ESB confirms transformer failure, not lightning, caused Amazon outage

11 Aug 2011

ESB Networks has said transformer failure, not a lightning strike, caused the loss of electricity supply to customers in CityWest business campus last Sunday, which affected one of Amazon’s data centres along with several others in the area.

In a statement issued late yesterday, the power company said the cause of the failure is still being investigated “but our initial assessment of lightning as the cause has now been ruled out”.

The ESB statement said: “ESB Networks can confirm that at 18:16 on Sunday August 7th, a number of customers in Citywest lost electricity supply. It’s an unfortunate reality for every power system that faults can occur due to vandalism, storms, fires, floods, plant failure and third-party interference. In this case, the problem was the failure of a 110kV transformer in the Citywest 110kV substation.”

As previously reported by, two different versions of events emerged following the loss of power last Sunday. The ESB’s later account contradicted an earlier statement issued by Amazon, which said lightning had caused an explosion.

A spokesperson for ESB Networks confirmed to that ESB staff at the site initially speculated that damage to the transformer might be consistent with a lightning strike.

This could explain how the confusion arose, as that assessment may have led Amazon to initially report that the outage was caused by lightning – a story that was widely reported internationally. requested a subsequent comment from Amazon about the matter but at press time the company has said nothing further about Sunday’s outage.

Amazon was not the only data centre provider affected by the loss of power. The ESB spokesperson added: “The fault resulted in loss of supply to 100 customers, including a number of data centres who in turn have a number of third-party clients. All customers had electricity available either from the mains supply or via standby generation within one hour and mains supply was restored to all by 11pm.”

Telecoms provider BT also experienced a mains outage that lasted for around an hour at its Dublin data centre last Sunday. A BT spokesperson said: “The protection layers of our facility were engaged as designed and maintained full uninterrupted service for customers.”

In its statement, ESB Networks said another Amazon data centre served by ESB in South County Dublin was not directly affected by the outage, although it did experience a voltage dip which lasted for less than one second.

Gordon Smith was a contributor to Silicon Republic