You've got to get lucky once in a while. My PDB is activated by a pneumatic valve located out of sight and in such an inconvenient place that I really have to stop and think "Where is that bleeping valve?" That helps both inadvertent as well as out of sequence activation. Please, don't ask why I had to go to such extreme measures. I will say it's related to the reason my computer power switch is no longer anywhere near the coolant switch