Owner`s manual

Page 33

Installation

2.6.2 System Bonding Jumper

The MS Series inverter does not include an internal bond between the Grounded Conductor (AC

neutral/DC negative) and the equipment grounding terminals. This bond [System Bonding Jumper

(SBJ)] is usually done in the main distribution panel for each electrical system.

CAUTION: There should be one and only one point in each electrical system

(both AC and DC) where the Grounded Conductor is attached to the Grounding

Electrode Conductor.

AC Side – The size of the System Bonding Jumper (SBJ) in the AC electrical system is based on

the area of the largest AC ungrounded conductor. In accordance with the NEC, use Table 2-4 to

determine the System Bonding Jumper size compared to the largest AC ungrounded conductor.

DC Side - The size of the System Bonding Jumper (SBJ) in the DC electrical system must not be

smaller than the DC Grounding Electrode Conductor (GEC – DC) used, which is determined from

the grounding method that will be used (see section 2.6.1).

2.6.3 Equipment Grounding Conductor

The inverter case and all other non-current-carrying exposed metal surfaces in the entire electrical

system that may be accidentally energized must be grounded. The equipment-grounding conductor

must be sized to safely carry the maximum ground-fault current likely to be imposed on it from

where a ground-fault may occur. In accordance with the NEC, use Table 2-5 to size the equipment-

grounding conductors. This table requires that the equipment-grounding conductor be sized

according to the rating of the overcurrent device protecting the circuit.

CAUTION: The connections and wiring for the equipment-grounding conductor must

be continuous to allow fault currents to properly operate overcurrent devices. Where

equipment is removed and this disconnects the bonding connection between the

grounding electrode conductor and exposed conducting surfaces, a bonding jumper

must be installed while the equipment is removed.

AC Side - Where the AC output from the inverter is connected to an AC load center, there should

be an equipment grounding conductor connected between the inverter case and the grounding

point in the AC load center. The AC Equipment Grounding Conductor (EGC – AC) is sized per Table

2-5 and is connected to the inverter’s AC equipment grounding terminal shown in ﬁ gure 2-10.

DC Side - Since the currents on the DC side are higher than the AC side (10 times at 12 volts,

5 times at 24 volts), the equipment grounding needs are different. The DC Equipment Grounding

Conductor (EGC – DC) is sized per Table 2-5 and connected to the DC equipment grounding terminal

on the inverter shown in ﬁ gure 1-2 (item 12).

Table 2-5, Equipment Grounding Conductor Sizing

Rating of Overcurrent

Device

Minimum Size of Copper

Ground Wire

15 amp #14 AWG

20 amp #12 AWG

30 - 60 amp #10 AWG

100 amp #8 AWG

200 amp #6 AWG

300 amp #4 AWG

400 amp #3 AWG