CCT

1. Correlated Color Temperature. The same as Color Temperature. "Correlated" as it is based on a theoretical black body locus. See color temperature (external link).

2. A UK manufacturer of lighting fixtures. Website. From this document:

CCT Theatre Lighting Limited was founded in Carshalton in 1965 by three Theatre enthusiasts
Colin Philips, an Advertising Agency executive, Colin Turner, a British Telecom engineer and Terry Fitzgerald, a Theatre Production Manager. Hence the name 'CCT'. They have all since left the Company. The Company was run successfully by Mr Don Hindle who joined the Company in 1968, David Manners in 1969 (he spent the previous 10 years at the Pembroke and Ashcroft Theatres in Croydon) and Mr George Chapman in 1991 when the Company was re-titled CCT Lighting Limited. The present Directors who brought the Company in 2004 under a management buyout are Mr John Shaw, an apprenticed trained Rolls Royce Production Engineer, Mr Richard Stokes, Theatre Lighting Engineer and Mr Gary Redfern, Electrical Engineer, all of which were employees of CCT Lighting and before then, Furse Theatre Products.
...CCT has always been known for its innovative ideas introducing the first variable beam angle Profile spotlight to this Industry, followed by the revolutionary Pebble Convex lens.

3. Sometimes used as an abbreviation for "circuit" on lighting paperwork (Hook-ups, Instrument Schedules, and the like), although "ckt." is more common.