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Planning Your Installation
208V 3-Phase Wye-Connected
With a Wye-connected secondary, any two of
the legs can be used to provide 208V to the
Wall Connector. For example, L1 and L2, or L1
and L3, or L2 and L3. The two used phases
must each measure 120V to neutral.
Note: A current-carrying neutral is not
required.
L3 (NOT USED)
Caution: The unused leg (L3 in the
illustration) must remain open. Do not
connect to a neutral bar, or to earth
ground.
Caution: The center point of the three
phases (normally used as neutral) must
be grounded to earth at only one point.
This is usually at the breaker panel.
8
L1
120V
208V
NEUTRAL
(NOT USED)
120V
L2 (NOT USED)
GND
240V Three-Phase Delta-Connected
With the delta connection, one leg must be
center tapped, and only the two phases on
either side of the center tap can be used. The
two used phases must each measure 120V to
neutral.
Consult the transformer manufacturer's
literature to verify that the single leg can
supply the required power.
Note: The Wall Connector's contactor closes
only if it detects the presence of an earth
ground wire connected to a neutral point on
the transformer secondary.
L3 (NOT USED)
120V
120V
Caution: The third line (L3 in the
illustration) of the delta is 208V, with
respect to neutral, and is sometimes
referred to as a "stinger." Do not use this
third line.
Caution: Do not use a three-phase delta-
connected transformer secondary
without a center tap on one leg. No
neutral point is available for the required
earth ground connection.
L1
NEUTRAL
240V
(NOT USED)
L2
GND
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