MCM-Inst-1.10
Page 15 of 27
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Use copper conductors only. The screw terminals are only rated for copper wire.
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Do not place more than one wire in a screw terminal; use wire nuts or terminal blocks if needed.
●
Verify that the highest line-to-neutral or line-to-line voltage is nominally between 100 and 600 Vac.
The absolute maximum operating voltage is 690 Vac.
●
Torque all screws as specified on the information label on the inside of the enclosure door.
Connect neutral (if present) to the white DIN rail screw terminal (TB1) labeled
N
.
Connect line voltage conductor to
L1
,
L2
, and
L3
labeled terminals on the circuit breaker, fuse block,
or DIN rail screw terminals.
Connect each line voltage wire, as shown in
above.
3.5.3 Grounding
The MCM includes a grounding block (GB1) in the upper-right corner of the backplate. Connect earth
ground to any available position. See
above.
If you are using a fiberglass enclosure, use grounded conduit bushings and wire the bushings to the
grounding block.
3.6 Current Transformer Connections
The meter must be used with UL Listed or UL Recognized current sensors or transformers. UL has
only approved listed CTs for retrofit applications in panelboards; do not use recognized CTs for this
application.
The standard MCM supports CTs with a 0.33333 Vac output (one-third volt). With the correct options,
the MCM can support CTs with a 40 milliamp output: contact CCS for details.
3.6.1 Current Transformer Installation
See the web article
Selecting Current Transformers
for information on selecting appropriate current
transformers (CTs).
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WARNING:
To reduce the risk of electric shock, always open or disconnect the circuit from the
power-distribution system or the building service before installing or servicing CTs.
●
WARNING:
When using UL Recognized CTs, they must be installed on insulated conductors only
and maintained away from all live parts.
●
Do not
use 1 amp or 5 amp current output CTs!
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Treat CTs as class 1 circuits. They are not suitable for Class 2 wiring methods.
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Use plastic cable ties to secure the current transformers and route the lead wires so that they do
not directly contact uninsulated live terminals or conductors.
●
Split-core CTs can be opened for installation around a conductor. A nylon cable tie may be
secured around the perimeter of the CT to prevent inadvertent opening.
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Do not install current transformers where they would: 1) exceed 75 percent of the wiring space of
any cross-sectional area within the equipment, 2) would block ventilation openings, or 3) would be
in an area of breaker arc venting.
●
See the CT datasheets for the maximum input current ratings.
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To minimize current measurement noise, avoid extending the CT wires beyond 100 feet (30
meters), especially in noisy environments. You may extend the wires with twisted-pair wire 18 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. CTs are directional, so if they are mounted backward or with their white and
black wires swapped, the measured power will be negative. The power status LEDs indicate nega-
tive measured power by flashing red.
Note: negative power and red LEDs may also occur if the
