How many feet should there be between a standpipe and five hydrant FDC?

The most appropriate choice reflects that there may not be a specific distance requirement outlined in the applicable codes or regulations concerning the placement of standpipes in relation to fire department connections (FDC). Standpipes and FDCs are critical components of a fire protection system, and while certain guidelines dictate the overall installation and accessibility of these systems, the exact distance may not be universally specified.

It is important for sprinkler fitters and fire protection professionals to consult local and national codes, such as the National Fire Protection Association (NFPA) standards, which provide general guidelines for fire protection systems, to determine if any local amendments apply. However, when there are no explicit requirements regarding spacing between a standpipe and FDC, it would be appropriate to conclude that such specificity is not mandated, hence the answer indicating that it is "not specified" is valid.

When working in the fire protection industry, always ensure adherence to locally adopted codes and standards, as this may vary by jurisdiction and can directly affect safety and compliance in fire protection systems.