4.6.4. The fire alarm gongs shall be heard above the normal noise level and shall be located so that there is at least:(a) one 100 mm diameter gong for each 100 m2 of floor area;
(b) one 150 mm diameter gong for each 550 m2 of floor area; or
(c) one 250 mm diameter gong for each 1,200 m2 of floor area.