How to calculate Voltage Drop calculation for 14 AWG Fire Alarm Cable Is it necessary to Spare one Entire loop in FACP for future maintenance purpose?

This is a calculator for the estimation of the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current. Please note this calculator assume the circuit is operate in a normal condition—room temperature with normal frequency. The actual voltage drop can vary depend on the condition of the wire, the conduit being used, the temperature, the connector, the frequency etc. It is recommended that the voltage drop should be less than 5% under the fully loaded condition.