Crestron
CNHBLOCK
Multi-Type Network Distribution Block
Operation & Installation Guide - DOC. 8157
Multi-Type Network Distribution Block: CNHBLOCK
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5
Network Wiring
When calculating the wire gauge for a particular Cresnet run, the length of the run and the
load factor of each network unit to be connected must be taken into consideration. If Cresnet
units are to be daisy-chained on the run, the load factor of each unit to be daisy-chained must
be added together to determine the load factor of the entire chain. If the unit is a home-run
from a Crestron system power supply network port, the load factor of that unit is the load
factor of the entire run. The length of the run in feet and the load factor of the run should be
used in the following resistance equation to calculate the value on the right side of the
equation.
Resistance Equation
R = Resistance (refer to next table).
L = Length of run (or chain) in feet.
LF = Load factor of entire run (or chain).
R <
L x LF
40,000
Where:
The required wire gauge should be chosen such that the resistance value is less than the value
calculated in the resistance equation. Refer to the table below.
Wire Gauge Values
RESISTANCE (R)
WIRE GAUGE
4
16
6
18
10
20
15
22
13
24 (Double-CAT 5)
NOTE:
All 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.
NOTE:
When daisy-chaining Cresnet units, always twist the ends of the incoming wire and
outgoing wire which share a pin on the network connector. After twisting the ends, tin the
twisted connection with solder. Apply solder only to the ends of the twisted wires. Avoid
tinning too far up the wires or the end becomes brittle. After tinning the twisted ends, insert
the tinned connection into the Cresnet connector and tighten the retaining screw. Repeat the
procedure for the other three conductors.
Connecting the CNHBLOCK to Cresnet Devices
CAUTION: Do not connect or daisy-chain more than one power input (power pack or
power supply) to the CNHBLOCK. Multiple power inputs may damage one or more
power packs and/or power supplies.
