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AVOIDING AN FPL WIRE MIX-UP
Q: My local AHJ wants me to use power-limited fire alarm (FPL) wire for the telephone line attached to the Digital Alarm Communicator Transmitter (DACT). Is this a new rule?
A: No, it isn't a rule. There are several ways to go here. You decide which of these is best to use. You should not need all five.
- Telephone interface jacks (i.e. RJ31X) are required by the phone company to isolate your equipment from the rest of the phone system wiring, if needed. Phone jacks are made to only accept 22 to 26 gage wire by virtue of their UL listing.
- Use telephone cable with a CM designation (Cat 5) and show the inspector that this is equal to FPL cable and is in compliance with Table 760.61 of the NEC.
- The installation instructions for your listed fire alarm control panel (FACP) do not specify FPL wiring for the DACT connections.
- The section of the NEC covering power-limited fire alarm wiring, "Article 760, Fire Alarm Systems, Figure 760.61," doesn't permit FPL to be used as a substitution for CM (communications) cable.
- The section of the NEC covering telephone wiring installations, "Article 800, Communications Circuits, Table 800.154," doesn't list FPL as a permitted substitution for CM (telephone) cable.
THE FPL METHOD
Q: When is FPL cable required and where should I use conduit with single conductors?
A: The NEC doesn't outright require FPL wiring to be used. Actually, the NEC allows either of two methods to be used. It is your choice whether to use the non power-limited method described in Part A of Article 760.15 or the power-limited method described by Part B, shown below. Following are the installation methods allowed if you choose the power-limited (FPL) method.
NFPA 70 (NEC) Article 760, (B) PLFA Wiring Methods and Materials. Power-limited fire alarm conductors and cables described in 760.82 shall be installed as detailed in 760.52(B)(1), (B)(2), or (B)(3) of this section. Devices shall be installed in accordance with 110.3(B), 300.11(A), and 300.15.
- Exposed or Fished in Concealed Spaces. In raceway or exposed on the surface of ceiling and sidewalls or fished in concealed spaces. Cable splices or terminations shall be made in listed fittings, boxes, enclosures, fire alarm devices, or utilization equipment. Where installed exposed, cables shall be adequately supported and installed in such a way that maximum protection against physical damage is afforded by building construction such as baseboards, door frames, ledges, and so forth. Where located within 2.1 m (7 ft) of the floor, cables shall be securely fastened in an approved manner at intervals of not more than 450 mm (18 in.).
- Passing through a Floor or Wall. In metal raceways or rigid nonmetallic conduit where passing through a floor or wall to a height of 2.1 m (7 ft) above the floor, unless adequate protection can be afforded by building construction such as detailed in 760.52(B)(1) or unless an equivalent solid guard is provided.
- In Hoistways. In rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, or electrical metallic tubing where installed in hoistways. Exception: As provided for in 620.21 for elevators and similar equipment.
In a commercial application, you would use conduit and single-conductor wire for the 120 VAC primary power source.
GREG KESSINGER, SET, CFPS, president of an alarm installing company since 1981, teaches NICET training classes to fire alarm system designers and installers and continuing education seminars for Ohio's fire alarm inspectors. You can reach him at 888-910-2272; e-mail: Greg@firealarm.org; or visit his website at www.FireAlarm.org.
author: By Greg Kessinger