N93-586-84 Issue 04 AB Page 6 of 32 © Protec Fire Detection plc 2015
3.0 3500 General Cabling Requirements
3.1 Zone, Alarm and Auxiliary Circuit Wiring
All wiring associated with the system must conform to the current I.E.E Regulations, and cabling
must conform to the relevant BS specifications. ECA recommended cable separation for
electromagnetic compatibility in buildings must be followed.
To comply with EMC regulations Protec recommends the use of screened cabling throughout the
installation. Where screened cables are used it is important to ensure that screen continuity is
maintained between cable segments. Any screen wiring in the 3500 panel enclosure must be
sleeved and securely bonded to the earth terminals provided.
For further information on cables, wiring and other interconnections please consult clause 26 of
BS5839 part 1.
3.2 Alarm Circuit Wiring
Two alarm circuits are provided on the 3500. Each alarm output can provide 400mA of current and
must be terminated with the correct value end of line resistor, even if the alarm output is not used.
The gauge of the alarm circuit wiring must be chosen such that the volt drop along the wiring does
not exceed specified limits. The maximum wiring resistance may be calculated using the following
formula.
R
wiring_max
= (20.5 – V
device min
) / (I
device max
)
Where R
wiring_max
is the maximum resistance of the alarm circuit wiring ( both conductors )
V
device min
is the minimum Voltage the alarm circuit devices are specified to work down to
I
device max
is the maximum total current that will be drawn on the alarm circuit
For example, if alarm devices are specified to work to a minimum of 16V and the maximum alarm
circuit current is 80mA, the maximum alarm cable resistance is 56.25Ω ( 28.13Ω per conductor ).
All devices connected to the alarm circuits must be polarised and suppressed.
Alarm devices must not be connected on spurs from the main alarm circuit wiring as
a spur will not be monitored for open circuit faults.
3.3 Mains Input Rating Label
The mains rating label is located on the inner door of the 3500 and should be consulted before
starting installation. The label details the working voltage, frequency and maximum current of the
3500.
3.4 Mains Wiring
The 3500 requires a mains supply exclusive to the panel that uses fixed three-core wiring (between
0.75mm
2
and 2.5mm
2
) which is fed from a double pole isolating fused spur, fused at 3A.
Unauthorised operation of the mains supply must not be allowed and the fused spur should be
labelled “ FIRE ALARM PANEL: DO NOT SWITCH OFF ”.
Mains wiring must be segregated from all other system wiring. The wiring clamp
must be used to secure the incoming cables.
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