Tens of thousands of small businesses and individuals were forced offline on Thursday, after a power failure at Telehouse Docklands affected several UK Internet service providers.
Telehouse is a major UK co-location facility which provides hosting facilities for many ISPs and larger companies. It offers the promise of a secure, resilient infrastructure, thanks to its multiple power supplies and dedicated connectivity.
However, a power outage on Thursday morning caused significant disruption to several ISPs, including PlusNet and Clara.net.
It appears that problems began just before 8am on Thursday, when one of Telehouse's power-distribution units failed after a cable connection burned out. At noon, Telehouse implemented a workaround, which took some other connections offline temporarily.
"Power was restored to affected customers at approx 12.20pm and this was achieved without the need to isolate the power-distribution unit, thereby avoiding further customer disruption. A post-event review is underway," said Telehouse in a statement.
The problems affected several server suites used by PlusNet. Its broadband connectivity and email and usenet servers were hit, and around half its customers who were connected at the time were knocked offline. Users were unable to connect via Telehouse until the afternoon, which means only half of PlusNet's 200,000 customers could get online at once.
Most services were restored by mid-afternoon on Thursday, although PlusNet's telephone system was still suffering problems.
It appears that those affected will not be eligible for compensation. A PlusNet spokesman said the company had apologised to those who were affected and thanked them for their patience during the engineer repair work.
A Telehouse spokesman added that an inquiry was underway to find out how a single connection failure could have caused such damage.