©
2013 Magnum Energy, Inc.
Page 23
Installation
2.6.1
Sizing the Grounding Electrode Conductors
AC Side
– The size of the AC grounding electrode conductor (GEC-AC) depends on the size of
the largest ungrounded conductor feeding the AC load center. One 8.4 mm
2
(#8 AWG) copper
conductor will serve as an AC grounding electrode conductor (GEC-AC) for AC power conductors
smaller than and including 33.6 mm
2
(#2 AWG) copper. See
Table 2-3 for additional values.
Table 2-3, AC Grounding Electrode Conductor Sizing
Size of Largest
Ungrounded Conductor
Minimum Size of
Grounding Electrode Conductor
33.6 mm
2
(#2 AWG) or smaller
8.4 mm
2
(#8 AWG)
42.4 to 53.5 mm
2
(#1 to #1/0 AWG)
13.3 mm
2
(#6 AWG)
67.4 or 85.0 mm
2
(#2/0 or #3/0 AWG)
21.1 mm
2
(#4 AWG)
85.0 mm
2
(Over #3/0 AWG) thru 350 kcmil
33.6 mm
2
(#2 AWG)
DC Side
– To size the DC grounding electrode conductor (GEC-DC), you must
fi
rst determine
which one of the following three methods will be used to connect the DC and AC grounding points
in the inverter’s two electrical systems to the common earth ground:
•
Method 1 (Figure 2-11):
This method uses a separate grounding electrode for the DC system
and the AC system. In this method—since there are multiple connections to the DC grounding
electrode (GE-DC)—the size of the DC grounding electrode conductor (GEC-DC) cannot be
smaller than the largest conductor in the DC system (usually the battery-to-inverter cable).
The DC grounding electrode (GE-DC) must be bonded to the AC grounding electrode (GE-AC)
to establish a grounding electrode system; this bonding conductor (BC) cannot be smaller than
the largest grounding electrode conductor (GEC), either AC or DC.
Figure
2-11, Multiple Connections to DC Ground Rod (Method 1)
AC
DC Service
Panel
AC Service
Panel
DC Electrical System
AC Electrical System
Neutral
Positive
Negative
DC
Grounding
System
Negative
SBJ
GC
GEC-AC
EGC - AC
AC Ground
DC Ground
SBJ
EGC - DC
GC
Neutral
Hot
GEC-DC
GE
GE
GBB
GBB
Grounding Electrode
(DC side dedicated)
Grounding Electrode
(AC side dedicated)
MS-PE Series Inverter/Charger
BC
