6
Ø
B
Ø
C
N
Ø
A
W
ATT
N
ODE
®
Ø
B
CT
Ø
A
CT
Ø
C
CT
L3
L2
L1
Earth
2.2.5 Three-Phase Four-Wire Wye with Neutral
This is a common commercial and industrial service.
Ø
B
Ø
C
N
Ø
A
W
ATT
N
ODE
®
Ø
B
CT
Ø
A
CT
Ø
C
CT
L3
L2
L1
Neutral
Earth
2.2.6 Three-Phase Four-Wire Delta with Neutral (Wild Leg)
The uncommon four-wire delta electrical service is a three-phase delta service with a center-tap
on one of the transformer windings to create a neutral for single-phase loads.
The high-leg or phase with the higher voltage as measured to neutral has traditionally been des-
ignated “Phase B”. A change to the 2008 NEC now allows the high leg of a four-wire three-phase
delta service to be labeled as the “C” phase instead of the “B” phase. The WattNode meter will
work correctly with the high-leg connected to
Ø
A
,
Ø
B
, or
Ø
C
.
See the web article
https://ctlsys.com/support/four_wire_delta_circuits/
for more information.
Ø
B
Ø
C
N
Ø
A
W
ATT
N
ODE
®
Ø
B
CT
Ø
A
CT
Ø
C
CT
L3
L2
L1
Neutral
Earth
2.2.7 Grounded Leg Service
In rare cases with delta services or single-phase two-wire services without neutral, one of the
phases may be grounded.
The WattNode meter will correctly measure services with a grounded leg, but the measured volt-
age and power for the grounded phase will be zero. The status LEDs will not light for the grounded
phase, because the voltage is near zero. This type of service may result in unusual power factors.
For more information, see
