beautypg.com

Fire-Lite ECC-FFT Firefighters Telephone User Manual

Page 18

background image

18

ECC-FFT Instruction Manual — P/N LS10031-000FL-E:B 9/4/2013

Installation

SLC Device Installation

Figure 2.8 and Figure 2.9 show how length is determined for out and return style wiring.

When using T-taps, the total length of all taps and the main bus must not exceed 40,000 feet. This
requirement must be met in addition to the maximum distance requirements for the various wire
gauges.

Figure 2.8 Calculating Wire Run Length

The dotted line path shows how the
wire distance is calculated for the
SLC device at the end of the run.
The wire distance must be less than
the maximum per wire gauge.

SLC device

SLC device

SLC device

SLC device max loop resistance = 40 ohms

SLC Circuit

Figure 2.9 Calculating Wire Run Length for a T-tap

In this example:

= 1000 feet

= 1600 feet

= 3500 feet

16 AWG wire can be used
because the greatest distance is
3500 feet

The device located farthest from
the SLC must be less than the
maximum distance per wire gauge.

SLC device

SLC device

SLC device

SLC device max loop resistance = 40 ohms

SLC Circuit