One gas meter to 3 properties

[Plumberwales]

Please advise, we have one commercial gas meter serving 3 buildings each with its own secondary ECV and test point after the main ECV and meter, we are RGI but not commercial, can't access the other two properties but need to do work in the 3rd property, we've isolated our ECV and carried out a tightness test on the property we need to work I and its passed. Do we still need to test the complete system or can we test, work, re-test from the secondary ECV or do we need to test all the properties. Btw were looking at installing a new combi

 

[jtsplumbing]

You need to ring GS, commercial property, you may not be aloud to fit the combi,