GR 1089–Core
GR 1089–Core
In the United States, the telecommunication network is primarily operated by the Regional
Bell Operating Companies (RBOC) who follow the standards set by GR 1089 or a derivative
thereof. GR 1089–Core (often referred to as GR 1089), “Electromagnetic Compatibility and
Electrical Safety Generic Criteria for Network Telecommunications Equipment,” covers the
requirements for telecommunications equipment connected to the outside world through
twisted pair. It also addresses the criteria for protection from lightning and AC power cross
disturbances.
Because twisted pair are metallic conductors exposed to lightning and AC power faults,
GR 1089 documents the requirements to be met by manufacturers of public switched
telephone network (PSTN) equipment to ensure safe and reliable operation.
The criteria for these standards are based on transient conditions at exposed sites, such as
remote facilities, central offices, and customers’ premises where operating companies
provide some type of primary voltage protection to limit transient voltages to 1000 V peak
for surge conditions and 600 V rms for power cross conditions.
All network equipment shall be listed by a Nationally Recognized Testing Laboratory
(NRTL) if the equipment is directly powered by Commercial AC. Network equipment located
on customer premises shall be listed by NRTL.
In conjunction with primary voltage protectors, operating companies also may incorporate
fuse links if there is the possibility of exposing the twisted pair to outside power lines. These
fuse links are equivalent to 24- or 26-gauge copper wire and are coordinated with the
current-carrying capacity of the voltage protector.
The last element of protection that may be provided by the operating company are current
limiters which, if provided, are found on the line side of the network equipment after the
primary voltage protection device. These current limiters typically come in the form of heat
coils and have a continuous rating of 350 mA.
Requirements
Equipment required to meet GR 1089 must be designed to pass:
•
•
•
Both First and Second Level Lightning Surge and AC Power Fault Tests
Current Limiter Test
Short Circuit Test
A minimum of three units are tested for each of the operating states in which the Equipment
Under Test (EUT) may be expected to function — idle, transmit, receive, on-hook, off-hook,
talking, dialing, ringing, and testing. Table 4.1 and Table 4.2 show test connections, and
Figure 4.1 shows the connection appearances.
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