FA Circuit

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
THey are asking for class X for SLC( which are the data circuits). What exatly is calss X wiring? See attached. Thanks.
 

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ron

Senior Member
NFPA 72 Section 12.3 Pathway Class Designations.
12.3.7 Class X. A pathway shall be designated as Class X when it performs as follows:
(1) It includes a redundant path.
(2) Operational capability continues past a single open, and the single open fault results in the annunciation of a trouble signal.
(3) Operational capability on metallic conductors continues past a single short-circuit, and the single short-circuit fault results in the annunciation of a trouble signal.
(4) Operational capability on metallic conductors continues past a combination open fault and ground fault.
(5) Conditions that affect the intended operation of the path are annunciated as a trouble signal.
(6) Operational capability on metallic conductors is maintained during the application of a single ground fault.
(7) A single ground condition on metallic conductors results in the annunciation of a trouble signal.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Ron,
Are you seeing anyone actually using Class X pathways?
Actually, Siemens is moving to this as the default system architecture. For the high-end product line, they use their XDLC module which is an upgrade from their DLC module that enables X Class. The great thing about it is that it can operate as either Class B or Class X. Along with that, their smoke and heat detectors and input/output modules all come Class X ready, and the only difference between the classes is how you wire the devices on the SLC.
 
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