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GROUNDING AND BONDING NATIONAL ELECTRICAL CODE ARTICLE 250 By Jim Biesterveld Some of the material is taken from Mike Holt and Soars presentaGons
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GROUNDINGANDBONDING NATIONALELECTRICALCODE … · (6)Condionsunderwhichguards,$ isolaon,orinsulaonmaybe$ substutedforgrounding Thecodehasit’sdefinionsand theseneedtobeunderstoodto

Aug 25, 2019

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Page 1: GROUNDINGANDBONDING NATIONALELECTRICALCODE … · (6)Condionsunderwhichguards,$ isolaon,orinsulaonmaybe$ substutedforgrounding Thecodehasit’sdefinionsand theseneedtobeunderstoodto

GROUNDING  AND  BONDING  NATIONAL  ELECTRICAL  CODE  ARTICLE  250  

By  Jim  Biesterveld  

Some  of  the  material  is  taken  from  Mike  Holt  and  Soars  presentaGons    

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NEC  250.1  Scope  

(1)  Systems,  circuits,  and  equipment  require,  permi=ed,  or  not  permi=ed  to  be  grounded  

(2)  Circuits  conductors  to  be  grounded  on  grounded  systems    

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(3)  LocaBon  of  grounding  connecBons  

(4)  Type  and  size  of  grounding  and  bonding  conductors  and  electrodes  

(5)  Methods  of  grounding  and  bonding  

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(6)  CondiBons  under  which  guards,  isolaBon,  or  insulaBon  maybe  subsBtuted  for  grounding  

The  code  has  it’s  definiBons  and  these  need  to  be  understood  to  properly  understand  and  interpret  the  code  requirements  of  the  NEC  and  Wisconsin  Comm  16  

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Figure  NFPA  250.1  

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Severity  of  Electric  Shock  1  

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Severity  of  Electric  Shock  2  

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Series  and  Parallel  Paths  

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•  EARTH  IS  NOT  AN  EFFECTIVE  GROUND-­‐FAULT  CURRENT  PATH  

250.4  General  Requirements  for  Grounding  and  Bonding  

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•  BONDING  CONDUCTIVE  MATERIALS  •  To  quickly  remove  ground-­‐fault  voltage  by  the  opening  of  the  circuit  protecBon  device,  metal  parts  of  the  building  structure  must  be  connected  to  the  source  via  the  equipment  grounding  conductor.  

250.4  General  Requirements  for  Grounding  and  Bonding  

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•  Service  equipment  supplied  from  a  grounded  system  must  have  the  neutral  conductor  grounded.  

250.24  Service  Equipment  

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Grounding  electrode  system  –  250.50  

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Supplemental  electrodes  

COMM  16  2-­‐rods  

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No  switching  acBon  in  grounded  conductor  –  generator  gets  connected  to  

system  with  neutral  and  grounds  separate.    

Grounded  conductor  remains  as  a  grounded  conductor  because  it  is  

grounded  at  service.  

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Insulated  neutral  at  separate  building  250.32(B)  

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Submersible  pump  well  casing  

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Grounding  at  agricultural  installaBons  

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•  An  equipotenBal  plane  must  be  installed  at  indoor  and  outdoor  concrete  confinement  areas  where  metallic  equipment  is  located  that  may  become  energized  and  is  accessible  to  livestock.  

547.10  EquipotenBal  Planes  and  Bonding  of  EquipotenBal  Planes  

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Bonding  &  Grounding  at  Agricultural  Buildings  

•  Specific  requirements  regarding  grounding  and  bonding  

•  Two  major  concerns:  

–  Integrity  of  grounding  path  due  to  corrosive  condiBons  that  exist  in  these  locaBons  

–  Neutral  to  earth  stray  voltages,  if  excessive,  can  cause  behavior  responses  and  can  lead  to  loss  of  producBon  and  health  problems  in  livestock  

•  Equipment  grounding  conductor  run  underground  to  these  locaBons  must  be  insulated  or  covered  copper  

•  See  ArBcle  547  for  specific  Code  secBons.  

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EquipotenBal  bonding  requirements  

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EquipotenBal  bonding  planes  in  animal  confinement  areas  

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•  The  equipotenBal  plane  must  be  connected  to  the  building  or  structure’s  electrical  grounding  system  with  a  copper  conductor  not  smaller  than  8  AWG.  

547.10  EquipotenBal  Planes  and  Bonding  of  EquipotenBal  Planes  

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