One of my company's clients specifies Square D safety switches exclusively (i.e., no substitutions.) However, their spec calls for Heavy Duty. I noticed the recall are for Standard Duty. I wonder what the difference is?
There are major differences between Square D general/standard duty and heavy duty switches. I don't think the 30A ones have any parts in common at all. The heavy duty units are designed for 600V applications (even if they have 250V fuse spacing). The general duty units are designed for 250V max.
I had a landlord report that a whole apartment "shorted out" when he tried to close the knife switch. When I got there I found the insulating part of the throw lever had broken off and when he tried to close it the metal handle came into contact with the blades, that were still stuck in the slots on the line side. Made quite a boom he said. The switch was actually closed anyway, the problem was a blown fuse.