Hi Roger,
A side note: You may be interested, Dale Wheat did a project similar to this for Circuit Cellar May 2009 issue using AVR AT Tiny and Charlieplexed LEDs to display voltage, he used C but some pointers may be had by looking at it, He also sells kits on his Web Site.
http://www.dalewheat.com/slameter.html
ftp://ftp.circuitcellar.com/pub/Circuit_Cellar/2009/226

How about a crowbar circuit with a fuse inline with your sense line ?