Gwz,
To properly apply overcurrent protective devices with an adequate interrupting rating, there are only two ways to do things.
The first and preferred way to comply is to select a fully rated system as required by NEC 110.9.
The second way to comply is to provide a fully rated system with limited applications of series rating combinations provided the additional requirements and considerations are met. There really is no such thing as a "series rated system", I would prefer to think of it as stated above. This is kind of a play on words, and I know 110.22 refers to a series rated system because the first rule of thumb should be to fully rate all devices with an adequate interrupting rating in compliance with 110.9, then look for special situations where series rated combinations may be applied.
Series rated combinations may be used, provided the requirements of 240.86 and 110.22 are met and other considerations are reviewed. Because of the requirements of the NEC, additional considerations, and the available tested, listed and marked series rated combinations, the application of series ratings is often limited to lighting and appliance branch-circuit devices and the upstream feeder.
The specific application you have suggested may be permitted. To see if it is permitted, please see the attached article on the Bussmann Website and the series rated charts (showing fuse/circuit breaker series rated combinations for GE, Sq. D, C-H, and Siemens).
The link for the article is:
http://www.bussmann.com/library/techspec/SimpApproach.pdf (note this article will be updated evently to reflect the discussion above).
The link for the charts and additional information is:
http://www.bussmann.com/apen/pubs/series.asp
