2
Connect the line voltages to the meter inputs as shown in the following figures
for each service type. See
Figure 1
above for an overview.
2.2.1 Single-Phase Two-Wire with Neutral
This is a common residential and branch circuit connection. Up to three such
circuits may be monitored with one meter by also using the
Ø
B
and
Ø
C
inputs.
Ground
Ø
B
Ø
C
N
Ø
A
W
A
TT
N
O
D
E
®
Neutral
Line
2.2.2 Single-Phase Two-Wire No Neutral
This circuit occurs in residential (commonly 120/240 Vac) and some commercial
applications. The meter is powered from the
Ø
A
and
Ø
B
terminals. We recom-
mend connecting the
N
terminal to ground to provide a clean voltage reference
for the measurement circuitry (no current will flow through this terminal).
Ground
Ø
B
Ø
C
N
Ø
A
W
A
TT
N
O
D
E
®
L1
L2
2.2.3 Single-Phase Three-Wire with Neutral
This is a common residential service at 120/240 Vac.
Ground
Ø
B
Ø
C
N
Ø
A
W
A
TT
N
O
D
E
®
Neutral
L1
L2
2.2.4 Three-Phase Three-Wire Delta No Neutral
This is common in commercial and industrial settings. In some cases, the
service may be four-wire, wye but the load may only be three wire (no neutral).
Occasionally, a load will only be connected to two of the three lines (say
L1
and
L2
). For this case, connect the two active lines to the
Ø
A
and
Ø
B
terminals and
connect two CTs for the two lines.
Ground
Ø
B
Ø
C
N
Ø
A
W
A
TT
N
O
D
E
®
L1
L2
L3
2.2.5 Three-Phase Four-Wire Wye with Neutral
This is a common commercial and industrial service.
Ground
Ø
B
Ø
C
N
Ø
A
W
A
TT
N
O
D
E
®
Neutral
L1
L2
L3
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 tra-
ditionally been designated “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
for more information.
Ground
Ø
B
Ø
C
N
Ø
A
W
A
TT
N
O
D
E
®
Neutral
L1
L2
L3
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 voltage and power for the grounded phase will be zero and the
status LEDs (if present) will not light for the grounded phase, because the volt-
age is near zero. Also, this type of service may result in unusual power factors.
See the web article
for more information.
3 Installation
3.1 Installation Checklist
See the sections referenced below for installation details.
□
Mount the WattNode meter (see
□
Turn off power
before making line voltage connections.
□
Connect circuit breakers or fuses and disconnects (see
).
□
Connect the line voltage wires to the meter’s green terminal block (see
□
Mount the CTs around the line conductors. Make sure the CTs face the
source
□
Connect the twisted white and black wires from the CTs to the black
terminal block on the meter, matching the wire colors to the white and
black dots on the meter label (see
).
□
Check that the CT phases match the line voltage phases (see
□
Record the CT rated current for each meter, because it will be required
during commissioning.
□
Connect the output terminals of the WattNode meter to the monitoring
equipment (see
□
Check that all the wires are securely installed in the terminal blocks by
tugging on each wire.
□
Apply power to the meter.
□
Verify that the LEDs indicate correct operation (see
,
3.2 Mounting
●
Protect the meter from temperatures below –30°C (-22°F) or above 55°C
(131°F), excessive moisture, dust, salt spray, or other contamination, using
a NEMA rated enclosure if necessary. The meter requires an environment
no worse than pollution degree 2 (normally only non-conductive pollution;
occasionally, a temporary conductivity caused by condensation).
●
The meter must be installed in an electrical service panel, an enclosure,
or a limited access electrical room.
●
Do not
use the meter as a drilling guide; the drill chuck can damage the
screw terminals and metal shavings may fall into the connectors.
The meter has two mounting holes spaced 136.6 mm (5.375 in) apart (center-
to-center). These mounting holes are normally obscured by the detachable
screw terminals. Remove the screw terminals to mark the hole positions and
mount the meter.
Self-tapping #8 sheet metal screws are included. Don’t over-tighten the screws,
as long-term stress on the case can cause cracking.
3.3 Connect Voltage Terminals
3.3.1 Circuit Protection
The WattNode meter is considered “permanently connected equipment” and
requires a disconnect means (circuit breaker, switch, or disconnect) and over-
current protection (fuse or circuit breaker).
