How do I wire smoke detectors to a conventional fire alarm panel like the Fire-Lite MS-5UD

Updated Source: 52626 Rev C7Source: 52626 Rev C7
Quick answer

On a Fire-Lite MS-5UD (five zones) or MS-10UD (ten zones), each Initiating Device Circuit is Class B: loop the wire from the panel through every detector and put the 4.7 KΩ, ½ watt end-of-line resistor (P/N 71252) after the last device. 2-wire 24 VDC smoke detectors run on the zone pair alone. 4-wire smoke detectors also need the panel's resettable 24 VDC 4-wire smoke power (500 mA) and a UL listed power supervision relay at the end of the run.

Steps

From: MS-5UD & MS-10UD Series manual, pp. 24-25, 27, 55

  1. Confirm the devices are compatible
    Each IDC accepts i3 smoke detectors, normally-open contact devices and conventional 2-wire or 4-wire 24 VDC smoke detectors listed in the Fire-Lite Device Compatibility Document.
  2. Run the zone as Class B
    Take the pair from the zone terminals to each detector in turn, in and out of every base. Each circuit is Style B (Class B) and is supervised for opens, shorts and ground faults.
  3. Install the end-of-line resistor
    At the last device: 4.7 KΩ, ½ watt, P/N 71252. Put a 4.7 KΩ, ½ watt dummy load (P/N 71245) on every unused circuit.
  4. For 4-wire detectors, add power
    Take resettable 24 VDC 4-wire smoke detector power (500 mA maximum, terminals 3 and 4) to every detector, and end the power run on a UL listed power supervision relay so a broken power wire shows as a trouble.
  5. Check loop resistance
    The maximum loop resistance for each IDC is 100 ohms, or 700 ohms per zone for linear heat detection.
  6. Program the zone type
    In Edit Input Zone Screen #2 press 2 for Type and pick 2-Wire Detector, Fire, Pull Station, Waterflow or another type. A 2-wire detector zone causes a fire alarm.
  7. Test each zone
    By opening the circuit for a trouble, then alarming one detector and resetting.

Specs & limits

From: MS-5UD & MS-10UD Series manual, pp. 24-25, 27, 31

ZonesMS-5UD five IDCs, MS-10UD ten IDCs
IDC styleStyle B (Class B); Style D (Class A) with the CAC-5X
End-of-line resistor4.7 KΩ, ½ watt, P/N 71252
Loop resistance100 ohms max per IDC
4-wire smoke power24 VDC resettable, 500 mA
Aux power jumperJP31 pins 1 & 2 nonresettable, pins 2 & 3 resettable

Common mistakes

From: MS-5UD & MS-10UD Series manual, pp. 24, 27, 31

  • Putting 2-wire smoke detectors on a zone used for linear heat detection. The manual says not to.
  • Feeding 4-wire detectors from nonresettable power. They latch in alarm and won't reset; use the resettable 4-wire smoke terminals.
  • With a CAC-5X installed, a zone you want to keep Class B is wired only to the B+ and B- terminals with the end-of-line resistor after the last device. Don't also wire the A+ and A- terminals on the CAC-5X.

Applies to

MS-5UD · Manual 52626 rev C7MS-10UD

Also asked as: “how to wire smoke detectors to conventional facp”

Sources

  1. MS-5UD & MS-10UD Series Manual, p. 24 (52626 Rev C7)
  2. MS-5UD & MS-10UD Series Manual, p. 25 (52626 Rev C7)
  3. MS-5UD & MS-10UD Series Manual, p. 27 (52626 Rev C7)
  4. MS-5UD & MS-10UD Series Manual, p. 55 (52626 Rev C7)
  5. MS-5UD & MS-10UD Series Manual, p. 31 (52626 Rev C7)
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