Safety systems for power equipment and components and brake cartridges for use in those safety systems are disclosed. The safety systems, components and brake cartridges are specifically applicable for woodworking equipment such as saws. An exemplary brake cartridge includes a housing and a braking component configured to engage a moving part of the power tool upon occurrence of a predetermined event. The brake cartridge may further include a switch configured so that proper installation of the cartridge in the power tool triggers the switch.