A CPSU have the ballot papers of its employees union election as a practice.Can anybody seek inspection of those documents under RTI ?  Is it not a third party information? Is it not an information given in goodfaith?

Ballot paper is absolutely a property of an individual and it is not at all a public property whereas RTI Act is only applicable to the information of public interest whichever available with a public authority,  A ballot paper of an individual is not at all a public property.  Therefore, it is not even a "Third Party information" and so a public authority is not authorised to publish it even in good faith.  If done so, it will be treated as "broken the democratic rights of a citizen" and it will be treated as "Rashtradroh" in a democratic nation.  Moreover, publishing of own ballot paper by an individual itself will be treated as "CANVASSING".