October 2009

Process Industry Practices

Electrical

PIP ELSSG03
Design and Fabrication of Medium Voltage
Metal-Enclosed Load Interrupter Switchgear

PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice has
been prepared from the technical requirements in the existing standards of major
industrial users, contractors, or standards organizations. By harmonizing these technical
requirements into a single set of Practices, administrative, application, and engineering
costs to both the purchaser and the manufacturer should be reduced. While this Practice
is expected to incorporate the majority of requirements of most users, individual
applications may involve requirements that will be appended to and take precedence
over this Practice. Determinations concerning fitness for purpose and particular matters
or application of the Practice to particular project or engineering situations should not
be made solely on information contained in these materials. The use of trade names
from time to time should not be viewed as an expression of preference but rather
recognized as normal usage in the trade. Other brands having the same specifications
are equally correct and may be substituted for those named. All Practices or guidelines
are intended to be consistent with applicable laws and regulations including OSHA
requirements. To the extent these Practices or guidelines should conflict with OSHA or
other applicable laws or regulations, such laws or regulations must be followed.
Consult an appropriate professional before applying or acting on any material
contained in or suggested by the Practice.
This Practice is subject to revision at any time.

Process Industry Practices (PIP), Construction Industry Institute, The

University of Texas at Austin, 3925 West Braker Lane (R4500), Austin,
Texas 78759. PIP member companies and subscribers may copy this Practice
for their internal use. Changes, overlays, addenda, or modifications of any
kind are not permitted within any PIP Practice without the express written
authorization of PIP.

PRINTING HISTORY
October 2009
Issued
Not printed with State funds

October 2009

Process Industry Practices

Electrical

PIP ELSSG03
Design and Fabrication of Medium Voltage
Metal-Enclosed Load Interrupter Switchgear
Table of Contents
1. Introduction..................................2
1.1
1.2

Purpose..........................................2
Scope.............................................2

2. References...................................2
2.1
2.2

Process Industry Practices.............2

Industry Codes and Standards.......2

3. Definitions....................................3
4. Requirements..............................3
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8.

Service Conditions..........................3
Ratings...........................................3
Basic Construction..........................3
Bus and Bus Supports....................5
Ground Bus....................................6
Grounding to Confirm
De-Energized Status......................6
Arc-Resistant Switchgear...............6
Load Interrupter Switch..................8

4.9 Switch Interlocking and Transfer Schemes

4.10 Switch Motor Operator and
Shunt Trip.......................................9
4.11 Fuses and Fuse Compartment.......9
4.12 Surge Protection...........................10
4.13 Incoming and Outgoing Power Terminations
4.14 Wiring and Devices.......................10

Process Industry Practices

10

Page 1 of 17

4.15
4.16
4.17
4.18
4.19
4.20
4.21
4.22
4.23
4.24

Potential Transformers.................12
Current Transformers...................12
Instruments, Meters, Control Devices and Indicating Lights
Space Heaters..............................13
Paint.............................................14
Test and Inspection.......................14
Nameplates and Labels................15
Documentation.............................15
Shipment......................................16
Conflict Resolution........................17

13

October 2009

1.

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

Introduction
1.1

Purpose
This Practice provides requirements for medium voltage metal-enclosed load
interrupter switchgear.

1.2

Scope
This Practice describes the requirements for design, fabrication, inspection,
testing, and shipment of medium voltage metal-enclosed load interrupter
switchgear for installation in non-classified areas. This Practice covers
assemblies for medium voltage application for nominal 2.4 kV to 38 kV, 60 Hertz
systems.
This Practice does not include no-load interrupter switches.

2.

References
Applicable parts of the following Practices, industry codes and standards, and references
shall be considered an integral part of this Practice. The edition in effect on the date of
contract award shall be used, except as otherwise noted. Short titles are used herein where
appropriate.
2.1

Process Industry Practices (PIP)

PIP ELSSG03D - Data Sheet for Medium Voltage Metal-Enclosed Load
Interrupter Switchgear
PIP ELSSG12 - Design and Fabrication of Outdoor Enclosures for Motor
Controllers and Switchgear
PIP ELSBD01 - Design and Fabrication of Metal-Enclosed NonsegragatedPhase Bus Duct Assemblies
PIP ELSBD01D - Data Sheet for Design and Fabrication of MetalEnclosed Nonsegragated-Phase Bus Duct Assemblies
PIP ELSBD02 - Design and Fabrication of Metal-Enclosed NonsegragatedPhase Bus Duct Assemblies
PIP ELSBD02D - Data Sheet for Design and Fabrication of MetalEnclosed Nonsegragated-Phase Bus Duct Assemblies

2.2

Industry Codes and Standards

American National Standards Institute (ANSI) and Institute of Electrical and
Electronics Engineers (IEEE)
ANSI/ IEEE C37.20.2 - IEEE Standard for Metal-Clad Switchgear
ANSI/ IEEE C37.20.3 - IEEE Standard for Metal-Enclosed Interrupter
Switchgear
ANSI/ IEEE C37.20.7 - IEEE Guide for Testing Medium-Voltage MetalEnclosed Switchgear Rated Up to 38kV for Internal Arcing Faults

Process Industry Practices

Page 3 of 17

3.

Definitions
owner: The party who owns the facility wherein the load interrupter switchgear will be
used
purchaser: The party who awards the contract to the supplier. The purchaser may be the
owner or the owners authorized agent.
supplier: The party responsible for furnishing the load interrupter switchgear

4.

Requirements
4.1

Service Conditions
Equipment shall be designed to perform satisfactorily under the ambient
conditions specified on purchasers PIP ELSSG03D Data Sheet.

4.2

4.3

Ratings
4.2.1

The ratings of the switchgear assemblies and the system parameters shall
be as specified on purchasers PIP ELSSG03D Data Sheet.

4.2.2

Temperature limits for insulation material shall be as specified on

purchasers PIP ELSSG03D Data Sheet and in accordance with
ANSI/IEEE C37.20.3 - 2001, Table 2.

Basic Construction
4.3.1

The metal-enclosed switchgear shall be in accordance with the

switchgear features and requirements of ANSI/IEEE C37.20.3.

4.3.2

The switchgear assembly shall consist of metal-enclosed free standing

vertical steel structures containing power buses, a ground bus, load
interrupter switches, fuses, cable terminations, and auxiliary control
devices in accordance with purchasers one-line diagram and
PIP ELSSG03D Data Sheet.

4.3.3

Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet,

enclosure rating shall be NEMA 1.

4.3.4

Main front and rear doors if any shall have door stops that can hold the
door in the full open position until released.

4.3.5

Front doors shall be provided with hand operated latches and shall have
provisions for padlocking.

4.3.6

Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet, if

a rear compartment is provided, bolted covers shall be provided for
access.

4.3.7

Non-hinged bolted doors and removable panels shall be configured as

follows:
a. Secured with captive slotted fasteners, machine screws, or machine
bolts engaging captive nuts or tapped holes in structural members

October 2009

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

b. Provided with two lifting handles if panel weight is greater than

50 pounds (22.7 kg)
4.3.8

Ventilation openings shall be provided with vermin-proof, 1/8 inch

(3.2 mm) opening mesh, 304 stainless steel screens on the inside of the
switchgear. If approved by purchaser, painted carbon steel screens may
be provided.

4.3.9

A view window with a clear, shatter-proof polycarbonate cover in

accordance with ANSI/IEEE C37.20.3 - 2001, Appendix A, Section A
3.11 shall be provided for viewing all three phases of the interrupter
switch position in both the open and closed positions.

4.3.10 If specified on purchasers PIP ELSSG03D Data Sheet, a 120 VAC light
with an on-off switch that is externally accessible or mounted in the low
voltage compartment shall be provided for each cubicle containing an
interrupter switch.
4.3.11 If specified on purchasers PIP ELSSG03D Data Sheet, switchgear shall
be designed for expansion on the ends, and the enclosures shall be of
modular design so that additional units may be safely and readily
installed. Provisions for expansion shall include, but not limited to,
predrilled buses, terminal blocks for secondary wiring, and removable
enclosure end covers secured by captive hardware on the structure.
4.3.12 Front doors on vertical sections of enclosures containing load interrupter
switches shall be interlocked with the switch to prevent the door from
being opened if the switch is not in the fully opened position. Also, the
interlock shall prevent the switch from being closed if the door is not
fully closed.
4.3.13 If specified on the purchasers PIP ELSSG03D Data Sheet, full height
and width grounded metal barriers shall be installed between front switch
enclosures and rear cable or bus areas. Through bushings shall be
provided to isolate the front and rear compartments.
4.3.14 The switchgear base shall be constructed of either of the following as
specified on purchasers PIP ELSSG03D Data Sheet:
a. G90 Galvanized steel, 1.5 inches (3.8 cm) high
b. 4-inch (10.6 cm) minimum channel
4.3.15 Full height, grounded metal barriers shall be provided between adjacent
vertical sections.
4.3.16 Bushings shall be provided for bus penetration between cable and switch
compartment and between adjacent vertical units.
4.3.17 Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet,
control power shall be furnished by the purchaser. Supplier shall wire
control power circuit to terminal blocks for connection by purchaser.
4.3.18 Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet,
space heater and lighting power shall be furnished by the purchaser.
Supplier shall wire space heater and lighting circuits to terminal blocks
for connection by purchaser.

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4.3.19 In any front or rear access switch compartment having a full height door,
and containing high-voltage parts which may remain energized after the
door is open, metal screen gates shall be provided behind all hinged
doors or panels covering primary voltage bare live parts.
4.3.19.1 The gates shall be provided with hinges and captive bolt
closing fastenings.
4.3.19.2 The metal gate screen shall be designed to resist collapse if a
person falls against the gate.
4.3.19.3 The metal gate screen shall be constructed of expanded or
punched 16 gage (1.31 mm2) minimum steel, with openings
not greater than 1 inch (2.54 cm).
4.3.19.4 Gates shall have warning signs that contain the following
information or equivalent: Danger High Voltage Keep Out
Qualified Persons Only.
4.4

Bus and Bus Supports

4.4.1

Power bus ratings shall be as specified on purchasers PIP ELSSG03D

Data Sheet.

4.4.2

Bus contact area shall be tin or silver plated as specified on purchasers

PIP ELSSG03D Data Sheet.

4.4.3

Bus Insulation
4.4.3.1 Unless otherwise specified on the purchasers PIP ELSSG03D
Data Sheet, phase bus shall be covered with a flame-retardant,
track-resistant, non-hygroscopic insulation.
4.4.3.2 Bus insulation, except at the joints, shall be bonded to the bus
bar and shall be either liquid dipped or fluidized bed epoxy.
4.4.3.3 If specified on the purchasers PIP ELSSG03D Data Sheet,
sleeve type or heat shrink tubing type insulating systems may be
provided.

4.4.4

Bus Bar Joints Insulation

4.4.4.1 Bus bar joints on insulated bus shall be covered with formed
insulating boots and reusable non-metallic hardware.
4.4.4.2 Termination connections for purchasers cable connections shall
have insulating boots provided with reusable non-metallic
hardware.
4.4.4.3 Taping of bolted joints shall not be permitted.

4.4.5

Insulating materials for barriers, cable supports and spacers shall be

made of flame-retardant, track-resistant, non-hygroscopic materials that
meet the same requirements of insulating materials covering buses in
accordance with ANSI/IEEE C37.20.3 - 2001, Section 5.2.7.

4.4.6

Air gaps around the bus and inserts shall not be permitted.

4.4.7

Bolted power bus connections shall be secured with corrosion resistant

hardware, including bolts, locking washers, and nuts or jam nuts.

October 2009

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

4.4.8

A label showing torque requirements for bolted connections shall be

provided inside each cubicle.

4.4.9

Cable shall not be used as a power, ground, or neutral bus except for load
side connections from fuse or switch to transformer primary connections
where bracing is adequate for the cables.

4.4.10 The continuous current carrying capability of the bus shall not be less
than the continuous current rating of any associated interrupter switch.
4.4.11 Bus insulators shall be wet process porcelain or cycloaliphatic epoxy as
specified on purchasers PIP ELSSG03D Data Sheet, and shall be braced
for the maximum short circuit current specified on purchasers
PIP ELSSG03D Data Sheet.
4.5

4.6

4.7

Ground Bus
4.5.1

A tin-plated copper ground bus, minimum 2 inches (5.1 cm) by 1/4 inch
(0.6 cm), shall extend throughout the length of the switchgear.

4.5.2

NEMA spaced holes (i.e., 9/16 inch (1.4 cm) diameter, spaced 1-3/4 inch
(4.4 cm) center to center) for two-hole lugs at each end of the bus shall
be provided.

4.5.3

For cubicles with cable terminations or bus duct entry in both front and
rear compartments, the ground bus shall be extended into both
compartments.

4.5.4

Circuit connections to the ground bus shall be made in a manner that

does not require the ground bus to be open circuited to remove any
connection.

Grounding to Confirm De-Energized Status

4.6.1

For each cubicle, the ground bus shall be extended toward the incoming
power cable termination points to allow easy access for safety ground
connection of a portable grounding clamp device.

4.6.2

Each incoming or outgoing power cable termination shall be provided

with an apparatus ground clamp cable connection for voltage testing and
grounding. The ground clamp cable connection shall be a grounding
stud, mounted as close as possible to the phase bus cable termination
point.

Arc-Resistant Switchgear
4.7.1

If specified on the purchasers PIP ELSSG03D Data Sheet, the

switchgear shall be arc-resistant design.

4.7.2

Unless otherwise specified on the purchasers PIP ELSSG03D Data

Sheet, switchgear shall be arc-resistant construction Type 2 (i.e.,
switchgear with arc-resistant construction at front, rear, and sides).

4.7.3

Testing
4.7.3.1 Arc-resistant switchgear shall be tested in accordance with
IEEE C37.20.7.

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Page 7 of 17

4.7.3.2 A written certificate of successful type testing, including all the

parameters used in the testing, shall be submitted to the
purchaser.
4.7.3.3 Testing shall be based on the withstand capability of the switch.
4.7.4

Potential transformer (PT) and control power transformer (CPT) drawers,

and switchgear shall be designed for closed door racking.
Arc-resistant integrity shall be maintained during closed door racking.

4.7.5

Relay compartment doors shall be designed and tested to permit the

compartment door to be opened without affecting the arc-resistant rating
of the switchgear.

4.7.6

The front and rear compartment doors shall be designed to withstand the
effects of an internal arcing fault.

4.7.7

The PT compartment door and the instrument and control compartment

doors shall have steel hinged doors that are in accordance with IEEE
C37.20.7 testing requirements.

4.7.8

The design of openings shall be in accordance with IEEE C37.20.7, with

respect to the emission of arc/flash products.

4.7.9

Openings intended to close on initiation of a fault to preserve arcresistant construction shall be provided with the necessary guards on top
and sides to prevent dropping of any foreign material that can prevent
openings from closing.

4.7.10 Design and construction of the switchgear shall prevent effects of any
fault in the high voltage compartment from entering the low voltage or
instrument compartment.
4.7.11 Opening cover plates provided to preserve arc-resistant contruction shall
be accessible for inspection.
4.7.12 If rear doors interlocks are specified on the purchasers PIP ELSSG03D
Data Sheet, a means shall be provided to defeat the interlocks by a
deliberate act that is not considered part of a normal operating procedure
for maintenance purposes. The interlock shall be reset by closing the
door after the interlock has been circumvented.
4.7.13 A single-handle latch system with position labeling and provision for
padlocking shall be provided on each door such that arc-resistant
integrity is maintained if the latch is in closed position. Additional tie
down bolts or latches shall not be required on the doors to maintain arcresistant construction.
4.7.14 Plenum System
4.7.14.1 Personnel shall be protected from arc products and noise
expelled from the switchgear enclosure. Unless specified
otherwise on the purchasers PIP ELSSG03D Data Sheet,
a plenum system shall be provided.
4.7.14.2 Plenum system shall exhaust arc products from the switchgear
room.
4.7.14.3 Exhaust outlet shall be weatherproof and directed to an area

October 2009

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

that minimizes personnel exposure.

4.7.14.4 Plenum minimum volume shall be tested and certified in
accordance with IEEE C37.20.7.
4.8.

Load Interrupter Switch

4.8.1

Load interrupter switch ratings shall be as specified on the purchasers

PIP ELSSG03D Data Sheet.

4.8.2

Switch Configuration
4.8.2.1

A load interrupter switch shall be three-pole gang operated,

single-throw with all parts of operator and switch assembly
adequate to withstand the stresses of normal operation.

4.8.2.2

Switch shall be operable from the exterior of the enclosure.

4.8.2.3

Switch shall be equipped with a quick-make, quick-break,

stored energy mechanism to open and close the switch.

4.8.2.4

The quick-make quick-break mechanism of a manual

interrupter switch shall have a heavy-duty coil spring to
provide opening and closing energy.

4.8.2.5

The speed of opening and closing the switch shall be

independent of the operator.

4.8.2.6

Switch shall be designed not to break or make the current with

the main current carrying contact.
Comment: This requirement provides for maximum
endurance of the switch for fault close and load
interrupting duty.

4.8.2.7

Design of the switch shall not permit moving the switch into
an intermediate position under normal operation.

4.8.3

Access to the switch compartment shall be permitted only if the stored

energy mechanism of the switch is in the discharged or physically
blocked position.

4.8.4

A permanent Open-Closed switch position indicator, visible from the

outside of the switchgear enclosure, shall be provided.

4.8.5

If removable switch handles are provided, a handle shall be provided for

each switch and a handle storage area shall be provided on each switch.

4.8.6

Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet,

wet process porcelain or cycloaliphatic epoxy insulators and operator
rods shall be provided to insulate the switch hinge and jaw castings from
the frame.

4.8.7

If approved by purchaser, glass polyester operator rods may be provided.

4.8.8

If required to achieve bushing insulation level (BIL) rating or if specified

on purchasers PIP ELSSG03D Data Sheet, insulated barriers shall be
provided between each phase and between the outer phases and the
enclosure.

Process Industry Practices

Page 9 of 17

4.8.9

If specified on the purchasers PIP ELSSG03D Data Sheet, a horizontal

insulated barrier shall be provided between any switch compartment and
its associated fuse compartment and shall extend from the front to as far
back into the compartment as practical.

4.8.10 If specified on the purchasers PIP ELSSG03D Data Sheet, two normally
open (NO) and two normally closed (NC) (DPDT) auxiliary contacts that
indicate fully open and closed switch positions shall be provided and
wired to a terminal block for purchaser use. The terminal block shall be
located in a low voltage compartment.
4.8.11 If specified on the purchasers PIP ELSSG03D Data Sheet and/or the
single-line diagram, key interlocks shall be provided between specified
switches or specified switches and external equipment.
4.8.12 If specified on the purchasers PIP ELSSG03D Data Sheet, one of the
following options shall apply:
a. All three phases of each switch shall be grounded when the switches
are in the full open position.
b. A separate grounding switch shall be provided.
4.9

Switch Interlocking and Transfer Schemes

If a switch interlocking or transfer scheme is shown on purchasers single-line
diagram and specified on purchasers PIP ELSSG03D Data Sheet, the scheme
shall be arranged to operate as shown on the diagram and in accordance with any
supplemental descriptions provided.

4.10

Switch Motor Operator and Shunt Trip

If shown on purchasers single-line diagram and specified on purchasers
PIP ELSSG03D Data Sheet, a motor operator and shunt trip shall be provided.

4.11

Fuses and Fuse Compartment

4.11.1 Fuses shall be provided where shown on purchasers single-line diagram
and as specified on purchasers PIP ELSSG03D Data Sheet. The type of
fuse shall be as specified on the purchasers PIP ELSSG03D Data Sheet.
4.11.2 If specified on the purchasers PIP ELSSG03D Data Sheet, spare power
and control fuses shall be provided in the quantities specified.
4.11.3 If specified on the purchasers PIP ELSSG03D Data Sheet, a normally
closed contact shall be provided for blown power fuse indication and
shall be wired to a terminal block for purchaser use. The terminal block
shall be located in a low voltage compartment.

4.12

Surge Protection
If specified on purchasers single-line diagram or purchasers PIP ELSSG03D
Data Sheet, surge protection shall be provided.

4.13

Incoming and Outgoing Power Terminations

4.13.1 Incoming and outgoing power circuit terminations shall be in accordance
with purchasers PIP ELSSG03D Data Sheet.

October 2009

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

4.13.2 Cable
4.13.2.1 Unless otherwise specified on purchasers PIP ELSSG03D Data
Sheet, cable lugs shall be furnished by purchaser.
4.13.2.2 Type of cable termination used by the purchaser shall be shown
on purchasers PIP ELSSG03D Data Sheet.
4.13.2.3 Switchgear cable termination compartment space shall facilitate
bringing cables to line or load terminals with a minimum of
cable bending.
4.13.2.4 Unless otherwise specified on the purchasers PIP ELSSG03D
Data Sheet, cable penetrations shall be from the bottom.
4.13.3 If bus duct or cable bus is specified on purchasers PIP ELSSG03D Data
Sheet, bus duct and bus duct terminations or cable bus and cable bus
terminations shall be in accordance with PIP ELSBD01 and
PIP ELSBD01D or PIP ELSBD02 and PIP ELSBD02D.
4.13.4 Transformer Close Coupled
4.13.4.1 Switchgear shall be cable or bus connected to the transformer
bushings as specified on the purchasers PIP ELSSG03D Data
Sheet.
4.13.4.2 If a cable connection is specified, the cable for the connection
to the transformer shall be provided.
4.13.4.3 If a cable connection is specified, the cable shall be supported
by wet process porcelain or cycloaliphatic epoxy standoff
insulators and inserts where the cable passes through barriers.
4.14

Wiring and Devices

4.14.1 General
4.14.1.1 All control and low-voltage power wiring shall be flameresistant, 600 volts rated insulation, Type SIS or Type TBS
flexible insulated stranded copper wire with insulation rated for
90C conductor temperature.
4.14.1.2 Power wiring shall be minimum No. 14 AWG.
4.14.1.3 Control wiring, for use between component devices or parts of
switchgear assemblies, shall be minimum No. 14 AWG.
4.14.1.4 Extra flexible stranding type wires shall be provided from doors
or hinged panels to compartments and wires shall be arranged
in a spiral configuration rather than bending at these locations.
4.14.1.5 Wiring shall be terminated with insulated locking fork type
connectors.
4.14.1.6 All grounding conductors shall be green insulated wires.
4.14.1.7 Adhesive backed wire supports shall not be permitted.
4.14.1.8 All energy isolating devices shall have provisions for pad lock
in Off or Disconnected position only.

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4.14.2 Current Transformer Circuits

4.14.2.1 Current transformer (CT) secondary circuits shall be minimum
No. 10 AWG copper conductors Type SIS.
4.14.2.2 The two individual leads from each CT shall be wired to front
accessible, shorting terminal blocks. CT grounding shall also be
connected on these terminal blocks.
4.14.2.3 CT circuits shall be provided with compression type, insulated
sleeve, seamless ring tongue lugs.
4.14.3 Control and Secondary Wiring
4.14.3.1 Control and secondary wiring shall be of one continuous length
from terminal to terminal.
4.14.3.2 Splicing shall not be permitted.
4.14.3.3 All control wiring leaving a compartment shall leave from
terminal blocks. Control wiring shall not leave from devices in
the compartment.
4.14.4 Terminal Blocks
4.14.4.1 All terminal blocks shall be rated 600 volts minimum and
suitable for holding spade type or ring type lugs.
4.14.4.2 A maximum of two wires may terminate at each terminal.
4.14.4.3 Terminal blocks shall be arranged and positioned for easy
access for making external cable terminations, testing,
inspection and maintenance.
4.14.4.4 Terminal strips mounted in the low voltage compartments and
that contain circuits of 50 volts and greater shall be guarded.
4.14.4.5 A minimum of 20% spare terminals shall be provided.
4.14.5 Wire Ends and Auxiliary Devices Identification
4.14.5.1 The ends of each wire shall be tagged with the origin and
destination points or with its wire number.
4.14.5.2 Each wire shall be permanently marked at both ends in
accordance with the wiring diagrams.
4.14.5.3 All wires shall be properly identified with sleeve type wire
markers.
4.14.5.4 Adhesive-back wire markers, labels and wire holders shall not
be permitted.
4.14.5.5 Each relay, fuse block, circuit breaker, terminal block, control
switch, auxiliary switch, instrument transformer and other
auxiliary devices shall be permanently labeled in accordance
with the schematics and wiring diagrams.
4.14.5.6 Terminal block numbers shall be prefixed with the cubicle
numbers in which the terminal blocks are located.

October 2009

4.15

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

Potential Transformers
4.15.1 Unless specified as drawout or tiltout type on purchasers
PIP ELSSG03D Data Sheet, potential transformers (PT) shall be fixed
mounted.
4.15.2 Drawout PTs shall be mounted on a tilt-out or draw-out type carriage
with two handles. Means shall be provided to ground the primary of the
PT in the fully drawn out position and to isolate the primary
disconnecting devices from the operator when the PT is withdrawn.
4.15.3 PT rating shall be as shown on purchasers PIP ELSSG03D Data Sheet or
single-line diagram.
4.15.4 The PT BIL rating shall be coordinated with the switchgear BIL rating.
4.15.5 PT primaries shall be protected with current limiting fuses.
4.15.6 Secondary circuits shall be protected with fuses.
4.15.7 Means shall be provided to pad lock the draw-out or tilt-out PTs when in
disconnected position.
4.15.8 Wye-Wye PTs shall be provided with secondary loading resistors to
prevent primary fuse blowing from ferroresonance.
4.15.9 Fuse holders shall be labeled to show the size and type of fuses required.

4.16

Current Transformers
4.16.1 Current transformers (CT) shall be window type and installed in a
manner that provides for ease of maintenance or replacement.
4.16.2 CTs shall be designed to mechanically and thermally withstand the shortcircuit stresses imposed by the rating of the associated interrupter switch
for one second.
4.16.3 Except for zero sequence CTs, CTs shall have the following
characteristics:
a. 5 ampere secondary winding rating
b. Voltage rated insulation
c. ANSI metering and relaying accuracy classification in accordance
with the system ratio and class shown on purchasers
PIP ELSSG03D Data Sheet
d. CT accuracy class ratings in accordance with, IEEE C37.20.2-1999,
Table 4
4.16.4 CTs shall be sized to prevent saturation during maximum system faults.
4.16.5 CT polarity markings shall be visible when access doors or barriers are
opened or removed.

4.17

Instruments, Meters, Control Devices and Indicating Lights

4.17.1 If specified on the purchasers PIP ELSSG03D Data Sheet, each load
interrupter switch shall be provided with the following devices:
a. Red indicating light - Switch closed

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b. Green indicating light - Switch open

c. Other colors of indicating lights
d. Control switch for switch operation (open-closed)
e. A microprocessor-based monitoring device to indicate the following
minimum three-phase quantities: amperes, volts, kW, kWH, kVAR,
kW demand.
f.

A switchboard type ammeter with 1 percent accuracy. Scale shall

be 250 degree type and shall be linear.

g. A switchboard type voltmeter with 1 percent accuracy. Scale shall

be 250 degree type and shall be linear.
4.17.2 If specified on purchasers PIP ELSSG03D Data Sheet, space heater
ammeters shall be provided, and shall be miniature analog type, 2%
accuracy class, for indicating and monitoring space heater circuits.
4.17.3 Ammeter switches shall be four position rotary type.
4.18

Space Heaters
4.18.1 The interrupter switchgear assembly shall be equipped with space heaters
to minimize condensation.
4.18.2 Space heaters shall be powered as shown on purchasers wiring
diagrams.
4.18.3 Each vertical switchgear assembly shall be provided with a space heater
rated at 240 volts.
4.18.4 Space heaters shall be sized to provide the required heat output if
operated on a 120 volt system.
4.18.5 Space heaters shall be provided with high temperature wiring within 6
inches (152 mm) of the heater terminals.
4.18.6 Space heaters shall be mounted on a stand-off insulator and provided
with means for personnel protection from thermal burns.
4.18.7 A caution nameplate, as shown in Figure 1, shall be provided on the door
of each cubicle that contains space heaters.
OBSERVE CAUTION EXTERNAL POWER SOURCE
Figure 1

4.18.8 An over-current protection and disconnect for each space heater circuit
shall be provided in each vertical switchgear assembly.
4.18.9 If specified on purchasers PIP ELSSG03D Data Sheet, each space heater
in the vertical switchgear assemblies shall be controlled by a humidistat
or thermostat. The humidistat or thermostat shall be equipped with an
ammeter and a bypass switch as specified.

October 2009

4.19

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

Paint
4.19.1 The switchgear enclosures shall be cleaned and treated for rust
resistance.
4.19.2 The inside of the switchgear control compartment shall be painted as
specified on purchasers PIP ELSSG03D Data Sheet.
4.19.3 Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet,
exterior finish color for switchgear shall be ANSI No. 61, light gray.
4.19.4 One quart of touch-up paint shall be provided for each five vertical
switchgear assemblies and for each paint color used.

4.20

Test and Inspection

4.20.1 Design Tests
Copies of certified reports of all design tests described in IEEE C37.20.3
shall be provided to the purchaser.
4.20.2 Production Tests
4.20.2.1 Certified reports of all production tests described in IEEE
C37.20.3 shall be provided.
4.20.2.2 The control wiring insulation test shall be performed by
applying 1500 volts to ground, 60 Hz for one minute.
4.20.2.3 Switchgear mounted devices that have been individually tested
may be disconnected with the permission of the purchaser.
4.20.2.4 All control wiring shall be checked for functional operation to
verify the correctness of wiring.
4.20.2.5 Ratio and polarity of all current transformers shall be verified.
4.20.3 To meet conformance requirements, assemblies shall successfully pass
all tests described above.
4.20.4 Purchaser reserves the right to observe the manufacturing, fabrication or
any part of work which concerns the subject equipment; inspect materials
documents and manufacturing operations; witness final test; and evaluate
results of non-destructive examinations, if specified on the purchasers
PIP ELSSG03D Data Sheet.
4.20.5 Purchaser or purchasers inspector shall be provided with free plant
access, suitable facilities, and seven working days notice of scheduled
work on the contract.

4.21

Nameplates and Labels

4.21.1 Permanent engraved lamacoid nameplates shall be provided identifying
each compartment front mounted instruments and devices, including
transformers, interrupter switches, and auxiliary compartments.
4.21.2 Equipment and terminal blocks within the compartments shall be
suitably identified.
4.21.3 Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet,
nameplates shall be mounted with self tapping stainless screws.

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4.21.4 Permanent engraved lamacoid nameplates shall be provided on each bay

on front and rear identifying the circuits fed by the load break switch.
4.21.5 All devices inside the compartments shall be identified with engraved
lamacoid nameplates or machine printed adhesive acrylic labels.
4.21.6 A stainless steel nameplate or machine printed permanent label showing
suppliers name, type and identification number, year of manufacture,
continuous current rating, interrupting rating in amperes, and maximum
voltage rating shall be provided on the front outside of each switchgear
assembly.
4.22

Documentation
4.22.1 One reproducible set of drawings shall be provided plus the specified
number of copies of all documentation and operating manuals as
specified on purchasers PIP ELSSG03D Data Sheet.
4.22.2 Unless otherwise specified on purchasers PIP ELSSG03D Data Sheet,
format for reproducible drawings shall be CAD convertible .dxf
electronic format.
4.22.3 Drawings and data requirements shall be as shown in Table 1.
Table 1. Documentation Requirements

A
With
Bid

B
For
Review
X

C
Final
Certified
X

D
As
Built
X

X
X

X
X
X
X(1)

X
X

X
X

X
X

Description
Bill of materials giving schematic identification, quantity,
make, rating, model, and manufacturer of component
Extended warranty information
Proposed layout of equipment, showing estimated
dimensions and weights
Equipment drawings, showing floor plans, front view
elevations, relay and control device panel layouts, typical
sectional views. Drawings shall show all locations of all
equipment and devices.
Installation drawings, showing dimensions and weights of
all shipping sections and location and type of all
interconnections between shipping splits
Connection wiring diagrams for all electrical equipment
3-line, and control schematic diagrams
Certified Test Reports
Installation, Operation, and Maintenance Manual
Complete parts list
Recommended spare parts list with pricing

Notes:
A. These documents shall be provided with the proposal.
B. These documents shall be provided for the purchasers review and authorization to proceed
before fabrication.
C. These documents shall be provided as part of the final certified document submittal.
(1) Equipment shall be shipped with one set of installation, operation, and maintenance
manuals.
D. The final as-built documents shall be provided within 2 weeks following shipment.

October 2009

4.23

PIP ELSSG03
Design and Fabrication of Medium Voltage Metal-Enclosed Load Interrupter Switchgear

Shipment
4.23.1 Details on shipping requirements shall be furnished by purchaser in the
contract documents.
4.23.2 Yellow tags, marked TO BE REMOVED BEFORE EQUIPMENT IS
PLACED IN SERVICE, shall be attached to all temporary shipping
braces.
4.23.3 Instructions for storage of equipment shall be attached to the equipment.
4.23.4 Equipment shall be protected from weather elements during shipping.
4.23.5 One set of installation, operation, and maintenance manuals shall be
shipped with the equipment.

4.24

Conflict Resolution
Any conflicts between the referenced documents shall be identified in writing to
the purchaser for resolution. If resolving conflicts, the following order of
precedence shall apply:
a. Purchase order
b. One line diagram and associated documents
c. Purchasers PIP ELSSG03D Data Sheet
d. This Practice
e. Referenced standards

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