• If the length of a branch circuit exceeds 100 feet, increase all conductors
(including ground) one wire size for each additional 100 feet of length.
• The neutral conductor from the main or source panel to the dedicated MICROS
panel is two sizes larger than the phase conductors. The larger wire size is
necessary to accommodate the third harmonic current caused by the switching
power supplies in the MICROS equipment. It also minimizes the possibility of
common mode noise occurring on the power distribution circuits.
• Install all power distribution circuits in a dedicated ferrous metal conduit that
contains only the MICROS supply and ground conductors.
• Install all data communication cables in separate ferrous metallic conduits. The
Cable Requirements section provides information about installing the data
communications cables.
• Ensure all AC Power Receptacles are the isolating ground type. Install according
to the specifications in the AC Power Receptacles Grounding section.
• For Servers, an Oracle MICROS-approved Uninterruptable Power Supply (UPS) is
required.
Despite the proper installation of the Preferred AC Power System, it is possible to
have power problems resulting from the power company or from other equipment in
the building. If this occurs, use the Oracle MICROS-approved Power Conditioners to
correct.
AC Power System Grounding
This section contains AC system grounding options for the Oracle MICROS hardware.
• MICROS Power Panel Grounding
• MICROS Branch Circuit Grounding
• AC Power Receptacles Grounding
MICROS Power Panel Grounding
1. Install the insulated equipment grounding conductor (sized the same as the supply
conductors) in the same conduit as the supply conductors from the main or source
panel to the dedicated MICROS panel.
2. Terminate this equipment grounding conductor on the ground bus in the main
panel.
3. At the MICROS-equipment panel, install a ground bus that is electrically isolated
from the panel frame, and then terminate the feeder equipment grounding
conductor on this bus bar.
4. Use the metallic feeder conduit as the equipment grounding system for grounding
the AC power panel frame, metallic conduit system, and metallic junction boxes.
MICROS Branch Circuit Grounding
For each branch circuit from the dedicated power panel to the device receptacles,
include a full size (same as supply conductors) insulated equipment grounding
conductor installed in the same conduit as the supply conductors. Ensure the conduit
is dedicated to MICROS equipment. Terminate this isolated grounding conductor on
Chapter 22
AC Power System Grounding
22-3
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