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20.20.027 <br />battery or battery bank exceeds the <br />interrupting or withstand ratings of <br />other equipment in that circuit. The <br />installation of current-limiting fuses <br />shall comply with 690.16. <br />(D) Battery Nonconductive Cases <br />and Conductive Racks. Flooded, <br />vented, lead-acid batteries with more <br />than twenty-four 2-volt cells con- <br />nected in series (48 volts, nominal) <br />shall not use conductive cases or <br />shall not be installed in conductive <br />cases. Conductive racks used to <br />support the nonconductive cases shall <br />be permitted where no rack material <br />is located within 150 mm (6 in.) of <br />the tops of the nonconductive cases. <br />This requirement shall not apply to <br />any type of valve-regulated lead-acid <br />(VRLA) battery or any other types of <br />sealed batteries that may require steel <br />cases for proper operation. <br />(E) Disconnection of Series Battery <br />Circuits. Battery circuits subject to <br />field servicing, where more than <br />twenty four 2-volt cells are connect- <br />ed in series (48 volts, nominal), shall <br />have provisions to disconnect the <br />series-connected strings into seg- <br />ments of 24 cells or less for mainte- <br />nance by qualified persons. Non- <br />load-break bolted or plug-in discon- <br />nects shall be permitted. <br />(F) Battery Maintenance Disconnect- <br />ing Means. Battery installations, <br />where there are more than twenty- <br />four 2-volt cells connected in series <br />(48 volts, nominal), shall have a <br />disconnecting means, accessible only <br />to qualified persons, that disconnects <br />the grounded circuit conductor(s) in <br />the battery electrical system for <br />maintenance. This disconnecting <br />means shall not disconnect the <br />grounded circuit conductor(s) for the <br />remainder of the photovoltaic electri- <br />cal system. A non-load-break-rated <br />switch shall be permitted to be used <br />as the disconnecting means. <br />(G) Battery Systems of More Than <br />48 Volts. On photovoltaic systems <br />where the battery system consists of <br />more than twenty-four 2-volt cells <br />connected in series (more than 48 <br />volts, nominal), the battery system <br />shall be permitted to operate with <br />ungrounded conductors, provided the <br />conditions in 690.71(G)(1) through <br />(G)(4) are met: <br />(1) The photovoltaic array source <br />and output circuits shall comply <br />with 690.41. <br />(2) The do and ac load circuits <br />shall be solidly grounded. <br />(3) All main ungrounded battery <br />input/output circuit conductors <br />shall be provided with switched <br />disconnects and over current pro- <br />tection. <br />(4) A ground-fault detector and <br />indicator shall be installed to moni- <br />tor for ground faults in the battery <br />bank. <br />690.72 Charge Control. <br />(A) General. Equipment shall be <br />provided to control the charging <br />process of the battery. Charge control <br />shall not be required where the de- <br />sign of the photovoltaic source cir- <br />(Pleasanton April 2003) '] 10_30 <br />