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8. Wiring
This section provides cabling details and notes on cable sizing for DC applications with respect to the Alpha CXPS-C
series power system.
• Only qualified personnel should install and connect the power components within the Alpha power system.
• All wiring must be in accordance with applicable electrical codes.
• Use of an LVBD is recommended to automatically disconnect the batteries after a complete discharge to prevent
possible permanent damage to the batteries.
• Electrical codes require that conductors carrying AC current be installed separately from conductors carrying DC
current and signals.
8.1 Installation Notes
8.1.1 Installer Responsibility
The system arrives pre-wired, and the installer is responsible for connecting the following:
• Utility input to the system
• Battery strings
• System to the load
• Chassis and battery return to the reference ground
• Inter bay alarm signals and CAN cables
All signaling wires (for example, alarms from the controller) interfacing with the outside world exit the frame through
the top or bottom.
8.1.2 Calculating Output Wire Size Requirements
Although DC power wiring and cabling in telecommunication applications tend to ex-
ceed electrical code requirements, mostly due to the voltage drop requirements, all
applicable electrical code(s) take precedence over the guidelines and procedures in the
present chapter, wherever applicable.
Wire size is calculated by first determining the appropriate maximum voltage drop requirement. Use the formula
below to calculate the circular mil area (CMA) wire size requirement. Determine the size and number of conductors
required to satisfy the CMA requirement.
CMA = (A x LF x K) / AVD
A = Ultimate drain in amps.
LF = Conductor loop feet.
K = 11.1 constant factor for commercial (TW type) copper wire.
AVD = Allowable voltage drop.
Check again that the ampacity rating of the cable meets the requirement for the installation application. Consult local
electrical codes (NEC, CEC, etc.) for guidelines. If required, increase the size of the cable to meet the code.
Refer to Table H for cable size equivalents.