|
. ,..�,. .. i , .n c.,-ca-"'•:-r�du-'-p 1�....
<br /> + � ARTICLE 250—(3ROUNDlNq + 70-127 70-12$ NATIONAL EIECTR�GAI.CODG
<br /> jumper shall be sized in accordance with Table 250=95 using the rating of (b) Metal Frame oi the Bullding. 1fie mekal frame of the building,where
<br /> the circuit that may ener�ize the PiP�S� effectivety gcounded. � •s} �
<br /> The eyuipment groundu�g conductor for the circuit that may energize the Fp ; Effeckive
<br /> piping shall be permitted to,setve,as the bcinding tneans. � M ►y gronnded means�intentionally rnnnected to earth through a
<br /> ground connecdon or connections of suHiiciently!ow impodance and having suffi-
<br /> {FPN)• Bonding all piping aud metal air ducts within the premises will grovide cient current-carrying capacity to.prevent tha buildnp of valtag�that may resu]t in
<br /> additionat saiety. , undue hazard to cQnnected eqwpment or to persons.
<br /> H.Groursding�lectrade System (c) Conerete-Encased Electrode. An electrade encased by a't teast 2
<br /> , inches{50.8 mm)of c+ancrete,.tocated within and near the bottam•of a�n-
<br /> 250-ei. Grounding Electrode Sy�tem. If available on the remises at ��te foundation or footing that is in direct cantact with the.earth,oonsist-
<br /> P m of at least 20 feet (6.1 m)of one.or more bare or zinc galvanized or
<br /> each building ar strucriue served,each item{a�throu�(d)below,and any� Q��r�����y�nductive coated steel reinfarcing bars or rods of no#
<br /> made etectrodes in acxordance with Sections 2SQ-S (c) and (d), shall be l�g �� y2 inch (12."7 mm) diameter, or consisting of.at least 20 feet
<br /> bonded together to form the grounding electrode system. Interior metal� �6.1 m)of bare copper conductor not smaller Wan No.4.
<br /> water pipin lcrcated more than 5 feet(152 cm}from the point of entrance
<br /> to the huii�ing shall not be used as a conductor ta interconnect the eleo- (d} Graund Ring. A ground ring encireting the buiiding or structure,in
<br /> trodes and the grounding electrode conductor.The bonding jumper shall be ������1����the earth at a depth belaw earth surface not less than
<br /> instailed in accordance with Sectians 250-92(a) and (b}, sha[I be sized in 2�a feet{?62.mm),consisting of at leasi 20 feet{6.1 m}of.baze capper con-
<br /> accordance with Seetion ?SO-94, and shail be connected in the manner( �u�tor not smaiter than No.2. �
<br /> specified in Section 250-115.The unspliced grounding electrode conductor
<br /> shall be pernutted to run to atty convenient groe�nding electrode available 2��• Made and.Other Etectralea Where none of the electrodes spec-
<br /> in tha grounding elei;trode system.It shalt be sized for the targest groetnd- ��d���an 250-81 is availabie,one or more of the etectrades specif'ied
<br /> ing electrode conduckor required among all the available electrodes. in(b)throuph(d)below shall be used.Where practicable,nQacie electrodes
<br /> Exceptian No. 1: It shall be per»�itted to splice the grtar�ruling electrr�de Sb����rnbedded below perinaneat moisture level.Made electrocies shalt
<br /> conductor by means of irreversibte compressron-t,ype connectors listed for �fr��°m noncanductive coatings,such as paint or enatnel.Where mare
<br /> the pwpose or the exothen»ic weldiftg process, than one electrade is used,each electrode of one grounding system(includ-
<br /> ing that used for lightning�rods)shall not be less than b feet(1,83 m)from
<br /> E.rception No. 2: fn indurtrial and corrrmer�iul buildings where ccrndi- �y other etectrale of another grounding sysiem. '
<br /> lions af mnintenance and supeivision ensure that only quolifted persans
<br /> will seYvice the instaUation and the enti�length of the interior metal water ���� �'o or more electrodes that are efl'ectively bonded together are to be
<br /> pipe that is beittg userl for ihe conductar�s exposed. u�t�d es a singtc ciectrode system in this scnse, ;,�, ,
<br /> (FPN): See Section 547-8 for special grouading and bonding requirements for � ��1 Metei Underground Gea Piping System. A rnetal underground g,as
<br /> agricultaral buildings. piping system shall not be used as a gounding electrode.,
<br /> {s} Me#ai Underground Water Plpe. A metat upderground water pipe in �} ��r�;Metai Underground Sysfema ar Structures. Other IocaI
<br /> direct contact with the earth for 10 feet (3.05 m) or moze (including any metal underground systems or structures, such��as piping systems and
<br /> metal wel!casing effeetively bonded to the pige)and electrically continu- �derground tanks. �
<br /> aus(ar made electrically continuavs b�bond"mg araund insulating joints or �e) Rod and Plpe Etectrodes. Rod and gipe eleetrades shall not be less
<br /> sections or insulating pipe).ko.the pamts of connection of the grounding ��8 feet(2.44 m)in length and shall wnsist of the following materials,
<br /> electrode wnductor and the bonding conductors.Continuity of the groupd- �d shall be installed in the followiag manner;
<br /> ing path ar the bonding connection to mteriar piping shall not reIy on water (i) Etectrades af pipe or conduit sball not be smaller than�/4-inch tracie
<br /> meters. A metal underground water �ipe shall be supplemented by an size and,where of iron ar steel,shall have the outer surface galvanized or
<br /> additional electrode af a type specified in Secdon 750-81 or in Secdan 2SQ- atherwise metai-coated for cozrosion protection.
<br /> 83. The sugplemental electrode shalt b� permitted to be bonded to the (2j Electrodes of rods of.iron or steel shall be at least�'�irtch(15.87 mnn)
<br /> grounding electrode conductor,the grounded service-entrance canductor, .�, diameter. Stainless steel r�ds less than 3�g inch (15.87 mrn)'in diameter,
<br /> the grounded service raceway,or any grounc�ed service enclosure. �)nonferrous rods or their
<br /> W�re the supplemental electrode is a made electrode as in Section 250- ���ch{22.7 mm)in diame er.��nt slYall be Iisted and shatt not be Iess than
<br /> 83(c)or(d),that portion of the bondin jumper that is the sole connection ��
<br /> ta the su plemental oundin eleckr (3) The electrode shall be installed such that at least 8 feet 2.44 m)of
<br /> P pp �' g e shall not be required to be larger �ength is in contact with the so$.It shal!be driven to a depth of not Iess
<br /> than No.6 co er w�re or No.4 alt�minum wire, than 8 feet (2.44 m} except that, where rock bottom is encountered, the
<br /> Exce,�tion: The supplemental elechrxie shall be permitted to be bonded. electrode shall be drrven at an oblique angle not to eaceed 45 degees from
<br /> to the rnterior metal water piping at arry convenient point as coverred in �the verticai ar sha(i be buried in a trench that is at least 2�l2 feet{?62 mm) J
<br /> Sectian 23f�81,.�rcephbn Na. 2. • deep.The upger end of the etectrode shall be$ush with ar betow gmnnd I
<br />
|