The following line voltage tests are not required by NFPA 99. ECRI Institute has included them as optional tests. These tests should be performed following new construction, renovations, or major repairs to the electrical distribution system to ensure that voltage taps are set correctly on distribution transformers. Repeating the tests after typical loads are applied or in existing facilities may indicate poor wiring or inadequate system capacity. The tests may also be helpful in diagnosing suspected problems and indicating whether a more extensive investigation of the electrical distribution system is necessary