Magnum Energy Mini Magnum Panel (MMP Series) - Manual (Page 42)

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©
2013 Magnum Energy, Inc.
Installation
2.10 MMP/Inverter System Grounding
The MMP/inverter system uses both AC and DC electrical systems, therefore each electrical system
is required to be properly connected to a permanent, common “ground” or “earth” reference. A
MMP/inverter system that is properly grounded limits the risk of electrical shock, reduces radio
frequency noise, and minimizes excessive surge voltages induced by lightning. To understand how
the conductors in the electrical circuit will be connected to the system ground, the following terms
should be understood (also refer to Figure 2-16):
• Grounded
Conductor (GC): The wire/cable in the electrical system that normally carries current
(usually the AC neutral and/or the DC negative), and is intentionally connected or “bonded” to
the ground system. This wire or the ends of this wire must be colored white or gray.
• Equipment Grounding Conductor (EGC): A wire/cable that does not normally carry current
and is used to connect the exposed metal parts of equipment—that might be accidentally
energized—to the grounding electrode system or the grounded conductor. This wire or the
ends of this wire must be green, or green with a yellow stripe; or, this wire can be bare copper.
• Grounding Electrode Conductor (GEC): The wire/cable that does not normally carry current,
and connects the grounded conductor and/or the equipment grounding conductor to the
grounding electrode at the service equipment.
• Grounding Electrode (GE): A ground rod or conducting element that establishes an electrical
connection to the earth or common ground reference.
• System bonding jumper (SBJ): The connection between the grounded circuit conductor in the
electrical system and the equipment grounding conductor at a separately derived system.
There are two types of grounding – equipment grounding and system grounding.
The exposed metal parts of the equipment in the system usually don’t carry electricity. However, if
the exposed metal becomes electrifi ed by a live wire, a person touching this live part could complete
the electrical circuit and receive a shock. Equipment grounding prevents shock by connecting all
the exposed metal parts of equipment (via Equipment Grounding Conductors – EGC) together
at a common ground point (Ground BusBar – GBB). This common ground point—installed in the
service disconnect panel for each electrical system (AC and DC)—is then connected (via Grounding
Electrode Conductor – GEC) to the common ground reference, such as a ground rod (Grounding
Electrode – GE). This connection to earth is made at only one point in each electrical system;
otherwise, parallel paths will exist for the currents to fl ow. These parallel current paths would
represent a safety hazard and are not allowed in installations wired per the NEC/CEC.
System grounding takes one of the current carrying conductors (Grounded Conductor – GC) and
attaches it to the common ground point (Ground BusBar – GBB), usually by a System Bonding
Jumper (SBJ) in each electrical service disconnect panel. On the AC side, that is the neutral
conductor (GC-AC); on the DC side, it’s the negative conductor (GC-DC). The closer the grounding
connection is to the source, the better the protection from high voltage surges due to lightning.
Figure 2-16, Grounding System for Inverter with MMP Enclosure
DC
S OURCE
M AIN AC P ANEL
H
OT
1
N
EUT
G
ND
H
OT
2
MMP or
AC
S OURCE
AC and DC sides shared DC side dedicated AC side dedicated
or
or
DC Electrical
System
AC Electrical
System
Grounding System
G
ND
P
OS
N
EG
HOT 1
HOT 2
NEUT
GBB
SBJ
GEC-DC
GE
GE
GEC-AC
GE
GBB
SBJ
M AGNUM
I NVERTER
BAT
BAT
or
GC-DC GC-AC
E NCLOSURE