Synapse Server Setup needs to be properly earthed, since the devices in use (Synapse Server, PRI termination device, other PBX, Analog Gateway) all are electrically powered devices and are made up of Metal parts. IN addition, Synapse Server (PRI card) and the PRI termination are extremely sensitive devices, which can get affected due to improper earthing.

This document explains the reason for having proper earthing, and how to measure the earthing leakage.

The main reason for doing earthing in electrical network is for the safety. When all metallic parts in electrical equipments are grounded then if the insulation inside the equipments fails there are no dangerous voltages present in the equipment case.

If the live wire touches the grounded case then the circuit is effectively shorted and fuse will immediately blow. When the fuse is blown then the dangerous voltages are away.

Purpose of Earthing

  1. Safety for Human life/ Building/Equipment    

    1. To save human life from danger of electrical shock or death by blowing a fuse i.e. To provide an alternative path for the fault current to flow so that it will not endanger the user

    2. To protect buildings, machinery & appliances under fault conditions.

    3. To ensure that all exposed conductive parts do not reach a dangerous potential.

    4. To provide safe path to dissipate lightning and short circuit currents.

    5. To provide stable platform for operation of sensitive  electronic equipments  i.e. To maintain the voltage at any part of an electrical system at a known value so as to prevent over current or excessive voltage on the appliances or equipment .

  2. Over voltage protection

    1. Lightning, line surges or unintentional contact with higher voltage lines can cause dangerously high voltages to the electrical distribution system. Earthing provides an alternative path around the electrical system to minimize damages in the System.

  3. Voltage stabilization

    1. There are many sources of electricity. Every transformer can be considered a separate source. If there were not a common reference point for all these voltage sources it would be extremely difficult to calculate their relationships to each other.

    2. The earth is the most omnipresent conductive surface, and so it was adopted in the very beginnings of electrical distribution systems as a nearly universal standard for all electric systems.


Effect of Improper Earthing

  • Data is transferred as electric waves, which due to earthing this gets distorted.

  • Improper grounding causes NOISE in lan.

  • More speed means more data in shorter cycles, Which is more prone to effect. (so 1 gbps can have more problem than 100 mbps)

  • With Low voltage devices, this problem increases.

  • The problem is worsened when the protocol is udp and not tcpip

  • Many cisco equipments have grounding LUG (special connector provided by Cisco)

How to measure if earthing is proper (within limits or not)

  • Generally in there are three pin plugs. - Phase, Neutral & Earth

    • Phase - bottom right -

    • Neutral - bottom left.

    • Earthing - Top

Checking Earthing - method 1 (old way)

  • Get a 100 watts bulb.

  • Now put one wire into phase and other in neutral, and check whether it glows or not. (not the intensity of light)

  • Now put one wire into phase and other in Earthing, and check whether it glows or not. (not the intensity of light)

  • Compare both intensity, if its same - it means earthing is proper.

Checking Earthing - method 2 (new way)

  • Use multimeter - set it of 750V AC

  • Check Phase + Neutral - (generally it should show 220 V in India)

  • Now check Phase + Earthing (note the readings - it should be +/- 5V as compared to reading no. 1) e.g.: 227

  • Now check Earthing + Neutral (best is 2 or below, but it should be near 5V) - e.g.: 8

  • Total leakage is : (B-A) + C = (227-220) + 8 = 15

  • 15 V leakage is a high leakage. Maximum permitted Leakage is 5 V.

Check if your electrical wiring system is perfectly earthed, to avoid damage to systems.