Nortel Networks BCM50 - Manual (Page 78)

78 Chapter 6 Checking the installation prerequisites
NN40020-302
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) must 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. Nortel
recommends that you do not 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
The following sections describe the requirements for wiring digital telephony devices (digital
loop) and analog telephony devices (analog loop) to the BCM50 system:
• Digital loop on page 78
• Analog loop on page 78
Digital loop
You must meet the following parameters 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
Analog loop
You must meet the following parameters for an analog loop:
• maximum DC loop resistance of 208
Ω
• maximum cable length (0.5 mm or 24-AWG) of 1220 m (4000 ft.)
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. If these ground connections are
not connected, contact the appropriate electrical inspection authority. Do not try to make
the connections yourself.