Smoke Alarm Interconnection

Do you know the rules when it comes to Interconnecting Smoke alarms?
NFPA 72 and UL specify that 18 Total "DEVICES" can be interconnected
of which ONLY 12 can be smoke Alarms. If the 1 or 2 Family Dwelling needs
additional Detection, YOU MUST INSTALL a FIRE SYSTEM (commercial listed FACP)
Trouble now is : IS the Electrical Contractor Licensed to Install, Maintain and Service the system?
IS he Licensed OTHER than his Electrical License......New York State DOS says he either Must be
Licensed as per Article 6D OR he must REGISTER his Electrical License(s) with DOS and have
in his possession a valid LOCAL Alarm License.

Support

Outlet boxes can be supported by the structural or supporting elements of a suspended ceiling, if securely fastened by one of the following methods [314.23(D)]:

1. Ceiling-framing members. An outlet box can be secured to suspended-ceiling framing members by bolts, screws, rivets, clips, or other means identified for the suspended-ceiling framing member(s). If framing members of suspended-ceiling systems are used to support luminaires, they must be securely fastened to each other and must be securely attached to the building structure at appropriate intervals. In addition, luminaires must be attached to the suspended-ceiling framing members with screws, bolts, rivets, or clips listed and identified for such use [410.36(B)].
2. Independent support wires. Outlet boxes can be secured, with fittings identified for the purpose, to the ceiling-support wires. If independent support wires are used for outlet box support, they must be taut and secured at both ends [300.11(A)] (see Figure). See 300.11(A) on the use of independent support wires to support raceways and cables.

Fire Alarms & Detection: Smoke Detector Sensitivity

In other than one- and two-family dwellings, system detectors or singleor
multiple-station smoke alarms should be subjected to a sensitivity test
within one year after they are installed. The test is intended to ensure
the sensing chamber remains calibrated within the sensitivity range
established by the manufacturer. If a detector is too sensitive, it will be
susceptible to nuisance alarms. If it is not sensitive enough, it may not
operate in the presence of smoke.
According to the National Fire Protection Association (NFPA) 72, National
Fire Alarm Code®, the sensitivity should be checked and calibrated every
alternate year after the first test. If, however, after the second required
calibration test, sensitivity tests show that the device has remained within
its listed and marked sensitivity range (or 4-percent obscuration light gray
smoke if not marked), the length of time between calibration tests may be
extended to 5 years.
For sensitivity tests, any of the following tests may be performed to ensure
that each detector is within its listed and marked sensitivity range:
1. Using a recognized, calibrated test method with smoke or listed
aerosol. This testing device provides a calibrated release
of artificial smoke. It tests detector performance and can be used to evaluate
the sensitivity.
2. Using the detector manufacturer’s calibrated sensitivity test
instrument.
3. Using listed control equipment (fire alarm control panels) that are
arranged to perform sensitivity tests.
4. Using a combination smoke detector/control unit where the detector causes a signal at the control unit when
its sensitivity is outside its listed sensitivity ranges.
5. Using any other calibrated sensitivity test methods approved by the code official.
Note that for the sensitivity tests, it is not required that smoke or aerosol be introduced into the detector.
However, when conducting a performance test—to ensure that the detector senses smoke and generates an
alarm—smoke or listed aerosol must enter the detection chamber. Performance tests and sensitivity tests are
intended to achieve different results: the first is to ensure the device works, the second is to verify it remains
within its listed range.

For additional information, refer to NFPA 72,2010, Chapter 14.4.2.2.14(g)

Minimum Wire AWG?

Mike,
 Maybe you can answer a questions. I remember somewhere in NEC that the minimum wire gauge for initiating devices is 16AWG and notification 14AWG.  Am I right. Can’t find it.

NEC 2008:
760.130
Wiring Methods and Materials on load side of Power Limited Fire Alarm Power Source:

shall be permitted to be installed using methods and materials in accordance with 760.130(A), 760.130(B) or Both
(A) in accordance with 760.46 -solid or stranded Copper

760.130 (A) exception 2 allows them to be installed as per 760.49 and 760.53

760.49(A) only Cu conductors 18AWG and 16 AWG are permitted: PROVIDING they do not exceed the load ampacities of 402.5

402.5 allowable ampacities are: 6A for 18AWG, 8A for 16AWG, 17A for 14AWG and 23 A for 12
 AWG

and are in a raceway, approved enclosure or listed cable/assembly.

760.53 adresses multiconductor NON-power limited cables (ie those that can carry 120V A/C-like NYC Fire Circuits)

760.130(B): as described in 760.179 (ie FPL, FPLR, and FPLP)
760.179(A) solid or stranded Cu
760.179 (B) size in a multiconductor cable /assembly: no smaller than 26AWG; single conductor: no smaller than 18AWG
No where is there a minimum AWG for initiating /notification devices mentioned in NEC 

Maybe in NYS Fire Code?

Checked that----nope!

Grounding of Alarm Panels

National Electrical Code Requires our Alarm Equipment to be Grounded.
How do we know what size conductor to use?

NFPA 70 2002 states in Article 250.122: Size of equipment grounding Conductor:

(A) General Cu, Al, or Cu-clad Al equipment grounding conductors of the wire type shall not be smaller (2008 NFPA 70 adds: but in no case shall they be larger than) than the circuit conductors supplying the equipment

TABLE 250.122 Minimum Size Equipment Grounding Conductors for grounding equipment Rating or setting of Automatic Overcurrent Device in the Circuit AHEAD of Equipment:
Not Exceeding: (AMPERES) 15 :   14AWG Cu  or 12AWG Cu-clad or Al
Not Exceeding: (AMPERES) 20:    12AWG Cu  or 10AWG Cu-clad or Al

So for our Security, CCTV and Access Systems Supplied by Class II Transformers, we first size it by the Equipment Grounding Conductor in the Supply Branch Circuit: 14AWG(Cu) for General Lighting Circuits and 12AWG(Cu) for Dedicated Branch Circuits.
For Fire Alarm Systems supplied by a Dedicated Branch Circuit, that Circuit must be 20A so our minimum size grounding conductor is 12AWG(Cu)

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