The Square D by Schneider Electric brand Heavy Duty Safety Switch is designed to be tough, reliable. These switches provide exceptional performance in the most grueling conditions, from commercial and institutional to industrial and manufacturing facilities. F Series safety switches provide significantly higher levels of mechanical endurance than NEMA KS-1 or UL98 standards require. The design life of a F-Series switch is a minimum of three times the NEMA requirement. Applications Heavy duty safety switches are designed for the following applications. Commercial and industrial installations. Up to 600 V ac or 600 V dc maximum. Up to 200,000 rms symmetrical amperes short circuit current. 301200 A. Horsepower ratings.