Stephen Kaufman, Principal Mechanical Engineer at ETS-Lindgren asked:

We are a manufacturer of testing equipment for the electro-magnetic compatibility market. One product that we make are large metallic paddles up to 60" square that rotate within a test chamber up to 16 rpm. Testing personnel can come in contact with these rotating paddles and the paddles can be activated remotely. Would an emergency stop be required by OSHA in this case? The emergency stop that we have incorporated into the system now is not at the point of contact, it is actually outside the room on a control enclosure. Test personnel enter these types of shielded rooms regularly to set-up or change test equipment.

SafetyMan says:

OSHA and NFPA 79 require that emergency stop controls be within reach of all affected employees. Therefore, employees in the area you describe should have an e-stop control.