2-3
MEGA3 NFPA Medical Gas Notification System
4107 9016 59.03
2.3 Wiring
2.3.1 General Requirements
1. All alarms are to be powered from life
safety branch of emergency power system
as required by applicable standards.
2. Protect all wiring from physical damage
by raceways or conduit as required by ap-
plicable standards.
3. Wire alarm panels directly to switches or
sensors as required by applicable stan-
dards.
4. Wiring runs should be made with color
coded wire. Record color, signal, and
source of signal for each wiring lead to
aid in connection of alarm finish compo-
nents.
5. Avoid installing alarm panels near radio
transmitters, electrical motors, or switch
gear.
Figure 19: Zone Valve Box Location
2.3.2 Wire Type and Size
All low voltage wiring must meet the follow-
ing criteria:
• Copper wire no smaller than 22 AWG,
conductor insulation at least 0.010in
(0.25mm), jacket insulation at least
0.030in (0.76mm), rated for 300V and
60°C (140°F) minimum.
• Circuit length not to exceed 5000 feet.
• Cable must be twisted-pair shielded type.
Multi-pair cables within one common
shield are acceptable.
2.3.3 Determining Number of
Conductors
The following rules along with references
to this manual’s schematics clarify wiring
requirements.
• Digital Gas Sensor Modules
Two conductor cables (must be twisted pair
type with shield) are required for each Gas
Sensor module to the Gas Input board.
Refer to NFPA Area Wiring Diagram (Section
3.2).
• Switched signal inputs
Two conductor cables (must be twisted pair
type with shield) are required for each signal
between the signal input terminals and the
source signal switch.
These signals can originate at source equip-
ment or from pressure switches mounted on
main pressure / vacuum pipelines.
When two master alarms are required, the
same switch / relay contacts can be wired to
both alarm panels. (See CAUTION below).
Both pairs of wires should originate from
switch/relay contacts.
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