@Kevinthomas,
Kev I 'mem' someone askin' this qb4, ans'n something like 'Only certain kinds of failure.' For instance if there was a short from ret to gnd you'd probably never notice it 'til you electrocuted yourself
Now Tom I'm often critted for abbrs or for remarks not entirely clear to the esl. However I'm always available, and I'd be most happy to submit an OP describing what sorts of things can happen with each kind of failure. I think I have calculated something like 225, esp when two or more happen at the same time