Magnum Energy MM-AE Series - Manual (Page 19)

©
2010 Magnum Energy, Inc.
DC Overcurrent Protection
For safety and to comply with NEC (National Electrical Code) 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 can be a fuse or circuit-breaker, but 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. See Table 1 to select the DC overcurrent device based on the
minimum wire size for your inverter model.
If using a fuse, we recommend using a
class-T type or equivalent.
This fuse type is rated for DC operation, can handle the high short-
circuit currents, and allows for momentary current surges from the
inverter without opening.
DC Grounding
The inverter/charger should always be connected to a permanent,
grounded wiring system. The idea is to connect the metallic chassis
of the various enclosures together to have them at the same voltage
potential, which reduces the possibility for electric shock. For the
majority of installations, the inverter chassis and the negative battery
conductor are connected to the system’s ground bond via a safety-
grounding conductor (bare wire or green insulated wire) at only one
point in the system. Per the NEC, the size for the grounding conductor
is usually based on the size of the overcurrent device used in the DC
system. Refer to Table 1 to select the appropriate DC ground wire
based on the overcurrent device used for your inverter model.
2.0 Installation
13
Table 2, DC Wire Size For Increased Distance
Minimum recommended DC wire size (one way)
3 ft or less 3 to 5 ft 5 to 10 ft 10 to 15 ft
MM612AE #2 AWG #1 AWG #1/0 AWG #2/0 AWG
MM1512AE # 1/0 AWG #1/0 AWG #2/0 AWG #4/0 AWG
MM1524AE # 1/0 AWG #1/0 AWG #2/0 AWG #4/0 AWG