The SawStop bench saw drew blood today. An electric field surrounds the spinning blade, if something conductor touches it, it stops violently by forcing a single-use perforated aluminium block into the teeth of the blade. Momentum then forces the blade under the bench top.
In this case the victim inadvertently touched the side of the blade when the workpiece kicked back. As the blade dropped below the table top (rotation had stopped), a few of the 60 teeth travelling downward have brushed against his finger & fingernail, peeling back a flap of skin & damaging the fingernail.
A couple of sticking plasters fixed the bleeding.
As for the safety cartridge, we need to buy two of tgen: one for the saw & one for a spare.
If we give the triggered unit to the supplier, they send it off to the manufacturer who analyses the onboard data. When they determine it was contact with human skin that triggered the safety mechanism, they reimburse us the cost of the cartridge.