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APPENDIX C — BACNET COMMUNICATION OPTION (cont)
To install a BT485 terminator, push the BT485 terminator
on to the BT485 connector located near the BACnet connector.
NOTE: The BT485 terminator has no polarity associated with
it.
To order a BT485 terminator, contact your Carrier represen-
tative.
MS/TP WIRING RECOMMENDATIONS — Recommen-
dations are shown in Tables C and D. The wire jacket and UL
temperature rating specifications list two acceptable
alternatives. The Halar* specification has a higher temperature
rating and a tougher outer jacket than the SmokeGard† specifi-
cation, and it is appropriate for use in applications where the
user is concerned about abrasion. The Halar jacket is also less
likely to crack in extremely low temperatures.
NOTE: Use the specified type of wire and cable for maximum
signal integrity.
Table C — MS/TP Wiring Recommendations
LEGEND
Fig. E — BT485 Terminator Installation
SPECIFICATION
RECOMMMENDATION
Cable
Single twisted pair, low capacitance, CL2P, 22 AWG (7x30), TC foam FEP, plenum rated cable
Conductor
22 or 24 AWG stranded copper (tin plated)
Insulation
Foamed FEP 0.015 in. (0.381 mm) wall 0.060 in. (1.524 mm) O.D.
Color Code
Black/White
Twist Lay
2 in. (50.8 mm) lay on pair 6 twists/foot (20 twists/meter) nominal
Shielding
Aluminum/Mylar shield with 24 AWG TC drain wire
Jacket
SmokeGard Jacket (SmokeGard PVC) 0.021 in. (0.5334 mm) wall 0.175 in. (4.445 mm) O.D.
Halar Jacket (E-CTFE) 0.010 in. (0.254 mm) wall 0.144 in. (3.6576 mm) O.D.
Dc Resistance
15.2 Ohms/1000 feet (50 Ohms/km) nominal
Capacitance
12.5 pF/ft (41 pF/meter) nominal conductor to conductor
Characteristic Impedance
100 Ohms nominal
Weight
12 lb/1000 feet (17.9 kg/km)
UL Temperature Rating
SmokeGard 167 F (75 C)
Halar -40 to 302 F (-40 to 150 C)
Voltage
300 vac, power limited
Listing
UL: NEC CL2P, or better
AWG
—
American Wire Gage
NEC
—
National Electrical Code
CL2P
—
Class 2 Plenum Cable
O.D.
—
Outside Diameter
DC
—
Direct Current
TC
—
Tinned Copper
FEP
—
Fluorinated Ethylene Polymer
UL
—
Underwriters Laboratories
*Registered trademark of Solvay Plastics
†Trademark of AlphaGary-Mexichem Corp.