NFPA 99, 2012 Section 5.1.9.2.3.8 states that "Master alarm signals shall not be relayed from one master alarm panel to another."

What if you have already met the requirement for 2 master alarm panels and are looking to add another in a more convenient location?  Can you slave the third panel off of one of the existing ones? 

I've addressed a similar question at one of my facilities recently.

My interpretation is that if the minimum requirements of the two locations (5.1.9.2.1) are met, then a third (slave) panel would be considered redundant, and could be relayed off one of those, with the caveat that its failure doesn't affect the compliance of the two required panels.  5.1.9.2.3.1 explicitly addresses the "mandatory" panels, but I see no code that prohibits adding redundancy.