This part of IEC 60076 gives guidance and explanatory comments on the existing procedures for lightning and switching impulse testing of power transformers to supplement the requirements of IEC 60076-3. It is also generally applicable to the testing of reactors, see IEC 60289; modifications to power transformers being indicated where required. Information is given on wave-shapes, test circuits including test connections, earthing practices, failure detection methods, test procedures, measuring techniques and interpretation of results. Where applicable, the test techniques are as recommended in IEC 60060-1 and IEC 60060-2.