8
3.3.2 Line Wiring
●
Always turn off power
before connecting the line voltage inputs to the meter.
●
For the line voltage wires, CCS recommends 16 to 12 AWG stranded wire, type THHN, MTW,
or THWN, 600 V.
●
Do not place more than one voltage wire in a screw terminal; use separate wire nuts or termi-
nal blocks if needed.
●
Verify that the line voltages are in the range of the line-to-line
Ø-Ø
and line-to-neutral
Ø-
N
values printed in the white box on the front label.
The screw terminals handle wire up to 12 AWG. Connect each voltage line to the green terminal
block as shown in
Figure 1
above. After the voltage lines have been connected, make sure both
terminal blocks are fully seated in the meter.
Connect each line voltage to the appropriate phase; also connect ground and neutral (if appli-
cable). The neutral connection “
N
“ is not required on delta models (3D-240, 3D-400, and 3D-480),
but we recommend connecting it to ground if neutral is not present.
When power is first applied, check that the LEDs behave normally. If you see LEDs flashing red-
green-red-green (see
Figure 7
), the line voltage is too high for this model, so disconnect the power
immediately!
3.3.3 Grounding
The WattNode uses a plastic enclosure, insulation, and internal isolation barriers instead of
protective earthing. The ground terminal on the green screw terminal block is a functional ground,
designed to improve the measurement accuracy and noise immunity. If necessary, this terminal
may be left disconnected on wye models (
-
3Y
).
3.4 Connect Current Transformers
To meet the UL listing requirements, the WattNode meter may only be used with UL Listed CTs
with a 333 mVac output or the following UL Recognized current transformer models, which all gen-
erate 333 millivolts AC at rated current. See the current transformer datasheets for CT ratings.
ACT-0750-
xxx
CTL-1250-
xxx
CTM-0360-
xxx
CTS-0750-
xxx
CTS-1250-
xxx
CTS-2000-
xxxx
CTB-
WxL
-
xxxx
CTT-0300-
xxx
CTT-0500-
xxx
CTT-0750-
xxx
CTT-1000-
xxx
CTT-1250-
xxx
CTRC-
yyyyy
-
xxxx
●
“
xxx
” indicates the full scale current rating.
●
“
WxL
” indicates the opening width (
W
) and leg length (
L
) in inches.
●
“
dddd
” indicates the opening diameter of the loop for flexible Rogowski CTs.
●
“
yyyyy
” indicates the opening size in mils (thousandths of inches).
See the web article
https://ctlsys.com/selecting_current_transformers/
for information on
selecting appropriate current transformers (CTs).
●
Do not
use ratio or current output CTs such as 1 amp or 5 amp output models!
●
See the CT datasheets for the maximum input current ratings.
●
Be careful to match the CTs with the voltage phases. Make sure the
Ø
A CT
is measuring the
current on the same phase as the
Ø
A
voltage input, and the same for phases B and C. Use the
supplied colored labels or colored tape to identify the CT leads.
●
To minimize current measurement noise, avoid extending the CT wires, especially in noisy
environments. If it is necessary to extend the wires, use twisted pair wire 22 to 14 AWG, rated
for 300 V or 600 V (not less than the service voltage) and shielded if possible.
●
Find the source arrow or label “THIS SIDE TOWARD SOURCE” on the CT and face/point
toward the source of current.
●
OPTIONAL: if you see spurious readings on unused phases, jumper the unused CT inputs:
for each unused CT, connect a short wire from the terminal marked with a white dot to the
terminal marked with a black dot.