Installation 17
For solid-core CTs, turn off the power and disconnect the conductor being measured to install it
through the CT opening.
Split-core and bus-bar CTs can be opened for installation around a conductor. Different models
have different opening mechanisms, so you should familiarize yourself with the CT mechanism
before starting the installation. A nylon cable tie can be secured around the CT to prevent
inadvertent opening. A second cable tie through the CT opening can position the CT on the
conductor.
Some split-core CT models have flat mating surfaces. When installing this type of CT, make sure
that mating surfaces are clean. Any debris between the mating surfaces will increase the gap,
decreasing accuracy.
Connect the CT lead wires to the meter terminals labeled
Ø
A CT
,
Ø
B CT
, and
Ø
C CT
. Route the
twisted black and white wires from the CT to the meter. Strip 1/4 inch (6 mm) of insulation off the
ends of the CT leads and connect to the six position black screw terminal block. Connect each
CT lead with the white wire aligned with the white dot on the label, and the black wire aligned with
the black dot. Note the order in which the phases are connected, as the voltage phases
must
match the current phases for accurate power measurement.
Record the CT rated current as part of the installation record for each meter. If the conductors
being measured are passed through the CTs more than once, then the recorded rated CT current
is divided by the number of times that the conductor passes through the CT.
Circuit Protection
The WattNode meter is considered “permanently connected equipment”, because it does not
use a conventional power cord that can be easily unplugged.
Permanently connected equip-
ment must have overcurrent protection and be installed with a means to disconnect the
equipment.
●
A switch, disconnect, or circuit breaker may be used to disconnect the meter and must be
as close as practical to the meter. If a switch or disconnect is used, then there must also be a
fuse or circuit breaker of appropriate rating protecting the meter.
●
WattNode meters only draw 10-30 milliamps; CCS recommends using circuit breakers or
fuses rated for between 0.5 amps and 20 amps and rated for the line voltages and the cur-
rent interrupting rating required.
●
The circuit breakers or fuses must protect the ungrounded supply conductors (the terminals
labeled
Ø
A
,
Ø
B
, and
Ø
C
). If neutral is also protected (this is rare), then the overcurrent protec-
tion device must interrupt neutral and the supply conductors simultaneously.
●
Only used ganged circuit breakers when monitoring more than one line voltage.
●
Any switches or disconnects should have at least a 1 amp rating and must be rated for the
line voltages.
●
The circuit protection / disconnect system must meet IEC 60947-1 and IEC 60947-3, as well
as all national and local electrical codes.
●
The line voltage connections should be made with wire rated for use in a service panel or
junction box with a voltage rating sufficient for the highest voltage present. CCS recommends
14 or 12 AWG (1.5 mm
2
or 2.5 mm
2
) stranded wire, rated for 300 or 600 volts. Solid wire may
be used, but must be routed carefully to avoid putting excessive stress on the screw terminal.
●
The WattNode meter has an earth connection, which should be connected for maximum
accuracy. However, this earth connection is not used for safety (protective) earthing.
