Dc Grounding - Magnum Energy MMS Series Owner's Manual

Installation
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 disconnect device in these installations. These
installations also do not normally use conduit, so the fuse must be
installed in the ungrounded conductor (usually the positive DC cable
line) within 18 inches (45.7 cm) of the battery—to protect the DC
wiring system.
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.

2.2.3 DC Grounding

The MMS 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 2-1 to select the appropriate DC ground
wire based on the overcurrent device used for your inverter model.
If the inverter is in a recreational vehicle, DO NOT connect the battery
negative (–) cable to the vehicle's safety ground. Only connect to
the inverter's negative battery terminal. If any non-factory installed
appliances are onboard the vehicle, DO NOT ground them at safety
ground. Only ground them at the negative bus of the DC load center
(as applicable).
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