Annual Temporary Isolation of the Site Power at our Maidenhead Facility – Pulsant 2 & 3 Only

Dear Customer,

Please be aware of the following essential maintenance being carried out at our Maidenhead Facility – Pulsant 2 & 3 only.


As part of Pulsants planned maintenance regime, we are required to undertake an annual darken building test will be carried out to ensure all infrastructure works correctly in the event of a full loss of mains power and to minimise further interruptions.


NONE – No interruption or disruption to service is expected during these essential works, however due to the level of switching that will be undertaken during executing our Darken Building Test and isolation of power, we are issuing a courtesy At Risk notification to all our customers.


As part of Pulsant’s maintenance regime, it is necessary for us to undertake an annual inspection of the Transformers and ring main unit to ensure all infrastructure works correctly in the event of a full loss of mains power. To do this we will be working with our 3rd party contractors to isolate the mains power to the site and perform essential testing of our HV and LV infrastructure.

During this period, it will be necessary to run the site on Generators. Pulsant will follow our normal Darken Building Test procedure, which will isolate the utility supply during these essential tests.

The testing will be completed by Pulsant staff and a number of specialised 3rd party contractors.

All Diesel supplies to the site have been checked and confirmed adequate supplies with reserve supplies on standby. Once works have been completed, the fuel supplies will be replenished accordingly.

We have provisioned a maintenance window of up to 8 hours to complete all the necessary tests. All personnel will remain on-site during this maintenance window and for a period of up to 1 hour post the maintenance window.

Works are expected to be non-service affecting as customers will remain on UPS protected supplies whilst the Generators take up the load and then remain on Generator load (in an N+1 configuration) until all works are completed. This maintenance does involve changes to power source to the site, hence an at Risk notification is being sent out.


Pulsant confirm that the maintenance window is noted below and the associated At-Risk period:

Tuesday 22nd November 2022, commencing at 09.00 GMT and completed by, Tuesday 22nd November 2022 by 17.00 GMT.

The At Risk window will be kept to an absolute minimum and the site will have utility mains power restored and resuming full site protection at the earliest opportunity.

Please accept our sincere apologies for any inconvenience this may cause.

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