TO: NECA 400-200X ANSI Canvass Participants FROM: Billie Zidek ...

TO: NECA 400-200X ANSI Canvass Participants 

FROM: Billie Zidek 

Director of Standards 

DATE: December 12, 2006 

RE: Revision of NECA 400, Standard for Installing and Maintaining 

Switchboards, as an American National Standard 

As a result of comments received on the first ballot, the proposed standard has 

been revised. Section 6 has been completely rewritten for your review and 

comment. 

NECA 400-200x reballot is attached for your review. Please note that the 

Foreword and Annexes are not a part of the proposed American National 

Standard. 

Also enclosed is a copy of the canvass list for this standard indicating the various 

interests represented and a comment response form. 

Action Request: 

After completing your review, please email or fax your ANSI canvass ballot to 

301-215-4500. We would appreciate receiving your response on or before 

Monday, January 29, 2007. 

NATIONAL ELECTRICAL CONTRACTORS ASSOCIATION 

3 Bethesda Metro Center, Suite 1100, Bethesda, MD 20814 

301-657-3110 x546 ℡; 301-215-4500 �; billie.zidek@necanet.org �

Date: March 30, 2006 

ANSI CANVASS REAFFIRMATION 

LETTER BALLOT 

Ballot Due Date: January 29, 2007 

TOPIC: Revision of NECA 400-200X, Standard for Installing and 

Maintaining Switchboards, as an American National Standard. 

QUESTION: Should this standard, developed by the National Electrical 

Contractors Association (NECA), be approved as an American 

National Standard? 

_____ Yes No technical changes required. 

_____ Yes With Editorial Comments 

_____ No Technical changes required (see attached file). 

_____ Abstain If you find you cannot vote “yes” or “no” and 

want to be recorded as abstaining, please explain 

the reasons for your abstention on the reverse 

side. 

Signature: ___________________________________________ 

Name: ___________________________________________ 

Email Address: 

Organization 

______________________________________ 

Represented: ______________________________________ 

Phone No.: ______________________________________ 

Fax No.: ______________________________________ 

Date: ______________________________________ 

Return to: 

Billie Zidek 

Standards & Safety 

National Electrical Contractors Association 

3 Bethesda Metro Center, Suite 1100 

Bethesda, MD 20814 

301/215-4546 ℡ 

301/215-4500 � 

billie.Zidek@necanet.org

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NECA 400-200X – Reballot Draft 

TABLE OF CONTENTS 

Foreword..........................................................................................................................ii 

1. Scope .......................................................................................................................1 

2. Switchboard Receiving, Handling and Storing ....................................................2 

3. Installation ...............................................................................................................5 

4. Pre-Energizing Checkout Procedure...................................................................15 

5. Energizing the Switchboard.................................................................................18 

6. Switchboard Maintenance ................................................................................19 

7. Adverse Circumstances .......................................................................................27 

8. Recommended Torque Values.............................................................................30 

9. Switchboard Insulation Resistance Chart ..........................................................32 

10. Operations and Maintenance Documents.......................................................33 

Appendix A: Reference Standards .............................................................................34 

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(This foreword is not part of the standard) 

Foreword 

National Electrical Installation Standards (NEIS ® ) are designed to improve 

communication among specifiers, purchasers, and suppliers of electrical 

construction services. They define a minimum baseline of quality and 

workmanship for installing electrical products and systems. NEIS are intended to 

be referenced in contract documents for electrical construction projects. The 

following language is recommended: 

Deadfront distribution switchboards rated 600 volts or less shall be 

installed and maintained in accordance with NECA 400, Standard for 

Installing and Maintaining Switchboards. 

Use of NEIS is voluntary, and the National Electrical Contractors Association 

(NECA) assumes no obligation or liability to users of this publication. Existence 

of a standard shall not preclude any member or non-member of NECA from 

specifying or using alternate construction methods permitted by applicable 

regulations. 

This publication is intended to comply with the edition of the National Electrical 

Code (NEC) in effect at the time of publication. Because they are quality 

standards, NEIS may in some instances go beyond the minimum safety 

requirements of the NEC. It is the responsibility of users of this publication to 

comply with state and local electrical codes when installing electrical products 

and systems. 

Suggestions for revisions and improvements to this standard are welcome. They 

should be addressed to: 

NECA Standards & Safety 

3 Bethesda Metro Center, Suite 1100 

Bethesda, MD 20814 

(301) 657-3110 telephone 

(301) 215-4500 fax 

neis@necanet.org 

www.neca-neis.org 

To purchase NEIS, contact the NECA Order Desk at (301) 215-4504 tel, (301) 

215-4500 fax, or orderdesk@necanet.org. NEIS can also be purchased in .pdf 

download format at www.neca-neis.org/standards. 

Copyright © 200x, National Electrical Contractors Association. All rights reserved. Unauthorized 

reproduction prohibited. 

National Electrical Installation Standards and NEIS are trademarks of NECA, National Electrical 

Code and NEC are registered trademarks of the National Fire Protection Association. 

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1. Scope 

This standard describes installation procedures for deadfront distribution 

switchboards rated 600 volts or less. 

1.1 Products and Applications Included: 

It also covers periodic routine maintenance procedures for switchboards, and 

special procedures to be used after adverse circumstances such as a shortcircuit, 

ground-fault, or immersion in water. 

1.2 Regulatory and Other Requirements: 

a) All information in this publication is intended to conform to the National 

Electrical Code (ANSI/NFPA 70). Installers should always follow the NEC, 

applicable state and local codes, manufacturer’s instructions, and contract 

documents when installing switchboards. 

b) Only qualified persons familiar with the construction and installation of 

switchboards should perform the work described in this publication. It is 

recommended that all work be performed in accordance with NFPA 70E, 

Standard for Electrical Safety in the Workplace. 

c) General requirements for installing electrical products and systems are 

described in NECA 1, Standard Practices for Good Workmanship in 

Electrical Contracting (ANSI). Other NEIS provide additional guidance for 

installing particular types of electrical products and systems. A complete 

list of NEIS is provided in Annex A. 

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2. Switchboard Receiving, Handling and Storing 

2.1 Receiving the Switchboard 

a) Unload carefully, observing all packing label warnings. 

b) Use forklifts or other loading equipment only for palletized 

shipments. 

c) Leaving protective coverings in place as much as possible, open 

and inspect the switchboard completely for shipping damage. 

Undamaged material should be carefully repacked unless intended 

for immediate installation. 

NOTE: Depending on company policy or project circumstances, it may be 

necessary to receive, unpack and check all material at the company shop 

or other staging area, in which case, careful repacking is essential. 

2.2 Handling the Switchboard 

Switchboards are typically large, bulky pieces of equipment weighing several 

hundred pounds or more. The packing list will provide the actual weight of each 

item. Handle the switchboard properly in order to avoid injury to personnel and 

damage to equipment. Verify that the lifting capacity of the handling equipment 

is more than the shipping weight and type of truck making the delivery prior to 

receiving the shipment. Delivery on an open truck at the job-site is 

recommended. 

Suitable protection against the weather must be provided if the equipment is 

designed only for indoor installation (NEMA Type 1). 

There are two primary ways of lifting the equipment: with lifting straps and with 

lifting straps, using a sling instead. Using the manufacturer’s lifting straps is the 

preferable method when these are supplied. 

2.2.1 Handling with lifting straps 

Switchboard manufacturers provide lifting straps as standard equipment when 

the weight of the switchboard section(s) does not exceed the recommended 

capacity of the lifting straps. Use a rigid spreader or a spanner beam to provide 

vertical lift on the lifting straps (see Figure 1), and avoid damage to the frame or 

finish. Follow lifting warning labels on the switchboard. 

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2.2.2 Handling without lifting straps 

Lifting straps are not furnished on switchboards when the weight of the section(s) 

exceeds their capacity, or when the lifting straps would cause stress to the 

switchboards. They also are not provided when the design does not permit, such 

as NEMA Type 3R outdoor equipment with overhangs. These switchboards can 

be handled by either slings, forklifts, rollers or a combination of these means. 

Typically, a handling warning is provided on those switchboard sections for which 

lifting straps are not provided. 

a) Sling: A crane or suitably rigged equipment with a chain arranged 

in a sling, or wire cable with safety hooks and shackles, should be 

used to lift a switchboard shipping section not equipped with lifting 

straps. Rig the sling completely around the switchboard and 

shipping stringers (see Figure 2), and use a forklift or jacks to lift 

the switchboard vertically off the floor to attach the sling. 

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b) Forklifts: Forklifts are an alternate method of handling 

switchboards. Verify that the capacity of the forklift is more than the 

weight of the load to be lifted. Always insure that the form lengths 

extend under the entire switchboard and extend beyond the 

opposite side (see Figure 3). 

c) Rollers: If equipment is not available for lifting the switchboard, or 

the ceiling is not high enough, rollers suitable for the application 

may be used to move the switchboard into position. A forklift or 

jacks can be used to initially lift the switchboard and position it on 

the rollers. Rollers should be positioned approximately every 18 

inches (457 mm), and be at least the width of the switchboard for 

stability. Extreme care should be taken when using rollers due to 

switchboard height and weight. Rollers are most suitable for 

moving switchboards on a level surface; use a winch or chainfall 

where inclines must be traveled over to prevent “runaway.” 

2.2 Storing the Switchboard 

a) Cover the switchboard with a tarp or plastic to keep the equipment 

from getting wet and accumulating dust or debris (cement dust can be 

corrosive and cause insulation breakdown when it accumulate across 

insulators). The cover should be heavy enough to keep from tearing 

during wind gusts at the storage location. 

b) To reduce condensation within the switchboard, store the switchboard 

indoors whenever possible to keep harmful condensation from 

accumulating inside the enclosure. 

c) Install a minimum of 250 watts of heat per vertical section, even for 

outdoor enclosures. Remove all loose packing or materials that could 

catch fire prior to applying the heat. 

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3. Installation 

Proper installation is essential to the proper operation of all switchboard 

components. Thoroughly study associated instruction manuals, literature and 

drawings before attempting to install the switchboard. In most cases, this 

information will already have been requested prior to the shipment of the 

switchboard to enable advanced planning. 

3.1 Location 

a) The floor plan of the structure for an inside switchboard, or the site 

plan for an outdoor switchboard will show the area where the 

switchboard is to be installed. The location of the switchboard should 

comply with all building codes and at a minimum should meet the 

working space requirements of the NEC, Section 110.26. 

NOTE: Provisions for temporary ramps or installation hoists may require 

working clearances greater than NEC minimums. 

b) Consult the switchboard drawings to determine where accessibility is 

required for the switchboard (e.g., a rear access switchboard cannot 

be placed against a wall). 

c) Indoor switchboards in damp locations require shielding to prevent 

moisture and water from entering and accumulating. If the room 

temperature around the indoor switchboard is not between 77° – 104°F 

(25 – 40°C), use a minimum of 250 watts of heating per vertical section 

until the suitable environment can be provided. 

d) In locations where a sump pump is required, the pump should be 

properly working before the switchboard is installed to prevent 

accumulation of water that may seriously damage the switchboard and 

its internal components (see Section 7, Adverse Circumstances). The 

sump pump should be connected to a standby power source. 

3.2 Foundation Preparation 

a) The floor or foundation on which the switchboard will be installed needs to 

be strong enough to support the weight of the switchboard without bowing 

or sagging. A concrete surface is preferred. 

b) In special instances where earthquakes may occur, 4000 psi concrete 

should be used along with specific anchoring means such as stud 

anchors, sleeves anchors or concrete anchor bolts (anchoring hardware is 

not supplied as a standard item with most switchboards). Performance of 

the switchboard under earthquake conditions is directly related to the 

foundation preparation. 

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NOTE: Local building codes may have seismic requirements that affect 

switchboard installation. Installers should consult these codes or 

coordinate with the general contractor prior to installing switchboards. 

c) A level mounting pad raised four inches (100 mm) above the general floor 

level is typical with the surrounding floor area gently sloping toward a 

drain. To ensure correct bus bar alignment within the switchboard and to 

enable bolting vertical sections together it is critical that the mounting pad 

or floor be smooth and level. 

NOTE: Provisions for temporary ramps or installation hoists may require 

working clearances greater than NEC minimums. 

d) If floor channels are embedded in the concrete pad, they should be level 

over the entire length of the switchboard in order to avoid distortion of the 

switchboard structure. 

e) Before pouring the concrete for the pad, install all conduits including future 

conduits required for bottom entry into the switchboard. Consult the 

switchboard drawing bottom view during this process to verify that the 

conduit layout matches the available conduit entry area into the 

switchboard. The manufacturer will already have taken into account the 

NEC and product listing requirements for conduit entry. 

f) Embedded conduits typically project above the finished pad approximately 

2 inches (50.8 mm). If embedded conduits project more than 2 inches 

(50.8 mm) above the concrete pad, it may be necessary to lift each 

shipping section vertically into place using a crane, timbers, jacks, or 

forklift. After the sections are installed, and approximate extension 

sleeves added to the conduits, the maximum projection should be 3 

inches (76 mm); NEC Section 408.5 prohibits projections greater than 3 

inches (76 mm). 

3.3 General Installation Instructions 

a) Clean dirt and debris from the pad and surrounding area where the 

switchboard will be located before moving the switchboard into its final 

position. 

b) Remove the shipping skids before installing the switchboard on the 

pad. 

c) If the switchboard is equipped with bottom closure plates, temporarily 

remove these plates and set them aside. Cut holes for the conduits 

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based on that section’s conduits. Once the vertical sections have been 

installed, reinstall the bottom closure plates. 

d) Block the opening of each conduit with material that rodents will not be 

able to gnaw through, squeeze through, or push out of the way. 

Bottom closure plates will not keep out rodents that come in through 

the conduits. 

3.4 Installing Vertical Sections 

3.4.1 Initial placement 

a) If the switchboard has incoming cables or busway near or in its center, 

start with that vertical section first and work outward on each side. 

b) If the switchboard is left-feed, start from the left. If right-fee, start from 

the right. 

c) If the switchboard is close-coupled to a transformer, start at the 

transformer and work away from the transformer. 

3.4.2 Positioning 

Position each shipping section carefully, following the instructions in 2.2 Handling 

the Switchboard. Level with shims if necessary, and align each section with the 

previous section. Proper alignment will make joining the structures and throughbus 

easier. 

NOTE: Improper alignment of the through-bus may result in property loss, death, 

or serious injury. 

3.4.3 Lifting straps 

Remove lifting straps or slings so that vertical sections can be joined flush. 

Leave lifting straps or hardware on the switchboard if their removal is not 

required to join adjacent sections flush together. 

3.5 Joining Switchboard Sections 

a) Open or remove the front and, if necessary, the rear door or panels 

that provide access for bolting adjacent shipping sections together. 

b) Torque the bolts based on the manufacturer’s instructions. 

NOTE: The authority having jurisdiction (AHJ) may require that all bolts 

connecting bus sections be inspected for proper torque prior to closing up the 

switchboard. 

3.6 Anchoring the Switchboard 

Switchboard sections are freestanding structures but hard bumps or shifting 

movements can result in damage to interior components, conduit hubs and 

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cable/busway connections. Therefore, each vertical section of the switchboard is 

anchored to the floor. Some manufacturers provide formed base channels that 

run the entire length of the switchboard, mounting holes in the structure base, or 

both (see Figure 4). 

Anchor each section using the hardware recommended (but not usually supplied 

by) the switchboard manufacturer and torque the bolts to their recommended 

value. 

3.6.1 Seismic considerations 

Carefully follow the plans and specification when anchoring a switchboard for 

seismic conditions since the top of the switchboard structure can move as much 

as 3 inches (76 mm) in any direction. 

NOTE: Local building codes may have seismic requirements that affect 

switchboard installation. Installers should consult these codes or coordinate with 

the general contractor prior to installing switchboards. 

3.7 Installing Cables 

Install the incoming services conductors and load side cables after all 

switchboard sections are properly joined together and the entire switchboard 

structure is anchored to the floor. If the switchboard is in a seismic environment 

and cables or busway enter at the top of the switchboard, it is necessary to take 

into account the motion of the top of the switchboard during a seismic 

occurrence. 

NOTE: If the switchboard consists of only one shipping section, proceed to 

Section 3.10. 

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3.8 Installing Interconnections between Switchboard Sections 

Switchboard vertical sections are electrically connected together using either 

through-bus or cables. 

3.8.1 Through-bus splice connections 

Through-bus splice connections are extremely important to the performance of 

the switchboard, since these connections are expected to carry the full current 

intended for their operation. Failure to properly make through-bus splice 

connections may result in property damage, death, or serious injury. 

a) Through-bus splice kits are provided by the switchboard manufacturer 

when more than one section is required to be electrically connected 

together by through-bus. 

b) Splice kits may come in separate boxes, be installed on the throughbus 

of one or more vertical sections, or be stored inside the sections to 

be spliced. 

c) Follow the proper sequence of hardware installation, as specified in the 

manufacturer’s installation instructions. Install conical washers such 

that their convex or “top” side is against the nut (see Figure 5). 

d) Torque the splice bolts to their recommended values. Mark each 

torqued connection with a permanent marker. 

e) The through-bus of some switchboards is covered with an insulating 

material. Follow the manufacturer’s instructions for installing insulation 

on each through-bus splice connection. 

3.8.2 Cable Interconnections 

Install the interconnection cables (which may or may not be supplied by the 

manufacturer) between sections as shown on manufacturer’s drawings. Torque 

all connections to the manufacturer’s recommended values. 

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3.9 Ground Bus Splice Connections 

Ground bus splice kits are provided by the switchboard manufacturers when 

more than one section is required to be electrically connected (see Figure 6). 

Proper installation of ground bus splice connections is essential to providing a 

low-impedance path to ground for temporary current resulting from phase-toground 

faults. 

a) Splice kits may come in separate boxes, be installed on the ground 

bus of one or more sections, or be stored inside the switchboard 

sections. 

b) Follow the proper sequence of hardware installation, as specified in the 

manufacturer’s installation instructions. Install conical washers such 

that their convex side is against the nut. 

c) Torque the splice bolts to the recommended value. Mark each torqued 

connection with a permanent marker. 

3.10 Grounding and Bonding 

3.10.1 Ground systems – service-entrance switchboards and 

switchboards used on separately derived systems 

NEC Section 250.64 describes complete grounding requirements for grounded 

separately derived systems. 

a) Run a grounding electrode conductor from the grounding electrode at 

the installation site to the grounding electrode conductor connection, 

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commonly called a ground lug, located on the switchboard ground bus 

(see Figure 7). 

b) NEC Section 250.67 describes requirements for grounding electrode 

conductor material, installation, and size. 

c) Torque the ground lug binding screw based on the manufacturer’s 

recommendation or crimp in accordance with the crimp tool’s 

instructions. 

d) For service entrance equipment, or a switchboard used on a 

separately derived system, install the system bonding jumper between 

the neutral bus and the ground bus. A label on the front of the 

switchboard will identify the section(s) that incorporate the system 

bonding jumper(s). 

e) Torque the hardware of the main bonding jumper in accordance with 

the manufacturer’s recommendations. 

f) Equipment ground-fault protection will be rendered inoperative if the 

system is grounded down-stream from the ground fault sensor. 

g) For switchboards with multiple source of power, there will be two or 

more main bonding jumpers to install. 

3.10.2 Ungrounded systems – service-entrance switchboards 

and switchboards used on separately derived systems. 

NEC Section 250.64 describes complete grounding requirements for ungrounded 

separately derived systems. 

a) Run a grounding electrode conductor from the ground electrode at the 

installation site to the grounding electrode conductor connection, 

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commonly called the ground lug, located on the switchboard ground 

bus (see Figure 7). 

b) NEC Section 250.66 describes requirements for grounding electrode 

conductor material, installation, and size. 

c) Torque the ground lug binding screw based on the manufacturer’s 

recommendation or crimp per the crimp tools instruction. 

3.11 Busway Connections 

Power is often distributed from switchboards using busway, also called bus duct. 

Busway is provided in different configurations by different manufacturers; one 

typical configuration is shown in Figure 8. 

a) When connecting busway, install conical washers so the convex side 

of the washer is against the nut. 

b) Confirm proper phasing of the busway before energizing the busway 

run. 

c) Do not use the switchboard to support the weight of the busway. 

Support the busway independently of the switchboard. 

3.12 Conduit Area 

a) The switchboard conduit entry drawings show the available conduit 

entry for the switchboard. External circuit cables for each section 

should be routed into and through these designated conduit areas, 

then routed internally to their designed termination areas. 

b) Do not use the switchboard to support the weight of the conduits. 

Support the conduits independently of the switchboard. 

c) If a bottom plate is furnished, remove it to cut holes for the conduit and 

cable entry. Bottom plates with holes are not furnished as a standard 

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item. Reinstall the bottom plates after the holes are made. Saw kerf 

between conduit holes in bottom plate for installations where individual 

conduits, such as duct bank risers. 

d) Under seismic conditions, the top of the switchboard may move up to 3 

inches (76 mm) in any direction. Any cables entering the top of the 

switchboard need sufficient slack to accommodate this motion. If the 

floor of the switchboard is designed for movement during a seismic 

event, the cables entering the bottom of the switchboard should also 

have enough slack to accommodate this motion. 

e) Use approved hubs and ring connectors to protect the cables and 

prevent condensation from entering the switchboard through the 

conduits. 

f) Bond all conduits, stubs, and ring connectors to the switchboard 

enclosure following the manufacturer’s recommendations. 

3.13 Cable Pulling 

Switchboard components are arranged to provide clearance and wire bending 

space for both line and load cables. Each cable should be pulled into the 

switchboard to conform to the arrangement specified on the switchboard 

drawings. 

a) Verify that the lugs correspond to the switchboard cable schedule and 

are suitable for the cables being terminated. Consult the markings on 

overcurrent protective devices to determine that the conductor size 

range is correct and the temperature rating is appropriate. Conductors 

rated 194°F (90°C) are permitted to be used with most connectors and 

terminals, but only at 167°F (75°C) ampacity. Some overcurrent 

protective devices, mostly those listed for operation at 100 percent of 

rated ampacity, require the use of 194°F (90°C) conductors sized at 

167°F (75°C) ampacity. 

b) Consult NEC Article 310 to calculate the proper size and number of 

conductors for the loads served. 

c) Prior to pulling the cables into the switchboard, plan ahead as to which 

overcurrent device to cable first. This is particularly important for 

group-mounted constructions. 

d) Cable pulling lubricants should not be allowed to drip or come into 

contact with overcurrent devices and/or plating of the bus bars. 

Remove all pulling compound from the interior of the switchboard prior 

to energizing the unit. 

e) Position the conductors in the switchboard enclosure so they are not 

subject to physical damage. If any conductors are in contact with 

structural members, place suitable protective material at the contact 

point to protect the cable insulation. 

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f) NEC Section 300.20(a) requires that all phase and grounded 

conductors of the same circuit pass through the same metal opening 

together. Otherwise, a magnetic loop will be created causing 

overheating within the switchboard. 

g) Where required, brace or lace the conductors in accordance with the 

manufacturer’s instructions or consulting engineer’s specification. 

h) Train cables within wire gutters of switchboards in a neat and 

workmanlike manner. 

3.14 Cable Terminations 

Terminating and tightening cable connections to the manufacturer’s 

recommended torque is imperative for a satisfactory connection. Follow these 

steps when terminating conductors at the switchboard: 

a) Strip a sufficient length of insulation from the cable end to fit into the 

full length of the lugs barrel. Use a proper insulation stripping tool to 

avoid nicking conductor strands. Stripping cable too long should be 

avoided since the through-air clearance could be reduced below the 

minimums required by the NEC. 

b) Mechanical lugs (set-screw type) are the most common type of 

connector furnished with switchboards. Torque these lugs in 

accordance with the manufacturer’s recommendations to avoid 

stripping threads or cracking the lug body. 

c) When compression lugs are used to terminate aluminum conductors, 

remove oxides from the conductors and apply an anti-oxidant 

compound to the aluminum conductor before inserting into the lug 

body. Oxides on aluminum conductors are poor conductors and will 

cause abnormal heating at the connection. 

d) Remove compression lugs from their point of termination in order to 

crimp them onto cables. Follow the manufacturer’s recommendation 

as to the proper number of crimps and their position on the lug. Use 

the recommended sealant. Re-install the crimp lugs to the lug pad and 

toque the hardware used with the lugs. 

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4. Pre-Energizing Checkout Procedure 

4.1 General 

Conduct a complete inspection of the switchboard before it is energized to 

ensure that the components within the switchboard function properly. 

a) Check all field installed bus bar connections for correct torque value. 

b) Check all accessible connections for tightness. 

c) Check all factory and field installed lug terminations for the correct 

torque value. 

d) Visually check the bussing insulators for cracks and supports for 

damage. 

e) Check to insure that dents or other damage to the enclosure have not 

resulted in clearances that violate NEC requirements. 

f) Remove foam blocks, packing material, and temporary cushioning 

from the switchboard and components inside the switchboard. 

g) Check all relays, meters and instrumentation device wiring and 

terminations. 

4.2 Insulation Test 

Perform a direct current (DC) insulation test on the switchboard and record the 

value for future maintenance tests; a switchboard insulation resistance chart is 

shown in Section 9. Values less than 1 megohm are typically unacceptable. 

Prior to this test, remove control power fuses and any other equipment that 

should not be subjected to this level of potential. 

4.3 Current Transformers 

Ensure that current transformers secondary terminals are connected to a load or 

are shorted together using shorting straps or terminal block shorting screws. 

CAUTION: Open secondary terminals may have high voltages, which could be a 

hazard to people or equipment. 

The shortening means are removed when the current transformers operate 

normally with their intended load. 

4.4 Circuit Breakers and Fusible Switches 

a) Manually open and close all circuit breakers and fusible switches to 

ensure proper operation. 

b) Adjust the magnetic trip on thermal magnetic circuit breakers to their 

proper setting based on the system study or switchboard schedule. A 

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setting too low for a load that has a high peak inrush current will trip 

the circuit breaker on start-up. 

c) Electronic circuit breakers have functions such as long-time, 

instantaneous, short-time, and ground fault, that requires initial 

adjustment. Settings typically are provided in a coordination study 

prepared by the consulting engineer, or other persons responsible for 

the switchboard set-up. 

NOTE: These values typically are not found on the drawings supplied by the 

switchboard manufacturer. 

If values are not provided, consult the manufacturer’s circuit breaker 

instruction manual for values that will set the electronic circuit breaker 

functions to emulate thermal magnetic circuit breaker characteristics. 

4.5 Ground-fault Protection 

a) The trip and time-delay on ground-fault protective equipment are 

typically set by the manufacturer at their lowest settings. Adjust these 

settings based on information provided in a coordination study 

prepared by the consulting engineer, or other persons responsible for 

the switchboard set-up. 

b) Some ground-fault protection systems require field connections at the 

job site. Consult the switchboard interconnection wiring diagram for 

details. 

c) Check the ground-fault circuitry and establish that there are no 

grounds on the neutral downstream from the service entrance point. 

d) The NEC requires that the ground-fault protection system be 

performance tested when first installed, and that a written record of this 

test be available to the AHJ. A testing group with experience in 

switchboard ground-fault testing should perform an injection test. 

4.6 Interconnections 

Verify that all interconnecting wiring between switchboard sections has been 

connected. 

4.7 Power Fuses and Control Power Disconnects 

Replace all control power fuses removed in the Insulation Test (see Section 4.2) 

and turn on all control power disconnects. 

4.8 Clean-up 

Vacuum all scrap, wire, dust and other debris from the switchboard. Do not use 

compressed air to blow debris out of the switchboard, since debris may, instead, 

settle inside devices and impair their ability to function. 

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4.9 Close-up 

Replace all covers. Check for any pinched wires and close all doors. Make sure 

that the enclosure parts are properly aligned and fastened securely. 

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5. Energizing the Switchboard 

WARNING: Arc flash, arc blast, and shock hazards exist when energizing 

switchboards. Switchboards should only be energized by qualified persons, 

following work practiced defined in the NFPA 70E. 

Hazards exist in energizing a switchboard; energizing should only be 

performed by qualified electrical personnel. 

If a short circuit or ground-fault condition exists, caused by damage or poor 

installation practices, and this is not detected and corrected during the check-out 

procedures, serious personal injury and/or damage to the switchboard can result 

when the switchboard is first energized. Follow the steps below to energize the 

switchboards; read all steps before proceeding. 

Step 1 Turn off all downstream loads. No load should be on the 

switchboard when it is first energized. 

Step 2 Use remote operators, if available, to close devices and energize 

switchboards and loads for the first time. 

Step 3 Prior to energizing any circuit that supplies rotating machinery, 

verify that the phase sequence is correct. Serious damage can 

result to motors and similar equipment rotating in the wrong 

direction. 

Step 4 One by one, close each circuit breaker or fusible switch in the 

switchboard. 

Step 5 Proceed to energize (turn on) the downstream loads (lighting 

circuits, contactors, heaters, motors, etc.) one at a time. 

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6. Switchboard Maintenance 

Periodic maintenance of switchboards extends service life and increases 

reliability. Cleaning, inspection, maintenance, and testing should only be 

performed by qualified personnel on switchboards to which power has been 

turned-off, disconnected, and electrically isolated, unless required for testing, so 

that no accidental contact can be made with energized parts. Follow all 

manufacturer’s warnings and instructions. 

The interval between maintenance checks varies depending on the environment, 

such as ambient temperature and conditions in the switchboard room, and usage 

of the equipment. Perform routine inspections, such as making limited visual 

observations and recording operational data, periodically with switchboards 

energized and in service. 

Perform cleaning, inspections, maintenance and testing of switchboards at least 

annually, but as often as the operating environment requires keeping 

switchboards clean. Perform the first inspection and maintenance no more than 

one year after the original installation. Plan cleaning, inspections, maintenance 

and testing to minimize outages. 

Clean, inspect, maintain, and test switchboards following any unusual operating 

condition, such as whenever an overcurrent protective device opens, or a phaseto-phase 

short circuit or ground-fault occurs (see Section 7.1), in accordance with 

manufacturer recommendations. 

6.1 Routine Inspections 

Inspect areas and spaces around switchboards for any accumulation of dirt or 

dust. Remove any accumulations of dirt or dust. Remove trash, combustible 

material, and other debris from areas around switchboards. Use the rate of 

accumulation of dust and moisture on visible surfaces as a guide for scheduling 

cleaning, inspections, maintenance, and testing. 

Inspect switchboards for external signs of overheating. Measure and record the 

ambient temperature. Check equipment installed near switchboards that might 

be an external source of heat. Eliminate external sources of heat to 

switchboards. Check the operating temperature of switchboards that have been 

operating under normal load and at normal ambient temperature for a minimum 

of 3 hours by measuring the surface temperature of switchboard access covers, 

doors, circuit breakers and switches. If the temperature exceeds manufacturer 

recommendations, de-energize switchboard and investigate sources of 

overheating. 

Record switchboard voltage and load currents, if equipped with meters, noting 

the date and time of day. Provide comments regarding known causes of 

variations in loading, such as load additions or equipment maintenance outages. 

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Check all accessible exterior switchboard hardware for tightness. 

Visually inspect enclosures for physical damage. Repair physical damage, if 

practical and as approved by the manufacturer. Consult owner and switchboard 

manufacturer for recommendations for suitable protective barriers to prevent 

future damage. 

Inspect areas and spaces around switchboards for evidence of water or 

moisture. Eliminate sources of water or moisture, or provide suitable protection 

for switchboards from sources of water. 

6.2 Safety Procedures 

Before cleaning, inspecting, testing, or maintaining, de-energize and electrically 

isolate equipment in accordance with established procedures. Consider all 

circuits live until they are confirmed to be de-energized by testing and are locked 

out of operation. Do not work on energized equipment. Guard energized 

conductors and equipment in close proximity to work. Failure to observe these 

precautions may result in severe personal injury or death. 

Personnel working on or near energized switchboards should follow the safe 

work practices described in NFPA 70E, including the use of personal protective 

equipment (PPE) appropriate for the task being performed. 

Apply lockout/tagout procedures in accordance with documented and established 

policies and practices. Render electrical circuit conductors and circuit parts 

electrically safe by removing all sources of energy by opening all upstream 

source disconnecting means, locking and tagging out all source disconnecting 

means, verifying the absence of voltage using an approved voltage testing 

device, and guarding any exposed energized components. 

Remove the front cover of the switchboard and attach grounding leads to the line 

terminals of the main circuit breaker or main lugs, to the neutral terminal bus bar, 

if so equipped, and to the grounding terminal. 

6.3 Cleaning and Inspections 

Consult manufacturer recommendations for cleaning and inspecting 

switchboards and components. De-energize switchboards in accordance with 

Section 6.2 prior to performing any cleaning or inspections. 

Visually inspect switchboards for evidence of discoloration, abnormal dust 

accumulation, metal shards, or any other indication of overheating, wear, or other 

abnormal conditions prior to cleaning. 

Visually inspect the switchboard for signs of overheating. Discoloration and 

flaking of insulation or metal parts are indications of possible overheating. 

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Correct conditions that cause the overheating, and replace the affected parts 

before re-energizing the switchboard. 

Vacuum the inside of switchboards to remove any debris, dirt, or dust that has 

accumulated, noting anything unusual such as signs of insects or rodent activity 

or moisture. Avoid blowing dust into switchboards. Do not use a blower or 

compressed air. Maintain adequate ventilation during cleaning. 

Wipe bus bars, insulators, conductors and other parts with a clean, dry lint-free 

cloth. Do not use chemicals or petroleum-based solvents that may degrade 

plastics or insulating materials. 

Visually inspect the inside of the switchboard for moisture, condensation build-up 

or signs of any previous wetness. Moisture causes insulation failures and rapid 

oxidation of current carrying parts. Pay particular attention to conduit entrances 

and the top of the switchboard between sections. Remove any moisture present 

inside the switchboard and seal off all leaks. Replace any components that show 

evidence of damage from moisture. 

Carefully inspect all switchboard devices for any worn-out, cracked or missing 

parts. Inspect terminations, connections, and lugs for alignment, physical 

damage, burns, corrosion, discoloration, flaking, heat damage, arcing, pitting, 

melting, deterioration, carbonization, cracks, chips, breaks, partial discharge, or 

moisture. Replace damaged components. Investigate and eliminate sources of 

damage. 

Plated parts may become dark over a period of time due to oxidation. Removing 

this discoloration will reduce the thickness of the plating. Consult the 

manufacturer for recommendations regarding discoloration of parts. 

Verify that all key interlocks and door interlocking provisions are working 

properly. 

6.4 Maintenance and Testing 

Consult manufacturer recommendations for maintaining and testing switchboards 

and components. De-energize switchboards in accordance with Section 6.2 prior 

to performing any maintenance or testing. 

6.4.1 Infrared Scan 

After cleaning and inspecting switchboards and components in accordance with 

Section 6.3, perform an infrared scan in accordance with switchboard and test 

equipment manufacturer recommendations. With the switchboard de-energized, 

remove accessible covers, plates, weathershields, etc. Provide supplemental 

barriers and safety precautions during infrared scan to prevent accidental contact 

with exposed energized components. Personnel working on or near energized 

switchboards should follow the safe work practices described in NFPA 70E, 

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including the use of personal protective equipment (PPE) appropriate for the task 

being performed. 

Energize the switchboard in accordance with Section 6.6, and turn on all normal 

loads supplied by the switchboard. Perform an infrared scan of all switchboard 

electrical connections and terminals while energized and operating under normal 

load conditions. 

Use an infrared scanning device designed to measure actual operating 

temperatures, or designed to detect significant deviations from surrounding 

conditions. Provide documentation of device calibration. 

Prepare a certified report identifying the switchboard tested and describing the 

results of the infrared scan. Include notations of deficiencies detected, remedial 

actions taken, and results from retesting after remedial actions. 

Consult switchboard manufacturer for repair or replacement recommendations if 

infrared scan results indicate overheating of components. 

De-energize the switchboard in accordance with Section 6.2. 

6.4.2 Bus Bar Joints 

Consult the manufacturer’s recommendations concerning bus bar joints and retorque 

where required. Some switchboard bus bar joints are maintenance-free. 

Additional tightening after installation may degrade these connections. 

Replace parts that show indications of pitting, corrosion, discoloration or 

annealing due to overheating. Do not use abrasive materials on bus bar joints. 

Use hardware and washers of a grade identical to or better than the hardware 

replaced. 

6.4.3 Molded-Case Circuit Breakers 

a) Clean circuit breaker surfaces. Remove dust, soot, grease, moisture, and 

foreign material. 

b) Operate circuit breakers several times to exercise the mechanism and 

contacts, and to ensure smooth operation. Many circuit breakers have a 

test feature which trips, exercises and lubricates the mechanism. This 

method of exercising circuit breakers should be used if available. If 

unavailable, operate circuit breakers manually. Do not oil or grease parts 

of molded case circuit breakers. Replace circuit breakers that do not 

operate smoothly. 

c) Check circuit breakers for visual defects, chips, cracks, breaks, burns, and 

deterioration. Visually check circuit breakers for evidence of overheating 

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and thermal damage. Investigate and eliminate sources of overheating. 

Replace damaged circuit breakers. 

d) For circuit breakers that use solid-state circuitry or a microprocessor, run 

the self-diagnostic program, if available. For electronic circuit breakers, 

use the test set to run trip unit test automatically with user prompts. 

Repair or replace circuit breakers in accordance with manufacturer 

recommendations. 

6.4.4 Bolted Pressure Switches 

Exercise bolted pressure switch operating mechanisms. Check the cover 

interlock with the switch in the “on” position. The cover should not open using 

normal hand force. Lubricate parts using materials and methods in accordance 

with manufacturer’s recommendations. 

6.4.5 Fusible Switches 

a) Thoroughly clean fusible switches inside and outside. Clean contact 

areas of fuses and fuse holders. Wipe insulating areas of fuses with a 

clean, dry, lint-free cloth. 

b) Operate each switch several times to ensure that all mechanisms are free 

and in proper working order. Check switches for damaged or broken 

parts, free movement, corrosion, dirt, and excessive wear. Verify proper 

blade penetration, travel stops, and mechanical operation. Repair or 

replace switches in accordance with manufacturer recommendations. 

c) Inspect contact surfaces, blades, and jaws for discoloration, overheating, 

pitting, arcing, and corona. Inspect arc chutes. Clean and dress readily 

accessible copper electrical contacts, blades, and jaws in accordance with 

manufacturer recommendations. Repair or replace burned contacts. 

Many contact surfaces, such as arcing contacts, are silver tungsten or 

other types of materials that must never be dressed. When contacts of 

these materials require maintenance, they must be replaced. If contact 

clips have lost their tension, replace clips or replace the switch. Consult 

the manufacturer for recommendations. 

d) Tighten fuse holder connections in accordance with manufacturer 

recommendations. Inspect each fuse holder to determine whether it 

seems to be adequately supporting the fuse and that the fuse holder is 

securely attached to the mounting base. Inspect fuse clips for 

discoloration, overheating, corrosion, or physical damage. Replace weak 

or burned clips. Install new fuse clips and suitable clamps. Use 

manufacturer’s replacement parts. 

e) Lubricate operating mechanisms and sliding contact surfaces, if required, 

according to manufacturer’s instructions. If no instructions are given on 

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the devices, sliding copper contacts, operating mechanisms, and 

interlocks may be lubricated with clean, light grease. Wipe off excess 

lubrication to avoid contamination. 

f) Check the cover interlock with the switch in the “on” position. The cover 

should not open using normal hand force. Inspect switches for any 

damaged or broken parts. Check the fuse mounting clips or bolted 

contact area for corrosion or discoloration due to overheating. Replace 

damaged or broken parts as necessary. 

6.4.6 Inspecting and Replacing Fuses 

Ensure that equipment is de-energized before inspecting and replacing fuses. 

Test line and load terminals of switches for the presence of voltage before 

replacing fuses. Turn the switches to the “off” position before opening the door. 

Do not defeat cover interlocks to gain access to fuses. 

Visually inspect switch blades to verify that all blades are disconnected from the 

line connections. Consult the manufacturer for recommendations when blades 

do not disconnect from line connections. 

a) Check all fuses to assure that the correct type and rating are installed. 

Where renewable fuses are used, examine fuse links to ensure that the 

correct link is installed. 

NOTE: Certain switchboard manufacturers do not recommend the use of 

renewable link fuses in their equipment. 

b) Look for fuses that have been bridged with wire, metal strips, disks, or 

appear to have been forced or hammered in, etc. Replace with correct 

fuses and consult the manufacturer for recommendations for preventing a 

recurrence. 

c) Look for evidence of overheating of cartridge fuses. Replace fuses having 

discolored or weakened casings. Investigate the cause of overheating. 

d) Inspect ferruled or knife blades of cartridge fuses for corrosion or 

oxidation. Clean and polish contact surfaces. Clean surfaces with a noncorrosive 

cleaning agent. Plated parts may become dark over a period of 

time due to oxidation. Removing this discoloration will reduce the 

thickness of the plating. Consult the manufacturer for recommendations 

regarding discoloration of parts. 

e) Measure fuse resistance. Investigate fuse-resistance values that deviate 

from each other by more than 15 percent. Replace defective or partiallyburned 

fuses. Re-tighten plug fuses. 

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f) Replace fuses with fuses of like types and ratings. Ensure that noncurrent-limiting 

devices are not used as replacements for current-limiting 

devices. Do not defeat any rejection feature in any switchboard fusible 

device. 

6.4.7 Ground-Fault Protection Systems 

a) Check the torque of terminal connections on ground-fault protection 

systems annually. Inspect for corrosion and for physical, thermal, and 

electrical damage. Replace any damaged components. 

b) Test the ground-fault protection system in accordance with manufacturer 

recommendations. Testing may be conducted with or without tripping 

main or branch overcurrent protective devices. Testing with trip is 

preferable since it ensures the whole system is functioning. Energize the 

switchboard in accordance with Section 6.6 prior to testing. 

c) If the ground-fault protection system does not operate properly and 

additional equipment has been connected to the installation since the last 

maintenance test/check, de-energize the entire system in accordance with 

Section 6.2, disconnect the main bonding jumper, and check for continuity 

between the neutral and ground on the load-side of the main bonding 

jumper. If grounds are found, remove them and test again. If no grounds 

are detected and the ground-fault protection system is still not functioning 

properly, consult the switchboard manufacturer for recommendations. 

d) If the ground-fault protection system does not operate properly and no 

additional equipment has been connected to the installation since the last 

maintenance test/check, check the devices for physical or electrical 

damage and replace accordingly. Check wiring for damage or loose 

connections and correct any problems found. Consult the switchboard 

manufacturer for recommendations. 

6.5 Insulation Resistance Test 

Perform an insulation resistance test on switchboards using a 1000 V dc 

megohmmeter. Disconnect all accessories and electronic devices that may be 

subjected to the test voltage. Test from phase-to-ground and from phase-tophase 

with all switches and circuit breakers in both the open and closed 

positions, all instrumentation and control fuses removed, and no loads connected 

to the switchboard. Ground all phases not being tested. Connect megohmmeter 

between each phase and ground and between each phase. Measure insulation 

resistance at one minute intervals following the application of the test voltage. 

Record the megohm values of each phase and between each phase, along with 

the description of the instrument, voltage level, humidity, temperature, time, and 

date of the test. Consult switchboard manufacturer's published data for 

acceptable test results. If published data is not available, investigate any values 

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that deviate from previous test results under similar conditions by more than 50 

percent of the lowest value. Investigate any results less than 1 megohm with the 

overcurrent protective devices in the open position for possible tracking on 

insulation or insulation breakdown. Ground each phase at the completion of the 

test. Maintain records of testing for future reference. 

6.6 Re-energizing Switchboards 

Energize switchboards in accordance with Section 5. Remove grounding leads 

from the line terminals of the switchboard. Visually inspect the system to ensure 

that all tools, electrical jumpers, test devices, etc., have been removed. Visually 

inspect equipment and areas around equipment to ensure that all persons are 

clear from circuits and equipment to be re-energized. Remove locks and tags 

only after work is complete and tested, and all personnel are clear of the area. 

Test for short circuits or ground faults. Energize circuits using established 

switching procedures. Close disconnect means starting at the source, working 

towards the load. Measure phase-to-phase and phase-to-neutral voltages, if 

applicable. Investigate source of voltage unbalance greater than 3 percent. 

Measure switchboard feeder and branch load currents. Verify that conductors 

are properly sized and protected for actual loading. 

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7. Adverse Circumstances 

Special procedures are necessary to determine whether a switchboard can 

safely remain in service following a short-circuit, ground-fault, or exposure to 

water. 

7.1 Inspection Following a Short-Circuit or Ground-Fault 

Condition 

Do not attempt to re-energize a switchboard following a short-circuit or groundfault 

condition within the switchboard. Do not re-energize a feeder or branch 

overcurrent protection device in the switchboard that has opened due to a short 

circuit or ground-fault until the problem downstream has been corrected. 

Following a short-circuit or ground-fault within a switchboard, inspect the 

equipment thoroughly as described in Section 6.1 to verify that damage has not 

occurred to conductors or insulators within the switchboard. 

NOTE: The insulating properties of some organic insulating materials may 

deteriorate during an electrical arc. Replacement of the damaged insulating 

material is the only remedy. 

7.1.1 Short-circuits develop high mechanical stresses that can 

damage conductors and insulation 

Improper and loosened connections may result in conductors pulling out of their 

terminations on subsequent short-circuits; for this reason all connections should 

be inspected and, if necessary, re-evaluated. Great care must be taken in 

evaluating the cause of the short-circuit. Do not replace the fuse(s) and turn the 

overcurrent protective device back on, or reset the circuit breaker, without first 

determining whether it is safe to energize the circuit. Phase-to-phase shortcircuits 

that originate on bus bars can travel the length of the bussing system 

through the switchboard, and the greatest damage may not occur where the 

arcing condition originated. Conduct an insulation test to determine the integrity 

of the switchboard insulation prior to re-energizing the switchboard. 

7.1.2 Ground-faults are unintentional current paths between a phase 

conductor and ground 

Depending on the magnitude of the ground-fault and its duration, carbon build-up 

and metallic splatter may need to be removed, insulators cleaned or replaced. 

Perform phase-to-phase and phase-to-ground insulation tests, with a minimum 

reading of one megohm, prior to turning the switchboard power back on. 

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7.2 Replacing a Switchboard Soaked by or Submerged Under 

Water 

a) Do not work on energized electrical equipment when standing in water. 

b) Do not energize a switchboard that is wet. 

c) Do not clean or repair a switchboard that has been exposed to large volumes 

of water or submerged. Current-carrying parts, insulation systems, and 

electrical/electronic components may be damaged beyond repair through 

contamination by chemicals, river or creek water, sewage and other 

pollutants. In this event, replace the switchboard rather than attempt to repair 

it. 

7.3 Inspecting and Re-Energizing a Switchboard Sprayed or 

Splashed with Clean Water 

Apply heat (a minimum of 250 watts per section) to the switchboard to dry it out 

until visible signs of dampness cannot be seen. Remove materials that could 

catch fire prior to applying the heat. Consult the manufacturer’s 

recommendations for specific guidelines on how to insure that it is safe to reenergize 

the switchboard, or follow this procedure. 

7.3.1 Preliminary Inspection 

Follow the steps in Section 7.3.2 to re-energize the switchboard only if a 

preliminary inspection verifies that the following conditions are satisfied: 

a) There are no signs of physical damage to the equipment. 

b) The switchboard has not been soaked or submerged in water. 

c) The water that has been in contact with the switchboard has not been 

contaminated with sewage, chemicals or other substances. 

d) Water has not entered any area of the switchboard enclosure that contains 

wiring, and has not come into contact with any live part. Look for water 

entering through conduits. 

If all of the conditions listed above are satisfied, proceed as follows. 

7.3.2 Cleaning, testing, and re-energizing a switchboard 

Step 1 Completely de-energize and electrically isolate the switchboard so 

that contact cannot be made with energized parts. 

Step 2 Wipe off all moisture from bus bars, insulators, and insulating 

materials with a clean, dry, lint free cloth. Never use cleaning 

agents or sprays unless specifically recommended by the 

switchboard manufacturer. 

Step 3 Prepare the switchboard for an insulation resistance test by 

disconnecting all line-side supply conductors and all load-side 

28

1031 

1032 

1033 

1034 

1035 

1036 

1037 

1038 

1039 

1040 

1041 

1042 

1043 

1044 

1045 

1046 

1047 

1048 

1049 

1050 

1051 

1052 

1053 

1054 

1055 

1056 

1057 

1058 

1059 


conductors to isolate the switchboard from the wiring system. Turn 

all circuit breakers or fusible switches to the “ON” position. Voltage 

cannot be present on the switchboard during the insulation 

resistance test. 

Step 4 Use a DC insulation resistance tester with a capacity of 500-1000 

volts DC to perform phase-to-ground and phase-to-phase insulation 

tests. 

NOTE: Use of an AC dielectric tester is not recommended. 

a) Measure each phase (A, B, C) to ground with the circuit 

breakers or fusible switches “ON”. 

b) Measure each phase to another phase with the circuit breakers 

or fusible switches “ON”. Record the values of the insulation 

resistance on the insulation resistance chart shown in Section 9. 

Step 5 Do not re-energize the equipment if any of the resistance 

measurements are not at least one megohm. If moisture is the 

cause of the low resistance readings, the moisture can be removed 

from the switchboard by providing a minimum of 250 watts of heat 

per vertical section. 

Step 6 If the resistance measurements are greater than 0.5 megohom, the 

equipment can be re-energized. 

29

1060 

1061 

1062 

1063 

1064 

1065 

1066 

1067 

1068 

1069 

1070 


8. Recommended Torque Values 

If the switchboard manufacturer does not provide specific torque 

recommendations, use the following as a guide. 

30

1071 

1072 

1073 

1074 


31

1075 

1076 

1077 

1078 

1079 

1080 

1081 

1082 


9. Switchboard Insulation Resistance Chart 

NOTE: The use of an AC dielectric tester for testing the switchboard is not 

recommended. Use an insulation resistance tester with a capacity of 500-1000 

VDC. 

32

1083 

1084 

1085 

1086 

1087 

1088 

1089 

1090 


10. Operations and Maintenance Documents 

This standard refers to manufacturer’s packing label warnings (2.1a), instruction 

manuals, literature, drawings (Section 3), recorded values of tests (4.2, 7.3.2, 9), 

and set values of adjustable trips (4.4 and 4.5a, 4.5d). This material, plus asbuilt 

drawings, should be assembled, identified and delivered to the owner of the 

facility at the completion of the installation. 

33

1091 

1092 

1093 

1094 

1095 

1096 

1097 

1098 

1099 

1100 


(This appendix is not part of the standard) 

Appendix A: Reference Standards 

This publication, when used in conjunction with the National Electrical Code and 

switchboard manufacturer’s literature, provides sufficient information to install 

and maintain deadfront switchboards operating at 600 volts and less. The 

following publications may also provide useful information: 

NECA will insert the list at publication. 

34

TO: NECA 400-200X ANSI Canvass Participants FROM: Billie Zidek ...

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