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2.2 Installation of the Hybrid IP-PBX
40 Installation Manual
2.2.5 Frame Ground Connection
IMPORTANT
Connect the frame of the Hybrid IP-PBX to ground.
• Be sure to comply with applicable local regulations (e.g., laws, guidelines).
• Proper grounding (connection to ground) is very important to protect the Hybrid IP-PBX from the bad
effects of external noise or to reduce the risk to the user of electrocution in the case of a lightning strike.
• The ground wire of the AC cable has an effect against external noise and lightning strikes, but it may
not be enough to protect the Hybrid IP-PBX. A permanent connection between ground and the ground
terminal of the Hybrid IP-PBX must be made.
In most of the continental United States, the ground provided by the "Third wire ground" at the commercial
power outlet will be satisfactory. However, in a small percentage of cases this ground may be installed
incorrectly. Therefore, the following test procedure should be performed.
Test Procedure
1. Obtain a suitable voltmeter and set it for a possible reading of up to 250 V AC.
2. Connect the meter probes between the 2 main AC voltage points on the wall outlet. The reading
obtained should be 108 V AC to 132 V AC.
3. Move one of the meter probes to the 3rd prong terminal (GND).
Either the same reading or a reading of 0 volt should be obtained.
4. If a reading of 0 volt at one terminal and a reading of 108 V AC to 132 V AC at the other terminal
is not obtained, the outlet is not properly grounded.
This condition should be corrected by a qualified electrician (per article 250 of the National
Electrical Code).
5. If a reading of 0 volt at one terminal and a reading of 108 V AC to 132 V AC at the other terminal
is obtained, then set the meter to the "OHMS/RX1" scale, place one probe at the GND Terminal
and the other probe at the terminal which gave a reading of 0 volt.
A reading of less than 1 ohm should be obtained. If the reading is not obtained, the outlet is not
adequately grounded. See qualified electrician.
1. Loosen the screw.
2. Insert a grounding wire (user-supplied)*.
3. Tighten the screw.
4. Connect the grounding wire to ground.
* For grounding wire, green-and-yellow insulation is required, and the cross-sectional area of the
conductor must be more than 0.75 mm
2
or 18 AWG.
Screw
Grounding
wire
To ground