Installation guide

QuickMedia
®
Computer Centers Crestron QM-FBCC/WCC-1
28  QuickMedia
®
: QM-FBCC/WCC-1 Operations & Installation Guide – DOC. 6716B
When calculating the length of wire for a particular Cresnet run, the
wire gauge and the Cresnet power usage of each network unit to be
connected must be taken into consideration. Use Crestron Certified Wire
only. If Cresnet units are to be daisy-chained on the run, the Cresnet
power usage of each network unit to be daisy-chained must be added
together to determine the Cresnet power usage of the entire chain. If the
unit is home-run from a Crestron system power supply network port, the
Cresnet power usage of that unit is the Cresnet power usage of the entire
run. The wire gauge and the Cresnet power usage of the run should be
used in the following equation to calculate the cable length value on the
equation’s left side.
Cable Length Equation
L = Length of run (or chain) in feet
R = 6 Ohms (Crestron Certified Wire: 18 AWG (0.75 mm ))
or 1.6 Ohms (Cresnet HP: 12 AWG (4 mm ))
P = Cresnet power usage of entire run (or chain)
2
2
L <
40,000
R x P
Where:
Make sure the cable length value is less than the value calculated on the
right side of the equation. For example, a Cresnet run using 18 AWG
Crestron Certified Wire and drawing 20 watts should not have a length
of run more than 333 feet (101 meters). If Cresnet HP is used for the
same run, its length could extend to 1250 feet (381 meters).
NOTE: All Crestron certified Cresnet wiring must consist of two
twisted pairs. One twisted pair is the +24V conductor and the GND
conductor and the other twisted pair is the Y conductor and the Z
conductor.
Strip and Tin
Wire
When daisy-chaining Cresnet units, strip the ends of the wires carefully
to avoid nicking the conductors. Twist together the ends of the wires that
share a pin on the network connector and tin the twisted connection.
Apply solder only to the ends of the twisted wires. Avoid tinning too far
up the wires or the end becomes brittle. Insert the tinned connection into
the Cresnet connector and tighten the retaining screw. Repeat the
procedure for the other three conductors.