Magnum Energy Magnum Panel (MP Series) - Manual (Page 62)

© 2011 Magnum Energy, Inc. Page 55
3.0 Installation
3.11 MP/Inverter System Grounding
The MP/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
MP/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 3-30):
• 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 to 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 at the service
equipment (i.e., equipment delivering the electrical energy) to the grounding electrode.
• 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 3-30, Grounding System for Inverter with MP Enclosure
DC
S OURCE
M AIN AC P ANEL
. H
O
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1
.
N
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U
T
.
G
N
D
. H
O
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2
.
D
C
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IDE
.
A
C
S
IDE
MP E NCLOSURE 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
N
D
.
P
O
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.
N
E
G
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
EG
C
EG
C