Fire-Lite ECC-FFT Firefighters Telephone - Manual (Page 10)

10 ECC-FFT Instruction Manual — P/N LS10031-000FL-E:B 9/4/2013
Product Description Electrical Specifications
1.5.3 Wiring Specifications
Induced noise (transfer of electrical energy from one wire to another) can interfere with telephone
communication or cause false alarms. To avoid induced noise, follow these guidelines:
• Isolate input wiring from high current output and power wiring. Do not pull one multi-
conductor cable for the entire panel. Instead, separate the wiring as follows:
– SLC Loops
– Relay Circuit
– Audio Circuits
• Do not pull wires from different circuits (listed above) through the same conduit. If you must
run them together, do so for as short a distance as possible or use shielded cable. Twisted,
shielded wire on the Audio Circuits is recommended for maximum protection against EMI and
AFI emissions and susceptibility. Connect the shield to earth ground at the panel. You must
route high and low voltages separately.
• Route the wiring around the inside perimeter of the cabinet. It should not cross the circuit
board where it could induce noise into the sensitive microelectronics or pick up unwanted RF
noise from the high speed circuits. See Figure 2.4 for an example.
• High frequency noise, such as that produced by the inductive reactance of a speaker or bell,
can also be reduced by running the wire through ferrite shield beads or by wrapping it around a
ferrite toroid.