Why do Cisco state that they must be part of the same data stack then?   I have since found this in an old 3750-X document: -   Do not configure power stacks that span across data stacks. Cisco StackPower is limited to four switches per power stack although one stack of nine switches can be configured over multiple power stacks; this is a supported deployment. On the other hand, one power stack can also span over multiple data stacks although it is not recommended. It is not a recommended deployment because of display and control reasons. That is, StackPower reports the power budget, priorities, neighbor information, and similar parameters to the stack master; therefore having two stack masters would make management a nightmare. In this scenario, there would be two masters receiving information about the same power stack, that would confuse the administrator and would cause unexpected behavior in case of load sheds. ... View more

That's what I thought Georg, but the Cisco document states that they must be part of the same data stack. ... View more

Thanks Jaderson   I looked through the link and actually found the following statement: -   Switches in a power stack must be members of the same switch (data) stack.   So it does look like you can't have StackPower spanning 2 different data stacks.   I now need to find a calculator to size the number of power supplies required across the stack. ... View more

Thanks for the reply.   The 2960XR are connecting to the backbone, which uses OSPF and also down to the 2960X access layer switches. The devices will be WAPs and end user hosts. ... View more