Nexco elevator controllers also have an emergency rescue device, which allows elevators to be used during blackouts and prevents individuals from being trapped in elevators.

Traction elevators

When power is lost in a traction elevator system, the elevator comes to a stop and is then routed to the closest level. The elevator doors open, but it does not work until electricity is restored. People on the elevator may see an indicator light or hear a voice announcement indicating that the elevator is in Emergency Rescue Mode owing to a power outage.

Hydraulic Elevators 
In hydraulic elevator systems, emergency power lowers the elevators to the lowest landing and opens the doors to enable passengers to depart.