Owners Manual

© 2015 Sensata Technologies 13
Installation
DC Wire Size Exception: In an OEM RV application, smaller DC wire (with
appropriate overcurrent protection) may be used if the inverter will only be
connected to a dedicated load (as shown in Figure 2-2), and the inverter and
dedicated load have been thoroughly tested and sold together by the OEM
as a complete system.
Table 2-2, DC Wire/Overcurrent Device for Rated Use
Inverter Model
CMW412 CMW1012 CMW1512
Continuous Current
(@12.5)
38 amps 96 amps 140 amps
Maximum Continuous
Current
1
54 amps 137 amps 200 amps
Minimum DC Ground
Wire Size
2
#8 AWG
(8.36 mm
2
)
#8 AWG
(8.36 mm
2
)
#8 AWG
(8.36 mm
2
)
Minimum DC Wire Size
[75°C rating - free air]
#10 AWG
(5.26 mm
2
)
[50 amps]
#2 AWG
(33.6 mm
2
)
[170 amps]
#1/0 AWG
(53.5 mm
2
)
[230 amps]
Maximum DC Fuse Size
50 amps with
time delay
150 amps with
time delay
225 amps with
time delay
Increased
size for
longer
distance
5 - 10 feet
(1.5-3 m)
#8 AWG
(8.36 mm
2
)
#2 AWG
(33.6 mm
2
)
#2/0 AWG
(67.4 mm
2
)
10-15 feet
(3-4.6 m)
#6 AWG
(13.3 mm
2
)
#1/0 AWG
(53.5 mm
2
)
#4/0 AWG
(107.2 mm
2
)
Note
1
– Maximum Continuous Current is based on the inverter’s continuous
power rating at the lowest input voltage with an ineffi ciency factor.
Note
2
– The grounding conductor for the DC system shall meet the sizing
requirements specifi ed in the NEC for the application, but must be no smaller
than #8 AWG copper. In some applications, the DC grounding conductor is
required to be no less than the wire size of the DC positive/negative cables.
2.4.2 DC Overcurrent Protection
For safety reasons and to comply with electrical code regulations, DC
overcurrent protection must be provided as part of the installation. The DC
overcurrent protection device must be installed in the positive DC cable line,
it can be a fuse (with a disconnect switch) or a circuit breaker and must
be DC-rated. It must be correctly sized according to the size of DC cables
being used, which means it is required to open before the cable reaches its
maximum current carrying capability, thereby preventing a fi re. The NEC
requires both overcurrent protection and a disconnect switch.
Because batteries can deliver thousands of amps in an instant during a
short, you are required to install a DC-rated fuse (or circuit breaker) that
has a interrupt current rating (known as Amps Interrupting Current or AIC)
that can withstand the short-circuit current without explosion or damage.
If a fuse is used as an overcurrent device, a Class-T type or equivalent is
highly recommended when used with inverters. A Class-T fuse is rated for
DC operation, can handle very high short-circuit currents (up to 100,000