The law makes no special mandate. In 1789, Justice James Wilson was sworn in by the mayor of Philadelphia, Pennsylvania, where the court first sat. Thurgood Marshall, the nation's first African-American justice, took the Constitutional Oath in 1967 from Associate Justice Hugo Black, an Alabaman.
ballast - A device required by electric-discharge light sources such as fluorescent or HID lamps to regulate voltage and current supplied to the lamp during start and throughout operation.
Electronic Ballasts are not. Electronic Ballasts are not the only thing that injects harmonics, besides, the level of harmonics injected is really small in the working ranges. The ranges where large amounts are injected is often in the bands which are not used in Industry and hence is largely undocumented.