Abstract: A lighting unit comprises a mount for rotating a plasma light source within a cylinder of metal gauze that provides a primary Faraday cage for shielding against radio-frequency radiation from the light source. The shielding is extended using a parabolic reflector for the emitted light in combination with a gauze to establish a secondary Faraday shield enclosing the primary cage. The gauze covers a ring that is sealed between the rim of the front open-mouth of the reflector and a slide-in cassette of the lighting unit, and can be of a metallic honeycomb configuration enhancing the operation and light output from the unit.