Inherent Voltage Drop Phenomenon
This phenomenon is due to the inherent resistance of the power cable to current flow. A voltage drop develops across the cable, lowering the actual voltage and power levels to the pertaining equipment. The longer the wire, the larger the drop. It may be necessary to increase the circular mils or gauge of the wire to decrease the voltage drop, bringing it within the operating company’s specification.
The voltage drop of the discharge bus loop, including the drop across the over current protection devices between the battery terminals and the loads in the equipment frame, should be limited to a maximum of 2V at Class 2 amperage (typical). Most operating companies limit the power cable drop between the battery distribution fuse board (BDFB) and the distribution fuse/breaker alarm panel (DF/BAP) to 0.5V or less. Always verify with the operating company for specific voltage drop information for their individual installation requirements.