IS: 9921 (Part 4) - 1985 Reaffirmed 1992; Specification for alternating current disconnectors (isolators) and earthing switches for voltages above 1 000V Part 4 type tests and routine tests 

 - New Delhi  BIS  1985 
 - 39p 
<br/><br/><label>Universal Decimal Class. No.: </label> /