The following proceedings, required by or conducted pursuant to this chapter, are not subject to any provision of NRS which requires a meeting to be open or public:
1. Any negotiation or informal discussion between the Executive Department and a labor organization or employees as individuals.
2. Any meeting of a mediator with either party or both parties to a negotiation.
3. Any meeting or investigation conducted by an arbitrator.
4. Deliberations of the Board toward a decision on a complaint, appeal or petition for declaratory relief.