top 10 changes in nec

8/13/2019 Top 10 Changes in NEC

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Top 10 Changes in NEC-2008by Michael J. Johnston

Because new technologies are entering the market continually andcode rules must be developed or revised to address electrical safetyconcerns related to these emerging products, systems, methods, andequipment, the NE development process is dynamic!a vital, ever"moving force.

#he $%%& process demonstrated that revisions are inevitable and verynecessary. 'ere are ten of the most important changes.

1. Article 100 and Entire Code: Definitions

2008 NEC Products$%%& NE (oft over$%%& NE 'andbook$%%& NE )"*+MMore $%%& NE roducts

#hroughout the entire NE "$%%&, revisions have been made to numerous ode rules wheregrounding and bonding terms are used. (everal terms have been redefined and simplified foraccuracy. Effectively grounded has been deleted and a new definition of ungrounded hasbeen added. #he terms affected by this revision are as follows-

bonding (bonded) revised grounding electrode conductor revised grounding conductor, equipment revised grounding electrode revise ground revised grounding (grounded) revised grounded, effectively deletedungrounded new

/ppropriate ode"wide usage has been ensured, and grounding and bonding terms are usedmore consistently with their defined meaning. *ules throughout /rticle $0% and the NE havebeen revised to be more specific and prescriptive where rules related to grounding andbonding requirements were inconsistent with what is intended to be accomplished from aperformance perspective and what is required by the actual te1t used in the ode .

2. 110.26(C)(3) Personnel Doors#he second sentence in 22%.$34 54$5 was relocated to become item 465 and revised to addressspecific requirements relating to personnel doors. ersonnel access doors less than $0 feetfrom the working space are to open outward with simple pressure. (imilar revisions weremade in 22%.66 to the personnel door requirements for equipment rated over 3%% volts.
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Egress doors less than 25 feet from the working space (from page !)

3. 210.4( ) !ulti"ire ranc# Circuits7nformation about conductors of multiwire branch circuits originating from the samepanelboard or distribution equipment has been relocated to $2%.84/5. Now $2%.84B5 addressesdisconnecting means for simultaneously disconnecting all ungrounded conductors of allmultiwire branch circuits. (imultaneously disconnecting all conductors of multiwire branchcircuits is now e1panded to all multiwire branch circuits, not 9ust those that supply more thanone device mounted on the same yoke or mounting strap.


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"ultiwire branch circuits (from page 5 )

4. 210.8(A)(2) and (A)($) D"ellin% &nits#he :; 7 protection requirements for receptacles in basements, garages, and accessorybuildings have been e1panded to all 2$0"volt, single"phase, 20" and $%"ampere receptaclesregardless of accessibility or movability of an appliance from one location to another.

;our e1ceptions were deleted- the two from $2%.&4/54$5 and Nos. 2 and $ to 4/5405. /dditionalte1t added to $2%.&4/5405 indicates that any receptacles installed under the e1ception to

$2%.&4/5405 shall not be considered as meeting the requirements of $2%.0$4:5. / new ; Nrefers users to


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#$%& protection is required for receptacles in basements, accessory buildings, and garages ofdwellings unless e'empted by remaining e'ceptions. (from page 5!)

$. 210.12( ) D"ellin% &nits ombination"type /; 7"protective devices are now required in all dwelling unit rooms, e1ceptfor kitchens, bathroom, garages, basements, and rooms or areas not specified in this section.#his continues the incremental migration to provide whole"house /; 7 protection for dwellingunits that was the ob9ective of the original proposals in the 2=== NE development cycle.

#his section was revised to include a list of rooms and areas where the serving branch circuitsare to be protected by arc"fault circuit"interrupter protection. Essentially, the requirementsfor this protection are e1panded to most areas and rooms in the dwelling unit with thee1ception of those named above and other areas or rooms not specifically identified in thissection. #he /; 7"protective devices must be listed combination types.


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ocations of $%& protection in a typical dwelling (from page * )

6. 2$0.32( ) and E'ce tion *rounded +,ste-sEquipment grounding conductors are required to be installed with all branch circuits andfeeders supplying separate buildings or structures. #he e1ception applies to e1isting premiseswiring systems only.

#his change should help reduce the number of designs that purposely invite the possibilities ofinappropriate neutral"to"ground connections that can and often do happen in laterrenovations, which is uncontrollable by any NE rule. E1isting installations meeting therequirements of $0%.6$4B54$5 in previous editions of the NE would be allowed to remainoperational. #he restrictive conditions of the new e1ception >former $0%.6$4B54$5? still haveto be met and are sub9ect to approval of the applicable authority having 9urisdiction.


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Equipment grounding conductors in branch circuits and feeders supplying separate buildings(from page ++ )

. 310.1$( )(2)(c) and /a le 310.1$( )(2)(c) Conduits E' osed to +unli%#t on oofto sonductors and cables installed in conduit or tubing e1posed to direct sunlight on rooftops aresub9ect to temperature ad9ustment factors in accordance with the values in #able 62%.204B54$54c5 based on distance above the roof surface. #he temperature values in the table shall beadded to the ambient temperature and applied to the temperature correction factors

provided in #able 62%.20 and #able 62%.2&.

/ new requirement in subdivision 4c5 has been added to 62%.204B54$5. 7n addition to the newte1t in subdivision 4c5, a new companion #able 62%.204B54$54c5 has been added. #o correlatewith this change, the e1isting ; N to 62%.2% has been deleted.


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%onduits e'posed to sunlight on rooftops (from page +5 )

%onduits e'posed to sunlight on rooftops (from page +55)


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8. 406.11 /a- er esistant ece tacles in D"ellin% &nits@isted tamper"resistant receptacles are required for 2$0"volt, 20" and $%"ampere receptaclesin dwelling units in areas specified in $2%.0$.

(ubstantiation provided by #he A.(. onsumer roduct (afety ommission s NationalElectronic 7n9ury (urveillance (ystem indicated that during a 2%"year period, from 2==2 to$%%2, over $8,%%% children in the Anited (tates were in9ured when they inserted foreignob9ects into electrical receptacles. Every year, at least $,8%% children, on average, arein9ured when tampering with electrical receptacles. #he number of in9uries is significant anddemonstrates the need for more protection.

amper-resistant receptacles in dwelling units (from page 22!)


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amper-resistant receptacle (from page 22!)

. Ne" Article 626 Electrified /ruc Par in% + ace/rticle 3$3 provides installation requirements for truck stops that will supply electrical andcommunications services so that truck engines will be shut off for a time to lessen carbonemissions and to reduce fuel consumption.

+ver the past several years, the attention of regulatory agencies and environmental groupshas focused on means to reducing truck idling, thereby reducing emissions and fuelconsumption. More than twenty states and cities have already adopted legislation to reduce

the number of hours a truck idles. #his article includes provisions similar to those alreadye1isting in /rticles 00% and 002 that also include requirements for permanent power facilities.*equirements for standardiCed wiring methods, materials and configurations will result inuniform electrified truck parking spaces throughout the country. 7t will also ensure that alltruck fleets will have the ability to connect to Dshore power to run cab amenities 4hotelloads5 and the heating, ventilation and air"conditioning systems.


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Electrified truck parking space (from page 2!)

10. Ne" Article 08 Critical 5 erations Po"er +,ste-sritical operations power systems 4 + (5 provide requirements for facilities that aredesignated as mission critical and vital for national security such as =22 operations center,hospitals, telecommunications centers, air traffic control, water pumping stations, somefueling facilities and petrochemical plants. #his list is not e1haustive.

#he requirements in this article target electrical power continuity for systems and circuitsthat are vital to national security, the economy, or public health and safety. (ome of therules call for hardened electrical circuit wiring, specific power sources and source locationdesigns, overcurrent protection operational characteristics and locations, and systemperformance and analysis.


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%ritical operations power system (from page */)

Entrance to a critical operations power system (from page *0)

+u--ar,#here were 63&& proposals and $68= comments resulting in many significant and interestingrevisions in NE -$%%&. ;our new articles and two new anne1es have been added for this cyclealong with rules that address electrified truck parking space equipment and criticaloperations facilities. Each edition of the NE e1periences revisions necessary to keep up with


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the dynamics of the electrical field. NE -$%%& has been revised to enhance protection againstarcing faults in dwellings, thus increasing electrical safety for dwellings and occupants. #hee1pansion of ground"fault circuit"interrupter protection requirements in dwellings and otheroccupancies increases protection against electric shock and electrocution for persons.

#his article provides only a small review of some of the more significant changes in NE "$%%&,but many more revisions resulted in improved code"wide clarity and usability. #he7nternational /ssociation of Electrical 7nspectors is actively involved in the ode developmentprocess and provides detailed coverage of over 8%% of the $%%& ode revisions in 7/E7 s

nalysis of %hanges 1E%-2 /. ontact 7/E7 at 2"&%%"


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2008 NEC Article 100

Branch" ircuit +vercurrent )evice. / device capable of providing protection for service,feeder, and branch circuits and equipment over the full range of overcurrents between itsrated current and interrupting rating. Branch circuit overcurrent protective devices areprovided with interrupting ratings appropriate for the intended use but no less than 0,%%%

amperes.

/uthor s (ubstantiation- / new definition has been added to clarify that a branch circuitovercurrent device is capable of providing protection for a service, feeder, and branchcircuits.


lothes loset. / non"habitable room or space intended primarily for storage of garments andapparel. /uthor s (ubstantiation- / new definition has been added to clarify what constitutesa Dclothes closet.

200$ NEC $$0.2

Manufactured 'ome. / structure, transportable in one or more sections, that is $.0 m 4& bodyft5 4$.0m5 or more in width or 2$m 48% body ft5 42$ m5 or more in length in the traveling modeor, when erected on site, is 6% m$ 46$% ft$5 or moreH which is built on a chassis and designedto be used as a dwelling, with or without a permanent foundation, when connected to therequired utilities, including the plumbing, heating, air conditioning, and electrical systemscontained therein. alculations used to determine the number of square meters 4square feet5in a structure will be based on the structure s e1terior dimensions, measured at the largesthoriContal pro9ections when erected on site. #hese dimensions include all e1pandable rooms,cabinets, and other pro9ections containing interior space, but do not include inside baywindows.

;or the purpose of this ode and unless otherwise indicated, the term mobile home includesmanufactured homes.; N No. 2- (ee the applicable building code for definition of the term permanent

foundation.; N No. $- (ee art 6$&%, Manufactured 'ome onstruction and (afety (tandards, of

the ;ederal )epartment of 'ousing and Arban )evelopment, for additional information on thedefinition.


Manufactured 'ome. / structure, transportable in one or more sections, that, in the travelingmode, is & body"ft 4$.8 m5 or more in width or 8% body"ft 42$.$ m5 or more in length or, when

erected on site, is 6$% ft$ 4$=.< m$5 or more and that is built on a permanent chassis anddesigned to be used as a dwelling, with or without a permanent foundation, when connectedtherein. #he term manufactured home includes any structure that meets all the provisions ofthis paragraph e1cept the siCe requirements and with respect to which the manufacturervoluntarily files a certification required by the regulatory agency, and e1cept that such termshall not include any self"propelled recreational vehicle. alculations used to determine thenumber of square feet 4square meters5 in a structure are based on the structure s e1teriordimensions, measured at the largest horiContal pro9ections when erected on site. #hese


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dimensions include all e1pandable rooms, cabinets, and other pro9ections containing interiorspace, but do not include bay windows.

; N No. 2- (ee the applicable building code for definition of the term permanentfoundation.

; N No. $- (ee art 6$&%, Manufactured 'ome onstruction and (afety (tandards, of

the ;ederal )epartment of 'ousing and Arban )evelopment, for additional information on thedefinition.

/uthor s (ubstantiation- #his definition has been relocated from 00%.$ to /rticle 2%% to assistthe user by providing consistent meaning of defined terms throughout the National ;ireodes.

200$ NEC Article 100

)welling Anit. / single unit, providing complete and independent living facilities for one ormore persons, including permanent provisions for living, sleeping, cooking, and sanitation.


)welling Anit. +ne or more rooms arranged for complete, independent housekeepingpurposes, with space for eating, living, and sleepingH facilities for cooking, and provisions forsanitation.

/uthor s (ubstantiation- #his revision simplifies and clarifies what a dwelling unit is andmeets the needs of the 1E%, N; / 2, N; / 2%2, and N; / 0%%%.


Electrical ower roduction and )istribution Network. ower production, distribution, andutiliCation equipment and facilities, such as an electric utility system that delivers electricpower to the connected loads, that is e1ternal to and not controlled by an 7nteractive (ystem.

/uthor s (ubstantiation- / new definition has been added to correlate with the definition insection $.82 of Anderwriter @aboratory (tandard 2


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(ection 22%.$ requires conductors and electrical equipment required or permitted by the 1E% to be only acceptable if approved. /dding machinery will now make it clear that industrialequipment installations are covered by the 1E%.


:round. / conducting connection, whether intentional or accidental, between an electricalcircuit or equipment and the earth or to some conducting body that serves in place of theearth.


:round. #he earth.

/uthor s (ubstantiation- #he definition of ground has been simplified by deleting theintentional or accidental connection to earth or to some body serving in place of the earth.


:rounding Electrode. / device that establishes an electrical connection to the earth.


:rounding Electrode. / conducting ob9ect through which a direct connection to earth isestablished.

/uthor s (ubstantiation- #he present definition for grounding electrode was rewritten tobetter describe its function. #he grounding electrode establishes and maintains a directconnection to earth.


:rounding Electrode onductor. #he conductor used to connect the grounding electrode4s5 tothe equipment grounding conductor, to the grounded conductor, or to both, at the service, ateach building or structure where supplied by a feeder4s5 or branch circuit4s5, or at the sourceof a separately derived system.


:rounding Electrode onductor. #he conductor used to connect the grounding electrode4s5 toa system conductor or to equipment.

/uthor s (ubstantiation- #here are times where a grounding electrode conductor is connectedto equipment, such as permitted where a supplementary electrode is installed in accordancewith $0%.08.


:rounding onductor, Equipment. #he conductor used to connect the non"current"carryingmetal parts of equipment, raceways, and other enclosures and to the system groundedconductor or to grounding electrode conductor , or both, at the service equipment or at thesource of a separately derived system .



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:rounding onductor, Equipment. #he conductive path installed to connect normally non"current"carrying metal parts of equipment together and to the system grounded conductor orto grounding electrode conductor. ; N No. 2- 7t is recogniCed that the equipment groundingconductor also performs bonding. ; N No.$- (ee $0%. & for a list of acceptable equipmentgrounding conductors.

/uthor s (ubstantiation- #his revision has been written to apply generally throughout the 1E% and simply describe the purpose and function of the equipment grounding conductor.


7ntersystem Bonding #ermination. / device that provides a means of bonding communicationsequipment at the service equipment or the disconnecting means for any additional buildingsor structures.

/uthor s (ubstantiation- #his new definition describes a device used to connect thecommunications equipment to the service equipment or the disconnecting means foradditional buildings or structures in accordance with art 77 in /rticle $$0.

200$ NEC Article 100@uminaire. / complete lighting unit consisting of a lamp or lamps, together with the partsdesigned to distribute the light to position and protect the lamps and ballast 4whereapplicable5 connect the lamps to the power supply.


@uminaire. / complete lighting unit consisting of a light source, such as a lamp or lamps,together with the parts designed to position the light source and connect it to the powersupply. 7t may also include parts to protect the light source, ballast, or distribute the light. /lampholder itself is not a luminaire.

/uthor s (ubstantiation- #he rewording of the definition clarifies the issue that a lampholderis clearly not a luminaire and the remainder of the te1t was for clarification.


Neutral onductor. #he conductor connected to the neutral point of a system that is intendedto carry current under normal conditions.

Neutral point.#he common point on a wye"connection in a polyphase system or midpoint on asingle"phase, 6"wire system, or midpoint of a single"phase portion of a 6"phase delta system,or a midpoint of a 6"wire, direct current system.

; N-/t the neutral point of the system, the vectorial sum of the nominal voltages from all

other phases within the system that utiliCe the neutral, with respect to the neutral point, isCero potential.

/uthor s (ubstantiation- /dded two new definitions to provide information on whatconstitutes a neutral and a neutral point. $%%0 1E% " /rticle 2%% Iualified erson. +ne whohas skills and knowledge related to the construction and operation of the electricalequipment and installations and has received safety training on the haCards involved.



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Iualified erson. +ne who has skills and knowledge related to the construction and operationof the electrical equipment and installations and has received safety training on to recogniCeand avoid the haCards involved.

/uthor s (ubstantiation- /dding the phrase Dto recogniCe and avoid to the definition ofqualified person provides a reason for the safety training.


(hort" ircuit urrent *ating. #he prospective symmetrical fault current at a nominal voltageto which an apparatus or system is able to be connected without sustaining damage e1ceedingdefined acceptance criteria.

/uthor s (ubstantiation- /dding this definition provides a definition for the phrase used in22%.2% and various other locations in the ode.


(urge rotective )evices 4( )s5. / protective device for limiting transient voltages bydiverting or limiting surge currentH it also prevents continued flow of follow current whileremaining capable of repeating these functions and designated as follows-

#ype 2 " ermanently connected ( )s intended for installation between the secondaryof the service transformer and the line side of the service disconnect overcurrent device.

#ype $ " ermanently connected ( )s intended for installation on the load side of theservice disconnect overcurrent deviceH including ( )s located at the branch panel.

#ype 6 " oint of utiliCation ( )s.#ype 8 " omponent ( )s, including discrete components, as well as assemblies.; N No. 2-;or further information on #ype 2, #ype $, #ype 6, and #ype 8 ( )s, see A@

288=, (tandard for (urge rotective )evices.

/uthor s (ubstantiation- / new definition has been added to replace the term transientvoltage surge suppressor used in $&0.$.


Angrounded. Not connected to ground or a conductive body that e1tends the groundconnection.

/uthor s (ubstantiation- #he word Dungrounded is used e1tensively in the 1E%, previouslywithout a definition.


Atility"7nteractive 7nverter. /n inverter intended for use in parallel with an electric utility tosupply common loads and sometimes deliver power to the utility.

/uthor s (ubstantiation- #he purpose of this change is to add a new definition of Atility"7nteractive 7nverter that will be used in /rticle 3=%, 3=$, and /rticle


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respect to the interconnection of systems and equipment for use with distributed energyresources.

A@


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2008 NEC 110.20

Enclosure #ypes. Enclosures 4other than surrounding fences or walls5 of switchboards,panelboards, industrial control panels, motor control centers, meter sockets, and motorcontrollers, rated not over 3%% volts nominal and intended for such locations, shall be markedwith an Enclosure #ype number as shown in #able 22%.$%.

/uthor s (ubstantiation- #able 86%.=2, covering motor controller enclosure types, has beenused by many ode users for enclosures for numerous kinds of equipment, even though it isstated in 86%.=2 that it only applies to motor controller enclosures. Moving the requirementsof 86%.=2 and #able 86%.=2 into a general application area of the ode and specifically statingthe kinds of equipment to which they apply, will add clarity.

200$ NEC 110.22

7dentification of )isconnecting Means. Each disconnecting means shall be legibly marked toindicate its purpose unless located and arranged so the purpose is evident. #he marking shallbe of sufficient durability to withstand the environment involved. Ghere circuit breakers orfuses are applied in compliance with the series combination ratings marked on the equipmentby the manufacturer, the equipment enclosure4s5 shall be legibly marked in the field toindicate the equipment has been applied with a series combination rating. #he marking shallbe readily visible and state the following-

/A#7+N " EN:7NEE*E) (E*7E( +MB7N/#7+N (K(#EM */#E) L /M E*E(. 7)EN#7;7E)*E @/ EMEN# +M +NEN#( *EIA7*E)

; N- (ee $8%.&34B5 for interrupting rating marking for end"use equipment.

2008 NEC 110.22

7dentification of )isconnecting Means. Each disconnecting means shall be legibly marked toindicate its purpose unless located and arranged so the purpose is evident. #he marking shallbe of sufficient durability to withstand the environment involved.

Ghere circuit breakers or fuses are applied in compliance with series combination ratingsselected under engineering supervision and marked on the equipment as directed by theengineer, the equipment enclosure4s5 shall be legibly marked in the field to indicate theequipment has been applied with a series combination rating. #he marking shall be readilyvisible and state the following-

/A#7+N " EN:7NEE*E) (E*7E( +MB7N/#7+N (K(#EM */#E) L /M E*E(. 7)EN#7;7E)*E @/ EMEN# +M +NEN#( *EIA7*E)

; N- (ee $8%.&34B5 for interrupting rating marking for end"use equipment. /uthor s(ubstantiation- #he addition of the te1t in 22%.$$ for series"combination ratings selectedunder engineering supervision in e1isting installations provides coordination between (ections22%.$$ and $8%.&34/5, where permission for series rated systems selected by calculation wasadded in the $%%0 NE .

200$ NEC 110.26(C) Entrance to or in% + ace

4$5 @arge Equipment. ;or equipment rated 2$%% amperes or more that contains overcurrentdevices, switching devices, or control devices, there shall be one entrance to the requiredworking space not less than 32% mm 4$8 in.5 wide and $.% m 43 2 $ ft5 high at each end of


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the working space. Ghere the entrance has a personnel door4s5, the door4s5 shall open in thedirection of egress and be equipped with panic bars, pressure plates, or other devices thatare normally latched but open under simple pressure.

/ single entrance from the required working space shall be permitted where either of theconditions in 22%.$34 54$54a5 or 4 54$54b5 is met.

2008 NEC 110.26(C) Entrance to and E%ress fro- or in% + ace

4$5 @arge Equipment. ;or equipment rated 2$%% amperes or more and over 2.& m 43 ft5 widethat contains overcurrent devices, switching devices, or control devices, there shall be oneentrance to the required working space not less than 32% mm 4$8 in.5 wide and $.% m 43 2 $ft5 high at each end of the working space. Ghere the entrance has a personnel door4s5 that isless than 2.& m 43 ft5 from the working space, the door4s5 shall open in the direction of egressand be equipped with panic bars, pressure plates, or other devices that are normally latchedbut open under simple pressure.

/ single entrance to and egress from the required working space shall be permitted whereeither of the conditions in 22%.$34 54$54a5 or 4 54$54b5 is met.

/uthor s (ubstantiation- #he previous ode te1t appeared to only address the entrance into aworking space. By adding Degress from the working space there will be equal emphasis onpermitting sufficient room leave the electrical equipment work space.

#he new te1t clarifies that the personnel door4s5 requirement for panic bars and similarhardware and the opening in the direction of egress applies to personnel doors that are lessthan 3 feet from the equipment working space. #his requirement would not apply to doorslocated 3 feet or more from the working space.

#his change effectively returns the requirement for large equipment to be considered over 3foot in width, as well as being 2$%% amperes or more. #he over 3 foot requirement had been

deleted for the $%%0 NE .200$ NEC 110.33 Entrance and Access to or + ace.

4/5 Entrance. /t least one entrance not less than 32% mm 4$8 in.5 wide and $.% m 43 2 $ ft5high shall be provided to give access to the working space about electric equipment. Gherethe entrance has a personnel door4s5, the door4s5 shall open in the direction of egress and beequipped with panic bars, pressure plates, or other devices that are normally latched butopen under simple pressure.

2008 NEC 110.33 Entrance to Enclosures and Access to or in% + ace.

4/5 Entrance. /t least one entrance to enclosures for electrical installations as described in22%.62 not less than 32% mm 4$8 in.5 wide and $.% m 43 2 $ ft5 high shall be provided to giveaccess to the working space about electric equipment. Ghere the entrance has a personneldoor4s5 that is less than 6.< m 42$ ft5 from the working space, the door4s5 shall open in thedirection of egress and be equipped with panic bars, pressure plates, or other devices thatare normally latched but open under simple pressure.

/uthor s (ubstantiation- #he change in this section requires at least one entrance to provideaccess to the working space for a high voltage enclosure as described in (ection 22%.62. #henew te1t clarifies that the personnel door4s5 requirement for panic bars and similar hardware


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and the opening in the direction of egress applies to personnel doors that are less than 2$feet from the equipment working space. #his requirement would not apply to doors located2$ feet or more from the working space.

2008 NEC Changes: Chapter 2 (Part 2)

NE )igestF, )ecember $%%3 (necdigest3, 1ational Electrical %ode3, and 1E%3 areregistered trademarks of the 1ational $ire 4rotection ssociation, &nc., uincy, " 2+*0)

By James (tallcup, (r. and Mark +de

7n the second of a series discussing proposed changes to the $%%& 1ational Electrical %ode34NE F5, the authors cover important changes to hapter $ . #o help simplify and clarify eachchange, words that have been deleted are shown with a strike through and words that havebeen added are underlined.

200$ NEC

210.4 !ulti"ire ranc# Circuits4/5 :eneral. Branch circuits recogniCed by this article shall be permitted as multiwirecircuits. / multiwire circuit shall be permitted to be considered as multiple circuits. /llconductors shall originate from the same panelboard or similar distribution equipment.

; N- / 6"phase, 8"wire, wye"connected power system used to supply power to nonlinear loadsmay necessitate that the power system design allow for the possibility of high harmonicneutral currents.

4B5 )evices or Equipment )isconnecting Means. Ghere a multiwire branch circuit suppliesmore than one device or equipment on the same yoke, a means shall be provided todisconnect simultaneously all ungrounded conductors supplying those devices or equipment at

the point where the branch circuit originates.2008 NEC

210.4 !ulti"ire ranc# Circuits4/5 :eneral. Branch circuits recogniCed by this article shall be permitted as multiwirecircuits. / multiwire circuit shall be permitted to be considered as multiple circuits. /llconductors of a multiwire branch circuit shall originate from the same panelboard or similardistribution equipment.

; N- / 6"phase, 8"wire, wye"connected power system used to supply power to nonlinear loadsmay necessitate that the power system design allow for the possibility of high harmonicneutral currents.

4B5 )isconnecting Means. Each multiwire branch circuit shall be provided with a means thatwill simultaneously disconnect all ungrounded conductors at the point where the branchcircuit originates.

Aut#or7s Co--ent: #here were two reasons for the changes to the te1t in this section. #hefirst reason was to clarify that all conductors of a multiwire branch circuit must originatefrom the same panelboard or distribution equipment. #he change in 4B5 was done toemphasiCe the safety concerns associated with unintentional voltage being present on


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multiwire branch circuits during maintenance. )eleting the te1t that applied simultaneousdisconnecting requirements for a multiwire branch circuit to a single device or equipment onthe same yoke will require simultaneous disconnect of all ungrounded conductors on anymultiwire branch circuit at its origin.

200$ NEC

210.$ dentification for ranc# Circuits4 5 Angrounded onductors. Ghere the premises wiring system has branch circuits suppliedfrom more than one nominal voltage system, each ungrounded conductor of a branch circuit,where accessible, shall be identified by system. #he means of identification shall bepermitted to be by separate color coding, marking tape, tagging, or other approved meansand shall be permanently posted at each branch"circuit panelboard or similar branch"circuitdistribution equipment.

2008 NEC

210.$ dentification for ranc# Circuits4 5 Angrounded onductors. Ghere the premises wiring system has branch circuits suppliedfrom more than one nominal voltage system, each ungrounded conductor of a branch circuitshall be identified by system at all termination, connection, and splice points. #he means ofidentification shall be permitted to be by separate color coding, marking tape, tagging, orother approved means. #he means of identification shall be documented in a manner that isreadily available or shall be permanently posted at each branch"circuit panelboard or similarbranch"circuit distribution equipment.

Aut#or7s Co--ent: #he current wording in the $%%0 1E% requires marking of the conductorsat every conduit fitting and pull bo1 or any other location where the branch circuit isaccessible. #he locations where the branch circuit is terminated, connected or spliced are thecritical locations where the marking is needed. #he revised wording would account for branch

circuits installed as cables and branch circuits installed as single conductors in raceways. #hechange also e1pands the methods that can be used for identification to permit documentationthat is readily available or permanent posting at the panelboard or distribution equipment.

200$ NEC

210.8 *round 9ault Circuit nterru ter Protection for Personnel4/5 )welling Anits. /ll 2$0"volt, single"phase, 20" and $%"ampere receptacles installed in thelocations specified in 425 through 4&5 shall have ground"fault circuit"interrupter protection forpersonnel.

4$5:arages, and also accessory buildings that have a floor located at or below grade level notintended as habitable rooms and limited to storage areas, work areas, and areas of similar use

E1ception No. 2 to 4$5- *eceptacles that are not readily accessible.

E1ception No. $ to 4$5- / single receptacle or a duple1 receptacle for two appliances locatedwithin dedicated space for each appliance that, in normal use, is not easily moved from oneplace to another and that is cord"and"plug connected in accordance with 8%%.


23/34

405 Anfinished basements!for purposes of this section, unfinished basements are defined asportions or areas of the basement not intended as habitable rooms and limited to storageareas, work areas, and the like

E1ception No. 2 to 405- *eceptacles that are not readily accessible.

E1ception No. $ to 405- / single receptacle or a duple1 receptacle for two appliances locatedwithin dedicated space for each appliance that, in normal use, is not easily moved from oneplace to another and that is cord"and"plug connected in accordance with 8%%.


24/34

E1ception No. 2 to 465 and 485- *eceptacles that are not readily accessible and are suppliedfrom a dedicated branch circuit for electric snow"melting or deicing equipment shall bepermitted to be installed in accordance with the applicable provisions of /rticle 8$3.

E1ception No. $ to 485- 7n industrial establishments only, where the conditions of maintenanceand supervision ensure that only qualified personnel are involved, :; 7 protection shall notbe required on receptacles that are limited to use with equipment qualified under an assuredequipment grounding conductor program as specified in 0=%.34B54$5.

Aut#or7s Co--ent: #his revision requires :; 7 protection for all 20" and $%"ampere, 2$0"voltsingle"phase receptacles installed outdoors, rather than 9ust those in public spaces. /ne1ception was added to e1empt those receptacles in industrial establishments only, wherethe conditions of maintenance and supervision ensure that only qualified personnel areinvolved, that are limited to use with equipment qualified under an assured equipmentgrounding conductor program as specified in 0=%.34B54$5.

200$ NEC

210.8 *round 9ault Circuit nterru ter Protection for Personnel4B5 +ther #han )welling Anits. /ll 2$0"volt, single"phase, 20" and $%"ampere receptaclesinstalled in the locations specified in 425 through 405 shall have ground"fault circuit"interrupter protection for personnel-

4$5 ommercial and institutional kitchens!for the purposes of this section, a kitchen is anarea with a sink and permanent facilities for food preparation and cooking

2008 NEC

210.8 *round 9ault Circuit nterru ter Protection for Personnel4B5 +ther #han )welling Anits. /ll 2$0"volt, single"phase, 20" and $%"ampere receptaclesinstalled in the locations specified in 425 through 405 shall have ground"fault circuit"

interrupter protection for personnel-4$5 ommercial, institutional, and other nonresidential kitchens!for the purposes of thisrequirement, a kitchen is defined as an area with a sink and permanent facilities for foodpreparation and cooking

Aut#or7s Co--ent: /n office Dbreak area with a sink and permanent facilities for foodpreparation and cooking does not really qualify as either commercial or institutional, but thebreak area or room with a sink and permanent cooking facilities has the same shock haCardpotential. #his change clarifies that these break rooms or areas fall under the requirements ofthis section for ground"fault protection.

7n the third of a series discussing proposed changes to the $%%& 1ational Electrical %ode3 4NE F5, the authors cover more important changes to hapter $ . #o help simplify and clarifyeach change, words that have been deleted are shown with a strike through and words thathave been added are underlined.

200$ NEC


25/34

22$.18 Clearance fro- *round.+verhead spans of open conductors and open multiconductor cables of not over 3%% volts,nominal, shall have a clearance of not less than the following- >*emainder unchanged?.

2008 NEC

22$.18 Clearance for 5 er#ead Conductors and Ca les.+verhead spans of open conductors and open multiconductor cables of not over 3%% volts,nominal, shall have a clearance of not less than the following- >*emainder unchanged?.

/uthor s omment- #he term Dgrade was too sub9ective, as suggested in the proposal, sincethere is initial grade at time of construction, there is intermediate grade during construction,and then final grade at the end of construction. D:rade could ultimately be changed at anyfuture time. #he title change uses the actual te1t within the section itself.

200$ NEC

22$.3 atin% of Disconnect.#he feeder or branch"circuit disconnecting means shall have a rating of not less than the load

to be supplied, determined in accordance with arts 7 and 77 of /rticle $$% for branch circuits,arts 777 or 7 of /rticle $$% for feeders, or art of /rticle $$% for farm loads. 7n no caseshall the rating be lower than specified in $$0.6=4/5, 4B5, 4 5, or 4)5.

2008 NEC

22$.3 atin% of Disconnect.#he feeder or branch"circuit disconnecting means shall have a rating of not less than the loadto be supplied, determined in accordance with arts 7 and 77 of /rticle $$% for branch circuits,arts 777 or 7 of /rticle $$% for feeders, or art of /rticle $$% for farm loads. Ghere thebranch circuit or feeder disconnecting means consists of more than one switch or circuitbreaker, as permitted by $$0.66, combining the ratings of all the switches or circuit breakers

for determining the rating of the disconnecting means shall be permitted. 7n no case shall therating be lower than specified in $$0.6=4/5, 4B5, 4 5, or 4)5.

/uthor s omment- (ince a disconnect is a device or group of devices, permission is inherentto add each device to reach a total rating in compliance with this section. #he new revisedte1t will eliminate any confusion that there is inherent permission for breakers to be additivein calculating the rating of a disconnect means.

200$ NEC

230.24 Clearances.4B5 ertical learance from :round.

(ervice"drop conductors, where not in e1cess of 3%% volts, nominal, shall have the followingminimum clearance from final grade-

425 6.% m 42% ft5 at the electric service entrance to buildings, also at the lowest point of thedrip loop of the building electric entrance, and above areas or sidewalks accessible only topedestrians, measured from final grade or other accessible surface only for service"dropcables supported on and cabled together with a grounded bare messenger where the voltagedoes not e1ceed 20% volts to ground


26/34

4$5 6.< m 42$ ft5 over residential property and driveways, and those commercial areas notsub9ect to truck traffic where the voltage does not e1ceed 6%% volts to ground

465 8.0 m 420 ft5 for those areas listed in the 6.


27/34

2008 NEC

230.44 Ca le /ra,s.able tray systems shall be permitted to support service"entrance conductors. able traysused to support service"entrance conductors shall contain only service"entrance conductors.

E1ception- onductors, other than service"entrance conductors, shall be permitted to beinstalled in a cable tray with service"entrance conductors, provided a solid fi1ed barrier of amaterial compatible with the cable tray is installed to separate the service"entranceconductors from other conductors installed in the cable tray. able trays shall be identifiedwith permanently affi'ed labels with the wording >9ervice-Entrance %onductors.? helabels shall be located so as to be visible after installation and placed so that the service-entrance conductors may be readily traced through the entire length of the cable tray.

/uthor s omment- #e1t has been added to the e1ception for conductors, other than serviceentrance conductors, to be installed in cable trays with service entrance conductors. Gherethese other conductors are added, they must be separated by a fi1ed solid barrier but, now,in addition, labels must be installed so as to be readily visible after installation and placed so

the service entrance conductors can be readily traced through the entire length to the cabletray.

200$ NEC

230. 1 !a'i-u- Nu- er of Disconnects.4/5 :eneral. #he service disconnecting means for each service permitted by $6%.$, or for eachset of service"entrance conductors permitted by $6%.8%, E1ception Nos. 2, 6, 8, or 0, shallconsist of not more than si1 switches or sets of circuit breakers, or a combination of not morethan si1 switches and sets of circuit breakers, mounted in a single enclosure, in a group ofseparate enclosures, or in or on a switchboard. #here shall be not more than si1 sets ofdisconnects per service grouped in any one location. ;or the purpose of this section,

disconnecting means used solely for power monitoring equipment, transient voltage surgesuppressors, or the control circuit of the ground"fault protection system or power"operableservice disconnecting means, installed as part of the listed equipment, shall not beconsidered a service disconnecting means.

$6%.&$ Equipment onnected to the (upply (ide of (ervice )isconnect.+nly the following equipment shall be permitted to be connected to the supply side of theservice disconnecting means-

485 7nstrument transformers 4current and voltage5, impedance shunts, load managementdevices, and arresters

4&5 :round"fault protection systems or transient voltage surge suppressors, where installed as

part of listed equipment, if suitable overcurrent protection and disconnecting means areprovided

$6%.=8 *elative @ocation of +vercurrent )evice and +ther (ervice Equipment.#he overcurrent device shall protect all circuits and devices.

E1ception No. $- 'igh"impedance shunt circuits, surge arresters, surge"protective capacitors,and instrument transformers 4current and voltage5 shall be permitted to be connected andinstalled on the supply side of the service disconnecting means as permitted in $6%.&$.


28/34

2008 NEC

230. 1 !a'i-u- Nu- er of Disconnects.4/5 :eneral. #he service disconnecting means for each service permitted by $6%.$, or for eachset of service"entrance conductors permitted by $6%.8%, E1ception Nos. 2, 6, 8, or 0, shallconsist of not more than si1 switches or sets of circuit breakers, or a combination of not more

than si1 switches and sets of circuit breakers, mounted in a single enclosure, in a group ofseparate enclosures, or in or on a switchboard. #here shall be not more than si1 sets ofdisconnects per service grouped in any one location. ;or the purpose of this section,disconnecting means used solely for power monitoring equipment, surge protective devices,or the control circuit of the ground"fault protection system or power"operable servicedisconnecting means, installed as part of the listed equipment, shall not be considered aservice disconnecting means.

$6%.&$ Equipment onnected to the (upply (ide of (ervice )isconnect.+nly the following equipment shall be permitted to be connected to the supply side of theservice disconnecting means-

485 7nstrument transformers 4current and voltage5, impedance shunts, load managementdevices, surge arresters and #ype 2 surge protective devices

4&5 :round"fault protection systems or #ype $ surge protective devices, where installed aspart of listed equipment, if suitable overcurrent protection and disconnecting means areprovided

$6%.=8 *elative @ocation of +vercurrent )evice and +ther (ervice Equipment.#he overcurrent device shall protect all circuits and devices.

E1ception No. $- 'igh"impedance shunt circuits, surge arresters, #ype 2 surge protectivedevices, surge"protective capacitors, and instrument transformers 4current and voltage5 shallbe permitted to be connected and installed on the supply side of the service disconnectingmeans as permitted in $6%.&$.

/uthor s omment- Anderwriters @aboratories is combining the categories of (urge /rresters4/rticle $&%5 and #ransient oltage (urge (uppressors 4/rticle $&05 into one category and(tandard, A@ 288=, renamed (urge rotective )evices 4( )s5. A@ 288= will include ( )designations #ype 2 and #ype $ for permanently connected devices for use on circuits note1ceeding 3%% . #he technology of both low voltage (urge /rresters and # ((s is nowbasically the same, thereby 9ustifying coverage under one (tandard, A@ 288=, and one testprogram with consideration given to the installation location on the line side 4#ype 25 or loadside 4#ype $5 of the service disconnect overcurrent protection. #he (urge /rrester designationwill only be retained for devices used in circuits of 2 k and over and evaluated to 7EEE3$.22"2===.

200$ NEC

230.20$ Disconnectin% !eans.4/5 @ocation. #he service disconnecting means shall be located in accordance with $6%.


29/34

;or either overhead or underground primary distribution systems on private property, theservice disconnect shall be permitted to be located in a location that is not readilyaccessible.

/uthor s omment - #here are many installations where the service point is at the edge of theproperty and a high voltage switch is the actual service disconnect for the distributionsystem, which then becomes a feeder for multiple buildings on the propertyH the disconnectrequirements in $$0 would apply to the buildings.

200$ NEC

240.4 Protection of Conductors.4)5 (mall onductors. Anless specifically permitted in $8%.84E5 or 4:5, the overcurrentprotection shall not e1ceed 20 amperes for 28 /G:, $% amperes for 2$ /G:, and 6% amperesfor 2% /G: copperH or 20 amperes for 2$ /G:, and $0 amperes for 2% /G: aluminum andcopper"clad aluminum after any correction factors for ambient temperature and number ofconductors have been applied.

2008 NEC

240.4 Protection of Conductors.4)5 (mall onductors. Anless specifically permitted in $8%.84E5 or 4:5, the overcurrentprotection shall not e1ceed the following after any correction factors for ambienttemperature and number of conductors have been applied.

425 2& /G: opper. < amperes for 2& /G: copper provided all the following conditions aremet-

2. ontinuous loads do not e1ceed 0.3 amperes$. +vercurrent protection is provided by one of the following-

a. Branch"circuit rated circuit breakers listed and marked for use with 2& copper /G:wire

b. Branch"circuit rated fuses listed and marked for use with 2& /G: wirec. lass , lass J, or lass # fuses

4$5 23 /G: opper. 2% amperes for 23 /G: copper provided all the following conditions aremet-

2. ontinuous loads do not e1ceed & amperes$. +vercurrent protection is provided by one of the following-

a. Branch"circuit rated circuit breakers listed and marked for use with 23 copper /G:wire

b. Branch"circuit rated fuses listed and marked for use with 23 /G: wirec. lass , lass J, or lass # fuses

465 28 /G: opper or 2$ /G: /luminum. 20 amperes for 28 /G: copper or 2$ /G:aluminum and copper"clad aluminum.

485 2$ /G: opper. $% amperes for 2$ /G: copper.


30/34

405 2% /G: /luminum and opper"clad /luminum. $0 amperes for 2% /G: aluminum andcopper"clad aluminum.

435 2% /G: copper. 6% amperes for 2% /G: copper.

/uthor s omment- (mall conductors in 2& /G: and 23 /G: siCes were added to correspond

to the permission to use these smaller conductors based on N; /


31/34

47 $ / $ 5t O %.%2$0 log 2% >4#$ P $$&5 4# 2 P $$&5?

where-7 O short"circuit current in amperes

/ O conductor area in circular mils

t O time of short"circuit in seconds 4for times less than or equal to 2% seconds5

# 2 O initial conductor temperature in degrees elsius.

# $ O final conductor temperature in degrees elsius.

opper conductor with paper, rubber, varnished cloth insulation, # $ O $%%

opper conductor with thermoplastic insulation, # $ O 20%

opper conductor with crosslinked polyethylene insulation, # $ O $0%

opper conductor with ethylene propylene rubber insulation, # $ O $0%

/luminum conductor with paper, rubber, varnished cloth insulation, # $ O $%%/luminum conductor with thermoplastic insulation, # $ O 20%

/luminum conductor with cross"linked polyethylene insulation, # $ O $0%

/luminum conductor with ethylene propylene rubber insulation, # $ O $0%

4 5 /ransfor-er +econdar, Conductors of +e aratel, Deri ed +,ste-s. onductors shall bepermitted to be connected to a transformer secondary of a separately derived system,without overcurrent protection at the connection, where the conditions of $8%.=$4 5425, 4 54$5, and 4 5465 are met.

/uthor s omment- #he panel action will increase the enforceability needed by the inspectioncommunity and limit the application of e1panding feeder tap conductors for supervisedindustrial installations. #his action recogniCes the performance of the overcurrent device as afactor in determining the tap conductor siCe.

200$ NEC

240.21 ;ocation in Circuit4 5 /ransfor-er +econdar, Conductors. Each set of conductors feeding separate loads, shallbe permitted to be connected to a transformer secondary, without overcurrent protection atthe secondary, as specified in $8%.$24 5425 through 4 5435. #he provisions of $8%.84B5 shall notbe permitted for transformer secondary conductors.

; N- ;or overcurrent protection requirements for transformers, see 80%.6.

2008 NEC

240.21 ;ocation in Circuit4 5 /ransfor-er +econdar, Conductors. / set of conductors feeding a single or each set ofconductors feeding separate loads, shall be permitted to be connected to a transformersecondary, without overcurrent protection at the secondary, as specified in $8%.$24 5425through 4 5435. #he provisions of $8%.84B5 shall not be permitted for transformer secondaryconductors.


32/34

; N- ;or overcurrent protection requirements for transformers, see 80%.6.

/uthor s omment- #he panel has added wording to clarify that more than one set ofconductors often supply the same load when installed as parallel sets of conductors. #heintent of the $%%0 ode change was to clarify that these secondary conductor rules are notlimited in their application to one set per transformer and intended to clarify that more thanone set of conductors is permitted to be connected to a transformer secondary so long as theprovisions of 4 5425 through 4 5435 are complied with.

2008 NEC

$8%.=2 rotection of onductors.onductors shall be protected in accordance with $8%.8, unless otherwise permitted in$8%.=24/5.

4/5De ices ated o er 800 A- eres. Ghere the overcurrent device is rated over &%%amperes, the ampacity of the conductors it protects shall be equal to greater than =0R of therating of the overcurrent device defined in $8%.3, where the conductor is protected withinrecogniCed time vs. current limits for short circuit currents of up to 2%%% seconds duration.

/uthor s omment- #he proposal introduces the equivalent of a Dne1t standard siCee1ception for large conductors in (upervised 7ndustrial 7nstallations. 7n these installations,conductors are protected against overload by load calculation and by monitoring, and againstshort circuit by selection of the overcurrent device as part of an overcurrent coordinationstudy. +vercurrent protection of conductors in supervised industrial installations will bepermitted to e1ceed the &%%"ampere level rating permitted in $8%.84B5, where the conductoris rated for =0R of the overcurrent device rating based on standard siCes in $8%.3. #he timeduration of the short circuit current cannot e1ceed a 2%%% second duration.

200$ NEC

2$0.8 Connection of *roundin% and ondin% E


33/34

435 thread"forming machine screws that engage not less than two threads in the enclosure

4e. Main bonding 9umpers and system bonding 9umpers shall not be smaller than the siCesshown in #able $0%.33. Ghere the supply conductors are larger than 22%% kcmil copper or2e. Main bonding 9umpers and system bonding 9umpers shall be siCed in accordance with$0%.$&4)5425 through 4)5465.

425 Main bonding 9umpers and system bonding 9umpers shall not be smaller than the siCesshown in #able $0%.33. Ghere the supply conductors are larger than 22%% kcmil copper or2


34/34

the bonding 9umper shall be based on the assumed use of phase conductors of the samematerial as the bonding 9umper and with an ampacity equivalent to that of the installedphase conductors.

4$5 Ghere a service consists of more than a single enclosure as permitted in $6%.

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