Safety Ground/Protective Earth And Logic Return Wiring - Nortel 1000M Installation And Commissioning Manual

Page 78 of 456 Installing AC power

Safety ground/protective earth and logic return wiring

NN43021-310 Standard 02.01
Systems that use reserve power plug into the UPS, which in turn plugs into
the power source (associated batteries can be located within the UPS or
installed externally). Consult the UPS documentation for receptacle
requirements.
As a safety precaution, all AC service panels should be located in an area that
is easily accessible at all times to allow for emergency shutdown. An optimal
location would be near, or just outside the entry to the room containing the
Large System (or the UPS, if equipped). Each circuit breaker in the panels
should be clearly marked to identify the system component or components it
services.
A separate safety ground/protective earth connection is required. The safety
ground/protective earth wire must be #6 AWG or larger. It must connect the
pedestal to the single-point ground (SPG). Using an isolated ground (IG) bus
as the single-point ground is recommended. To fulfill this function, Nortel
offers the NT6D5304 Logic Return Equalizer (LRE), equipped with nine
terminations. A large ground bar (NT6D5303), equipped with 48
terminations, is also available.
An AC equipment ground (ACEG) bus in the service panel or transformer is
acceptable but not recommended. If used, the ACEG bus conductor must be
a low impedance path to an approved source for ground. It must not contain
induced electrical noise from sources such as building metallic structures
(building steel, metallic conduit, metal pipes, etc.). Figures 25, 26, and 27
beginning on page 79
Depending on the distances between columns, the location of the service
panel, and the availability of panel SPG connection points, safety ground/
protective earth wiring can be daisy-chained or run independently from each
column to the service panel. Figures 26 and Figure 27 show safety ground/
protective earth wiring in daisy-chain configurations.
Note: Refer to Communication Server 1000M and Meridian 1:
Large System Planning and Engineering (NN43021-220) for a complete
description of approved ground sources and methods. Insulated ground
wire must be used for system grounding.
December 2007
show an ACEG as the single-point ground.