9400000-J0 Rev E
20
7.1 Grounding
This power system is suitable for installation as part of a Common Bonding Network (CBN) and is intended to be
used in a DC-C configuration (common DC return).
Connect the isolated power system battery return bus (BRB) to the building master ground bus (MGB), or floor
ground bus (FGB) in a larger building. This acts as a system reference and as a low impedance path to the ground
for surges, transients, noise, etc. The MGB or FGB must have a direct low impedance path to the building grounding
system.
The cable from the power system to the MGB or FGB must be sized to provide sufficient ampacity to clear the larg-
est fuse or breaker on the power system, excluding the battery protection fuse or circuit breaker. 750 MCM is rec-
ommended. This is the minimum requirement. Other factors including the length of the cable and special grounding
requirements of the load must also be factored in. The insulated cable must be equipped with two-hole crimp type
lugs and must not have any tight bends or kinks.
Table B — Typical ground reference conductor selection
Power system ampacity
Ground reference conductor size
< 30A
#10
30 – 100A
#6-2
100 – 400A
0000
400 – 800A
350 MCM
> 800A
750 MCM
The power system frame must also be connected to the MGB or FGB. This is done for personnel safety and to meet
many telecom grounding requirements. Each bay must have its own frame or site ground connection. Refer also to
the customer connections drawing at the rear of the manual.
7.2 AC Feeder Protection/Sizing
To maximize system reliability, each power module should be fed from a dedicated protection feeder breaker located
at the AC distribution panel. The feeder breaker can also act as the disconnect device for the connected module.
Refer to the specifications for recommendations.
WARNING!
Ensure that the power at the AC service panel is switched off. Remove battery line fuses
or connections before attempting work on the wiring. Use a voltmeter to verify the ab-
sence of a voltage. Clearly mark the correct polarity of the battery leads before starting
work on DC connections.
7. Wiring
This chapter provides cabling details and notes on cable sizing for DC applications using the Cordex 48-3.6kW,
4.0kW and 12kW modular switched mode rectifier systems.
Refer to the Safety section on page 5 for safety precautions.
