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Issue 1 September 1995 A-1
A
Approved Grounds
This chapter describes the approved grounds appropriate for the single-carrier
cabinets.
Definition of Approved Ground
An approved ground is the closest acceptable medium for grounding the
building entrance protector, entrance cable shield, or single-point ground of
electronic Private Branch Exchange (PBX) equipment.
If more than one type of approved ground is available on the premises, the
grounds must be bonded together as required in Section 250-81 of the National
Electrical Code (NEC), or the applicable code in your country.
Acceptable Mediums for Protective
Ground
The following protective ground types are acceptable:
Grounded Building Steel. — The metal frame of the building where it is
effectively grounded by one of the following grounds: acceptable metallic water
pipe, concrete encased ground, or a ground ring.
Acceptable Water Pipe. — A metal underground water pipe, at least 1/2 inch
(1.3 cm) in diameter, in direct contact with the earth for at least 10 feet (3 meters).
The pipe must be electrically continuous (or made electrically continuous by
bonding around insulated joints, plastic pipe, or plastic water meters), to the
point where the protector ground wire is connected. A metallic underground
water pipe must be supplemented by the metal frame of the building, a concrete