Definition
Firing line has two complementary meanings. On site, it is the row of racks, cakes and ground pieces set up facing the audience, generally parallel to the spectator area and sometimes split into several staggered lines (front for low effects, rear for large shells). In wiring, it is the electrical conductor linking a module output to an igniter or a series of igniters, copper or aluminium in a sheath, from a few metres to several hundred metres for extended shows or those fired over water. A firing line is tested for continuity and resistance before arming, and never with a current capable of firing the igniter. Wireless firing systems shrink the lines to the few metres between the module and its tubes.
In practice, for the display company
The firing line is drawn on the site plan before rigging: it sets the distances to the audience, the location of the modules and the cable length to bring. PyroDesk places lines and positions on the site plan, counts cues per module, and PyroSimulator renders the show from the audience's viewpoint to check the staggering of the lines.