14
2.0 INSTALLATION
©2000 Xantrex Technology Inc.
Wiring (continued)
DC Disconnect and Over-current Protection
For safety and to comply with regulations, battery over-current protection is required. Fuses and
disconnects must be sized to protect the wiring in the system and are required to open before the
wire reaches its maximum current carrying capability.
The National Electrical Code (NEC) requires both over-current protection and a disconnect
switch for residential and commercial electrical systems. These items are not supplied as part of the
inverter. However, Xantrex offers a DC rated, DC250/175 ETL listed, circuit breaker disconnect
module specifically designed for use with Trace inverters to meet NEC compliance. Two amperage
ratings are available: a DC250 (250 amps) and a DC175 (175 amps) in either single or dual breaker
configurations for single or dual inverter installations.
NOTE: Trace DC disconnects are not designed to accept doubled (paralleled) cables which may
be required for long cable runs. Also, the plastic red and black covers on the DC inverter inputs are
not designed to accommodate dual cables. If dual cables are used, the optional conduit box (DRCB)
must be used.
Some installations may not require conduit or a disconnect device, although over-current
protection is still required. Xantrex offers a fuse block (TFB) providing the code required inverter
over-current protection for these applications. Refer to the table below for the proper size disconnect
device for specific cable diameters.
Cable Size
Required
Rating in
Conduit
Maximum
Breaker Size
Rating in "Free
Air"
Maximum Fuse
Size
#2 AWG 115 amps max N/A 170 amps max TFB200
#2/0 AWG 175 amps max DC175 265 amps max TFB300
#4/0 AWG 250 amps max DC250 360 amps max TFB400
975-0012-005
NOTE: The NEC allows rounding to the next standard fuse size from the cable rating (i.e., 150 amp
cable size rounds up to a standard 175 amp size). The term free air is defined by the NEC as
cabling that is not enclosed in a conduit or a raceway. Cables enclosed in conduit or raceways have
substantially lower continuous current carrying ability due to heating factors.
Table 2
Battery Cable to Maximum Breaker/Fuse Size
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