The placement of the fire department connection (FDC) for a wet-pipe automatic sprinkler system is governed by NFPA 13, Standard for the Installation of Sprinkler Systems.
The FDC must be located on the system side of the water supply check valve (A). This ensures that the fire department can pump water into the system effectively and directly supply the sprinkler system during an emergency.
Suction side of booster pumps (B): This placement would not supply water correctly to the system during firefighting operations.
Supply side of the check valve (C): This would prevent water from entering the sprinkler system since the check valve blocks backflow from the FDC.
Above the dry-pipe valve (D): This applies to dry-pipe systems, not wet-pipe systems.
Reference:
NFPA 13, Section 8.17.2.4: Location requirements for fire department connections.