MEA 2017 NEC Grounding And Bonding Part 2 Minnesota .
11/13/2018MEA 2017 NECGrounding and BondingPart 22-hour class presented byMinnesota Electrical AssociationThis seminar will satisfy the 2-hour electrical code training forelectricians required by the State of Minnesota.Minnesota Electrical Association1AcknowledgementsSome material and illustrations presented arewith permission of Cengage Learning from:Electrical Grounding and Bonding 2014by Phil SimmonsThe National Electrical Code (NEC) is:Document 70 from the National Fire ProtectionAssociation (NFPA)1
11/13/2018Objectives : Systems required to be grounded, Permitted but not required to be grounded Systems not permitted to be groundedRequirements for grounded systems Installing and sizing grounded service - andsystem conductors System conductors that are required to begrounded 3Objectives : Function of, and sizing, main and system bondingjumpersGrounding requirements for separately derivedsystemsGrounding for two or more buildings supplied bya feeder or branch circuitPortable and vehicle-mounted generatorsHigh-impedance grounded neutral systems42
11/13/2018One line grounding5250.20 AC Circuits and Systems to beGroundedAlternating-current circuits and systems arerequired to be grounded (connected to earth) if thesystem meets any of the conditions in 250.20(A),(B), (C), or (D) Voltage level supplied by the system is considered asa general rule Use of neutral for 3-phase systems also considered 63
11/13/2018250.20 AC Circuits and Systems to BeGroundedSome circuits and systems are permitted to begrounded - 250.20(C) other than portable ormobile equipment. (see 250.188) If systems are grounded, the methods mustcomply with Article 250 250.21 - Some circuits are not required to begrounded. Parts (A)–(C) 7250.20 Informational Note; ExampleCorner Grounded Delta Systems Systems permitted butnot required to begroundedMust meet 150-volttest of 250.20(A)(1)(if X-fmr exceeds 150Vto grnd)If grounded, mustcomply with all otherrules of Article 250Copyright Cengage Learning84
11/13/2018250.20(A) AC Systems of Less Than 50 VoltsAC systems of less than50 volts are required tobe grounded under anyof the followingconditions:Copyright Cengage Learning9Article 100 Def: Voltage to GroundCopyright Cengage Learning105
11/13/2018250.20(B) AC Systems of 50 to 1000VoltsAC systems of 50 to 1000 volts that supply premiseswiring and premises wiring systems are required tobe grounded under specific conditions:(1) Where the system can be grounded so themaximum voltage to ground on the ungroundedconductors does not exceed 150 volts11Systems 50 to 1000 Volts Required to beGroundedCopyright Cengage Learning126
11/13/2018Systems 50 to 1000 Volts Required to beGrounded(2) Where the system is3-phase, 4-wire, wyeconnected in which theneutral is used as acircuit conductorTypical voltages:208Y/120; 480Y/277;575Y/332; 600Y/346Copyright Cengage Learning13Systems 50 to 1000 Volts Required to beGrounded(3) Where the system is3-phase, 4-wire, deltaconnected in which themidpoint of one phasewinding is used as acircuit conductorTypical voltage is120/240-volt, 3-phase, 4wireCopyright Cengage Learning147
11/13/2018Copyright Cengage Learning250.20 (C) AC systems over 1000 V Ac systems that supply mobile or portableequipment shall be grounded as specified in250.188. Grounding of systems that supplymobile or portable equipment If supplying other than mobile of portableequipment, the systems are permitted to begrounded8
11/13/2018250.20 (D) Impedance groundedneutral systemsImpedance grounded neutral systems shall begrounded as per 250.36 or 250.187250.21 AC Systems of 50 to 1000 Volts NotRequired to be Grounded (but may be)1.Electric systems used exclusively to supplyindustrial furnaces for melting, refining,tempering, and the like.2.Separately derived systems used exclusively forrectifiers that supply only adjustable-speedindustrial drives.189
11/13/2018250.21 AC Systems of 50 to 1000 Volts NotRequired to be Grounded3.Separately derived systems supplied bytransformers that have a primary voltage rating1000 volts or less, provided all the followingconditions are met:a) The system is used exclusively for control circuitsb) Qualified persons service the installationc) Continuity of control power is required19250.21 AC Systems of 50 to 1000 Volts NotRequired to be Grounded4.Other systems that are not required to begrounded in accordance with the requirementsof 250.20(B)2010
11/13/2018Copyright Cengage LearningActual Ungrounded System Ungrounded systemsare grounded throughdistributedcapacitance wheninsulated conductorsare installed in metalenclosures. Sputtering faults cancause transient overvoltages.Copyright Cengage Learning2211
11/13/2018250.21(B) Ground Detection RequiredGround detectionrequired for anyungrounded systemfrom A(1) through A(4)from 120 V to 1000V Various types and levelsof sophistication areavailable. The detection system isto be as close aspracticable to thesystem supply NEC is silent on thetype installed Copyright Cengage Learning23Marking Requirement 250.21(C) Marking. Ungrounded systems shall belegibly marked “Caution Ungrounded System OperatingX Volts Between Conductors” at the source orfirst disconnecting means of the system. The marking shallbe of sufficient durability to withstand the environmentinvolved.Additionally -408.3(F)(2) Panelboards -UngroundedSystems.“Caution Ungrounded System Operating VoltsBetween Conductors”2412
11/13/2018250.22 Circuits Not to Be Grounded1.Circuits for electric cranes operating over combustiblefibers in Class III locations as provided in 503.155Copyright Cengage Learning25250.22 Circuits Not to Be Grounded2.Circuits in health carefacilities as provided in517.61- ClassifiedAnesthetizinglocations and517.160- Isolatedpower systemsUses Line IsolationMonitor (LIM)Copyright Cengage Learning2613
11/13/2018250.22 Circuits Not to Be Grounded3.Circuits for equipment within the electrolytic cellline working zone as provided in Article 668Copyright Cengage Learning27250.22 Circuits Not to Be Grounded4.Secondary circuits of lighting systems asprovided in 411.6(A): Lighting circuits at 30V orless – Class 2Copyright Cengage Learning2814
11/13/2018250.22 Circuits Not to Be Grounded5.Secondary circuits of lighting systems as providedin 680.23(A)(2): Underwater luminairesCopyright Cengage Learning29250.22 Circuits Not to Be Grounded6. NEW Class 2 load side circuits for suspendedceiling low voltage power grid distributionsystems as provided in 393.60(B)15
11/13/2018250.24(A) System Grounding Connectionsfor service supplied AC systemsA premises wiringsystem supplied by agrounded ac servicemust have a groundingelectrode conductorconnected to thegrounded serviceconductor at eachservice per250.24(A)(1) - (A)(5)Copyright Cengage Learning31250.24(A)(1) GeneralGEC connection shall bemade at any accessible pointfrom the load end of theoverhead serviceconductors, service drop,underground serviceconductors, or servicelateral to, including theterminal or bus to which thegrounded service conductoris connected at the servicedisconnecting means.Copyright Cengage Learning3216
11/13/2018Generally Accepted Locations1.2.3.4.At the weather-head foroverhead servicesAt the meter socket orcurrent transformerenclosure (verify withthe utility and electricalinspector)At a wireway or auxiliarygutter on the line side ofthe service equipmentWithin the serviceequipment enclosureCopyright Cengage Learning33250.24(A)(2) Outdoor TransformerIf the transformer supplying the service is located outside, atleast one additional grounding connection is required to bemade from the grounded service conductor to a groundingelectrode* Exception for high impedance grounded systemsCopyright Cengage Learning3417
11/13/2018250.24(A)(3) Dual-Fed ServicesA single groundingelectrode connection tothe tie point of dual-fedservices is permittedCopyright Cengage Learning35250.24(A)(4) Main Bonding Jumper asWire or BusbarIf the main bondingjumper is a wire orbusbar, the groundingelectrode conductor ispermitted to connect tothe equipmentgrounding terminal baror bus to which themain bonding jumper isconnected .Copyright Cengage Learning3618
11/13/2018250.24(A)(5) Load-Side GroundingConnections A grounding connection is not permitted on the load sideof the service disconnecting means unless permitted inArticle 250. (connections other than service panel as inSDS) IN: See 250.30 for separately derived systems, 250.32 forbuildings or structures supplied by a feeder or branchcircuit and 250.142 for other permitted uses.37FeedersCopyright Cengage Learning3819
11/13/2018Load-Side Grounding Connections Neutral terminal barisolated fromenclosure Equipment groundingconductor connectsto enclosureCopyright Cengage Learning39Hazard of Using a Neutral to GroundEquipment (Not allowed)EG: If equipment isgrounded to the neutralpast the service, a looseneutral connection willresult in a shock hazard ifa ground fault occursCopyright Cengage Learning4020
11/13/2018250.24(B) Main Bonding JumperFor a grounded system, amain bonding jumpermust connect theequipment groundingconductor(s) and theservice disconnectenclosure to thegrounded serviceconductor within eachservice disconnectenclosure as per 250.28Copyright Cengage Learning41An Exception to 250.24 (B) An unspliced mainbonding jumper isonly required in onesection of an assemblylisted for use asservice equipment Usually furnished bymanufacturerCopyright Cengage Learning4221
11/13/2018250.24(C) Grounded conductor to theservice equipment1000V or lessRun withungroundedconductors.Not smallerthan 102 C 1Copyright Cengage Learning43250.24(C) Grounded ConductorBrought to Service Equipment Grounded conductorrun to each servicedisconnecting meansfrom wireway. Provides vital path forfault current toreturn to the source(utility transformer)Copyright Cengage Learning4422
11/13/2018250.24(C) Grounded ConductorBrought to Service EquipmentGrounded conductor toeach servicedisconnecting meanssupplied from servicedrop or overhead serviceconductors45Copyright Cengage Learning250.24(C) Grounded ConductorBrought to Service EquipmentGrounded serviceconductor required tobe bonded to eachservice disconnectingmeans for 1-phase and3-phase servicedisconnects46Copyright Cengage Learning23
11/13/2018An Exception to 250.24(C)Grounded serviceconductor onlyrequired to be bondedto one section of listedservice equipmentconsisting of more thanone servicedisconnecting meansCopyright Cengage Learning47250.24(C)(1) Sizing for Single Raceway Grounded system conductor (often a neutral) isrequired to be not smaller than the requiredgrounding electrode conductor specified in Table250.102(C)(1) Not required to be larger than the largestungrounded service-entrance conductor4824
11/13/2018250.24(C)(1) Sizing for Single Raceway Obtain size of service-entrance conductors Use the size of these conductors in Table 250.102(C)(1) todetermine the minimum size of the grounded systemconductor Compare to the size of grounded conductor required fromload calculation in 220.61 Compare to instructions from design engineer Install the largest of these conductors49250.24(C)(1) Sizing for Single RacewayFor parallel sets of conductors installed incompliance with 310.10(H): If in one raceway such as a wireway, determine the areaof the largest set of conductors in parallel and consideras one conductor Follow Table 250.102(C)(1) for size of neutralconductor If area of ungrounded set of conductors is larger than1100 kcm copper then Table 250.102(C)(1), apply 12.5% rule5025
11/13/2018250.24(C)(2 ) Sizing for Parallel runs intwo or more racewaysThe grounded conductor shall also be installed in parallel.The size of the grounded in each raceway, or cable, shall bebased on the total CM area of the parallel ungroundedconductors in the raceway, or cable, but not smaller than1/0 AWGCopyright Cengage Learning26
11/13/2018Example350 kcmil aluminum service lateral conductors ineach conduit Table 250.102(C)(1) 2 AWG copper or 1/0 aluminum Compare to size required by load calculation Minimum 1/0 AWG for parallel grounded conductorinstallations Install largest required conductor53Example3/0 AWG copper conductors to 200 ampereservice disconnect Table 250.102(C)(1) requires 4 AWG copper or #2AWG aluminum grounded conductor Larger conductor may be required by load calculation5427
11/13/2018More Requirements For service-entrance conductors larger than1100 kcmil copper or 1750 kcmil aluminum, thegrounded system conductor must be not smallerthan 12½ percent of the area of the largestservice-entrance phase conductor This presumes all service conductors are in asingle raceway such as a wireway55Copyright Cengage Learning5628
11/13/2018ExampleAdd together the circular mil area of the largestset of service-entrance conductors Multiply this value by 0.125 (12½ percent) The result is the minimum size of grounded(neutral) conductor Go to Table 8 of Chapter 957ExampleTable 250.102(C)(1) can be used for conductor sizescovered by the table 800 ampere service with 2 sets of 500 kcmil serviceconductors 500 kcmil 2 1000 kcmil Table 250.102(C)(1) requires 2/0 AWG copper mainbonding, or system bonding conductor5829
11/13/2018ExampleFor ungrounded conductors larger than 1100 kcmilcopper or 1750 kcmil aluminum 1200 ampere serviceFour 350-kcmil service conductors4 350 kcmil 1400 kcmil (1,400,000 cm)1,400,000 cm 0.125 175,000 cmNext standard size 4/0 AWG (211,600 cm) (Table 8 ofChapter 9)59Parallel Service-Entrance ConductorsServiceAmpereRating1000120016002000Total Area ofUngroundedConductors(3) 400 kcmil 1200 kcmil(4) 350 kcmil 1400 kcmil(5) 400 kcmil 2000 kcmil(6) 400 kcmil 2400 kcmilMinimum Areaof GroundedConductor150,000 cmMinimum Sizeof GroundedConductor3/0175,000 cm4/0250,000 cm250 kcmil300,000 cm300 kcmil6030
11/13/2018250.24(C)(2) Parallel Conductors Applies where two or more raceways are installed Grounded conductor in each raceway sized on the circularmil area of the ungrounded conductor in the raceway Minimum size 1/0 AWG Table 250.102(C)(1) used for sizing, or calculated loadwhichever is larger61Copyright Cengage Learning31
11/13/2018250.24(C)(3) Grounded Conductor for3-Ph, 3-Wire (Delta connected service) The grounded conductor for a 3-phase, 3-wire, deltaconnected service (corner ground) is required to havean ampacity not less than the ungrounded conductors Applies to corner-grounded delta-connected 3-phasesystems. Grounded conductor treated like a neutral for a 120/240volt single phase system63Copyright Cengage Learning6432
11/13/2018250.24(D) Grounding ElectrodeConductor A grounding electrode conductor is required to be usedto connect the equipment grounding conductors, theservice-equipment enclosures and, where the system isgrounded, the grounded service conductor to thegrounding electrode(s) required by Part III of Article 250. Size conductor per 260.66 (both the written article andthe table) High-impedance grounded neutral system connections aregrounded in accordance with 250.3665250.24(D) Grounding Electrode Conductor 250.21 for groundingelectrode connection 250.50 for groundingelectrode system 250.52 for groundingelectrode descriptions 250.64 for installationrules 250.66 for sizingCopyright Cengage Learning6633
11/13/2018250.24(E) Ungrounded SystemGrounding Connections Metal enclosures forservice equipment andequipment groundingconductors requiredto be connected togrounding electrodesystem Results in “caseground”Copyright Cengage Learning67250.24(E) Ungrounded SystemGrounding ConnectionsSize grounding electrode conductor according to250.66 based on the size of the largestungrounded system conductor6834
11/13/2018250.26 Conductor to be Grounded –AC Systems1.Single-phase, 2-wire –one conductor Typically 120-voltsystems69Copyright Cengage Learning250.26 Conductor to be Grounded –AC Systems2. Single-phase, 3-wire –the neutral conductorTypically 120/240 volt,1-phase, 3-wire70Copyright Cengage Learning35
11/13/2018250.26 Conductor to be Grounded –AC Systems3.Multiphase systems havingone wire common to allphases - the commonneutral conductor Typically 3-phase, 4-wirewye systems71Copyright Cengage Learning250.26 Conductor to be Grounded –AC Systems4.Multiphase systemswhere one phase isgrounded – one phaseconductor Typically 3-phase, 3-wiredelta connectedsystems72Copyright Cengage Learning36
11/13/2018250.26 Conductor to be Grounded –AC Systems5.Multiphase systems inwhich one phase is usedas in (2) Single phase –the neutral conductor Typically 120/240 volt, 3phase, 4-wire systems73Copyright Cengage Learning250.28 Main and System BondingJumpers The main bonding jumpershall be copper or othercorrosion resistantmaterial- a wire, bus,(green) screw, or . Sized as per 250.28(D) 1-3 Main bonding jumpers areinstalled at the service System bonding jumpersare installed at separatelyderived systems Perform identicalfunctionsCopyright Cengage Learning7437
11/13/2018250.28(A) Material Permitted to be ofcopper or othercorrosion-resistantmaterial Permitted to consistof a wire, bus, screwor similar suitableconductor75Copyright Cengage LearningMain Bonding Jumper in r OutletsMotor ControlEnclosed SwitchesUL Product CategoryUL 67, PanelboardsUL 891, Dead-frontSwitchboardsUL 231, Power OutletsUL 845, Electric MotorControl CentersUL 98, Enclosed Switches7638
11/13/2018Suitable Only for Use as Service Equipment Neutral terminal barbonded to the enclosure Typically, not permittedat the “feeder” position May be acceptable atdisconnecting means forseparately derivedsystemSee UL White book at:ul.com/whitebook(NJAV) and (WEVZ)Copyright Cengage Learning77250.28(B) ConstructionWhere a mainbonding jumper is ascrew only, it isrequired to have agreen finish that isvisible with the screwinstalledCopyright Cengage Learning7839
11/13/2018250.28(C) AttachmentAttach main bonding jumpers in compliance with the generalrules for making grounding and bonding connections asprovided in 250.879250.28(D)(1) Size of main or systembonding jumpers(1) Main bonding jumpers and system bondingjumpers -Generally, not smaller than given in Table250.102C1 For supply conductors larger than 1100 kcmilcopper or 1750 kcmil aluminum, size not smallerthan 12½ percent of the area of the largest phaseconductor The bonding jumper in listed service equipmentcan be used without calculation8040
11/13/2018250.28(D)(2) Main Bonding Jumper for Servicewith More than One Enclosure If the service consists of more than a singleenclosure as permitted in 230.71(A), the mainbonding jumper for each enclosure is required tobe sized in accordance with 250.28(D)(1) basedupon the largest ungrounded service conductorserving that enclosure Manufacturer-provided main bonding jumper forlisted equipment can be installed withoutcalculation81250.28(D)(3) Separately Derived System withMore Than One Enclosure If a separately derived system supplies more than oneenclosure, the system bonding jumper must be installed ateither the source of the separate system, or first systemdisconnecting means If at the first disconnecting means, use main bondingjumper supplied for listed enclosure or size according to250.28(D)(1) If at the source, size system bonding jumper per250.28(D)(1) based on the sum of circular mil area ofderived ungrounded conductors for one phase8241
11/13/2018Example: More than one enclosureFeederDerivedConductorsNumber PerPhaseCircular MilArea400 Ampere600 kcmil1600 kcmil600 Ampere350 kcmil2700 kcmilTotal area1300 kcmilSystem Bonding Jumper 12½ Percent of162,500 cm1300 kcmil ( 3/0)83Copyright Cengage Learning8442
11/13/2018250.30 Grounding Separately DerivedSystemsDefinition of term in Article 100 To comply with 250.30(A) for grounded systems,or as provided in 250.30(B) for ungroundedsystems Separately derived systems shall comply with250.20, 250.21, 250.22, and 250.26 Multiple separately derived systems that areconnected in parallel shall be installed inaccordance with 250.30. 85Article 100 definition: SeparatelyDerived Systems“An electrical source, other than a service, having no directconnection(s) to circuit conductors of any other electricalsource other than those established by grounding andbonding connections.”8643
11/13/2018Example for Transformers Verify there is no connecting jumper from primary tosecondary in the transformerA connection will commonly exist fromthe grounding of the service-supplied system through theequipment grounding conductor connected to the frame ofthe transformer through the system bonding jumper to theneutral of the separately derived systemGrounding of the case87Copyright Cengage Learning8844
11/13/2018Strap bonds core to the case. NOTthe system bonding jumper.89Here’s How for Generators Look in the transfer switch If the neutral is switched, the system supplied isseparately derived If the neutral is not switched, the system suppliedis not separately derived9045
11/13/2018Copyright Cengage Learning91AutotransformersAutotransformerhas a conductorthat is common toboth primary andsecondary Cannot be aseparately derivedsystem Copyright Cengage Learning9246
11/13/2018250.30(A) Grounded Systems A separately derived system that is groundedmust comply with the rules in (A)(1) - (A)(8) A grounding to grounded connection is notgenerally permitted on the load side of thegrounding point of the separately derived system Load-side grounding permitted under specificrules in 250.32 and 250.14293250.30(A)(1) System Bonding Jumper Unspliced systembonding jumperrequiredComply with 250.28(A)through (D)Locate it from sourceto first disconnectingmeansMust remain withinoriginating enclosureIf outside, comply with250.30(C)Copyright Cengage Learning9447
11/13/2018250.30(A)(1) Size of System BondingJumper Size system bondingjumper based on sizeof ungrounded derivedconductors Table250.102(C)(1) If Bonding jumper isfurnished with listedservice equipment permitted withoutcalculation of sizeCopyright Cengage Learning95250.30(A)(1) Ex. No. 1 A single system bonding jumper connection atthe tie point is permitted for systems installed inaccordance with 450.6 (secondary tie points) This equipment is commonly double-endedequipment supplied from two separately derivedsystems. The neutral of the two systems is tied togetherby this connection9648
11/13/2018Copyright Cengage Learning97250.30(A)(1) Ex. 2Bonding jumper atboth source andfirst overcurrentdevice permittedwhere a parallelpath is notestablishedCopyright Cengage Learning9849
11/13/2018250.30(A)(1)(a) System Bonding Jumperat SourceThe system bonding jumper is required to connectthe grounded conductor to the supply-sidebonding jumper and the normally non–currentcarrying metal enclosure.99250.30(A)(1)(b) System Bonding Jumperat First Disconnecting MeansThe system bonding jumper is required to connectthe grounded conductor to the supply-sidebonding jumper, the disconnecting meansenclosure, and the equipment groundingconductor(s).10050
11/13/2018Copyright Cengage Learning101250.30(A)(2) Supply-Side BondingJumperIf the source of a separately derived system and thefirst disconnecting means are located in separateenclosures, a supply-side bonding jumper shall beinstalled with the circuit conductors from thesource enclosure to the first disconnecting means.10251
11/13/2018250.30(A)(2) Supply-Side BondingJumperA supply-side bonding jumper shall not be requiredto be larger than the derived ungroundedconductors.103250.30(A)(2) Supply-Side BondingJumperThe supply side bonding jumper shall be permittedto be of –nonflexible- metal raceway type or of thewire or bus type as follows:(a) A supply-side bonding jumper of the wire typeshall comply with 250.102(C), based on the size ofthe derived ungrounded conductors.10452
11/13/2018250.30(A)(2) Supply-Side BondingJumper(b) A supply-side bonding jumper of the bus typeshall have a cross-sectional area not smaller than asupply-side bonding jumper of the wire type asdetermined in 250.102(C).Exception: A supply-side bonding jumper shall notbe required between enclosures for installationsmade in compliance with 250.30(A)(1), ExceptionNo. 2.105Copyright Cengage Learning10610653
11/13/2018Table 2-3WiringMethodSizeMax OCPLengthFMCAll20 A6 ft(1.8 m)LFMC3/8 & ½LFMCLFMC¾ thru1¼Largerthan 1¼6 ft(1.8 m)6 ft60 A(1.8 m)NotNotpermitted permitted20 (6)107Copyright Cengage Learning10810854
11/13/2018Copyright Cengage Learning109250.30(A)(3) Grounded Conductor (A)(3)(a) Rules identical to sizing groundedconductor for service Ensures conductor is adequate for carrying fault current Also, size for calculated load (A)(3)(b) Rules identical to sizing groundedconductors for services when installed in parallel Table 250.102C111055
11/13/2018Copyright Cengage Learning111250.30(A)(4) Grounding Electrode The building or structure grounding electrodesystem shall be used as the grounding electrodefor a separately derived system. If locatedoutdoors, the grounding electrode shall be inaccordance with 250.30 (C) (Outdoor Source) * Exception: If the SDS originates in equipmentthat is listed and identified for use as serviceequipment, the grounding electrode used for theservice is permitted to be used as the GE for theSDS11256
11/13/2018250.30(A)(4) Grounding Electrode Primary purpose isbonding electricalstructures orequipment that islikely to becomeenergized Rules for water pipeelectrode apply Building or structuregrounding permittedRules for structuralmetal also applyCopyright Cengage Learning113250.30(A)(4) GEC, Single SeparatelyDerived System Connect groundedconductor ofseparately derivedsystem to groundingelectrode Connect at samepoint where systembonding jumper isconnectedCopyright Cengage Learning11457
11/13/2018ExampleAssume 600-ampere panelboard Two 350 kcmil THWN conductors connected inparallel 310 amperes 2 620 amperes 350 kcmil 2 700 kcmil Table 250.66 requires 2/0 AWG coppergrounding electrode conductor115Copyright Cengage Learning11658
11/13/2018Example Determine the minimum size of the groundingelectrode conductor for the derived system. Determine the size of equipment grounding busand grounding electrode conductor for theprimary section. Verify conductors are appropriate for groundingelectrode conductor.117Common GEC Common groundingelectrode and tap conductorspermitted Connect taps at same pointsystem bonding jumper isconnected This subsection acts asexception to 250.30(A)(5) Common GEC based on250.30 A(6)(a)(1) a wire typeconductor not smaller than3/0 cuCopyright Cengage Learning11859
11/13/2018250.30(A)(6)(a) Size of Common and TapGrounding Electrode Conductor(1) Minimum size permitted for common wire typeGEC is 3/0 copper or 250 kcmil aluminum (Also isthe maximum size required by this section)Size tap conductors from 250.66 based upon thesize of the derived ungrounded conductors(2) A metal water pipe that complies with 250.68(C)(1) The metal water piping system is allowed toserve as a grounding electrode if connected within5 ft of the entrance * with exceptions 119250.30(A)(6)(b) Tap Conductor sizeEach tap conductor from the SDS to the CommonGEC is sized as per 250.66 based on the derivedungrounded conductors* See exceptions for service rated equipment12060
11/13/2018250.30(A)(6)(c) ConnectionsCopyright Cengage Learning121250.30(A)(6)(c) Connections¼” thick, 2” wide,Sufficient length forterminationsCopyright Cengage Learning12261
11/13/2018250.30(A)(7) Installation (8) Bonding(7) Comply with 250.64(A), (B), (C) and (E) (A) Aluminum conductors(B) Installation rules(C) Unbroken unless installed in compliance with rules(E) Bonding of ferrous metal raceways that enclosegrounding electrode conductor(8) Structural steel and metal pipes shall beconnected to the grounded conductor of a SDS123250.30(B) Ungrounded Systems1.Grounding electrode conductor based on size ofungrounded derived conductor2.Except for portable and vehicle-mounted generators, thegrounding electrode is required to comply with250.30(A)(4)3.Install supply-side bonding jumper between the source ofthe separately derived system and the first disconnectingmeans in compliance with 250.30(A)(2)12462
11/13/2018Copyright Cengage Learning125250.30(C) Outdoors Source If the source of the separately derived system is locatedoutside the building or structure supplied, a groundingelectrode connection shall be made at the source locationto one or more grounding electrodes in compliance with250.50. In addition, the installation shall comply with250.30(A) for grounded systems or with 250.30(B) forungrounded systems. (previous slides) This rule requires the system bonding jumper to also belocated at the outdoor source. * See exception for impedance grounded systems12663
11/13/2018Copyright Cengage Learning127Copyright Cengage Learning12864
11/13/2018Copyright Cengage Learning129Copyright Cengage Learning13065
11/13/2018250.32 Buildings or Structures Suppliedby a Feeder(s) or Branch Circuit(s) Bond all grounding electrodes, installed as per Part IIIof Art 250, together at building or structure to formgrounding electrode system Connect at building disconnecting means inaccordance with 250.32(B) or (C) (following) Install grounding electrode(s) if none existSee 250.52(A) for description of grounding electrodesrequired to be used* See exception for a building with only one branchcircuit.131250.32 Buildings or Structures Supplied by aFeeder(s) or Branch Circuit(s)(A) Bond all groundingelectrodes together toform groundingelectrode system Connect in accordancewith 250.32(B) or (
250.20 AC Circuits and Systems to Be Grounded Some circuits and systems are permitted to be grounded - 250.20(C) other than portable or mobile equipment. (see 250.188) If systems are grounded, the methods must comply with Article 250 250.21 - Some circuits are not required to be grounded. Parts (A)–
Grounding Study and Analysis: Substation Grounding Practices Grounding Concepts - GPR and Touch Potential AEP Innovative Grounding Study Methods Grounding Installation: Traditional Approach and Challenges Grounding Application and Installation Change Management Testing: Grounding Integrity Testing Conclusion and .
6. grounding notes 6.1 a grounding electrode system in accordance with [nec 690-47] and [nec 250-50] through [nec 60 250-166] shall be provided. per nec, grounding electrode system of existing building may be used and bonded to at the service entrance. if existing system is inaccessible, or inadequate, a supplemental grounding electrode will be
NEC 250.62; 64 Grounding Electrode Conductor Material; Installation NEC 250.66, table Size of Alternating-Current Grounding Electrode Conductor NEC 810.21 Bonding Conductors and Grounding Electrode Conductors— Receiving Stations NEC 800 Part IV Grounding Methods (Communication Circuits) 5) In a building with 10 feet or more of metallic water .
Dec 02, 2017 · Based on 2017 National Electrical Code (NFPA 70) The Philippine Electrical Code Part 1 2009 Edition was based on NEC 2005 Regularly revised (every three years) to reflect the evolution of products, materials, and installation techniques. NEC 2008, NEC 2011, NEC 2014 & NEC 2017 NEXT NEC REVISION: NEC 2020, 2023, 2026, 2029
NEC 3 Professional Services Contract (PSC). NEC 3 Short Contract (ECSC) and Short Subcontract (ECSS). NEC 3 Adjudicator’s Contract (AC). NEC 3 Term Services Contract (TSC). NEC 3 Term Service Short Contract (TSSC). NEC 3 Framework Contract (Framework Contract). NEC 3 Supply Contract (SC).
the NEC would know that grounding and bonding requirements are found in Article 250. Scanning the information in the NEC Table of Contents, we find the requirements for the “Grounding Elec-trode System and Grounding Electrode Conduc-tor” are in Part III of Article 250, and they s
5 Location NEC 2008 NEC 2011 NEC 2014 NEC 2017 NEC 2020 Family Rooms AFCI AFCI AFCI AFCI AFCI Dining Rooms AFCI AFCI AFCI AFCI AFCI Kitchens - 125V Receptacles GFCI GFCI AF/GF AF/GF AF/GF Kitchens - 250V Receptacles TM TM TM TM GFCI1 Bedrooms AFCI AFCI AFCI AFCI AF/GF1 Living Rooms AFCI AFCI AFCI AFCI AFCI Garage - 125V Receptacles GFCI GFCI GFCI GFCI GFCI Garage - 250V Receptacles TM TM .
NEC Table 250.122 - Minimum size equipment grounding conductors for grounding raceway and equipment Table 2 – Minimum size equipment grounding conductors for grounding raceway and equipment Aluminum Cable Tray Systems Table 392.60(A) – Metal area requiremen
