As to FPE stab lock. I am the unfortunate owner of one of those panels
and am planning on replacing it this spring for SAFETY reasons.Would
of done it sooner lack of $$$ need to upgfrade to 200 amps. Existing
is 100 amp service here.

I accidently shorted a wire and watched it vaporize and explode

The #$@%$ breaker never tripped. Once a stab lock breaker trips ONCE
its 33% less likely to EVER trip again. Just search this panel and you
will understand........

The company falsified tests and went out of business over the mess.

Its a real fire hazard!!!!!!!