Site Telephony Wiring Requirements; Digital Loop - Nortel BCM50 Installation And Maintenance Manual

76 Chapter 6 Checking the installation prerequisites
Danger: Risk of electric shock
The safety of this product requires connection to an outlet with a third-wire ground. Use
only with the supplied BCM50 power supply and a three-wire power outlet.
Caution: Check ground connections
Ensure that the electrical ground connections of the power utility, telephone lines, and
internal metal water pipe system, if present, are connected together. If these ground
connections are not connected together, contact the appropriate electrical inspection
authority. Do not try to make the connections yourself.
You can connect the power supply to a power bar. The total length of the power cables from the
power supply to the electrical outlet (including power bar) should not exceed 2 m (6.5 ft.). You
must use a power bar approved by an appropriate National Test Body, with a third-wire ground. It
is recommended not to use an extension cord between the power supply and the power bar, or
between the power bar and the electrical outlet.

Site telephony wiring requirements

This section describes the requirements for wiring digital telephony devices (digital loop) and
analog telephony devices (analog loop) to the BCM50 system.
Refer to the following sections for information on the parameters for digital and analog loops:
•

"Digital loop"

• "Analog loop" on page 77
Digital loop
The following parameters must be met for a digital loop:
• one, two, or three twisted-pair cables per telephone
dc loop resistance of less than 64 Ω
•
• cable length (0.5 mm or 24 AWG) less than 300 m (975 ft.)
• use of a station auxiliary power supply (SAPS) for loops 300 m (975 ft.) to 1200 m (3900 ft.).
In North America, the SAPS must be a CSA- or UL-approved Class 2 power source.
In Europe, the SAPS must be a Class II power source and CE marked.
• no bridge taps
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