Heat run test - Design or Production Test?

[Phayze_Shift]

A project contains three identical 15kV Switchgear units varying only in the number of CTs, PTs, and Bus length. The first unit was subjected to all the design tests required by CSA C22.2 No.31 for switchgear assemblies (Dielectric strength, Partial Discharge, Heatrun etc...).

Is it necessary to perform another heatrun test on the two remaining units or has the design already been tested? I cannot find anything in C22.2 No.31 that suggests the heatrun test can be accepted as a design test.

Thanks