GE Industrial Solutions GE ZENITH SERIES MDU - Manual (Page 13)

Installation Procedures
GE Z ENITH C ONTROLS
MDU Owner’s Manual
601 S HILOH R OAD January 2013
Plano, TX 75074 Page 13
3.4. High Frequency (RF) Grounding (computer rooms)
In addition to the power grounding system, a reference grounding system for high frequency noise is
desirable (with the two systems being bonded together for the same reference potential). A grid
made up of (2) two foot squares will provide an effective signal reference grounding system. The
raised floor can be utilized if it has firmly connected metal stringers providing good electrical
connections. If this type of floor is not available, a grid can be fabricated by laying a mesh (2 foot
square) of braided copper strap directly on the concrete sub floor (electrically connected at each
intersection point). The frames of all the data processing equipment, including the MDU, should be
connected (by the shortest possible distance) to the reference grid with braided copper. Finally, the
reference grid should be bonded to the MDU for a single point potential ground reference.
For optimum performance all distances for power and high frequency grounding should be kept to
an absolute minimum. To summarize, a radial grounding of this type (utilizing a single ground point)
will ensure that your facility is electrically safe, complies with all code requirements, and will be
essentially free of ground caused computer noise and problems.
3.5. Input Power Junction Box and Cable Assembly (Optional)
Warning: Verify that incoming high voltage circuits are not energized before making any
connections in the input junction box.
If the MDU is equipped with an input junction box, then the input junction box (power J box) and
power cable assembly must be installed in accordance with all applicable electrical codes. The
power J box should be installed only by a qualified electrical contractor.
The location of the power J box in relation to the MDU is a critical relationship. The power J box must
be located within (6) six feet of the MDU. It must be positioned so as to allow accessibility after the
MDU has been installed. Extreme care should be taken so as not to restrict the positioning of any
power cabling. If the MDU is positioned with its rear panel up against a wall, the power J box must
be installed at least 36 inches (3 feet) from the wall and in a position that will allow future
accessibility. Do not obstruct the floor tiles located directly above the power J box.
It is recommended that the power J box location allows the input power cables to enter the unit
through the floor tile cutouts.
If a junction box is not furnished, the input power feeder should be connected to the main input
landings internal to the MDU.