Battery Cable Sizing; Dc Over Current Protection; Table 1, Minimum Recommended Battery Cable Size (In Free Air) - Trace Engineering LEGEND II Manual

possible. You may connect the system without going through the chassis ground terminal, but the
RC7's fuel gauge feature will not work properly.

Battery Cable Sizing

The bigger the battery cables the better. Undersized cables result in additional stress on the inverter,
lower efficiency, reduced surge power and lower peak output voltage. Don't use cables that are too
small in diameter. The following table gives recommended cable sizes for the various cable-run
lengths and inverter voltages.

Table 1, Minimum Recommended Battery Cable Size (In free air)

Inverter Typical DC
Model #
L2012 200 Amps
L2512 250 Amps
L3012 300 Amps
The term "Free Air" is defined by the NEC as the cabling not being enclosed in conduit or raceway.
Cables enclosed have a substantially lower continuous current carrying ability due to heating factors.
The National Electric Code (NEC) requires that the cables be protected by a fuse or breaker rated to
match the cables ampacity at 75 degrees Celsius. The NEC also allows rounding up to the next fuse
size from the cable rating, i.e. 150-amp cable size rounds up to a 175-amp fuse size.
Under-sized cables may melt or burn if the inverter is asked to produce high
power.

DC Over Current Protection

In order to comply with the UL 458 safety standard (Land Vehicle Installations) a UL approved type of
battery over-current protection is required. Fuses and disconnects must be sized to protect the
wiring in the system. The fuse is required to blow before the wire reaches its maximum current
carrying capability.
These installation parts are not supplied as part of the inverter. However, Trace Engineering offers a
DC-rated class T fuse and safety-covered fuse block which are compatible with the Legend Series II
WK

Minimum
Amps Fuse Size
250A
300A
400A
1 to 3 feet 3 to 5 ft
One Way One Way
00 00
00 0000
0000 0000
5 to 10 ft
One Way
0000
0000
0000