The document outlines important design considerations for raceway systems and conduits used in electrical installations, including various types like steel, aluminum, flexible metal, and nonmetallic conduits. It discusses their advantages and disadvantages, applications, and compliance with safety standards, specifically referencing NEC guidelines. Additionally, it covers topics such as floor raceways and underfloor duct systems designed to facilitate electrical services in modern office environments.

1. WIRINGAND
RACEWAYS
ENGINEERINGUTILITIES1
PresentedbyGroup4
Chapter26
Cable Tray
Design considerations for raceway systems
Conduits
Surface metal raceways (metallic &
nonmetallic
Outlet and device boxes
Floor Raceways
Raceways and manufactured wiring systems
CONTENTS:
steel
1.
aluminum
2.
flexible metal
3.
nonmetallic
4.
CableTray
It is simply a continuous open support for approved cables
used primarily in industrial applications
Remember:
When used as a general wiring system, the cables must be self-
protected
ADVANTAGES:
system are free-air-rated
cable ampacities
easy installation and
maintenance
relatively low cost
DISADVANTAGES:
Bulky
Accesibility Requirements
Design Considerations for Raceway
Systems
This section discusses closed wiring
raceways, focusing on their types,
applications, and limitations. While specific
construction details are provided by
manufacturers and NEC articles, readers
can gain a foundational understanding of
raceways used in electrical power systems
and for signal, data, and communications
wiring.

2. DesignConsiderationsforRacewaySystems
Key design considerations for raceways in data and communication systems
include:
Data-processing terminals: Number, type, and location.
1.
Networking requirements:
2.
Media type: Influences raceway space based on cable type (coaxial,
shielded, unshielded, fiber-optic).
Cable topology: Affects interconnection arrangements and space needs.
Remote network connections: Necessary for network interconnectivity.
Peripheral devices: Major devices like storage and printers.
3.
Subsystems: Locations of computer-aided design/manufacturing spaces.
4.
Presentation spaces: Areas needing network connections.
5.
Conduits
The purpose of conduit is to
STEEL CONDUIT
Protect the enclosed wiring from mechanical
injury and damage from the surrounding
atmosphere
1.
Provide a grounded metal enclosure for the wiring
in order to avoid a shock hazard
2.
Provide a system ground path
3.
Protect surroundings against a fire hazard as a
result of overheating or arcing of the enclosed
conductors
4.
Support the conductors
5.
Conduits
three types of steel conduit
STEEL CONDUIT
Heavy-wall steel conduit, also referred
to simply as rigid steel conduit; covered
by NEC Article 346
1.
Intermediate metal conduit, usually
referred to as IMC; covered by NEC
Article 345
2.
Metallic tubing, normally known as EMT
or thin-wall condui
3.
Conduits
STEEL CONDUIT

3. Conduits
Aluminum conduit has gained significant
popularity in recent years due to its lightweight
properties and cost-effectiveness. As industries
seek efficient and durable solutions for electrical
installations, aluminum conduit offers a
compelling alternative to traditional steel and
EMT conduits.
ALUMINUM CONDUIT
Conduits ALUMINUM CONDUIT
ADVANTAGES:
Weight Advantage: Lighter than steel and EMT,
leading to reduced labor costs.
Corrosion Resistance: Superior in most
environments; does not require painting.
Nonmagnetic Properties: Reduces voltage drop
and is nonsparking.
Conduits ALUMINUM CONDUIT
DISADVANTAGES
Concrete Interaction: Can cause spalling and
cracking when embedded in concrete. Coating and
controlled additives are necessary to prevent
damage.
Burying Issues: Not advisable to bury aluminum due
to rapid corrosion.
Mechanical Challenges: Potential for thread
deformation in joints and difficulty achieving proper
grounding connections
Conduits
Flexible metal conduit (FMC), commonly known as Greenfield,
is an essential component in electrical installations. Its design
allows for adaptability in various applications, particularly in
environments with vibration and movement.
Flexible Metal Conduit composed of spirally wound,
interlocked armor made of steel or aluminum and is commonly
covered under NEC Article 350.
Flexible metal conduit offers versatility and protection in
various electrical applications, especially where movement
and vibration are concerns.
Flexible Metal Conduit

4. Conduits NONMETALLIC CONDUIT
Nonmetallic conduit, classified under NEC
Article 347, is made from materials such as
fiber, asbestos-cement, soapstone, PVC, and
high-density polyethylene. It is designed for
noncorrosive locations and is typically used for
wiring operating below 300 V. This type of
conduit is usually installed in exposed areas
that are not subject to physical damage.
Conduits
KEY APPLICATIONS
Vibration Isolation: Ideal for motor connections, transformers,
ballasts, and other equipment subject to movement.
Physical Obstruction Navigation: Suitable for installations
where physical barriers are present.
Metal Partitions: Commonly used for wiring within metal
partitions.
Wet Location Use
When covered with a liquid-tight plastic jacket, flexible metal
conduit can be used in wet locations, often referred to by the
trade name Sealtite.
Non Metallic Conduit
Conduits
REQUIREMENTS
Above Ground: Must be flame-retardant and resistant to heat,
sunlight, and low temperatures.
Underground: The heat distortion and sunlight resistance
requirements are waived.
Grounding: A separate ground wire is required as the grounding
feature of metallic conduit is absent.
Non Metallic Conduit
Nonmetallic conduit is a versatile option for electrical installations,
particularly in nonhazardous areas, provided that its limitations
regarding temperature and physical strength are respected. PVC
conduit is preferred for indoor applications, while asbestos-cement
and fiber are suitable for outdoor and underground use.
SURFACE METAL RACEWAYS
It is intended to be mounted to the surface of a
structure, with associated couplings, connectors,
boxes, and fittings for the installation of electrical
conductors.
May be utilized only in dry, nonhazardous,
noncorrosive locations and may generally contain
only wiring operating below 300 V.
Normally installed exposed, in places not subject to
physical injury.
METALLIC & NONMETALLIC

5. SURFACE METAL RACEWAYS
The principal applications of surface metal raceways
are:
1. Where economy in construction weighs very heavily
in favor of surface raceways and where expansion is
anticipated.
2. Where outlets are required at frequent intervals and
where rewiring is required or anticipated.
3. Where access to equipment in the raceways is
required and/or where necessary due to the nature of
the wiring.
4. Where the extensive and expensive cutting and
patching required to “bury” a raceway during rewiring
is to be avoided.
METALLIC & NONMETALLIC OutletandDeviceBoxes
Outlet and device boxes are used in
buildings to protect electrical wiring
and hold devices like switches and
outlets. The most common sizes are 4-
inch square and octagonal boxes, as
well as 4x2-inch boxes for single
devices.
TypesofOutletBox
1. Cast-Iron Outlet Boxes
- Made of durable cast-iron, these boxes are built to
withstand harsh conditions, including outdoor
environments and areas exposed to moisture. It is used
in wet or damp locations, such as outdoor spaces.
2. Nonmetallic Outlet Boxes
- Typically made from PVC or other types of plastic,
nonmetallic outlet boxes are lightweight and non-
conductive. It is primarily designed for indoor use in
residential and commercial buildings, especially in
areas where exposure to moisture or physical damage
is minimal.
TypesofOutletBox
3. Steel Outlet Boxes
-Made from steel, these boxes offer strength and durability
while being lighter than cast-iron. Frequently used in
commercial buildings and industrial spaces and is suitable for
locations where wiring needs to be fully enclosed and protected
from damage.
4. Fiberglass Outlet Boxes
-These are made from reinforced fiberglass resin and
are often used for applications requiring fire
resistance. It is used in areas where fire resistance is
critical, such as in commercial buildings or in walls
that are rated for fire safety.

6. NEC(National
ElectricalCode)
Article300-21
NEC Article 300-21 is a part of the
National Electrical Code (NEC), which
sets safety rules for electrical
installations. Its main purpose is to
ensure that any holes or openings in fire-
rated walls and floors do not allow fire
and smoke to spread.
01.
02.
03.
PURPOSE
IMPORTANCE
APPLICATION
It ensures that electrical boxes, conduits, and
penetrations through fire-rated walls and floors
maintain the integrity of fire barriers.The primary
goal is to prevent the spread of fire and smoke
through electrical penetrations.
PURPOSE
Electrical boxes and raceways installed in fire-rated
floors must comply with NEC standards to ensure
safety. Boxes should be fire-rated and have specific
designs, like fire-rated inserts and seals to protect
the integrity of the fire-resistant materials
APPLICATION ollowing NEC Article 300-21 is crucial for fire safety
and meeting building codes. It helps prevent fire
risks and ensures that electrical systems support the
building's fire protection.
IMPORTANCE

7. Floor
Raceways
In big commercial areas, workstations
are usually placed far from walls that
have electrical outlets. Each
workstation needs power, phone lines,
and internet connections, so it’s
important to reduce visible wiring. To
solve this, outlets can be placed in the
floor near the desks or inside low
dividers. This setup keeps everything
neat and organized.
01.
02.
03.
Channel the floor and install a
conduit in the channel,
connecting it to the nearest wall
outlet. Patch the chased portion
of the floor.
Install a surface floor raceway. The
usefulness of this technique is very
limited because it presents a
tripping hazard and problems with
routine floor cleaning.
Drill through the floor twice and
connect the new outlet to a nearby
existing floor or wall outlet via a
conduit on the underside of the
floor slab. Floor penetrations must
be fireproof.
04.
To provide electrical services to
workstations, you can drill through the
floor and run conduit through the ceiling
below. Special fittings maintain the fire
rating and allow for all necessary
connections, which can be routed to a
floor outlet or used to wire partitions.
UnderfloorDuct
Underfloor duct systems in offices help bring power,
data, and signal outlets close to desks and furniture.
They use raceways under the floor, covered with
concrete, to allow access to wiring. While useful,
these systems are expensive and not very flexible,
leading to cheaper options like ceiling ducts and flat-
cable under-carpet wiring. Single-level underfloor
systems use less concrete, but complex junction
boxes can reduce efficiency. Newer systems with
triple-cell ducts and well-placed junction boxes offer
a more affordable solution for most wiring needs,
with the option to add under-carpet cables in busy
areas.
UnderfloorDuct
ADVANTAGES:
Ducts can be run in any direction, without conflict with structural elements
Finishing is simplified.
Coordination is simplified, and formwork and construction sequence are simplified.
DISADVANTAGES
Additional concrete increases costs directly by increasing the weight of
the structure. This is particularly expensive in seismic designs.
The building height may be increased.
Useofafillortopping CellularMetalFloor
Raceway
The underfloor duct system works best in
straight layouts, while open office designs
need a special floor that allows easy access to
both structural support and electrical wiring.
This floor can carry electrical connections
through ducts, and it is built to handle
separate systems for electricity, data, and
phone signals, with specific rules for mixing
some types of wiring.

8. This concrete system works like a cellular
metal floor, providing advantages such as large
capacity, versatility, and flexible outlet
locations. Although it usually costs more
upfront, it may save money over time. The
system includes tubular spaces in precast
concrete slabs that get power from header
ducts, which can be placed above or below, and
can also handle air distribution and plumbing,
usually found in a suspended ceiling.
PrecastCellularConcrete
FloorRaceways
Full-AccessFloor
This construction is designed for spaces
with heavy cabling needs and frequent
reconnections, providing easy access to
an underfloor area. It consists of
lightweight aluminum panels supported
by adjustable pedestals, allowing space
for cabling and conditioned air, while
also being fireproof; shorter pedestals
can be used when air distribution is not
needed, helping to minimize ceiling
height issues.
This system, described in NEC Article 328,
was created as a cost-effective and flexible
alternative to underfloor or cellular flooring,
featuring a factory-assembled flat cable
designed to be installed under carpet
squares. It allows for easy repositioning with
minimal disruption, can handle normal office
traffic, and has led to similar designs for
signal and communication wiring, with
manufacturers providing various connectors
and fittings to address common wiring issues
in open office environments.
Under-CarpetWiringSystem
CEILING RACEWAYS AND
MANUFACTURED WIRING SYSTEMS
These systems are actually more
flexible than their underfloor
counterparts because they energize
lighting, provide power and telephone
facilities, and even supply outlets for
the floor above, in addition to
permitting very rapid layout changes at
low cost.
The hung ceiling must consist of lift-
out panels because this type of wiring
system is not permitted in spaces
rendered inaccessible by the building
structure. These laterals act as sub
distribution raceways, feeding lighting
fixtures and data, signal, telephone,
and power outlets on the same floor
and, via poke-through fittings, outlets
on the floor above.

9. When electrical connections to poles, lighting
fixtures, receptacles, and communication/data
outlets are made with hard wiring, considerable
field labor is required, with a corresponding high
cost.
Ceiling raceways can be equipped with matching
receptacles, and connection to fixtures, poles,
and other devices becomes a simple matter of
plug insertion
The additional cost of manufactured
wiring elements is frequently offset by
the labor savings, even upon initial
installation and certainly after one or
two field changes.
Cable sets are available for power (120
V and 277 V), telephone, and all types of
low-voltage signal equipment.
The cables must be approved for use in
conditioned-air plenums and suspended
ceilings.
To take full advantage of the potential
labor cost savings inherent in the
system, field labor must be minimized.
Thank
youvery
much!
PresentedbySandraHaro
Project2030