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(D) Battery Nonconductive Cases and Conductive Racks. <br />Flooded, vented, lead-acid batteries with more than twenty- <br />four 2-volt cells connected in series (48 volts, nominal) <br />shall not use conductive cases or shall not be installed in <br />conductive cases. Conductive racks used to support the <br />nonconductive cases shall be permitted where no rack ma- <br />terial is located within 150 mm (6 in.) of the tops of the <br />nonconductive cases. <br />This requirement shall not apply to any type of valve- <br />regulated lead-acid (VRLA) battery or any other types of <br />sealed batteries that may require steel cases for proper op- <br />eration. <br /> <br />(E) Disconnection of Series Battery Circuits. Battery cir- <br />cuits subject to field servicing, where more than twentyfour <br />2-volt cells are connected in series (48 volts, nominal), <br />shall have provisions to disconnect the series-connected <br />strings into segments of 24 cells or less for maintenance by <br />qualified persons. Non-load-break bolted or plug-in discon- <br />nects shall be permitted. <br /> <br />(F) Battery Maintenance Disconnecting Means. Battery <br />installations, where there are more than twenty-four 2-volt <br />cells connected in series (48 volts, nominal), shall have a <br />disconnecting means, accessible only to qualified persons, <br />that disconnects the grounded circuit conductor(s) in the <br />battery electrical system for maintenance. This disconnect- <br />ing means shall not disconnect the grounded circuit con- <br />ductor(s) for the remainder of the photovoltaic electrical <br />system. A non-load-break-rated switch shall be permitted to <br />be used as the disconnecting means. <br /> <br />(G) Battery Systems of More Than 48 Volts. On photo- <br />voltaic systems where the battery system consists of more <br />than twenty-four 2-volt cells connected in series (more than <br />48 volts, nominal), the battery system shall be permitted to <br />operate with ungrounded conductors, provided the condi- <br />tions in 690.71 (G)(I) through (G)(4) are met: <br /> <br />(1) The photovoltaic array source and output circuits <br />shall comply with 690.41. <br />(2) The dc and ac load circuits shall be solidly <br />grounded. <br /> <br />84 <br /> <br /> <br />