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APPENDIX D — OPTIONAL BACNET COMMUNICATIONS WIRING (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, consult Commercial Products
i-Vu Open Control System Master Prices.
MS/TP WIRING RECOMMENDATIONS — Recommen-
dations are shown in Tables C and D. The wire jacket and UL
temperature rating specifications list two acceptable alterna-
tives. The Halar specification has a higher temperature rating
and a tougher outer jacket than the SmokeGard specification,
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
CL2P — Class 2 Plenum Cable
DC — Direct Current
FEP — Fluorinated Ethylene Polymer
NEC — National Electrical Code
O.D. — Outside Diameter
TC — Tinned Copper
UL — Underwriters Laboratories