NEGROS ORIENTAL STATE UNIVERSITY
COLLEGE OF ENGINEERING AND ARCHITECTURE
BAJUMPANDAN, DUMAGUETE CITY
CE 332
ENGINEERING UTILITIES 1
ELECTRICAL MATERIALS IN BUILDING
CONSTRUCTION
BANCAIREN, MONA LYN T.
KUA, JOAN MAE QUEENZIE O.
MENDOZA, ANGEL MAE
ENGR. NIEL CADUNGOG
INSTRUCTOR
Electrical Materials used in Building
Construction
Objectives:

To know the different Electrical Materials used in building construction and their uses.
Discussion:
What are electrical materials?

Electrical materials are used for the electrical installations, in case of house wiring or
building wiring electrical materials are used. We can’t do the electrical installations
without using electrical materials.
What is the purpose of electrical materials?

The electrical materials have many purposes, they can be used to control the current flow
in an electric circuit. There are certain electrical materials like circuit breaker and fuses
which can be used to protect the electrical appliances and devices and it can prevent fire
hazards and damage. Electrical material such as insulators can prevent users from getting
electric shocks while operating electrical appliances or instruments. Electrical materials
such as current-carrying wires or conductors are used to transfer the current from source
to the load.
Electrical Supplies and Materials
1. CONVENIENCE OUTLET - is a device that acts as a convenient source
of electrical energy for current consuming appliances. It maybe single,
duplex, triplex or multiplex and could be surface type or flush type.
2. Male/AC Plug - a device inserted to a convenience outlet to conduct
electric current.
3. Lamp Holder - an electrical device that is used to hold and protect
incandescent or compact fluorescent lamp.
4. Switch - a device that connects and disconnects the flow of electric current
in a circuit. Switches are classified as hanging, flush and surface types.
5. Fuse - a circuit protective device that automatically blows and cuts the
current when overload or short circuit happens.
6. CIRCUIT BREAKER - - a protective device used to cut or interrupt
automatically the current when trouble in the circuit such as short
circuit or overload occurs.
7. UTILITY BOX - - a rectangular shaped metallic or plastic (PVC)
material in which flush type convenience outlet and switch are
attached.
8.ELECTRICAL CONDUITS/PIPES - used as the passage of wires for
protection and insulation. These could be rigid metallic, flexible metallic
conduit (FMC), rigid non-metallic (PVC), and flexible non-metallic or
corrugated plastic conduit (CPC
Conductors

Wire - An electrical conductor is any material that conducts electrical current. A wire is a
common electrical conductor. Most conductors used in building applications are classified
according to a wire gauge standard and on the cross-sectional area of the wire in units
called circular mils. A mil is equal to 1>1000 inch, so one circular mil (cmil) is equal to
the cross-sectional area of a 0.001 in diameter circle.
Common conductor sizes are provided in Table 18.8. Small- and medium-gauge electrical
conductors are categorized by the American Wire Gauge (AWG), a standardized wire gauge
system used predominantly in the United State since 1857 for round, solid, electrically conducting
wire.
AWG gauge number is inversely proportional to the cross-section diameter of the wire—that is, a smaller number identifies a
thicker wire. AWG gauges range from No. 36 AWG through No. 0000 AWG. A No. 10 AWG is thicker than a No12; a No. 12
AWG is thicker than a No. 14 AWG; and so, on Large AWG wire sizes are expressed as a zero or multiple zeros from No. 0 AWG
through No. 0000 AWG (known as “ought” through “four-ought”). As a rough rule of thumb, if the diameter of a wire is doubled,
the AWG will decrease by about 6 (e.g., No. 1 AWG wire is about twice the diameter of No. 6 AWG wire).

Buses
 A bus, sometimes called a bus bar, is an electrical conductor (usually copper or
aluminum) that serves as a common connection for two or more electrical circuits.
Buses are typically solid bars used for power distribution. They are commonly
found in panelboards, switchboards, and other power distribution equipment.
Busbars are either flat strips or hollow tubes as these shapes allow heat to dissipate
more efficiently because of their high surface area to cross-sectional area ratio. The
skin effect generally makes hollow or flat shapes prevalent in higher current
applications. Table 18.9 provides specifications on selected commercially
available bus bars.

Conductor Material
 Scientifically, silver is the best electrical conductor material (other than a
superconductor material) because it has the least resistance of common materials.
It works so well as a conductor that several hundred pounds of silver wiring was
used in the first mainframe computer. Gold is also an excellent conductor. Both
materials, however, are too costly for building installations.

Conductor Insulator
 Conductors are covered with insulation that provides electrical isolation and some
physical protection of the conductor material. It prevents loss of power and the
danger of short circuits and ground faults. The type of insulation protecting a
conductor determines the environment in which it can be used safely. Wires used
indoors are subjected to less exposure to the elements than those designed for
outdoor use. Outdoor wiring is exposed to water and ultraviolet light, so the
insulation is designed to withstand these elements. Insulation on wires buried in the
ground must also be able to withstand the damp, corrosive environment of the soil.
For special applications, a jacket is applied over the insulation. A jacket provides
the necessary chemical, physical, or thermal protection required by the application.

Cable
 A cable contains more than one conductor bundled together in a factory assembly
of wires. An outer sheathing encases and protects the conductors, simplifying
installation of multiple wiring.

Nonmetallic-Sheathed Cable
 Nonmetallic-sheathed cable is classified as type NM or NMC and is commonly
called by its trade name, Romex. See Photo18.17. NM consists of two or more
insulated conductors enclosed within a moisture-resistant, flame-retardant outer
sheathing or jacket that is very flexible. NMC has conductors encased in the
sheathing. NM is reserved for use in dry, indoor applications. NMC can be used in
dry and damp applications but not wet and exposed conditions. Type NM and Type
NMC cables can typically be used only in one- and two-family dwellings, and in
multifamily dwellings permitted to be of type III, IV, and V construction.
 Underground Feeder Cable
 Underground feeder (UF) cables are flame retardant and moisture, fungus, and
corrosion resistant. UF cable is available in No. 14 AWG copper and No. 12
aluminum AWG through No.4/0 AWG. It looks much like NM or NMC except
that the sheathing fully encases the insulation-covered conductors. UF cable is
used in direct-burial applications as a feeder or branch circuit provided it is
protected by an overcurrent protection device (fuse or circuit breaker) before if
leaves the panelboard.
 Armored Cable
 Armored cable, classified as either AC or ACT, is sometimes referred to by the
trade name, BX cable. This cable consists of two to four copper conductors
between 14 AWG and 1 AWG in size that are enclosed within a flexible spiralshaped metallic enclosure. Armored cable is classified as type ACT if the
conductor insulation is thermoplastic and AC if the insulation is rubber. AC cable
contains a 16 AWG bonding strip, which is in constant contact with the metal
armor, allowing the armor-bonding strip combination to act as an equipment
ground. Armored (AC) installed in a steel-framed partition is shown in
 Photo 18.18.

Metal-Clad Cable
 Metal-clad (MC) cable is similar to armored cable except it is not limited to the
number sizes (from 18 AWG to 2000 kcmil) of conductors it can carry. The
conductors in MC cable may be copper, aluminum, or copper-clad aluminum.
The metal armor may be a smooth tube, corrugated tube, or interlocked metal
armor. MC cable does not contain a bonding strip like AC cable, and the armor
cannot be used by itself as an equipment ground. However, it supplements the
internal grounding conductor. MC cable can be used in many locations not
allowed with AC cable.

Flat Conductor Cable
 Flat conductor cable (FCC) is a wiring system composed of very thin cable with
three or more conductors and special connectors and terminals. It is designed to
rest between the topside of a smooth continuous subfloor and carpet squares. It
can serve general purpose and appliance circuits up to 20 A and individual
circuits up to 30 A, with a system voltage between the ungrounded conductors
not exceeding 300 V.

Thermostat Cable
 Thermostat cable is used in applications with voltages less than 30 V, such as
wiring to doorbells, chimes, and thermostats. It generally contains No. 16 AWG
or No. 18 AWG conductors that are bundled in a thin plastic sheathing.

Cords
 Cords are made of stranded conductors within a flexible insulated sheathing
material. They are designed for flexibility and bending. Cords are generally
manufactured of a lighter gauge (e.g., No. AWG 18 or No. AWG 16) stranded
conductors. They are designed for use on power tools, large stationary
equipment, or detachable computer power cords. Extension cords are made of
stranded wires because they require flexibility, allowing the cord to be bent and
twisted without stressing the conductors.

Concealed knob-and-tube wiring
 Concealed knob-and-tube (K&T) wiring consists of an old-style wiring
technique using insulated conductors strung between glass or porcelain knobs
and tubes. In this wiring method, the ungrounded (hot) wire is run along one
side of the joist/stud bay and the neutral is run along the other. To secure it to
the wood, the wire is wrapped around ceramic knobs spaced every 18 in or so.
To penetrate a joist/stud and prevent abrasion, the wire is separated from the
wood joist/stud by a ceramic tube.

Conductor Power Loss
 Heat generated by current flow through a conductor result in a loss of power.
This lost power is referred to as power loss or line loss. Power loss (Ploss) in a
conductor can be computed with amperage (I) or voltage (V) and resistance (R)
by the following formula:
The Basics of Switchboards, Switchgear, and Panelboards
1. Panelboard - The NEC defines a panelboard as: “A single panel or group
of panel units designed for assembly in the form of a single panel, including
buses and automatic overcurrent devices, and equipped with or without
switches for the control of light, heat, or power circuits; designed to be placed
in a cabinet or cutout box placed in or against a wall, partition, or other
support; and accessible only from the front” [NEC 100]. These can be divided
into load centers and panelboards, both of which are often referred to as
“Panels.”
2. Switchboards are defined in the NEC as “A large single panel, frame, or
assembly of panels on which are mounted on the face, back, or both,
switches, overcurrent, and other protective devices, buses, and usually
instruments. These assemblies are generally accessible from the rear as well
as from the front and are not intended to be installed in cabinets” [NEC 100].
3. Switchgear -The NEC identifies switchgear as: “An assembly
completely enclosed on all sides and top with sheet metal (except for
ventilating openings and inspection windows) and containing primary
power circuit switching, interrupting devices, or both, with buses and
connections. The assembly may include control and auxiliary devices.
Access to the interior of the enclosure is provided by doors, removable
covers, or both.”
When One Type of Gear is Preferred Over the Others
Factors that drive decisions about which type of gear to use include economics, space
constraints, utility service requirements, ability to shut down the facility, and the electrical
system size (voltage and current ratings).
 Economics
often drive decisions regarding which type of equipment to use. If the loads
are few and small, a load center may do the job. Since specialty enclosures can get
very expensive, if the environment requires such an enclosure, the smallest feasible
panelboard is normally used.
 Required space for switchboards or switchgear frequently becomes an issue, especially in
a leased facility where square footage equals income to the owner. Wherever possible,
panelboards are used to minimize wall and floor space needed for the electrical
equipment.
 In order to meet the utility’s service requirements, or to save space inside, often the main
service switchgear is mounted outside the building. This alleviates the need for a
Current Transformer (C/T) enclosure for the service entrance, as a section of the gear
can accommodate the utility C/Ts and meter.
 Shutting down the electrical system for maintenance may not be economically feasible in
industrial or critical operation facilities. Therefore, switchgear with draw-out breakers
is used.
 Depending on the facility’s power requirements, switchboards or switchgear may be
needed for the main distribution equipment. However, for the economic and space
considerations noted above, panelboards are used wherever possible throughout the
building.
Panelboard, Switchboard, Switchgear Comparison Table
Table: on the left to expand it. This document provides a comparison of
the various aspects of the different styles of gear. Note that the NEC does
not limit the use of any gear types to particular voltages or current ranges.
These are products that the electrical gear manufacturers have created to
meet the Code requirements and the needs of the electrical construction
industry. This table is based on gear ratings and sizes by ABB, Eaton, and
Schneider Electric for equipment commonly used in residential and
commercial facilities. Industrial facilities may use gear by other
manufacturers with additional ratings and sizes.
Conclusion
With options of panelboards, switchboards, and switchgear, the electrical system designer has a
robust palette of options to provide the required overcurrent protection for conductors throughout
the facility. Based on whatever factors are in play at a particular facility, there are always
workable solutions.
BUILDING TRANSFORMER

Transformers in commercial installations are
normally used to change a voltage level from a utility distribution
voltage to a voltage that is usable within the building, and are also
used to reduce building distribution voltage to a level that can be
utilized by specific equipment.
What Type of Transformer is Best for Commercial Building?
The installation of a transformer for a commercial building is typically used to change the voltage
level from a utility distribution voltage to a suitable voltage for the premises. The best type of
transformer cam minimizes building distribution voltage to a level that special equipment can also
utilize.
Most of the electricity used to power the commercial buildings flows through distribution
transformers on the customer’s side’s energy meter.
These kinds of transformers are relatively efficient, and those sold today can convert more than 97
percent of input power to output power. However, because most distribution transformers are
powered 24 hours per day and 365 days per year, incremental improvements can significantly
provide significant energy savings.
1. Single phase transformer is a type of transformer which operates on single-phase power. A
transformer is a passive electrical device that transfers electrical energy from one circuit to another
through the process of electromagnetic induction. It is most commonly used to increase (‘step up’)
or decrease (‘step down’) voltage levels between circuits.
A single-phase transformer consists of a magnetic iron core serving as a magnetic transformer part
and transformer cooper winding serving as an electrical part.
2. Three-Phase Transformers - Three-phase transformers are transformers that operate with a
three-phase electrical system. The type of transformer described in the previous chapter is a simple
single-phase transformer. The working principle of three-phase transformers is the same, Faraday
‘s Law of Induction. Single-phase and three-phase transformers differ in wiring configurations. To
further understand, it is better to take a look at three-phase electrical systems.

Conduit and Other Raceways
A raceway is as an enclosed channel such as a conduit, tube, or gutter designed for holding
wires, cables, or busbars. In some cases, metal raceways that are fully bonded serve to
provide a path for the flow of fault current to ground. Examples of race-way materials or
systems follow:
A. Rigid metal conduit is a heavy galvanized
steel or aluminum tube that looks like the
galvanized steel pipe used for plumbing
applications except it is much smoother and is
labeled with a UL Listed stamp or label. It has
threaded connections much like pipe. It can be
used in contact with earth and embedded in
concrete.
B. Intermediate metal conduit (IMC) is a
galvanized steel or aluminum tube that has a
thinner wall than rigid metal conduit. It has
threaded connections much like pipe or
threadless connectors and couplings. It can be
used in contact with earth and embedded in
concrete.
C Electrical metallic tubing (EMT) is a
thin-walled galvanized steel or aluminum
tube in nominal diameters up to 4 in. Unlike
conduit, EMT cannot be threaded. EMT is
labeled with a UL Listed stamp or label. It
is joined with threadless compression
couplings, couplings that are crimped into
the tubing with a special indenting tool, or
fittings that are tightened with screws.
D. Electrical nonmetallic tubing (ENT)
is a flame-retardant corrugated plastic tube
that is semiflexible such that it can be bent by
hand. ENT must be used behind fire-rated
finish materials. It is permitted in damp
locations and can be set in concrete above
ground. Plastic connectors snap together. It
can also be solvent welded to rigid polyvinyl
chloride (PVC) conduit. It can be used in any building,
but special precautions are required when used more than
three floors above grade.
E. Rigid nonmetallic conduit
is a thin-walled pipe of PVC.
It is joined with fittings that are solvent welded.
F. Flexible metal conduit is similar to armored cable, but
it is installed without cables or wiring in it; wiring must
be pulled.
G. Liquid tight flexible metal conduit is similar
to flexible metal conduit, but it is cover ed with a
plastic, watertight jacket that is sunlight resistant.
Unlike flexible metal conduit, the special
connectors are watertight.
H. Liquid tight flexible nonmetallic conduit is a
flexible plastic conduit used in a manner similar to
flexible metal
conduit. It cannot be used over 6 ft in length.
I. Cellular concrete floor raceways are
hollow voids in floors made of precast
concrete slabs (core slabs) found
in certain precast concrete buildings.
 Busways - A busway is of a standardized, factory-assembled enclosure
consists of outer duct-like housing, bus bars, and insulators. Busway systems
are typically used in service equipment or as feeders because these systems
are designed to carry large amounts of current.
Two general types of busway systems are available: feeder and plug-in.
 A feeder busway is used to deliver large amounts of power with low
voltage drop. It is available in sizes from 600 A to several thousand
amps.
 A plug-in busway is used to provide power tap-offs at multiple points.
It is available in 100 A to 3000 A sizes. Plug-in busways make power
distribution flexible. Power is available anywhere along the busway
without necessitating a main service interruption.
Thus, equipment (e.g., for manufacturing and machining) can be relocated and
placed in operation simply, economically, and quickly, merely by inserting a plugin unit into the nearest busway tap off point. Connections may be made at any point
along the busway. Rigid and flexible conduit or flexible bus drop cable extends from
the busway to the piece of equipment. As a result of initial cost, busways are only
used in large commercial and industrial installations (e.g., manufacturing plants)
where large loads are concentrated (about 600 A and higher), where a large number
of taps are required, or where superior fire and mechanical injury protection is
desirable. Busways can also be salvaged and moved more easily and costeffectively than ordinary conductors.
 Wireways
 Wire gutters or wireways are sheet metal or nonmetallic, flameresistant plastic troughs that serve as a housing that encloses and
protects conductors. Access to the enclosure interior is through a hinged
door or removable cover. Wire gutters and wireways typically carry
large conductors. Photo 18.22 shows conductors in an overhead wire
tray.