DISCOVER ELEMENT - DC Cable Requirements; DC Protection Requirements

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9.3 DC Cables
CAUTION
FIRE HAZARD
Undersized cables can become hot and may potentially catch fire.
Failure to follow these instructions can result in minor to moderate injury.
The DC battery cables should meet the following requirements:
1. Copper-stranded cable. DC cables must be stranded, copper, and rated 90°C
minimum. Terminate the cables with lugs that fit the DC terminals.
2. Minimum cable lengths. Select a location that minimizes the length of
battery cables to reduce voltage drop from the impedance leading to reduced
performance.
3. Appropriate cable gauge (AWG3, 25 mm
2
or thicker). The cables should be
capable of carrying the normally expected current, plus a margin of safety.
4. Proper polarity. Positive (+) is connected to positive (+), and negative (-) is
connected to negative (-).
9.4 DC Protection
CAUTION
FIRE HAZARD
• Undersized fuses and disconnects may become overloaded and potentially cause a
fire.
• Fuses and disconnects are required to open before the cable reaches its maximum
current carrying capability.
Failure to follow these instructions can result in minor to moderate injury.
Additional DC overcurrent protection and a DC disconnect switch are required to
protect the system and DC battery cables.
1. Appropriate size. Size the fuses and disconnects following local codes to protect
the wiring in the system and are required to open before the cable reaches its
maximum current carrying capability.
2. Install protection in the positive cable. The fuse and disconnect should be
located close to the battery module and installed in the positive cable. Local
codes may limit how far the protection can be from the battery module.
NOTE
• AC circuit breakers and DC circuit breakers are not interchangeable. Check the label
on the circuit breaker to ensure it is the correct type and rating. Use only DC circuit
breakers.
• Local electrical code in your area may require both positive and negative DC
disconnect switches. Refer to the applicable code and check with the authority having
jurisdiction to confirm local requirements.