I'm going to see what I can come up with. I'm no electronics guru, but I can follow a schematic. Since I was in the process of a DIY breakout box, I think I'll add the power failure relay. My basic assumptions are to use any mechanical relay that uses a 120vac coil trigger. Since the switch contacts will only be used to pass continuity to the apex, I assume nothing else is needed. Does anyone know if there is any transient voltage passed to the contacts from the coil? If there is, I would think it would be bad for the apex. Can anyone chime in on this topic?