Business disruptions due to power failure have increased more than 350% in a year, a survey has shown.

Business continuity specialist SunGard Availability Services said an analysis of customer call-outs revealed that power failures had risen dramatically, accounting for 26% of disruptions last year. In 2005 the figure was just 7%.

But the relatively high proportion of power failures in 2006 compared with the year before may be due to the fact that in 2005, more than a third of business disruption incidents (36%) were attributed to terrorism, with bombings in London happening in July that year.

Hardware failure remained the most frequent cause of business disruption in 2006, accounting fro nearly half of the 86 cases analysed. Flooding and infrastructure-related problems, such as air conditioning faults and uninterrupted power supply loss, were the third largest cause of business disruption, accounting for 5% of incidents each.

Keith Tilley, UK managing director at SunGard Availability Services, said: "These figures contain no surprises, yet no matter how trivial the cause, an outage can have potentially serious consequences for the business – particularly if the system in question is supporting a customer-facing website or a contact centre."

He added: "With IT equipment drawing more power than ever, it is imperative businesses plan around possible interruptions to their power supply."

Unusual reasons for business disruption experienced by SunGard customers included a cleaner unplugging the main server to use the vacuum cleaner and blocked sewers making toilets unusable.