
450
450
450
oListing
Cables and Insulated Conductors installed in
enclosures or raceways shall be listed for use in wet
locations.
o Underground Cables
Under Buildings
shall be in raceway that is extended

outside walls of the building.
beyond the
oConductors Entering Buildings
shall be protected to the point of entrance
oService Conductors
shall have their location identified by a warning
ribbon that is placed in the trench at least 300mm above
the underground
installation
Enclosure or Raceway Damage

shall be installed in rigid metal conduit,
intermediate metal conduit, thick wall rigid
nonmetallic conduit or equivalent
o Splices and Taps

Direct-buried conductors or cable shall be
permitted to be spliced or tapped without
the
use of splice boxes.
oBackfill
that contains large rocks, paving materials, cinders,
large or sharply angular substances, or corrosive material
shall not be placed in an
excavation
where
materials may damage raceways,
cables,
or
other substructures.
oRaceway Seals
Conduits or Raceways through which
moisture
may contact live parts shall be sealed or plugged at either
or both ends.
oBushing
shall be used at the end of the conduit
o Conductors of the Same Circuit
shall be installed in the same raceway
oGround Movement
shall be arranged to prevent damage to the
enclosed conductors or to the equipment connected to
the raceways.
SCOPE
Construction
Specification
USE
Installation
Article 3.32- Mineral- Insulated, Metal

Sheated Cable: Type MI
Mineral- Insulated, Metal Sheated Cable: Type MI
-A factory assembly of one or more conductors
insulated with a highly compressed refractory mineral
insulation and enclosed in a liquid tight and gas tight
copper or alloy steel sheath.

Uses Permitted
services, feeders, branch circuits
power, lighting, control and signal
circuits
dry or wet location
Indoors and outdoors
exposed to oils, and gasoline
In or attached to cable tray

Uses not Permitted
In underground runs
Where exposed to conditions that are
destructive and corrosive to the metallic
sheath .
Bending Radius
5 times the external diameter of metallic
sheath for cable not more than 19mm

3.32.2.1 Securing and Supporting
Staples
straps,
hangers or similar fittings

3.32.3 Construction Specification
Conductors
Copper
Nickel
Nickel coated copper
Equipment Grounding
copper, shall provide an adequate path for grounding
steel, an equipment grounding conductor shall provided

Insulation
Sh all be highly compressed refractory
mineral
Sheath
shall be continuous construction
Article 3.34- Non Metallic- Sheathed

Cable: Types NM,NMC, and NMS
Non metallic- Sheathed Cable
-A factory assembly of two or more
insulated conductors enclosed within an
overall nonmetallic jacket.
Type NM
-Insulated conductors enclosed within an
overall non metallic jacket
Article 3.34- Non Metallic- Sheathed Cable:

Types NM,NMC, and NMS
3.34.1.2 Definitions
3. Type NMC
-Insulated conductors enclosed within an overall,
corrosion resistant, non metallic jacket
4. Type NMS
-Insulated power or control conductors within signaling
and communications conductors within an overall
nonmetallic jacket.

3.34.2 Installation
Uses Permitted
Type NM, NMC,NMS
-dry locations
-Air voids in masonry block or tile walls
Uses Not Permitted
Types NM and NMS
-corrosive fumes
Embedded masonry, concrete, adobe, fill, plaster
excessive moisture or dampness

3.34.2 Installation
Ampacity
60C (140F) conductor temperature rating

Construction
Outer cable sheath should be nonmetallic material
Conductors
2.0 mm square (1.6 mm dia.)

-3.5 mmthrough 30 mm^2 copper conductors
or sizes

Equipment Grounding
-insulated or bare conductor
Insulation
The overall covering shall be flame retardant
and moisture resistant
Article 3.36
Power and Control Tray Cable : Type
TC
Power and Control Tray Cable, type

TC
-a factory assembly of two or more
insulated conductors,with or without
associated bare or covered grounding
conductors, under a nonmetallic jacket.
Uses Permitted
Power ,lighting, control and signal circuits

Cable Trays, raceways, outdoor locations
industrial establishments and in wet locations
Article 3.36 Power and Control Tray

Cable : Type TC
3.36.2 Installation
Uses not Permitted
exposed to physical damage
installed outside a raceway or cable tray

system
exposed to direct rays of the sun, unless
identified as sunlight resistant
Direct buried, unless identified for such use
Article 3.36 Power and Control Tray

Cable : Type TC
Bending Radius
Four times the overall diameter for cables 25 mm or

less in diameter
3.36.3.1 Construction Specification

Construction
A metallic sheath or armor
Conductors
shall be sizes 0.75 mm^2 through 500 mm^2 copper
3.5 mm^2 through 500 mm^2 aluminum and copper-clad
aluminum
Article 3.36 Service Entrance

Cable:type SE and Use
3.38.1.1 Definition
Service Entrance Cable
- A single conductors or multi
conductor assembly provided with or
without an overall covering an overall
covering, primarily used for services
and of the following types
Type SE
Service entrance cable having a flame
retardant, moisture-resistant covered

Cable:type SE and Use
Type USE
-Service entrance cable,
identified for underground use,
having a moisture resistant
covering but not required to a
flame retardant covering

Cable:Type SE and Use
3.36.2 Installation
Uses Permitted
Service entrance conductors
Branch circuits or feeders
-
Grounded Conductor Insulated

Grounded Conductor Not Insulated
Temperature Limitations
Construction
cabled single conductor, type USE construction
recognized for underground use shall permitted to have a
bare copper conductor cabled with the assembly.
Article 3.40- Underground Feeder and

Branch Circuit Cable: Type UF
3.40.2 Definition
Underground Feeder and branch Circuit Cable,
Type UF
- a factory assembly of one or more insulated conductors with
integral or an overall covering of non metallic material
suitable for direct burial on the earth.

3.40.2 Installation
Uses Permitted
use underground
single conductor cables
For wiring in wet, dry or corrosive locations
For solar photovoltaic locations
As single conductor cables
Supported by cable trays

3.40.2 Installation
Uses not Permitted
As service entrance cable
In commercial garage
In theaters and similar location
In storage battery rooms
Hoistways, elevator, escalators
Hazardous locations
Ampacity
60C (140F) conductors

3.40.3.1 Conductors
2.0 mm^2 copper

3.5 mm^2 copper clad aluminum
Sheath
flame retardant; moisture, fungus, and
corrosion resistant
Insulation
moisture-resistant types
the conductor insulation shall be rated 90C
(194F).
Article 3.42
Intermediate Metal Conduit : Type IMC
Intermediate Metal Conduit : Type
IMC
- A steel threadable raceway of circular
cross section designed for physical
protection and routing of conductors and
cables and for use as an equipment
grounding conductor when installed with
its integral couplings
Article 3.42
Intermediate Metal Conduit : Type IMC
Uses Permitted
All atmospheric Conditions and
Occupancies
Corrosion Environments
Cinder fill
Wet locations
Dissimilar metals
Size
Minimum-IMC 15 mm
Maximum- IMC larger than raceway size
100 mm shall not be used
Article 3.44- Rigid Metal Conduit:

Type RMC
Rigid Metal Conduit: Type RMC

- a threadable raceway of circular
cross section designed for the
physical protection and routing of
conductors and cables and for use as
an equipment grounding conductor
-made of steel with protective
coatings or aluminum.

Type RMC
3.44.2 Installation
Uses Permitted
All atmospheric Condition and
Occupancies
Corrosion
Wet location
Size
Minimum- RMC smaller than15mm
shall not be used
Maximum- RMC smaller than
raceway size 150 mm shall not be
used.

Type RMC
Reaming and Threading
All cut ends shall be reamed or
otherwise finished to remove
rough edges. Where conduit is
threaded in the field, a standard
cutting die with a taper of 1 in 16
( in. taper per foot) shall be used.
Article 3.48- Flexible Metal Conduit :

Type FMC
Flexible Metal Conduit (FMC)
-a raceway of circular cross section
made of helically wound, formed,
Uses Permitted
to used in exposed and concealed
location
Article 3.48- Flexible Metal Conduit : Type

FMC
3.48.2 Installation
Uses not Permitted
In wet locations
Hoistways, storage battery room
hazardous location
Where exposed to materials having
a deteriorating effect on the
installed conductors, such as oil and
gasoline
Where subject to physical damage
Article 3.50- Liquid Tight Flexible

Metal Conduit: Type FMC
Article 3.50- Liquid Tight Flexible

Metal Conduit: Type LFMC
Liquid tight flexible Metal
Conduit: Type LFMC
- a raceway of circular cross
section having an outer liquid
tight, nonmetallic sunlight
resistant jacket over an inner
flexible metal core with
associated couplings, connectors
and fittings for the insullation of
electric conductors.
Article 3.50- Liquid tight flexible Metal

Conduit: Type LFMC
Uses Permitted
Where conditions of installation,

operation and maintenance require
flexibility or protection from liquids,
vapors or solids
For direct burial
Uses not permitted

subject to physical damage
Article 3.50- Liquid tight flexible

Metal Conduit: Type LFMC
3.50.2 Installation
Size
Minimum- LFMC smaller than 15 mm electrical
raceway should not be used
Maximum- the maximum size of LFMC shall be 100
mm electrical raceway size

Marking- conduit suitable for direct burial shall be
so marked.
Article 3.52- Rigid Non metallic

Conduit: Type RNC
Rigid Non metallic Conduit: Type RNC
-A non metallic raceway of circular cross section,
with integral or associated couplings, connectors
and fittings for the installation of electrical
conductors and cables.
Article 3.52- Rigid Non metallic Conduit:

Type RNC
3.52.2 Installation
Uses Permitted:
Concealed
Corrosive influence
Cinders
wet location
dry and damp location
exposed underground installation

conduit: Type RNC
3.52.2 Installation
Uses not permitted
Hazardous locations
Support of luminaires
Physical damage
Ambient temperature
Insulation temperature Limitation
Theaters and Similar Locations

conduit: Type RNC
3.52.2 Installation
Size
Minimum RNC smaller than raceway size 15 mm
shall not be used
Maximum RNC larger than raceway size 150 mm
shall not be used
Article 3.52- Rigid Non metallic conduit:

Type RNC
Supports
Conduit Raceway Size (mm)
Maximum Spacing Between Supports

(mm)
15-25
900
32-50
1500
65-80
1800
90-125
2100
150
2400

conduit: Type RNC
RNC and fittings shall be composed of suitable non
metallic material that is resistant to moisture and
chemical atmosphere
Flame retardant to impact and crushing
Each length of RNC shall be clearly
and durably
mark 3000 mm
Article 3.53 High Density Polyethylene

Conduit: Type HDPE Conduit
High Density Polyethylene
-A non metallic raceway of
circular cross section, with associated
couplings, connectors, and fittings for
the installation of electrical conductors
Article 3.53 High Density

Polyethylene Conduit: Type HDPE
Conduit3.53.2 Installation
Uses
Permitted
In discrete lengths from reels
In location subject to severe
corrosive influence
In cinder fill
In direct burial installation on earth
or concrete
Article 3.53 High Density Polyethylene

3.53.2 Installation
Uses not permitted
Where exposed
Within a building
In hazardous location
Where subject to ambient temperature
Article 3.53
High Density Polyethylene Conduit:
Type HDPE Conduit
3.53.2 Installation
Size
Minimum- HDPE conduit smaller
than raceway 15 mm shall not be
used
Maximum- HPDE conduit larger
than raceway size 100 mm shall not
be used.
Article 3.54- Non metallic underground

conduit conductors: Type NUCC
Non metallic underground conduit
conductors: Type NUCC
-A factory assembly
of conductors or cables inside a

nonmetallic, smooth wall conduit with a circular
cross section.
Article 3.54- Non metallic

Underground conduit conductors:
Type NUCC
3.54.2 Installation
Uses Permitted:
For direct burial underground installation
Encased or embedded in concrete
In cinder fill
In underground locations subject to severe corrosive
influence

3.54.2 Installation
Uses Not permitted:

In exposed location
Inside Buildings
Bends
-shall be manually made so that the conduit will not
damage

1. General- NUCC is an assembly that is provided in
continuous length, shipped in a coil, reel or carton
Article 3.56- Liquid tight flexible Non

metallic conduit: Type LFNC
Liquid tight flexible Non
-a smooth seamless inner core and
cover bonded together and having one
or more reinforcement layers.
-a smooth inner surface with integral
reinforcement within the
conduit wall, designated as Type
LFNC-B
Article 3.56-Liquid tight flexible Non

Uses permitted
Where flexibility is required for
installation, operation and
maintenance
Where protection of the contained
conductors is required from vapors,
liquids, solids
For outdoor location

Uses not permitted:
Where the operating voltage of the
contained conductors is in excess of
600 volts.
Size
Minimum: LFNC smaller than
raceway size 15 shall not be used
Maximum: larger than raceway size
100 mm shall not be used

Bends
Bends in conduit shall be so made that the conduit is not
damae and internal diameter of the conduit is not effectively
reduced
Construction
shall be provided in continuous length capable of being
shipped in a coil, reel, or carton without damage.
Marking
-shall be marked at least every 600 mm
Article 3.58
Electrical Metallic Tubing:Type EMT
Electrical Metallic Tubing (EMT)
- An unthreaded thin wall raceway of
circular cross section designed for he
physical protection and routing of
conductors and cables and for use as
an equipment grounding conductors
when installed utilizing appropriate
fittings.
Article 3.58
3.58.2 Installation
Uses Permitted
Exposed and concealed
Corrosion Protection
Wet Locatiions
Uses Not Permitted

Where during installation or afterward/ it
will subject to dammage
Where protected from corrosion solely by
enamel
Article 3.58
Size
Minimum-EMT smaller than raceway size
15mm shall not be used
Maximum-shall be raceway size 100mm
Construction
factory threaded integral couplings shall be
permitted, theads should be factory made
Marking
-EMT shall be clearly and durably marked at least
every 3000mm
Article 3.60
Flexible Metallic Tubing: Type FMT
Flexible Metallic Tubing (FMT)
- A raceway that is circular in cross section,
flexible, metallic and liquid tight without a
nonmetallic jacket.
Uses Permitted
In dry location
Where concealed
In accessible location
For system voltage of 1000 volts
maximum
Article 3.60
Flexible Metallic Tubing: Type FMT
Uses not permitted
In hoistways
Storage battery rooms
Hazardous location
Underground for direct earth burial
In lengths over 1800 mm
Size
Minimum-smaller than raceway size 15 mm
shall not be used
Maximum-shall be raceway size 20mm
Article 3.62
Electrical Non metallic Tubing:Type ENT
Electrical Non metallic Tubing: Type
ENT
-a non metallic or associated couplings,
connectors, annd fittings for the
installation of electric conductors.
Uses Permitted
In any building not exceeding above grade
as follows
For exposed work
Concealed within walls,floors, ceilings.
Article 3.62
Uses permitted
In location subject to corrosive influence and where subject
to chemicals.
In concealed dry and damp locations
Above suspended ceilings
Uses not permitted
Hazardous locations
For the support of luminaires and other equipment
Where subject to ambient temperature
For direct earth burial
Article 3.62
Uses not permitted
Where the voltage is over 600 volts
In theaters
Exposed to the direct rays of the sun
Size
Minimum
-ENT smaller than raceway size 15 mm shall not be used
Maximum
-ENT larger than raceway size 50mm shall not be used.
Article 3.62
Construction
-ENT shall be made of material that does not exceed the
ignitibility, flammability, smoke generation, and toxicity
characteristic of rigid polyvinyl chloride
Markings
-shall be clearly and durably marked at least every 3000 mm.
-The type of material shall also be included in the marking
-type, printed, quantity are identified by printed tag
Article 3.66-Auxiliary Gutters

3.66.1.2 Definition
Metallic Auxiliary Gutters
-Sheet metal enclosure with hinged or
removable covers for housing and protecting
electric wires, cable, and bus bars in which
conductors are laid in place after the wire
ways has been installed as a complete system.
Non Metallic Auxiliary Gutters
-flame retardant, nonmetallic enclosure with
removable covers for housing and protecting
electric wires, cables, and bus bars in which
conductors are laid in place after the wire way
has been installed as a complete system.

3.66.2 Installation
Uses Permitted
Sheet Metal Auxiliary Gutters
Non metallic Auxiliary Gutters
Uses not Permitted
To enclose switches over current devices, appliances or
other similar equipment.
To extend a greater distance than 9000mm beyond the
equipment that it suplements.

Construction
Electrical and mechanical Continuity
Substantial Construction
Smooth rounded edges
Covers
Clearance of Bare live parts

Markings
Outdoors
-Suitable for exposure to sunlight
-Suitable for use in wet locations
-Installed conductor insulation temperature rating
Indoors
Installed conductor insulation temperature rating
Article 3.68 -Busways

3.6.1.2 Definition
Busway
- a grounded metal enclosure containing factory mounted bare
or insulated conductors, which are usually copper, aluminum,
bars, rods, or tubes.
3.68.2 Installation
Uses permitted
1. Exposed
2. Concealed
3. Through walls and floors

Uses not Permitted
1. Physical damage
2. Hoistways
3. Hazardous locations
4. Wet locations
5. Working platform

3.68.3 Construction
Markings
-shall be marked with the
voltage and current rating and
with manufacturers name /
trademark visible after
installation
Article 3.70-Cable Bus

Cable Bus
-an assembly of insulated conductors
with fittings and condutor terminations
in a completely enclosd, ventilated
protective metal housing.
Use
-permitted at any voltage or current for
which spaced conductors are rated and
shall installed only for exposed work
Article 3.70-Cable Bus
Types of Conductors
insulation rating of 75C (167F) or higher
Size and Number of Conductors

The size and number of conductors shall be that for
which the cablebus is designed, and in no case smaller
than 50 mm^2
ARTICLE 3.72
CELLULAR CONCRETE
FLOOR RACEWAYS
3.72.1.2 Definitions
Cell
- A single, enclosed tubular space in a floor made of
precast cellular concrete slabs, the direction of the cell
being parallel to the direction of the floor member.
Header
- Transverse metal raceways for electric conductors,
providing access to predetermined cells of a precast
cellular concrete floor.
ARTICLE 3.72
CELLULAR CONCRETE
FLOOR RACEWAYS
Uses Not Permitted
Where subject to corrosive vapor
In any hazardous (classified) 5.1.2.1(b)(3)
In commercial garages, othe r than for supplying
ceiling outlets or extensions to the area below the floor
but not above
ARTICLE 3.74 CELLULAR

METAL
FLOOR RACEWAYS
Cellular Metal Floor Raceway

-The hollow spaces of cellular
metal floors, together with suitable fittings,
that may be approved as enclosures for
electric conductors.
Cell
- A single enclosed tubular space in a cellular
metal floor
member, the axis of the cell being parallel to
the axis of the metal floor member.
ARTICLE 3.74 CELLULAR

METAL
FLOOR RACEWAYS
Header
-A transverse raceway for electric conductors,
providing access to predetermined cells of a
cellular metal floor.
Uses Not Permitted
Where subject to corrosive vapor
In any hazardous (classified) location exc
ARTICLE 3.76 METAL WIREWAYS

3.76.1.2 Definition
Metal Wireways
- Sheet metal troughs with hinged or removable covers
for housing and protecting electric wires and cable and
in which conductors are laid in place af ter the wireway
has been installed as a complete system.
ARTICLE 3.78 NONMETALLIC

WIREWAYS
3.78.1.2 Definition
Nonmetallic Wireways
-Flame retardant, nonmetallic troughs
with removable covers for housing and
protecting electric wires and cables in
which conductors are laid in place
after the wireway has been installed as
a complete system.

EXTENSIONS
Nonmetallic Extension.
-An
assembly of two insulated conductors

within a (anonmetallic jacket or an
extruded thermoplastic covering.

Uses Permitted.
From an Existing Outlet
Exposed and in a Dry Location.
Residential or Offices

EXTENSIONS
Uses
Not Permitted
In unfinished basements, attics, or roof spaces

Where the voltage between conductors exceeds 150
volts for nonmetallic surface extension and 300 volts for
aerial cable
Where subject to corrosive vapors
Where run through a floor or partition, or outside the
room in which it originates
ARTICLE 3.84 STRUT-TYPE

CHANNEL RACEWAY
Strut-Type Channel Raceway
-A metallic
raceway that is intended to

be mounted to the surface of or
suspended from a structure, with
associated accessories for the
installation of electrical conductors
and cables.
ARTICLE 3.86 SURFACE METAL

RACEWAYS
3.86.1.2 Definition
Surface Metal Raceway

-A metallic
raceway that is intended to

be mounted to the surface of a
structure, with associated couplings,
connectors, boxes, and fittings for the
installation of electrical conductors.
ARTICLE 3.88 SURFACE

NONMETALLIC RACEWAYS
Surface Nonmetallic Raceway
-A nonmetallic raceway that is
intended to be mounted to the
surf ace of a structure, with
associated couplings,
connectors, boxes, and fittings
for the installation of electrical
conductors.
ARTICLE 3.90 UNDERFLOOR

RACEWAYS
Use Permitted
be permitted beneath the surface of
concrete or other flooring material or
in office occupancies where laid fl
ush with the concrete floor and
covered with linoleum or equivalent
floor covering.
ARTICLE 3.92 CABLE TRAYS

Cable Tray System
-A unit
or assembly of units or
sections and associated fittings
forming a structural system used
to securely fasten or support
cables and raceways.
ARTICLE 3.94 CONCEALED KNOBAND-TUBE WIRING

3.94.1.2. Definition
Concealed Knob-and-Tube
Wiring
-A wiring method using
knobs, tubes, and flexible
nonmetallic tubing for the
protection and support of
single insulated conductors.
ARTICLE 3.94 CONCEALED KNOBAND-TUBE WIRING

3.94.2 Installation
Uses Permitted
For extensions of existing
installations
Elsewhere by special permission
Uses Not Permitted.
Commercial garages
Theaters and similar locations
Motion picture studios
Hazardous (classified) locations
ARTICLE 3.96 MESSENGER

SUPPORTED WIRING
Messenger Supported Wiring

-An exposed wiring support system
using a messenger wire to support

insulated conductors by any one of the
following:
A messenger with rings and saddles
for conductor support
A messenger with a field-installed
lashing material for conductor support
Factory-assembled aerial cable
ARTICLE 398 OPEN WIRING ON

INSULATORS
3.98.1.2 Definition.
Open Wiring on
Insulators
-An exposed wiring method
using cleats, knobs, tubes,
and flexible tubing for the
protection and support of
single insulated conductors
run in or on buildings.
H
V
D
C
It is related to the tap changer control system.

It occurs on both rectifier and the inverter side of the transmission.
(TC cont) Designed to control the Load tap changers of the converter transformers.
Objective is to keep the
ordered alpha
gamma
DC voltage
- at the preset values determined by the Voltage and Angle Reference Calculation
(VARC).
Operate much slower than the basic control function, acting on control angle alpha
One tap changer step takes some seconds to execute.

Thus there is no risk for interference between the basic converter control function
and the tap changer control systems.
One step gives a change of 1-1.5% of rated value in the valve side voltage.
(TC @ Rec Sta) PURPOSE: to maintain the delay angle alpha in a certain range
If the alpha reduces below the predefined value, it starts to increase the voltage by
varying the number of turns in the primary side to keep the alpha in certain range
for fast controlling current
If alpha increased above a certain predefined maximum value then the tap changer
would decrease the voltage to keep the alpha within the limit.
The voltage in the rectifier end of the line can be controlled by adding a proportional
amount of the line voltage drop, Rd *Id to the measured inverter end voltage.
Normally used to keep the firing angle as close as possible to the rated value which
normally chosen to 15 degrees.
The control characteristics must include a dead band also here and step of 1.25%
from rated value corresponds to a region from 12 to
17.5 in .
Udio *cos a in the expression constant, at varying rectifier AC voltage,
the current control system responds to it by changing .
The (TCC) system in the rectifier compares an a response signal to
a reference value and at a significant deviation it orders the tap changer to step and
change Udio.
(TC @ Inv Sta) Tap changer control maintains the DC voltage equal to reference voltage.
Normally, gamma is kept as constant for proper commutation.
Any increase or decrease in the DC voltage will be controlled by tap changer
Since tap changers would take more time to control the converter voltage than current
or voltage controller, dynamic interaction between both controllers can be avoided.
The tap changers in the inverter in the extinction angle control are normally used to
control the voltage on the DC line.
The voltage response measured by a voltage divider is compared to an order, Udi0.
For a significant difference between the two signals, the tap changer control system
(TCC) orders increase or decrease of the valve side voltage.
Because of the stepwise character of the tap changer, the control than characteristic harmonics
system must be provided with dead band. To bring the voltage
back to the reference value and thus avoid hunting, the dead band These are due to:
should have a width of at least one tap changer step
1. Inbalance in the operation s)of two bridges
firing a 12 pulse converter (residual harmonics)
When the inverter takes over the current control, the DC voltage
tap
changer
control
must
be
locked
(generation of
2. firing angle errors
triplen and eve
Harmonics
harmonics and
3. unbalance and distortion of AC Voltages
their analysis is
Harmonics are electric voltages and currents that appear on the
4.unequal transformer leakage impedances
complex)
electric power system as a result of non-linear electric loads.
Harmonic instability may occur in high-voltage dc (HVDC) links
due to dynamic interactions between HVDC terminals and the
impedance of the dc lines or cables.
The harmonics that come from the HVDC will not only increase
loss, thermal stress of equipment, reduce equipment life,
interference with communications, metering, protection and
control devices to work properly and in some cases, it can even
lead to the collapse of the system.
Two types of harmonics in electrical power systems

1. current harmonics
2. voltage harmonics
Generation of Harmonics
1. harmonics-characteristic
2. non-characteristic
Characteristic Harmonics - harmonics of those order which are
always present even under ideal operation Non Characteristic Harmonics- the harmonics of the order other
The presence of harmonics leads to low system efficiency, poor

power factor, increased loss and reactive power components
from AC and also on the equipment present in the system and
interference on the telecommunication lines.
for reduction of harmonics, filters are used. Here we use a
hybrid configuration of both passive and active filters for
improved power handling capacity of semiconductor devices
and better performance.
The above circuit diagram consists of a three- phase generator shunt and series. But these filters also have hybrid configuration
source of 345Kv at frequency of 50Hz which is connected to the of passive filters to improve the power handling capacity of
converter transformer for stepping down voltage to 211KV for semiconductor devices.
transmission over long distance. Further a 12-pulse thyristor
bridge converter is connected, which is called as rectifier forharmonic analysis in a basic HVDC transmission system and the
converting AC to DC while the converter at the other end isimportance of using filters for the reduction of the harmonic
referred as inverter for vice-versa conversion. The rectifier-enddistortions in the system to improve the efficiency and reduce
has firing angle () control for ignition of the thyristor while thevarious ill effects due to the harmonics.
inverter-end contains the extinction/gamma control ().
On observing the various waveforms with and without the
insertion of filters, we may conclude that on connecting the
harmonic filters the voltage values is increased and optimized
while the high current values are reduced.
A. Three Phase Converter - The converter transformers are
constructed by three phase three winding on same core
material by connecting primary and secondary windings as
either wyes or deltas.
B. Pulse Generator - a discrete twelve pulse generator is used to
fire the thyristors of HVDC rectifier built with two six pulse
bridges. The four inputs of a pulse generator are alpha firing
angle (in degrees), other three inputs are phase to ground
synchronizing voltages. There are two outputs of a pulse
generator, one connected to wye secondary winding of
transformer and other connected to delta winding of secondary
transformer. Similarly for gamma angle control at the inverterside, a twelve-pulse firing control and discrete gamma
measurement subsystem is used for the two extinction/gamma
angle triggering for the inverter.
C. Filters - Both the ends have AC filters for reducing the
harmonic distortion in the AC-side of the system and DC filters
or smoothening reactors on the DC line for reducing the ripple
content in the current. The AC filters comprises of both passive
and active components for efficient performance and economy.
Generally the passive filters used are of damped (high-pass) and
tuned (single, double or triple) types while active filters are of

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Wiring Methods and Materials

are substances or materials

Conductors shall be insulated

o are those electrical conductors

Wires and Cables are either:

oconsist of a group of wires twisted to

Different Types of Cables

Different Types of Cables

Different Types of Cables

Different Types of Cables

A factory assembly of one or more

Different Types of Cables

Different Types of Cables

Different Types of Cables

is also a factory assembly of two or

Different Types of Cables

Different Types of Cables

o Service Entrance Cables: Type SE and USE

Table 3.10.1.5 Minimum Size of Conductors

Insulated Conductors and Cables

Insulated Conductors and Cables

Insulated Conductors and Cables

Conductors of the same circuit

and Cables shall be marked to indicate the

Protection Against Corrosion and

Shall be materials suitable for the environment in which they are

Protection Against Corrosion and

Protection Against Corrosion and Deterioration

oOrganic Coatings on Boxes or Cabinets

Protection Against Corrosion and

shall be provided with supplementary

Protection Against Corrosion and Deterioration

Other Types of Raceways

Raceways To a Different Temperatures

shall be filled with an approved material to prevent the circulation of

Raceways To a Different Temperatures

Prior to the installation of conductors

Installations of Conductors with Other

Induced currents in Metal Enclosures or Metal

table 3.0.1.5 Minimum Cover Requirements, 0 to 600V,

TYPES OF WIRING METHODS OR CIRCUIT

All Locations not

In trench below 50mm

Under minimum of 100

TYPES OF WIRING METHODS OR CIRCUIT

Under streets, highways,

One and two family

In or under airport runways,

shall be in raceway that is extended

Enclosure or Raceway Damage

o Splices and Taps

Article 3.32- Mineral- Insulated, Metal

Article 3.32- Mineral- Insulated, Metal

Article 3.32- Mineral- Insulated, Metal

Article 3.32- Mineral- Insulated, Metal

Article 3.32- Mineral- Insulated, Metal

Article 3.32- Mineral- Insulated, Metal

Article 3.34- Non Metallic- Sheathed

Article 3.34- Non Metallic- Sheathed Cable: