I only allow the manufacturer's breakers or classified breakers. there are some of those little black breakers that don't fit very well in other manufacturers panels. I also let people know that if you don't use the manufacturer's breakers you void a warranty and anything that happens regardless of the reason will probably have no hope in court. I've seen breakers malfunction and busses melt. A flaw in the manufacturing process of the panel will be much harder to convince a judge if you use unclassified or unlisted breakers in the panel. The panel manufacturer's lawyer will talk his way out of this every time. He may even get away with it even if classified breakers were used.
Does it happen much? Never heard of a case. But I'd hate to be the first guy who gets screwed.
