EMB120 Captain reports failure of the emergency DC bus 2 at FL250. After discussion with the Dispatcher crew diverts to the nearest suitable airport. Landing gear is extended by emergency means.

Narrative

While level at FL250; we experienced a failure of the emergency DC bus 2 portion of the electrical system. We pulled the checklist for 'Emergency Bus Off' and verified that it was the emergency DC bus 2 system by the instruments that we lost. The checklist says to land as soon as practical. We then contacted our Dispatcher and told him of our situation and told him we were planning on diverting to ZZZ1. He agreed that this was the best course of action then he relayed our emergency situation to Maintenance Control. We then told Center of our intentions and declared an emergency shortly after. Then; we notified our Flight Attendant of our situation and notified the passengers. The emergency DC bus 2 checklist says that we lose; among other things: landing gear control; the A side gear indication lights; antiskid; right engine 'electronic engine control;' right engine torque and T6 gauges; and 1 power source to the multiple alarm panel. We then ran the appropriate checklists including landing gear extension by freefall and antiskid failure checklists to ensure we had enough runway length at ZZZ1 for a landing without antiskid (which we did). When we got the gear down; we only had 3 green lights illuminate instead of the normal 6 green lights due to the emergency DC bus 2 failure. So we decided to do a low approach into ZZZ1 to make sure the Tower saw the gear down as well. We then notified the Flight Attendant and came in for a full stop landing. Landing went without incident and we taxied to the gate and de-boarded the passengers. Our Maintenance personnel then found the problem and corrected it.