Article 240.87 in the NEC mentions that ZSI and something called "energy reducing maintenance switching with local status indicator" are two ways of meeting the requirements of this article.
What is ZSI? How is Eaton's version of the "energy reducing maintenance switching" (called ARMS) different from other vendor's versions?
Click on the image below to view a screencast of me presenting the contents in the attached PPT file below.
(https://pps2.com/v/m3/zsi+arms.jpg) (https://pps2.com/v/s/1/zsi_arms.php)