User's Manual

Appendix F Grounding Specifications
96 TDC-0971-011 CCU 100 and Repeater 100 Installation Guide
Proprietary and Confidential
Meggers come in three and four terminal configurations. To test the actual resistivity of
the soil itself, use a four terminal model. The advantage of this method is that you are not
connected to the electrical system during testing. An electrical line fault during testing can
send high current to the grounding system, resulting in high current and voltage at the test
leads and meter.
Warning Be safe when working on live electrical systems. Always use
proper protection equipment. If you are in contact with the grounding
system (particularly if the ground rod is disconnected) you are the ground
for the system.
Adjusting the Routing of the Grounding Conductor
If more than one ground can be referenced (such as in a campus environment), adjust the
routing of the grounding conductor. This is very important in the system’s ability to
reference the original equipment ground back at the service entrance utility service meter.
The normal routing procedure is to bring the HOT, the NEUTRAL, and the GROUND
wire into the remote electrical panel and terminate them to the appropriate busses. Then
route the GROUND wire down to the house grounding electrode (ground rod).
In this procedure, route the GROUND wire to the grounding electrode first, and then
route up to the ground bus within the panel. This simple adjustment still follows NEC
code, but provides an unobstructed pathway to divert surges to these ground rods while
continuing to reference the service entrance ground. The fundamental result of this
routing procedure is the elimination of potential equipment damage from the ground loop
created by multiple ground rods. This method of routing allows the electrical potential of
the entire facility to rise and fall in a uniform manner, reducing the possibility of
excessive current flow on the grounding system.
Finally, inspect and tighten all wiring terminations at the service entrance and at each of
the remote panels, disconnects, or equipment.
Note To lower resistance to grounding, keep all connections tight and free
of oxidation.
The following illustration shows a sample grounding layout.