Carson City Sheriff Ken Furlong, his staff and phone technicians spent much of Monday trying to determine how a power surge knocked out 911 emergency service for at least an hour Sunday night.
"We think a vacuum cleaner plugged into a socket caused an overload," he said. "This is horrifying to me to think that someone may have tried to call us and was not able to reach a dispatcher."
Furlong said dispatchers discovered the failure about 9 p.m., after five minutes. If someone had called 911, the phone would have rung on the caller's side, but the signal wasn't going into dispatch, he said.
Within an hour of the discovery, telephone crews had the system running again, he said.
Carson City dispatchers handle on average five to 10 calls for service an hour, said communications operator and supervisor Cindy Merrell. Communications with deputies through the radio system were uninterrupted, Furlong said.
"What happened was an amperage bump caused the system to go into a fail-safe mode to protect itself. The amperage bump shut down the call routing, but did not affect the calls coming in," said Lt. Ray Saylo.
Saylo said calls come into the front end of the dispatch system then are routed to the the dispatch center. The outage only affected the front end, leaving the backup systems useless.
"There are routing backups that would have sent all the 911 calls over to Reno and battery backup that would have allowed the system to continue to operate. But in this case, the calls were coming in, but going unanswered. This scenario didn't trip the backup," Furlong said.
He said he hadn't received any complaints Monday that people couldn't get through to dispatch.
"That system should never fail. When it does, you have a total break in public safety networking," he said. "This draws real serious concerns for me. We have to determine what needs to be fixed in order to prevent this from happening again."
Contact F.T. Norton at ftnorton@nevadaappeal.com or 881-1213.