The　remote　ignition　and　accelerated　flame　spread　in　multiple　fires　accidents　are　mainly　due　to　the　thermal　radiation.　The　merged　flame　height　and　external　radiative　heat　flux　distribution　of　the　square　fire　arrays　were　investigated　numerically.　Different　burner　spacing,　total　number　of　burners　and　heat　release　rate　(HRR)　of　an　individual　burner　were　considered.　Results　show　that　the　fire　plume　centerline　temperature　can　be　predicted　accurately　by　achieving　grid　independence　on　a　fine　enough　grid.　A　correlation　for　predicting　the　merged　flame　height　of　the　multiple　fires　is　developed　involving　the　number　of　burners,　HRR　of　each　burner　and　burner　spacing.　The　comparison　of　calculated　and　simulated　data　in　this　work　validated　the　accuracy　of　the　proposed　correlation.　The　radiative　heat　flux　distributions　surrounding　the　fire　array　can　be　divided　into　two　regions,　that　is,　the　near-　and　far-field　regions.　The　total　heat　release　rate　of　the　fire　array　is　shown　to　be　the　dominant　effect　on　the　radiation　distribution　throughout　the　whole　region,　whilst　the　burner　spacing　is　shown　to　only　have　an　effect　in　the　near-field　region.　To　distinguish　the　two　regions,　the　critical　distance　of　0.7　(Formula　presented.)　((Formula　presented.)　is　the　characteristic　fire　array　length)　was　obtained.　©　2021　John　Wiley　&　Sons　Ltd.