Alwayslearningelec
Senior Member
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- NJ
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- Estimator
FA Circuit
- Thread starter Alwayslearningelec
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- New Jersey
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- Journeyman Electrician
Class X uses devices that provide isolation so that a fault will still allow the devices on the rest of the circuit to operate.
Look here for various definitions:
nationaltrainingcenter.com
Look here for various definitions:
NFPA 72 circuits and pathways | National Training Center
nationaltrainingcenter.com
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
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.
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.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Ron,
Are you seeing anyone actually using Class X pathways?
Are you seeing anyone actually using Class X pathways?
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Not too often except for facilities where facilities are considered critical or difficult to access.
gadfly56
Senior Member
- Location
- New Jersey
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- Professional Engineer, Fire & Life Safety
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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