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©
2013 Magnum Energy, Inc
.
Installation
2.4 DC
Wiring
This section describes the inverter’s required DC wire sizes, the recommended disconnect/
overcurrent protection, and how to make the DC connections to the inverter and the battery bank.
Refer to Figure 2-4 when connecting the DC wires.
WARNING:
Even though DC voltage is “low voltage”, signi
fi
cant hazards may be
present, particularly from short circuits of the battery system.
CAUTION:
The inverter is NOT reverse polarity protected—which means that if the
negative and positive battery voltage is connected backwards to the inverter, the
inverter will likely be damaged. You should verify the correct voltage polarity using a
voltmeter BEFORE connecting the DC wires.
CAUTION:
Before wiring the DC cables, review the safety information at the beginning
of this manual and the information below to ensure a safe and long-lived system.
CAUTION:
DO NOT connect the battery cables to the inverter until all wiring is complete
and the correct DC voltage and polarity have been veri
fi
ed.
Refer to Figure 2-4 when connecting the DC wires, consider the following requirements to ensure
maximum performance:
• The DC positive and negative cables connected to the inverter from the battery bank should be
tied together with wire ties/straps or electrical tape approximately every 6 inches (15.3 cm).
This helps improve the surge capability and reduces the effects of inductance, which improves
the inverter waveform and reduces the wear of the inverter’s
fi
lter capacitors. Keeping the
battery cables close together also reduces the chance of radio frequency interference.
• Crimped and sealed copper ring terminal lugs with a 5/16” hole should be used to connect the
DC wires to the inverter’s DC terminals.
• The battery bank voltage MUST match the DC voltage required by the inverter (i.e., 24-volt
battery bank for a 24-volt inverter) or the inverter may be damaged.
• To ensure the maximum performance from the inverter, all connections from the battery bank
to the inverter should be minimized. The exceptions are the DC fuse and disconnect or the DC
circuit breaker—required at the battery to protect the DC wiring—in the positive line, and a
DC shunt—to allow battery charge state monitoring—in the negative line. Any other additional
connection will contribute to additional voltage drops, and these extra connection points may
loosen during use.
• All wiring to the battery terminals should be checked periodically (once a month) for proper
tightness. The torque requirement for the DC terminals is between 10 to 12 ft lbf (13.6 to 16.3
N-m). If you don’t have a torque wrench, ensure all DC terminals are tight and cannot move.
• Be aware that overtightening or misthreading the nuts on the DC terminals can cause the
bolts to strip and snap/break off.
• Make sure cables have a smooth bend radius and do not become kinked. Follow existing wire
runs where possible.
• A brief spark or arc may occur when connecting the battery cables to the inverter DC terminals;
this is normal and due to the inverter’s internal capacitors being charged.
• Before routing the wiring, color code the DC cables/wires with colored tape or heat shrink
tubing: RED for positive (+); WHITE for negative (–); and GREEN (or bare copper) for DC ground,
to avoid polarity problems.
• Do not attempt to use the chassis in place of the battery negative connection for grounding.
The inverter requires a reliable return path directly to the battery.
