In a theatrical dimming system, loads are rarely turned on full all at once. In addition, connected loads are typically far less than the "nameplate rating" or full-load capacity of the systems. These two conditions create "load diversity", that allows certain de-rating of system feeders and branch circuits under the rules of the NEC. For a view of typical loads connected to dimming systems, see the attached ETC Load Survey conducted in 2005. A relatively new condition affecting load diversity is the widespread use of arc-source automated fixtures, which draw full load for the entire performance, since their lamp is always on and dimming is accomplished via a mechanical douser. See also the article mentioned in the wiki entry Diversity, electrical.