ISOLATOR INSTALLATION, INSPECTION, AND SERVICE!

ISOLATOR INSTALLATION, INSPECTION AND SERVICE

Isolator module is used on the intelligent fire alarm control panels to protect the system against wire-to-wire short circuits on the analogue addressable loop wiring. Fire Projects designer know how and where to use this isolators to get optimum performance. Some of OEM told short-circuit isolator module which is designed to electrically separate and protect vulnerable parts of the bus.

SOME DO’s AND DON’T’s

In the last twenty (or so) years, I’ve been privileged to have been able to watch the tremendous advances in technology that continues to inspire several manufacturers around the world to explore new developments in electronic life safety systems.   Unfortunately, each new advance exposes some vulnerability that must also be addressed. 

In this article, we’re going to discuss “isolators” and more specifically, the correct wiring methods for the various types of circuits you’re going to encounter, as well as the testing that must be performed, both at the system’s commissioning/Verification and on an annual basis.  We’re going to focus on the changes currently adopted by the Canadian Standard for Installation of Fire Alarm Systems (CAN/ULC-S524) as well as what’s “in the pipe” in the way of amendments.

ISOLATOR TYPES AND TERMINOLOGY

What is an isolator, and how does it work?  Let’s begin by actually answering these two questions.  An isolator is a device that is designed to limit the extent a circuit is compromised by a single “short” fault.  In North America, there are four distinct “families” of short circuit isolators.  They are:

• Data Communication Loop (DCL) Isolators – some manufacturers call them Signal Line Circuit (SLC) Isolators
• Power Buss Isolators
• Audio Buss Isolators
• Suite Signal Isolators

Most isolators are “dumb” devices comprising a simple relay in a short sensing circuit on their “out” terminals.  As long as there is resistance on the circuit, they’re “happy”.  When the resistance drops to nothing (a short), they activate to preserve the loop integrity on their “in” side.  Some manufacturers have chosen to make their isolators “smart” by employing their panel’s protocols to “communicate” with each isolator.  This has the advantage of being able to “group bypass” an entire floor area from the common control if work is being performed there, without affecting the operational status of the rest of the system.  You’ll usually find these isolators employed by companies that are engaged in providing large scale networked type fire alarm systems (for the obvious reason that it also makes testing easier).

APPLICABLE CODES AND STANDARDS

NBC 2015, VBBL 2019

The only time isolators are actually mentioned in any Canadian Building Code is in conjunction with in-suite signalling means.  This is articulated in BCBC 2018 (as adopted from NBC 2015) in Section 3.2.4.19 called Audibility of Alarm Signals and reads in sentence (8):

“Audible signal devices within a dwelling unit or a suite of residential or care occupancy shall be connected to the fire alarm system:

a) in a manner such that a single open circuit at one device will not impair the operation of other audible signal devices on that same circuit that serve the other dwelling units or suites of residential or care occupancy, or

b) on separate signal circuits that are not connected to the devices in any other dwelling unit, public corridor or suite of residential or care occupancy. (See Appendix A.)”

CAN/ULC-S524-14

The Canadian Standard for Fire Alarm Installation is where we will find reference to the installation of Data Communication Link (DCL), network data, audio buss, and power buss fault isolators.  We will be using the abbreviations “DCL” “ND”, “AB” and “PB” for the purposes of this article.  It also deals with some specific installation requirements governing the use of insuite signalling isolators.

We’ve provided links to diagrams at the bottom of this page which detail both Class “A” interconnected field devices and a Class “A” Riser interconnected to field devices in a Class “B” configuration as part of this article.  This is one area where the manufacturer’s installation instructions also fall short and may even reference practices only acceptable outside of Canada (i.e. NFPA requirements).  The essential difference between the drawings you’ll see in the official amendment to the Standard and ours centres around one additional isolator which we’re suggesting be added to the “return” side of the loop to protect this part of the riser if you are employing uni-directional isolators.  In this instance, I’m of the opinion that this qualifies as an improvement on the actual requirements of the Standard (something that’s referred to as “good engineering practice”).

There are currently two versions of CAN/ULC-S524-14.  One includes the Amendments published in January of 2016 as a separate insert while the other will not have an amendment.  Please ensure your Standard includes the statement:  “Including Amendment 1” on the cover.

So, let’s begin with Clause 5.7.3:

“Where a data communication link utilizing active field devices or supporting field devices serves more than one National Building Code of Canada required fire alarm zone, a fault within one National Building Code of Canada Required fire alarm zone shall not prevent the normal operation of other input or output field devices in another National Building Code of Canada required fire alarm zone, except as noted in Clause 5.7.3.4.

Note:  See also Clause 4.3.1.8 and 4.3.1.9.”

5.7.3.4 states:

“Active field devices or supporting field devices serving water flow devices, supervisory devices on sprinkler systems, or duct type smoke detectors on HVAC systems that are located within a National Building Code of Canada required fire alarm zone but serve other National Building Code of Canada required fire alarm zones, need not be separately fault isolated from each other or the National Buiilding Code of Canada required fire alarm zone.”

5.7.3.5 states:

“A control unit or transponder or its associated data communication link that serves more than one floor area, shall be subject to the constraints of Clause 5.7.3.1.”

5.7.3.6 states:

“Data communication link style A with fault isolation modules, or data communication link style C with fault isolation modules, or an equivalent method shall be utilized to meet the requirements of Clauses 5.7.3.1, 5.7.3.4, and 5.7.3.5.  (Refer to Figure 5).”

Inbuild Isolator Brand Like: ESSER, COOPER... etc

Base Isolator Brand Like: GST, Edwards... etc

Isolator as a Separate product Brand Like: Edwards, Notifier, Morley, GST, Apollo, Ravel... etc

Section 4.3 is entitled “ELECTRICAL SUPERVISION”.

4.3.1.8 states:

“Except as permitted by Clause 4.3.1.10 or Clause 4.3.1.11, where a power buss circuit serves more than one National Building Code of Canada required fire alarm zone, a single fault (open circuit fault, short circuit fault or ground fault) shall not prevent the normal operation of input or output field devices in more than one National Building Code of Canada required fire alarm zone.

NOTE:  Refer to Appendix A (Informative) Explanatory Materials, Clause A4.3.1.8.”

4.3.1.9 states:

“Except as permitted in Clause 4.3.1.10, where an audio buss serves more than one National Building Code of Canada required fire alarm zone, a single fault (open circuit fault, short circuit fault, or ground fault) shall not prevent teh normal operation of input or output field devices in more than one National Building Code of Canada required fire alarm zone.”

4.3.1.11 states:

“Where a power buss serves supporting field devices which are located within a common National Building Code of Canada required fire alarm zone but serve other National Building Code of Canada required fire alarm zones, the power buss segment serving these supporting devices is not required to comply with Clause 4.3.1.8.”

4.3.1.12 states:

“Class A circuit with fault isolators installed in accordance with Subsection 10.2, Fault Isolators, or an equivalent method, shall be utilized to meet the requirements of Clauses 4.3.1.9 and 4.3.1.10.

NOTE:  For Data Communication Links, refer to Subsection 5.7.3, Field Device Data Communication Link.”

Section 10.2 is entitled “FAULT ISOLATORS”

10.2.1.1 states:

“This Subsection applies to the installation of fault isolation modules as required by Subsection 5.7.3, Field Device Data Communication Link, for data communication links between field devices.  (Refer to Figures 33.1, 33.2, 33.3, and 33.4.)

Note:  Where available, data fault isolators should be located in a fire separated electrical room.”

10.2.1.2 states:

“Data fault isolators shall be utilized when entering and leaving each National Building Code of Canada required fire alarm zone.   See also Appendix A (Informative) Explanatory Materials, Clause A4.3.1.8.”

10.2.1.3 states:

“Data fault isolators required by Clause 10.2.1.2 are not required between field devices located within the same floor area that are monitoring mechanical equipment serving other floor areas.

NOTE:  For example, water flow devices on sprinkler systems or duct type smoke detectors on HVAC systems serving other floor areas are considered part of the same area specified in Clause 10.2.1.2 and need not be separately fault isolated from other devices within that area.”

10.2.1.4 states:

“Except as noted in Clause 10j.2.1.5, data fault isolators, shall be located in a separate enclosure and installed so as to be visible and accessible at all times.”

10.2.1.5 states:

“Data fault isolators that are integral to a field device shall be mounted in accordance with the requirements of that field device.”

Note:  Field devices incorporating fault isolation modules complying with Clause 10.2.1.2 do not require additional dedicated data fault isolators.”

10.2.1.6 states:

“Where a fire separation is provided, data fault isolators required by Clause 10.2.1.2 shall be installed on each side of that fire separation.”

10.2.1.7 states:

“Data fault isolators installed on opposite sides of the same fire separation shall be offset horizontally to a minimum of 400 mm, and not located within the same stud space.”

10.2.1.8 states:

“Where no fire separation is provided between each National Building Code of Canada required fire alarm zone, a single fault isolation module shall be utilized when isolating zones within the same floor area.

Note:  This Clause would be applicable to large horizontal buildings, e.g., warehouses, shopping malls, factories, etc.”

10.2.1.9 states:

“Data fault isolators serving a single field device in an exit or vertical service space shall be installed on the floor area side.

Note:  Fault isolation modules are not required on the exit or vertical service space side.  See Figure 2.4”

10.2.1.10 states:

“Data fault isolators shall have an identifying mark or label on the cover plate or field device.  The identifier shall be visible after installation.  Where field devices incorporating fault isolation modules are used to comply with Clause 10.2.1.2, the first field device entering and the last field device leaving each National Building Code of Canada required fire alarm zone shall be marked.”