Trace Engineering Legend User Manual

INSTALLATION
Trace Engineering Co. Inc. Tel (360) 435-8826 Part Number 3179
5916 195
th
Street, NE Fax (360) 435-2229 Effective August 6, 1998
Arlington, WA 98223 USA www.traceengineering.com Page
35
Neutral-to-Ground Switching
All of the Legend Series units employ neutral to ground switching as required by the NEC (National
Electric Code). The purpose for this requirement is to ensure that the neutral conductor in a three-
wire system is "bonded" or connected to ground at only one point. This prevents a voltage
difference from developing between the vehicle's neutral and the AC source's neutral, which may
cause an electric shock. When the unit is operating as an inverter, the AC output neutral is connected
to the chassis ground by an internal relay, creating the bond within the inverter. When operating from
an external AC power source the internal relay in the inverter opens and removes the ground from
the neutral conductor and allows the "bond" to be provided by the external AC source.
The diagram below graphically describes the ground switching system in the inverter for a unit
operating as an inverter and feeding the AC sub-panel.
RY-A
RY-B
HOT OUT
The
neutral
conductor
shall be
insulated
from the
equipment
grounding
conductors
or
enclosures
NEUTRAL OUT
Neutral-to-Ground “BOND” is provided by the
internal relay for entire AC system
AC Sub-panel
(Inverter loads)
N
E
U
Inverter
AC
out
GND
Relay RY-A connects the
inverter out to the AC
HOT output.
Relay RY-B connects the NEUTRAL (OUT) to chassis or vehicle
ground when AC power is not present at the inverter input. This
assures all equipment in the vehicle is referenced to the same ground.
Figure 7, Neutral-to-Ground Switching without external AC source

Trace Engineering Legend Specifications

General

Brand	Trace Engineering
Model	Legend
Category	Inverter
Language	English