#102 – Knowing Your Fire Alarm System

by Shawn Lee

When it comes to personal enjoyment in the fire alarm field, my favorite activity is troubleshooting and repairing systems. I enjoy troubleshooting because it’s a challenge. For me, it’s genuine fun (most times).

There were many times when the problem seemed clear as day.  Just like there were times when I thought it would be easy and it turned out it wasn’t.  Sometimes it was because of something beyond my control, such as building construction.  It made troubleshooting more than a little difficult.  Other times it wasn’t easy to troubleshoot or repair the system because I failed to follow my number one rule of troubleshooting: “Know the system you are working on”.  I want to relay a story about one of those times.

There I was.  I remember it like it was yesterday.  I was stationed on Kadena Air Base on Okinawa.  It was a very long time ago…1998.  I received a call to report to the base club.  The system went into trouble and the trouble alert was really bugging the club manager.  And since it was dinner time and the building was occupied, I was directed to repair the system.  I arrived, talked with the club manager, and set out to find the problem.  I looked at the circuit board to see how everything was configured (it was Class B) and then I started searching for the problem.

This system was a conventional fire alarm system.  So that I do not unintentionally endorse a manufacturer, I will not tell you who made this panel or what its model name is, but I will say this was a very reliable panel and I had been working with this panel for the last two and half years.  I was very comfortable with it and knew its capabilities well.  In fact, when I was first assigned to the Alarm Maintenance Shop on Kadena in 1997, I spent an extra hour after work each day for a month learning this and other systems.  One of the initiating device circuits was in a trouble condition.  Probably an open in the wiring I thought.  I was confident I would be able to find the problem and be on my way home in no more than an hour.

Two hours later I was still working.  Not able to find the issue.  Fuming.  Muttering to myself.  I was using my tried and true technique of splitting the circuit in half and working towards the problem.  Since it was an open, I knew at some point there would be no voltage on the circuit.  Only, no matter which direction I searched the voltage was always there.  At first, I was a little confused.  Then came agitation.  Later still flat out anger.  Mostly at myself for not being able to get this done.

When I calmed myself down and started thinking clearly again, I decided that maybe the problem wasn’t with the circuit, but perhaps the control panel was causing the issue.  At the very least, if it wasn’t, then I could scratch it off the list of potential problems.  I went back to the control panel and looked at it again to make sure nothing was damaged or looked out of place.  Everything looked like it should.  I checked every fuse with my voltmeter.  All good. I focused on the expansion card. I think I looked at that expansion card for about two seconds when I found the problem.  It wasn’t the circuit board, the expansion card, or even the circuit out in the field.  The problem was me.  I had failed to follow my own rule: “Know your systems”.

Yes, I knew what this model of panel was capable of.  I knew how it operated.  I knew where the fuses were, their ratings, and what they protected.  I knew the panel well.  But I didn’t know THIS system.  The one in the base club.  THIS system had a mixture of Class A and Class B circuits.  THIS system had expansion cards and the circuit I was trying to repair was on one of those expansion cards.  The main circuit board was configured for Class B operation for the bells and the detectors circuits.  Yes, there were bells in that building, not strobes or horn/strobes.  This was 1998, remember? I saw that the main board was configured for Class B when I first examined the panel.  The expansion card with my circuit was configured for Class A.  I didn’t remember checking for that when I first checked out the system.  I made an assumption and got to work.  In the end, that assumption cost me time and about a year off my life due to the mental anguish I caused myself!

Once I realized that I was working with a Class A circuit, I labeled and disconnected one side of the circuit so that system voltage could only flow in one direction.  I then went back into the field and reconnected a few wires I had taken apart.  Now that everything was reconnected except for conductors I purposely left disconnected in the panel, I went back to troubleshooting.  I found the problem within 10 minutes.  I’m not kidding.  It was a bad wiring connection inside a junction box above the ceiling in the kitchen area. The time it took once I figured out the circuit I was troubleshooting was a Class A circuit to getting back in my truck to leave was approximately 45 minutes.  That included talking with the manager to let him know I was done and calling dispatch to tell them I was complete.  If I had known my system, the base club’s fire alarm system, I would have finished the job in less than an hour.

I learned some valuable lessons that day.  Don’t assume you know what’s going on because you’ve worked with a particular system before.  Each system is unique.  Check the control panel thoroughly before going out to the field wiring to troubleshoot.  Make note of how the system you are currently working on is set up.  With today’s systems, that may mean reviewing the programming or the input/output matrix if there is one.  Either way, make sure you know how the system is configured and what it is supposed to do before leaping into the unknown.

As aggravated and upset as I was that day, I look back at that job as one of the best I’ve been on.  I gained some valuable experience.  At the end of the day, I got the system back up 100% and made sure the building occupants and the building itself had a functioning fire alarm system.