# Control fault prevented backup generators starting at Google’s London cloud site

- URL: https://talkfuse.com/story/when-datacenters-lose-power-generators-should-kick-in-that-didnt-happen-for-google-in-london/
- Published: 2026-11-05T06:19:54+00:00
- Updated: 2026-11-05T06:47:38+00:00
- Original publisher: The Register
- Original article: https://www.theregister.com/off-prem/2026/11/05/when-datacenters-lose-power-generators-should-kick-in-that-didnt-happen-for-google-in-london/5307739
- Topics: Software

## Key points

- A London power cable failed while the second feed was under repair.
- Google’s backup generators did not start because of a control system flaw.
- Google says it has changed and tested the power setup.

## Summary

Google says a power outage at its London cloud facility on 20 October was worsened by a fault that stopped emergency generators starting automatically. The disruption affected services used by organisations including Lloyds, HSBC, Royal Mail and Revolut, and exposed a weakness in the site’s backup power controls.

An underground cable serving power feed A failed while feed B was disconnected for repairs after problems during a generator test. Although uninterruptible power supplies kept the facility running for about five minutes, a voltage-sensing flaw and misconfigured control system did not send the generators a start signal. Google says it has reprogrammed the controls, tested changes to the electrical setup and plans to improve incident notifications and infrastructure testing.

---
Summarised by TalkFuse (https://talkfuse.com/). Quote the original publisher for the reporting and link this page for the summary and discussion.