Electrical System Grounding- Static Grounding and Lightning Protection Grounding-And-lightning-protection

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  • 7/31/2019 Electrical System Grounding- Static Grounding and Lightning Protection Grounding-And-lightning-protection

    http:///reader/full/electrical-system-grounding-static-grounding-and-lightning-protection-grounding-and-lightning-pr 1/28

    DEPARTMENT OF THE AI R FORCEHEADQUARTERS UNI TED STATES AI R FORCE

    WASHI NGTON DC20330- 5000

    SUBJECT: Engi neer i ng Techni cal Let t er ( ETL) 90- 6:

    El ec t r i cal Syst em Gr oundi ng, St at i c Gr oundi ng and Li ght ni ngPr ot ec t i on

    See Di s t r i but i on Li s t

    1. At t ac hed f or y our i nf or mat i on and ac t i on ar e c r i t er i a f or t he des i gn ofel ec t r i c al gr oundi ng, s t at i c pr ot ec t i on and l i ght ni ng pr ot ec t i on s ys t ems f orAi r For c e f ac i l i t i es.

    2. Pur pose. Thi s ETL:

    a. Spec i f i es and c l ar i f i es bas i c r equi r ement s f or el ec t r i c algr oundi ng, s t at i c and l i ght ni ng pr ot ec t i on c r i t er i a f or t he des i gn of s af e

    and ef f ec t i v e pr ot ec t i on s ys t ems f or Ai r For c e f ac i l i t i es .

    b. Super sedes t hose por t i ons of r e f er enced publ i cat i ons onl y asspec i f i c al l y st at ed.

    c . I s aut hor i zed i n accor dance wi t h AFR 8- 7 , Ai r For ce Engi neer i ngTechni cal Let t er s (ETLs) , and i s t o be i mpl ement ed accor di ngl y . Wai ver s f orexpl os i ves f ac i l i t i es wi l l be pr ocessed i n accor dance wi t h AFR 127- 100. Al lot her wa i ver s wi l l be pr ocessed i n accor dance wi t h t he pr ocedur es es t abl i shedby t he Model I ns t a l l at i on Pr ogr am.

    3. Ef f ec t i v e Dat e. Thi s ETL i s ef f ec t i v e:

    a. For a l l pr oj ec t s whi ch have not r eached t he 35 percent p r el i mi nar ydes i gn s t age as of t he dat e of t hi s l et t er .

    b. For p r o j ec t s , r egar dl es s of t hei r d es i gn s t age, wi t h pr opos edsyst ems whi ch ar e unsaf e or i nadequat e f or accept abl e equi pment oper at i on asdet er mi ned by t he Maj or Command ( MAJCOM) .

    4. Thi s i s a coor di nat ed HQ USAF/ LEED and HQ AFESC/ DEM l et t er . Our poi ntof cont act i s Mr . Fer nandez at DSN 297- 4083.

    CHARLES L. PEARCE, Col onel , USAF 3 At chChi ef , I ns t al l at i on Dev el opment Di v i s i on 1. Di s t r i but i on Li s t

    Di r ec t or at e of Engi neer i ng and Ser v i ces 2. Des i gn Cr i t er i a3. I ndex

  • 7/31/2019 Electrical System Grounding- Static Grounding and Lightning Protection Grounding-And-lightning-protection

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    DI STRI BUTI ON LI ST

    DI STRI BUTI ON

    ACTI ON OFFI CES

    HQ 11TH AF/ DEE/ DEMELMENDORF AFB, AK 995506- 5001

    HQ AFCC/ DEE/ DEOSCOTT AFB, I L 622250- 6001

    HQ AFLC/ DEE/ DEMWRI GHT- PATTERSON AFB, OH 45433- 5001

    HQ AFRES/ DEE/ DEMROBI NS AFB, GA 31098- 5000

    HQ AFSC/ DEE/ DEM

    ANDREWS AFB, DC 20334- 5000

    HQ ATC/ DEE/ DEMRANDOLPH AFB, TX 78148- 5001

    HQ AU/ DEE/ DEM

    HQ ESC/ LEEE/ LEEPSAN ANTONI O, TX 78243- 5001

    HQ PACAF/ DEE/ DEMHI CKAM AFB, HI 96853- 5001

    HQ MAC/ DEE/ DEMSCOTT AFB, I L 62225- 5000

    HQ SAC/ DEE/ DEMOFFUTT AFB, NE 68113- 5001

    HQ AFSPACECMD/ DEE/ DEMPETERSON AFB, CO 80914- 5001

    HQ TAC/ DEE/ DEMLANGLEY AFB, VA 23665- 5001

    HQ USAFE/ DEE/ DEM

    APO NY 09012- 5001

    HQ USAFE/ DERRAF RUI SLI P ADM, UKAPO NY 09241- 5000

    At ch 1 ( 1 of 3)

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    HQ AFESC/ DEMMTYNDALL AFB, FL 32403- 6001

    1100 ABG/ DEE/ DEMBOLLI NG APB, DC 20332- 5000

    USAF RGN CI VI L ENGR - EASTERN REGI ON/ ROE77 FORSYTH ST. , SUI TE 291ATLANTA, GA 30335- 6801

    USAF RGN CI VI L ENGR - CENTRAL REGI ON/ ROE1114 COMMERCE ST, ROOM 207DALLAS, TX 75242- 0216

    USAF RGN CI VI L ENGR - WESTERN REGI ON/ ROE630 SANSOME ST, ROOM 1316SAN FRANCI SCO, CA 94111- 2278

    AFRCE- BMS/ DEE

    NORTON AFB, CA 92409- 6448

    AFI T/ DEEWPAFB, OH 45433- 6583

    HQ USAFA/ DEMACOLORADO SPRI NGS, CO 80840- 5671

    I NFO OFFI CES

    AAFES/ EN- CE

    ANGSC/ DEE/ DEO

    ANDREWS AFB, MD 20331- 6008

    NAVFAC CODE 04/ 05

    CEEC- ET/ ES

    HQ AFCOMS/ DEEKELLY AFB, TX 78241- 6290

    DEFENSE MEDI CAL FACI LI TI ES OFFI CE6 SKYLI NE PLACE 109 LEESBURG PI KEFALLS CHURCH, VA 22041

    HQ USAF/ LEYS/ SCTXWASHI NGTON, DC 20330- 5000

    SSD/ DELOS ANGELES AFB, CA 90009- 2260

    At ch 1 ( 2 of 3)

  • 7/31/2019 Electrical System Grounding- Static Grounding and Lightning Protection Grounding-And-lightning-protection

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    AD/ DEEGLI N AFB, FL 32542- 5000

    HQ AFOMS/ SGSFBROOKS AFB, TX 78235- 5000

    HQ AFI SC/ SEGNORTON AFB, CA 92409- 7001

    1842 EEG/ EELSCOTT AFB, I L 62225- 6001

    1839 EI G/ EI EEKEESLER AFB, MS

    HQ DNAATTN: RAEE6801 TELEGRAPH RDALEXANDRI A, VA 22310- 3398

    HQ DCA/ DTJ( B410)WASHI NGTON, DC 20305- 2200

    SAF/ FMABDWASHI NGTON, DC 20330- 5000

    SAF/ AQQSWASHI NGTON, DC 20330- 1000

    HQ AGMC/ MLMNEWARK AFB, OH 43055- 5000

    WL/ NTCABLDG 909KI RTLAND AFB, NM 87117- 6008

    EI D/ EI WTI NKER AFB, OK 73145- 5000

    AFCSC/ SRVTSAN ANTONI O, TX 78243- 5000

    HQ AFI SC/ SEWVNORTON AFB, CA 92409- 7001

    At ch 1 ( 3 of 3)

  • 7/31/2019 Electrical System Grounding- Static Grounding and Lightning Protection Grounding-And-lightning-protection

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    ETL 90- 63 OCTOBER 1990

    ENGI NEERI NG TECHNI CAL LETTER

    ELECTRI CAL SYSTEM GROUNDI NG,STATI C GROUNDI NG

    AND LI GHTNI NG PROTECTI ON

    Depar t ment of t he Ai r For ceUni t ed St at es of Amer i ca

    DI RECTORATE of ENGI NEERI NG AND SERVI CES

    I NSTALLATI ON DEVELOPMENT DI VI SI ONENGI NEERI NG BRANCH

    DI STRI BUTI ON STATEMENT: APPROVED FOR PUBLI C RELEASE DI STRI BUTI ON I S UNLI MI TED

  • 7/31/2019 Electrical System Grounding- Static Grounding and Lightning Protection Grounding-And-lightning-protection

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    Tabl e of Cont ent sPar a No. Ti t l e Page No.

    Par t 1 - Gener al

    1 I nt r oduct i on . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

    2 Ref er enced Publ i cat i ons. . . . . . . . . . . . . . . . . . . . . . 13 Def i ni t i ons. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

    Par t 2 - Requi r ement s

    4 Gener al . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74a Faci l i t y Gr oundi ng Syst em Funct i ons. . . . . . . . . . . . . . 74a( 1) Syst em Gr oundi ng . . . . . . . . . . . . . . . . . . . . . 74a( 2 ) Equi pment Gr oundi ng. . . . . . . . . . . . . . . . . . . . 74a( 3) I sol at ed Gr oundi ng . . . . . . . . . . . . . . . . . . . . 74a( 4) Li ght ni ng Pr ot ect i on Gr oundi ng . . . . . . . . . . . . . . 74a( 5) St at i c Gr oundi ng . . . . . . . . . . . . . . . . . . . . . 74a( 6) Si gnal Ref er enc e Gr i d Gr oundi ng. . . . . . . . . . . . . . 7

    4b Si ngl e Syst em. . . . . . . . . . . . . . . . . . . . . . . . . 84b( 1 ) Mi ni mum Requi r e ment s . . . . . . . . . . . . . . . . . . . 84b( 2) Bondi ng t o Ot her Sys t e ms . . . . . . . . . . . . . . . . . 84c Compl i ance . . . . . . . . . . . . . . . . . . . . . . . . . . 84d Gr oundi ng and Ov er al l Sy st em Per f or manc e . . . . . . . . . . . 8

    5 Syst em Gr oundi ng . . . . . . . . . . . . . . . . . . . . . . . . . 95a Gener al . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95b Neut r al and Gr ound Connec t i ons . . . . . . . . . . . . . . . . 95c Separ at el y Der i ved Syst ems . . . . . . . . . . . . . . . . . . 95c( 1 ) Dr y Type Tr ansf or mer s. . . . . . . . . . . . . . . . . . . 95c ( 2 ) St andby or Emer genc y Gener at or s . . . . . . . . . . . . . . 105d Gr oundi ng El ec t r ode Sy st em Res i s t anc e. . . . . . . . . . . . . 10

    5d( 1 ) Low Resi st ance Myt h. . . . . . . . . . . . . . . . . . . . 105d( 2) Basewi de Appl i cat i ons. . . . . . . . . . . . . . . . . . . 105d( 3) Commer c i al and I ndus t r i al Appl i c at i ons . . . . . . . . . . 115d( 4) Communi c at i on- el ec t r oni c s Appl i c at i ons . . . . . . . . . . 115d( S) Haz ar dous Ex pl os i v es Appl i c at i ons . . . . . . . . . . . . . 115d( 6) Ot her Appl i cat i ons . . . . . . . . . . . . . . . . . . . . 115d( 7 ) Obt ai ni ng Bet t er Gr o unds . . . . . . . . . . . . . . . . . 115e Gr ound Faul t Pr ot ect i on. . . . . . . . . . . . . . . . . . . . 12

    6 Equi pment Gr oundi ng. . . . . . . . . . . . . . . . . . . . . . . . 126a Subs t i t ut es f or Equi pment Gr oundi ng Conduc t or s . . . . . . . . 126b Separ at e Gr ounds . . . . . . . . . . . . . . . . . . . . . . . 126c Equi pment Gr oundi ng Conduc t or s . . . . . . . . . . . . . . . . 1 3

    7 Li ght ni ng Pr ot ect i on . . . . . . . . . . . . . . . . . . . . . . . 137a Nonconvent i onal Syst ems. . . . . . . . . . . . . . . . . . . . 13

    i

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    7b Changes t o AFM 88- 9, Chapt er 3 . . . . . . . . . . . . . . . . 1 37b( 1) Ai r Ter mi nal Types . . . . . . . . . . . . . . . . . . . . 137b( 2 ) Hazar d ous Locat i ons. . . . . . . . . . . . . . . . . . . . 137b( 3) Ter mi nal s. . . . . . . . . . . . . . . . . . . . . . . . . 137b( 4) St ai nl ess St eel Gr ound Rods. . . . . . . . . . . . . . . . 137b( 5) Hi gh Compr es si on Connec t i ons . . . . . . . . . . . . . . . 13

    7c Bondi ng. . . . . . . . . . . . . . . . . . . . . . . . . . . . 137d Subsyst em Resi st ance . . . . . . . . . . . . . . . . . . . . . 147e Ar r est or s. . . . . . . . . . . . . . . . . . . . . . . . . . . 147f Spaci ng f or Li ght ni ng Rods . . . . . . . . . . . . . . . . . . 14

    8 Gr oundi ng and Bondi ng f or St at i c Pr ot ec t i on. . . . . . . . . . . . 148a Syst em I nt egr at i on . . . . . . . . . . . . . . . . . . . . . . 148b St at i c Gr o und Resi st ance . . . . . . . . . . . . . . . . . . . 158c Except i on. . . . . . . . . . . . . . . . . . . . . . . . . . . 158d Conduct or Si ze . . . . . . . . . . . . . . . . . . . . . . . . 15

    9 El ec t r oni c Dat a Pr ocess i ng9. a Saf et y . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

    9a( 1) Pr emi ses Wi r i ng. . . . . . . . . . . . . . . . . . . . . . 159a( 2 ) Noi se and Dat a Er r or s. . . . . . . . . . . . . . . . . . . 169b Desi gn and Const r uct i on. . . . . . . . . . . . . . . . . . . . 169c Zer o Si gnal Ref er ence Gr i d . . . . . . . . . . . . . . . . . . 169c( 1) Rai sed Fl oor s . . . . . . . . . . . . . . . . . . . . . . . 169c( 2) Saf et y Connect i on. . . . . . . . . . . . . . . . . . . . . 169c( 3) Li ght ni ng Pr ot ect i on . . . . . . . . . . . . . . . . . . . 179d I sol at ed Gr ound Equi pment . . . . . . . . . . . . . . . . . . . 179d( 1) Recept acl es. . . . . . . . . . . . . . . . . . . . . . . . 179d( 2 ) Har dwi r ed Equi pment . . . . . . . . . . . . . . . . . . . . 179d( 3) I sol at i on Tr ansf or mer s . . . . . . . . . . . . . . . . . . 17

    Li s t of Fi gur es

    Fi gure 1 ( page 2) Typi cal syst em ground i ng schemat i c

    Fi gur e 2 ( page 3) Typi cal equi pment gr oundi ng schemat i c

    Fi gure 3 ( page 4) Typi cal i sol at ed gr oundi ng schemat i c

    Fi gur e 4 ( page 4) Li ght ni ng pr ot ec t i on f or var i ous r oof t ypes

    Fi gur e 5 ( page 5) St at i c gr oundi ng of char ged equi pment or bodi es

    Fi gure 6 ( page 6) Typi cal schemat i c of an equi pot ent i al p l ane wi t h opt i onal

    gr ound st r ap i n ADP syst em gr ound conduct or s

    i i

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    Par t 1 - Gener al

    1. I nt r oduc t i on. Thi s doc ument s pec i f i es and c l ar i f i es bas i c el ec t r i c algr oundi ng, s t at i c and l i ght ni ng pr ot ec t i on c r i t er i a f or t he mos t common Ai rFor c e appl i c at i ons . Ref er t o t he l i s t of publ i c at i ons bel ow f or addi t i onali nf or mat i on, def i ni t i ons and f or appl i c at i ons not c ov er ed.

    2. Ref er enced Publ i cat i ons.

    a. AFR 88- 4 , Chapt er 11, Cr i t er i a f or Dat a Pr ocess i ng Fac i l i t y Des i gnand Const r uct i on.

    b. AFR 88- 15, Cr i t er i a and St andar ds f or Ai r For ce Const r uc t i on ( Dr af tVer s i on, Jan 86) .

    c . AFM 88- 9, Chapt er 3, El ec t r i cal Des i gn, Li ght ni ng and St at i cEl ec t r i c i t y Pr ot ec t i on.

    d. AFR 91- 38, Mai nt enance of El ect r i ca l Gr oundi ng Syst ems.

    e. AFP 91- 43, Mai nt enance Respons i bi l i t i es f or Ai r For ce Gr oundi ngSys t ems.

    f . AFR 127- 100, Expl osi ves Saf et y St andar ds.

    g. DOD 6055. 9- STD, Ammuni t i on and Expl osi ves Saf et y St andar ds.

    h. Eng i neer i ng Techn i cal Let t er ( ETL) 86- 17, Power Condi t i oni ng andCont i nuat i on I nt er f aci ng Equi pment ( PCCI E) .

    i . Feder al I nf o rmat i on Pr ocess i ng St andar ds ( FI PS) Publ i cat i on 94,Gui del i ne on El ec t r i cal...

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