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Installation
The DC wires must have soldered and crimped lugs, crimped copper
compression lugs, or aluminum mechanical lugs. Soldered connections alone
are not acceptable for this application.
Table 1, Recommended DC Wire/Overcurrent Device
Maximum Continuous
Current
1
DC Grounding Electrode
Wire Size
2
Minimum DC Wire Size
°
[75
C rating in free air]
Maximum DC Fuse Size
Increased
5 to 10
size for
feet =
longer
10 to 15
distance
feet =
Note
– Maximum Continuous Current is based on the inverter's continuous power rating
1
at the lowest input voltage with an ineffi ciency factor.
Note
– Per the NEC, the DC grounding electrode conductor can be a #6 AWG conductor
2
if that is the only connection to the grounding electrode and that grounding electrode
is a pipe, rod, or plate electrode.
Note
– Wire size is based on the requirements needed to increase effi ciency and reduce
3
stress to the inverter.
Note
– The next larger standard size overcurrent device may be used if the derated
4
cable ampacity falls between the standard overcurrent devices found in the NEC.
If the inverter is expected to operate at a distance greater than three feet
from the battery bank, the DC wire will need to be increased to overcome the
increase in resistance—which affects the performance of the inverter. Continue
to use the overcurrent device and DC ground wire previously determined from
Table 1 and then, refer to the bottom part of Table 1 to determine the minimum
DC wire size you need for various distances based on your inverter model.
2.4.2
DC Overcurrent Protection
For safety and to comply with electrical code regulations, you must install a
DC overcurrent protection device in the positive DC cable line to protect your
DC cables. This DC overcurrent device must be DC rated and can be a fuse or
circuit breaker. 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.
to select the DC overcurrent device needed based on the minimum wire size
according to your inverter model.
Electrical systems in mobile installations typically do not require using a DC
disconnect, although an overcurrent protection device is still required. Because
the DC disconnect is not required, a fuse is usually used as the overcurrent
device in these installations. These installations also do not normally use
11
Inverter Model
MM612
80 amps
#6 AWG
(13.3 mm
)
2
#6 AWG
3
(13.3 mm
)
2
[95 amps]
90 amps with time
4
delay
#6 AWG
(13.3 mm
)
2
#4 AWG
(21.1 mm
)
2
© 2016 Sensata Technologies
MM1212/MM1212-G
160 amps
#8 AWG
(8.36 mm
)
2
#1 AWG
(42.4 mm
)
2
[195 amps]
175 amps with time
delay
#1 AWG
(42.4 mm
)
2
#1/0 AWG
(53.3 mm
)
2
See Table 1
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