What is this orange clip my ground wire is connected to?
That is a in-sure push-in wire connector.  It's spring-loaded.  To remove it, pull while twisting.  The full spec sheets on them are at http://www.idealindustries.com/prodDetail.do?prodId=in-sure&amp;div=0&amp;l1=push-in , and DIY.SE did a blog entry on them as well at http://diy.blogoverflow.com/2012/01/tool-review-ideal-in-sure-push-in-wire-connectors/