Erico Practical Guide to Electrical Grounding Manuel d'utilisateur

PracticalGuide ToElectricalGroundingPracticalGuide ToElectricalGroundingAnPublicationW. Keith SwitzerW. Keith Switzer$28.95 U.S.First Printing, First

2Practical Guide to Electrical GroundingGrounding Book 4/14/99 10/5/99 6:01 PM Page 2 (Black plate)

The electromotive series (Table 6-1) lists several materialsfrom the most anodic, or most active, at the top of the list tothe most cathodic, or least

93Chapter 6: Special Grounding Situationsand/or are damaged when the pipe is installed. The breaksin the coating (called holidays) are protected by t

made below the liquid level. Pure fuel will not burn orexplode. It will burn or explode only when mixed withoxygen (air) within certain ratios.Codes &

95Chapter 6: Special Grounding SituationsFig. 6-7Fig. 6-8Cable Tap To TubeTube To Ground RodTube TeeTube SpliceFig. 6-9CADWELD Connections on copper

Practical Guide to Electrical GroundingSTATIC GROUNDINGStatic electricity is a major cause of fires and explosionswhere flammable powders and liquids

97Some specific areas where static electricity is generatedinclude:Piping Systems - In piping systems, the generation rate andthe subsequent accumulat

Practical Guide to Electrical Groundinglevel in the mixer and/or providing a liquid conductivemedium to dissipate the charge will help. If this is not

99through most paint, rust and surface contaminates. Singlepoint clamps are superior to battery type and “alligator”type clamps for making direct cont

Conductor Sizing Proper sizing of conductors is determined by many factorssuch as industry standards, insurance requirements, localcodes, etc. These s

101Chapter 6: Special Grounding SituationsOverhead Track Type Door GroundingFig. 6-17Grounding ReelExothermicWeld To Overhead DoorDoor Track(Typical

3BUILDING GROUNDING —AN OVERVIEWDespite the electrical designers’ best efforts, electricalground faults, short circuits, lightning and other transient

Practical Guide to Electrical Grounding102Fig. 6-2136"4"CADWELD SpliceConnection To GroundSee Detail "B"1/4 x 3 Copper BusSee Deta

103Chapter 6: Special Grounding SituationsAttachments to ground bus.Fig. 6-23Bus to facility ground and pipe grounding.Fig. 6-26Temporary bonding jum

Practical Guide to Electrical Grounding104Drum and pail bonding.Fig. 6-29Drum and pail bonding.Fig. 6-31Pipe and drum.Fig. 6-30Mixer bonding.Fig. 6-32

105Chapter 6: Special Grounding SituationsDrum storage rack bonding.Fig. 6-34Pipe Swivel JointB2616Axx Pipe ClampsWith A806A3F5 CableB2614A Spring Cl

Practical Guide to Electrical Grounding106WIRE MESHERICO prefabricated wire mesh is a convenient, efficientand economical means of improving grounding

107Chapter 6: Special Grounding SituationsPrefabricated wire mesh is custom made to meet the needsof the installation. Wire size can range from No.6

Practical Guide to Electrical Groundingmost commonly used is No.6 copperbonded steel, 30%conductivity. CADWELD connections are used to connectthe cond

109With the perimeter conductor one meter outside the fence,a worker standing inside the fence will have an increase intouch potential, but only by ab

Following are fence and gate grounding details which maybe helpful. (Fig. 6-52, 6-53 and 6-54)Various styles of clamps are available for fence postgro

111Chapter 6: Special Grounding SituationsGrounding Book 4/14/99 10/5/99 6:02 PM Page 111 (Black plate)

BUILDING GROUNDINGElectrical design and installation professionals need toconsider several different building grounding systems forany building or str

113Chapter 7: Application Of Surge Protection DevicesChapter 7Application Of SurgeProtection DevicesGrounding Book 4/14/99 10/5/99 6:02 PM Page 113

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115Chapter 7: Application Of Surge Protection DevicesSURGE PROTECTIONGood grounding without good surge protection may not betotally effective in prote

Practical Guide to Electrical Grounding116present. (Fig. 7-1) Power line faults, power line equipmentproblems and lightning are the greatest threat at

117Chapter 7: Application Of Surge Protection DevicesLocation Category And Exposure Levels As Defined By IEEE STD C62.41-1991For Line-Line & Line-

Practical Guide to Electrical Grounding118OutbuildingOutbuildingXformerUnderground ServiceUnderground ServiceMeterMeterMeterABCServiceEntranceServiceE

119DefinitionsDEFINITIONSAir Terminal: That component of a lightning protectionsystem that is intended to intercept lightning flashes,(commonly known

Practical Guide to Electrical Grounding120Lightning Protection System: A complete system of airterminals, conductors, ground terminals, interconnectin

121References and BibliographyREFERENCES[1] ANSI/NFPA 70-1996, National Electrical Code(NEC).[2] ITU K27-1991, Bonding Configurations andEarthing Insi

INDEX122PageAAC System, electrode system grounding 16Active Attraction Systems, lightning 24Active Prevention Systems, lightning 24Air Terminal, light

5When “inspection wells” are required to expose points fromwhich to measure system resistance, several methods areavailable. Inspection wells are usua

INDEX123PageL (Cont.)Low Impedance Conductor, lightning 26Low Resistance Grounding System,lightning protection 32MMade Electrodes, grounding 14, 82Mag

124NotesGrounding Book 4/14/99 10/5/99 6:02 PM Page 124 (Black plate)

When the required resistance is not achieved using theusual grounding layouts, ERICO prefabricated wire meshcan be added to lower the overall groundin

72. If a conducting gate is used, a buried bondingjumper must be installed across the opening(Fig. 1-11).3. Where gates are installed, they shall be b

Other items that are located on the outside of the buildingthat should be considered are lighting fixture standards, pullbox covers and rails. Handhol

9Grounding conductors shall be protected against physicaldamage wherever they are accessible (Fig. 1-21).Grounding conductors installed as separate co

The grounding electrode system is designed to providemultiple electrical paths into the earth. As stated in thePreface, grounding of electrical system

11The third component of the grounding electrode system isconcrete-encased electrodes. These are usually referred toas “rebar,” which is short for rei

Electrical Protection Products34600 Solon RoadSolon, Ohio 44139W. Keith Switzer, Senior Staff EngineerPhone: (440) 248-0100Fax: (800) 677-8131E-mail:

electrode conductor is connected to buried electrodes theclamp or fitting must be listed for direct soil burial.CADWELD offers the best solution for c

13Chapter 1: Building and Service Entrance Grounding Soil BackfillSoil4"GEM1"4"30"TrenchGEM1"GEMGround ConductorSoil Backfill

14Practical Guide to Electrical GroundingSection 250-83 contains requirements for other (frequentlyreferred to as “made”) electrodes. These electrodes

15Also fitting into this category are chemical type groundelectrodes consisting of a copper tube filled with salts.Moisture entering the tube slowly d

16Practical Guide to Electrical Groundingeach end of the enclosure or raceway to the groundingconductor. IEEE paper No. 54 and other studies have show

CONCRETE ENCASED ELECTRODES,“UFER GROUNDING”Herb Ufer reported on probably the first use of concrete-encased electrodes at a bomb storage facility at

18Practical Guide to Electrical GroundingThe damage to the concrete can be explained due to itsnon-homogeneous character and moisture content. Duringa

19Chapter 1: Building and Service Entrance Grounding Grounding Book 4/14/99 10/5/99 6:01 PM Page 19 (Black plate)

Practical Guide to Electrical Grounding20Grounding Book 4/14/99 10/5/99 6:01 PM Page 20 (Black plate)

21Chapter 2: Building Lightning Protection Chapter 2Building LightningProtectionA Critical Extension OfGroundingGrounding Book 4/14/99 10/5/99 6:01

PracticalGuide ToElectricalGroundingPracticalGuide ToElectricalGroundingAnPublicationFirst Printing, First Edition, August 1999W. Keith SwitzerW. Keit

22Practical Guide to Electrical GroundingGrounding Book 4/14/99 10/5/99 6:01 PM Page 22 (Black plate)

LIGHTNING - AN OVERVIEWLightning is an electrical discharge within clouds, fromcloud to cloud, or from cloud to the earth. Lightningprotection systems

New detection devices have been installed around the U.S.which count the total number of lightning strokes reachingthe earth. This data results in pre

25Chapter 2: Building Lightning Protection There is general agreement that the best theoreticallightning system is a solid faraday cage around whatev

inception over 200 years ago, the nature and scope oflighting protection has changed considerably. Lightningprotection then was principally a defense

27Calculation of the Protective Coverageoffered by an air terminalCollection Volume Design MethodA more efficient air terminal demands a new designphi

alternative structure or feature on the ground). This leads tothe development of a limiting parabola. The enclosedvolume is known as the Collection Vo

29Chapter 2: Building Lightning Protection The following are basic components for a lightningprotection system. Sketches at the end of this section d

30Practical Guide to Electrical Groundingair without support for more than 3 feet (0.9 m) (Fig. 2-8)and they must be fastened at a maximum of every 3

31Chapter 2: Building Lightning Protection necting or bonding of the two systems helps to ensure thatthere is little possibility of a difference of

Table of ContentsChapter Description Page1 Building and Service Entrance Grounding - 1The grounding of buildings and facilities where people work.Bui

32Practical Guide to Electrical Groundingelectrodes as required by the NEC (250-81 and 250-86) andthe several lightning codes such as NFPA 780. Noexce

33Chapter 2: Building Lightning Protection NFPA 780, STANDARD FOR THEPROTECTION OF LIGHTNINGSYSTEMS - AN OVERVIEWIn addition to the general requireme

34Practical Guide to Electrical Grounding10. Section 3-19.4: Where the building structural steelis used as the main conductor of the lightningprotecti

35Chapter 2: Building Lightning Protection Fig. 2-20Protection must be provided to the conductor inareas where physical damage or displacementmay occ

36Practical Guide to Electrical GroundingFig. 2-22Downleads following steel members must bebonded to the steel at the upper and lowerextremities and a

37Chapter 2: Building Lightning Protection Fig. 2-26The main conductor must never becoursed upward.Fig. 2-27If a projection is over 40 feet on the th

38Practical Guide to Electrical GroundingFig. 2-28If a projection extends over 40 feet, a downlead at(A) must be provided on the projection.Fig. 2-29

39Chapter 2: Building Lightning Protection 12" x 12"(1 Square Foot)Fig. 2-35Electrodes made from copper or steel plates areoften used in s

40Practical Guide to Electrical GroundingFig. 2-38On large flat roofs or gently sloping roofs, airterminals are placed in the center area at intervals

41Chapter 2: Building Lightning Protection Fig. 2-45Structural steel may be used as the conductor ifproperly bonded.Fig. 2-46Air terminal placement o

WHY DO WE NEED ANOTHERBOOK ON GROUNDING?This book is designed for the contractor who finds thatinstalling grounding systems, which are in compliance w

42Practical Guide to Electrical GroundingFig. 2-48Very large buildings require more air terminals,down leads and ground terminals.Fig. 2-47More extens

43Chapter 2: Building Lightning Protection Ground GridDead End ClampShield WireLightning MastTA ConnectionCADWELD TypeOr Type PB ConnectionPC Connec

44Practical Guide to Electrical GroundingFig. 2-57Flat or gently sloping roofs are defined as shown.Fig. 2-56Air terminal placement shown on various t

45Chapter 2: Building Lightning Protection Grounding Book 4/14/99 10/5/99 6:01 PM Page 45 (Black plate)

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47Chapter 3: Building Interior Bonding and Grounding Chapter 3Building InteriorBonding And GroundingThe Bonding AndGrounding Of Building Steel,Electr

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INTRODUCTIONIn addition to electrical service grounding and supple-mental building grounding, designers and installers ofelectrical systems face criti

devices. This would include fittings such as bonding-typelocknuts and grounding bushings. These fittings aredesigned to make good contact with the met

comprise the grounding electrode system. While theseguidelines may appear to be somewhat vague, a good ruleof thumb to follow is: If the interior meta

Practical Guide to Electrical Groundingessential to provide a reference function. Another suitableconductive body may be used instead.The function of

Practical Guide to Electrical Grounding52Steel BeamCADWELD ConnectionType QW To Flange Of Beam(Or Type VN on Large Beam)Steel ColumnCADWELD Connection

53extend to each floor (Fig. 3-7). For accessible ground pointsat each floor, ground bars provide the ideal solution. Theycan be bolted to either the

Practical Guide to Electrical Grounding54Fig. 3-8Fig. 3-9...

55Chapter 3: Building Interior Bonding & Grounding Fig. 3-10Fig. 3-11Fig. 3-13RightHandWeldLeftHandWeldCopper Left Hand Right Hand WeldBar Size M

Practical Guide to Electrical Grounding56Fig. 3-14Fig. 3-15Detail - Conductive Floor GroundFig. 3-16Fig. 3-173/8" BronzeStud W/3 NutsAnd Lock Was

57EQUIPMENT BONDINGEquipment within the facility must be carefully consideredas to its need to be bonded to the facility ground system. Ofcourse, all

Practical Guide to Electrical GroundingGROUNDINGGeneral Provisions - Equipment Fastened in Place. Asnoted above, the primary reason equipment and encl

59500 - 517 of the NEC and installers and designers ofelectrical systems should review these articles prior todesigning or installing electrical syste

Practical Guide to Electrical Groundingemploy a system of double insulation which is distinctivelymarked on the tool or appliance.Receptacle Grounding

61Chapter 3: Building Interior Bonding & Grounding isolated ground (IG) receptacles. These IG receptacles arefrequently used for electronic/data

Prefaceare some of the best, long lasting and cost effective productsavailable. Here we combine these with our knowledge ofmethods to assist the indus

Practical Guide to Electrical Grounding62CADWELD ConnectionGround Bar To Ground RodType CRGround Wire FromTransformerCADWELD TerminalTYPE GL With NEMA

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Chapter 4Transients And OtherHigh Frequency BondingAnd “Grounding”The Bonding AndGrounding Of ElectronicSystems65Chapter 4: Transients & Other Hi

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67INTRODUCTION TO ELECTRONICSYSTEM “GROUNDING”Grounding electronic equipment for personal safety andclearing of faults is no different than that of a

Practical Guide to Electrical GroundingSOME IMPORTANT POINTS ABOUTGROUNDING(1) Typically the safety grounding of equipment isexactly the same for elec

69much as 200% of the ampacity used for the related lineconductors. This is regularly done in order that a fire beavoided due to current overload from

to ensure good longitudinal coupling. In addition tobeing well grounded/bonded to the equipment at theends of the run, the conduit or raceway should a

an isolation transformer is installed adjacent to theserved loads and is positioned between the output ofa transfer switch and the input of the served

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Practical Guide to Electrical GroundingGROUND CURRENT INTERFERENCEWITH CATHODE RAY TUBE (CRT)BASED EQUIPMENTLow frequency magnetic fields such as thos

73Chapter 4: Transients & Other High Frequency “Grounding” & Bonding Ground Loop (unwanted)— Any conductive pathinvolving “ground” via a grou

Practical Guide to Electrical Grounding74(1). Where possible, cluster the interconnectedelectronic equipment into an area that is served by asingle si

75Chapter 4: Transients & Other High Frequency “Grounding” & Bonding ELECTRONIC GROUNDING DETAILWhen a metallic mesh is embedded in the struc

Practical Guide to Electrical Grounding76TELECOMMUNICATIONS SYSTEMSGROUNDINGGrounding of telecommunications systems, such as voiceand data grade telep

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79Chapter 5: Selection of Components Used In Grounding Chapter 5Selection OfComponents Used InGroundingGrounding ConductorsConnectorsGrounding Electr

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81SELECTION OF GROUNDINGSYSTEM COMPONENTSThe overall effectiveness of any grounding system will bedetermined by the individual components that are use

Chapter 1Building and ServiceEntrance GroundingBuilding GroundingGround ResistanceElectrical Service GroundingUfer Grounding1Chapter 1: Building and S

aluminum. Copper-clad aluminum is constructed of aminimum of 10% copper which is metallurgically bondedto the aluminum core. The GEC is permitted to b

This type of electrode is commonly called a “UferGround”. (A plastic sheet must not be used toseparate the concrete from the earth.) Figure 5-1shows a

However, when copper is interconnected electrically tosteel in the presence of an electrolyte, the steel will corrodeto protect the copper. Since the

Although the welded type are more expensive, they assurethat the couplings will not become a high resistancemember in the current path over the life o

CONNECTORSFor most connector applications there is a choice of good -better - best. This choice depends on required life, expectedcorrosion, expected

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89Chapter 6: Special Grounding SituationsChapter 6Special GroundingSituationsAreas Not CoveredElsewhereAirportsCorrosion And Cathodic ProtectionRadio

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91Chapter 6: Special Grounding SituationsAIRPORTSAirports require special attention to grounding. They notonly handle fuel in close proximity to mass