When testing large switchgear and controlgear, the part of equipment through which the
test voltage is applied may be subjected to numerous test sequences to check the
insulating properties of other downstream parts of equipment (circuit-breakers,
disconnectors, other bays). It is recommended that parts be tested in sequence, starting
with the first connected part. When this part has passed the test according to the abovementioned criteria, its qualification is not impaired by possible disruptive discharges which
could occur in it during further tests on other parts.