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In stal la tion of OITs
Con trol Panel Grounding
The control panel should be connected to a good, high-integrity earth ground both for safety considerations and
shielding purposes. Maple Systems cannot overemphasize the importance of good grounding. If you fail to use
good grounding procedures during installation, sporadic malfunction of the OIT may occur:
Connect the OIT's chassis ground terminal to a reliable earth ground with a low-resistance path.
Route all earth ground wires that lead from the OIT, the PLC, the power supply, and the line filter to a
central earth ground point such as a barrier strip. This will ensure that no ground current from one device
influences the operation of the other devices.
Connect the OIT chassis ground terminal to the control panel door using a heavy-gauge short braided cable
or ground wire to minimize resistance.
Connect the power cable's shield wire to the OIT's chassis ground terminal.
Connect the control panel to earth ground using a copper grounding rod close to the OIT and control panel.
Hinged doors on control panels do not provide a long-term electrical connection to the rest of the enclosure.
Corrosion develops over time and prevents good electrical contract. For this reason, a separate wire braid should be
installed from the hinged control panel to the rest of the enclosure.
For a more in-depth overview of ground wiring techniques, refer to technical note #1027, "OIT Ground Wiring and
Electrical Noise Reduction," which you can find on our web site.
Con nect OIT Chas sis Ground to Con trol Panel
To reduce the possibility of electrical interference, connect the chassis ground terminal of the OIT to a clean earth
ground. If the control panel is metal, make sure it is properly grounded. Then connect a short heavy-gauge wire
(#18 AWG) from the chassis ground terminal of the OIT to a mounting bolt on the control panel door. The
mounting bolt must have good electrical contact to the control panel; scrape away any paint that may be covering
the panel to provide a good connection.
If the control panel is made of a non-conductive material, it is essential that you connect the chassis ground terminal
of the OIT to a clean earth ground point located close to the panel.
Control panel
(connected to earth ground)
Typ i cal Chas sis Con nec tion
Frame ground (marked FG)
Stud or screw
Area on panel free of paint
9
1010-1007W, Rev 06
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