Earth Ground Connection

This product has been designed and laboratory-tested to ensure its resistance to damage from generally expected levels of lightning and electrical discharge, and does not normally require an earth ground.

If an earth ground is desired for additional protection in areas of severe electrical activity, terminal 25 on the control board, or the cabinet, may be used as the ground connection point.

Installation Manual For More Information:

https://turbifycdn.com/ty/cdn/yhst-51756635596032/honeywell-vista-15p-control-panel-installation-setup-guide.pdf