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Off-Premises Circuit Protection
October 2002
Off-Premises Circuit Protection
Protection from hazardous voltages and currents is required for all off-premises (out of
building) trunks, lines, and terminal installations. Both over-voltage protection (lightning,
power induction, and so forth), and sneak current protection are required. Sneak current
protectors must be either UL listed/CSA certified, or must comply with local safety standards.
Sneak current protectors must have a maximum rating of 350 mA, and a minimum voltage
rating of 600 V, or as required by local regulations. The following devices protect the S8700
Multi-Connect configuration from over-voltages:
• Analog trunks use the 507B sneak protector or equivalent. Over-voltage protection is
normally provided by the local telephone company.
• Analog voice terminals use one of the following types of combined over-voltage and
sneak current protection, or equivalent:
• Carbon block with heat coil for UL code 4B1C
• Gas tube with heat coil for UL code 4B1E-W
• Solid state with heat coil for UL code 4C1S
• DCP and ISDN-BRI terminals use the solid state 4C3S-75 with heat coil protector, or
equivalent
• DS1/E1/T1 circuits require isolation from exposed facilities. This isolation may be
provided by a CSU (T1), LIU (E1), or other equipment that provides equivalent
protection
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