We are one of a limited number of companies able to offer this G99 Testing service. We have a team of highly qualified competent G59 Testing Engineers and as such we can offer you a nationwide G99 testing service. We provide you with a reliable and professional service by providing you with one of our test engineers who have carried out many Witness tests and worked with many of the DNO's.



We are able to carry out Witness tests on the majority of the main G99 relays used including;

  • ComAp
  • Woodward
  • ABB
  • Megacon
  • Bender


We bring all the required specialist equipment and paperwork required to carry out the tests to enable the DNO to sign your project off to be connected to the grid. We will be required to perform the following tests to prove your system falls within the required G99 parameters;

  • Under Voltage Stage 1
  • Under Voltage Stage 2
  • Over Voltage Stage 1
  • Over Voltage Stage 2
  • Under Frequency Stage 1
  • Under Frequency Stage 2
  • Over Frequency Stage 1
  • Over Frequency Stage 2
  • Stability Tests
  • VectorShift
  • ROCOF (Rate of Change of Frequency)
  • LOM (Loss of Mains)

For your reliable and professional testing service contact us today to see how we can help.


G59 Projects Ltd

Grosvenor House

3 Chapel Street


CW12 4AB


Phone: 0330 113 2689


Email: sales@g59projects.co.uk


Or use our contact form

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