Nortel Meridian 1 option 11C Planning And Installation Manual page 40

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Before installing an Option 11C and applying AC power, measure the
impedance of the building ground reference. (An ECOS 1023
POW-R-MATE or similar meter is suitable for this purpose.) If the ground
path connected to the Option 11C has an impedance of 5 Ohms or more, better
grounding arrangements should be made. Any improvements to the
grounding system should be made before the Option 11C is installed.
Other grounding requirements are as follows:
• The impedance of the link between the ground post of the system
cabinets and the Single Point Ground (SPG) to which it is connected
must be less than 0.25 Ohms.
• Never connect the single point ground conductor from the Option 11C
system to structural steel members or electrical conduit. In particular,
never tie this conductor to a ground source or grounded electrode that is
not hard-wired to the building reference conductor.
• Ground conductors for the Option 11C system:
— must not be smaller than #6 AWG (#40 metric) at any point
— must be routed through the same conduit as the phase conductors
serving the system
— must not be smaller than any phase conductor in the same conduit
— do not carry current under normal operating circumstances.
• All ground conductors in the building:
— must be isolated from the neutral bus except at the service entrance
to the building
— must be hardwired to the main ground reference.
• Avoid spliced conductors. Continuous conductors have lower impedance
and are more reliable than spliced ones.
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