The NE724I line-voltage sensing submodule is an optional module for line-voltage sensing and correction.

The NE724I is plugged from the front into the module casing of the ZA724I central interface module. The slot is located in the busbar area. If the NE724I is not used, the opening is sealed with the busbar cover. If the line-voltage sensing submodule is used, the cover is used for shock-hazard protection.