NaviSite representatives have attributed last week’s prolonged downtime at the company’s Silicon Valley data center to an electrical surge that came from the grid and damaged relays in the facility’s transfer switches, crippling its ability to automatically switch to generator power.

“The generators didn’t receive a signal to start once the street power was lost,” NaviSite Chief Marketing Officer Claudine Bianchi said. “We then manually started the generators and transferred the load.”

Power to the entire data center was down for 40 minutes – the time it took to dispatch a master electrician on site and for that electrician to manually switch the facility to generator power. While looking looking for ways to add resiliency to the facility’s electrical infrastructure to ensure automatic transfer in case of similar events in the future, NaviSite has already made the now-obvious adjustment.

“We’ve augmented our staff there to include someone who can manually switch over (to generator power),” Bianchi said. The facility will now be staffed around the clock with a qualified electrician.

The incident was preceded by a power outage over a wide geographical area in San Jose, Calif. The utility serving the area is PG&E, which has attributed the outage to severe storms that descended on the Bay Area region last week.

Utility power to the NaviSite data center was cut off around 4:20 a.m. PST on Jan. 19, Bianchi said. Since the generators failed to start, the facility continued to run on UPS power until 4:56 a.m., when UPS batteries were drained and power to the facility was down completely.

While the facility was up on generator power by 5:35 a.m., it took up to 24 hours to restore some customers’ environments. More than 100 customers total were affected by the outage.

The company’s VP of Managed Services Allen Allison said engineers focused first on restoring systems of those customers that used the site for primary business-critical applications, with redundant elements taking lower priority.

Bianchi said all those affected were notified about the incident immediately by email. The company used its blog and its Twitter feed for status updates. The account management team also kept customers updated by telephone.

As of Wednesday, no lawsuits in relation to the outage had been filed either against or by NaviSite, Bianchi said.

Allison said the provider would compensate customers that were affected in accordance with their SLA’s.

NaviSite uses the 25,000 square foot data center to provide colocation and managed services.