Avaya 6211 Guia Do Utilizador

primary protector operates at a lower threshold. A secondary protector protects against currents and, in

some cases, residual voltages that get past the primary protector.

When analog circuit packs, analog voice terminals, and the distribution cables and cross-connect fields

serving them are exposed to lightning,  power crosses, and/or ground-potential rise, they require only
overvoltage protection because they already have built-in, sneak-current protection in the circuit packs
and terminals. These sneak-current devices protect against moderate levels of sustained current caused
by voltages too low to activate the high voltage protection device.

Sneak-current protection is not built into hybrid and digital voice terminals and ports, therefore when
these devices are exposed to lightning, ground-potential rise, power crosses, or power induction, they
require both overvoltage and sneak-current protection.

The telephone company installs primary overvoltage protection in its BEFs for its cables from the
central office (CO) when it has determined that those cables are exposed; it does not install sneak-
current protection. Determine whether or not their primary protection adequately safeguards AT&T’s

cables and equipment and if it does not, add the proper protectors. For customer BEFs, assess the
possible electrical hazards and the protective requirements since the telephone company, in most
instances, does not provide this information.   See the Premises Distribution System Design Guide  (555-
600-402) guidelines for determining if an installation is susceptible to one or more of the principal
electrical hazards.

Discussions of primary, enhanced primary, and secondary protectors follow, and figure 3-1, Placement of
Electrical Protectors on CO Side of Switch, shows where the protectors are placed in a wiring path
between the CO and the switch.

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