Installation Guide for Instrument
Cables, Conduits and Cable Trays
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CONTROL SYSTEMS
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References
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3DS-E53G-00001, Electrical Design Standard
Conduit and Tray Notes, Symbols & Details
EW-0000-501, Electrical Design Standard for
Cable Installation Notes and Details
BecWeb & Internet
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Definition
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What is a Cable Tray?
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Assembly of units or sections and associated
fittings forming a rigid structural system used to
securely fasten or support cable and raceways.
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Why is Cable Tray?
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Cable trays are preferred in the areas with high
cable density and scattered devices to be
connected. The tray system also offers the
flexibility of accommodating the minor device
location changes.
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Types of Cable Trays
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Ladder Type
Ventilated Trough
Solid Bottom
Channel
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Types of Cable Trays
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Cable Tray Standards
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The National Electrical Code (NEC)
publishes the standards for all types of electrical
applications. Articles 318, 250 & 800 cover
various aspects of cable tray systems.
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NEMA (National Electrical Manufacturers
Association) – NEMA VE1, FG1 & VE2
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Cable Tray Standards
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NEMA VE1 covers general cable tray
definitions, manufacturing standards,
performance standards, test standards and
application information
NEMA FG1 addresses the standards for
fiberglass cable tray systems
NEMA VE2 is a cable tray installation guideline
which covers receiving and unloading material,
storage of material and general installation
practices
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Cable Tray Selection criteria
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Ladder Cable Tray
Maximum strength for long span applications.
Ladder cable tray is generally used in applications.
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Solid Bottom Cable Tray
Non ventilated continuous support for delicate
cables. Solid Bottom cable tray is generally used
for minimal heat generating electrical or
telecommunication applications.
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Cable Tray Selection criteria
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Trough /Perforated Cable Tray
Trough cable tray is generally used for moderate
heat generating applications.
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Channel Cable Tray
Used for cable drops and branch cable runs
from the backbone cable tray system. Channel is
used with limited numbers of cables where
conduit is undesirable.
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Channel Size & no. of Cables
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Cable Tray routing design
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Choose the shortest feasible paths on major
runs and provide good overall area coverage of
equipment on all other runs.
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Cable tray should be designed such that there is
adequate structure available to support cable
trays utilizing standard cable tray support details
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Cable Tray Installation Notes
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Trays shall be kept a reasonable distance from heat
sources like steam piping, steam generators &
boilers etc.
Trays shall be no closer than 12” above the top of
hot pipe insulation on hot pipes 65ºC to 120ºC
and 18” above the top of hot pipe insulation on
hot pipes 121ºC to 260ºC.
Instrument Cable Trays & Electrical Cable Tray
shall be separated from each other based on low or
high voltage.
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Cable Tray Installation Notes
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When running parallel above pipes these
distances should be further increased by 6”.
Cable trays shall be grounded in accordance with
the Standard Grounding Notes.
Cable trays shall be constructed of hot dipped
galvanized after fabrication steel or aluminum.
Ventilated or raised covers shall be used for
power trays
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Cable Tray Installation Notes
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Trays shall be inspected for burrs, sharp edges,
or any other defects and such defects must be
corrected before cable installation.
After cable installation, covers shall be installed
on each top tray in a stack, where the stack runs
below floor gratings or in open areas subject to
falling debris.
Cable Tray support is designed on the basis of
cable size, Cable Tray weight & cable weight.
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Cable Tray Support System
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Cable Tray Support System
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Cable Tray Accessories
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Cable Tray Joining plates
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Cable Standards
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National Electrical Code (NEC)
Institute of Electrical and Electronic Engineers Standard 383
American Petroleum Institute - RP 540 Recommended
Practice for Electrical Installations in Petroleum
Processing Plants
Underwriters' Laboratories (UL)
IEEE Standard No. 48 "IEEE Standard Test
Procedures and Requirements for High Voltage
Alternating Current Cable Terminations."
IEEE Standard No. 422 "IEEE Guide for the Design
and Installation of Cable Systems in Power Generating
Stations."
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Instrument Cable Installation
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The routing for all scheduled cables is given in
the circuit Schedule and deviations from these
routings are not permitted without prior
approval from Engineering. Routing of nonscheduled cable is by construction.
Cables shall be installed without splices. Splices,
when required, shall be made in manholes or
pull boxes. Splices shall not be pulled into
raceways.
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Instrument Cable Installation
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Cables shall not be installed in partially completed
raceways. When field conditions dictates to do
so, the responsible field engineer shall determine
that completion of the raceways will not result in
any damage to the installed cables.
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Instrument Cable Installation
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Tie in cable to the tray bottom at approximately
6 feet intervals for horizontal & 5 feet on
vertical cable tray runs.
Cable shall be formed to avoid sharp bends over
edges of conduit bushings upon entering or
leaving boxes or cabinets.
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Cable Tray Storage
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Hot dipped galvanized (H.D.G.A.F.) steel,
aluminum, and stainless steel cable tray and
fiberglass or other non-metallic cable tray can be
stored outside without cover.
In that case, they should be loosely stacked,
elevated off the ground, and ventilated to
prevent storage stain.
Mill galvanized or electro-galvanized cable tray
must be protected or stored in a well ventilated,
dry location.
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Cable Tray Storage
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PVC or painted cable tray should be protected
and stored indoors if possible.
Cable tray must be protected from scratching
and marring of finish.
Cable tray should be stored away from high
traffic areas
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Cable Tray Safety Notes
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Do not use a cable tray as a walkway, ladder,
or support. Using cable trays as walkways can
cause personal injury and also damage cable
tray and installed cables.
The performance of a cable tray wiring system
is dependent on its proper installation,
including supports and cables.
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Cable Tray Safety Notes
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Installation and maintenance of cable tray
wiring systems shall be conducted only by
qualified personnel.
Neglecting installation and maintenance
guidelines may lead to personal injury as well
as damage to property.
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Cable Conduits
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Standards for Conduit
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ANSI C80.1 - Galvanized rigid steel conduit.
ANSI C80.3- Electrical metallic tubing.
ANSI C80.5 - Aluminum rigid conduit
ANSI C80.6 - Intermediate metal conduit
NEMA TC-6 and TC-8 - Rigid nonmetallic
conduit
All conduits, with the exception of PVC duct
type DB, shall be UL listed.
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Cable Conduit Installation Notes
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Conduit connections to any equipment subject to
vibration shall be made with a flexible connection.
The flexible conduit, when used at the end of a
scheduled rigid conduit, will not be listed in the
Raceway Schedule and shall be sized the same as the
connecting rigid conduit.
Conduits are available in different sizes.
i.e. ¾”, 1”, 1 ½”, 2” & 3”.
Minimum length of flexible conduit shall be 12” for
¾” & 1” conduit, 18” for 1 ½” & 2” conduit, and
24” for 3”and above.
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Conduits & Support
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Cable Conduit Installation Notes
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Conduit shall not have any welds applied to it.
To ensure good ground continuity, conduit
threads must be clean of any nonconductive
coatings.
Ends of all exposed conduit shall be plugged
or capped during construction. All spare
conduits shall be capped or plugged for future
use.
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Cable Conduit Installation Notes
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Conduit type and size shall be identified in the
circuit and raceway schedule.
When a conduit is routed to a tray, it must be
installed to the tray section specified in the
circuit and raceway schedule.
All conduits cut in the field shall be reamed
and free of burrs before installation.
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