It is not necessary to put in all the sprinklers. At best only a handful closest to the fire will activate. I normally put in a 3 x 3, or 4 x 4 matrix around the fire location.
However, if you do want to put all or some of them in then determine the spacing. In North America, it's often 10 ft or 3 m. Put in a sprinkler at the end of a row, use the copy feature to make the rest of the row, then use the copy feature to copy the new row as many times as required.
Dave
