Installing Safety Ground/Protective Earth And Logic Return Wiring - Nortel Meridian 1 Manual

Installing safety ground/protective earth and logic return
wiring
Appendix A: NT0R72, NT6D82, QBL12, QBL15, QCA13
The single point ground required by the system can be an isolated ground (IG)
bus or AC equipment ground (ACEG) bus in the service panel or transformer.
The system is to be connected to safety ground/protective earth in accordance
with national requirements. For international use, the system is to be
connected to safety ground/protective earth in accordance with Paragraph 2.5
of EN60950/IEC950.
Note: Refer to Meridian 1 installation planning (553-3001-120) for a
complete description of approved ground sources and methods. Insulated
ground wire must be used for system grounding.
Depending on the distances between columns and the service panel, safety
ground/protective earth wiring can be daisy-chained or run independently
from each column to the service panel.
Figures 148, 149, 150, and 151 show the ACEG as the single point ground
and safety ground/protective earth wiring in daisy-chain configurations.
Multiple-column systems often use a logic return equalizer (LRE) as the point
where the logic return wires from different columns are consolidated before
connecting to the single point ground. The NT6D5303 large LRE (usually
used with DC power systems) is available from Northern Telecom.
The LRE used with the QBL12 is a copper bus bar that is mounted on a wall
next to the QBL12. The positive bus in the QBL15 is used as the LRE. The
LRE used with the QCA13 is located on top of the QCA13 cabinet. The LRE
used with the NT6D82 is a copper bus bar mounted in the control/distribution
panel or the power plant.
Figures 148, 149, 150, and 151 show the logic return points and wiring
configurations.
Page 403 of 500
System installation procedures