Hose Box for External Hydrants CAD drawing includes grating of min size with 16 mm sq. bars & frame @ 20 mm clear spacing fixed at the mouth of pipe as per site condition and direction of engineer in-charge, hydrant valve as per i.s. 5290 type 'a' (oblique) with 63 mm standard outlet to take instantaneous type threaded male coupling for connection to hose pipe.typical details of maintenance free(mf) earthing system details. download DWG file of house box for external hydrants detail.