IMO - they do NOT CAUSE fires... Electrical faults cause fires....
While FPE has an extremely bad rep for their name they did make some decent larger breakers and switches. But the Stab-lock line was of poor design and unfortunately widely sold.
As far as thermal magnetic breaker design goes - they have a lot to be desired. The buss work is often looses contact pressure - arcs eventually to open. The breaker contacts often fuse shut. And even when they are not, seem to hold currents that damage wiring, And in direct bolted shorts will often hold with very little current limiting, often vaporizing the conductor at the short and never tripping, or melting the insulation. While the fault is not because of the breaker - they do little to protect from the damage during one.
So IMO they do not CAUSE fires - but may do very little to keep you from having one due to some other cause.
Breaker design has come a long way - there are safer options. And since the cost of some replacement parts for FPE can exceed the cost of a new panel and it's breakers, (in some places even some portion of the labor to install a new one) it is often more economical to get rid of it, and you'll sleep better.....
