Fire & Life Safety: Pop Quiz - 5 Quick Resolutions

Sept. 10, 2015
Test yourself on solving these scenarios involving aging fire alarm systems

Every technician should know the theory behind basic troubleshooting practices. And even those technicians that prefer only new installations should learn enough to diagnose and fix their own mistakes — because everything eventually needs to be adjusted, repaired or replaced.

That said, every good installer does not necessarily have to be a good repair person; however, a good installer becomes a great technician (and key employee) when they are able to solve problems quickly and efficiently. Technicians able to perform accurate diagnostics will give their customers real assurance that they have hired the best alarm company.

Customers often recognize when a technician they have called in for service on their equipment is just replacing part after part while whispering into their phone to someone back at the office who is (apparently) more qualified. Although this sort of technician may eventually get the problem fixed, the customer’s confidence and loyalty may have evaporated.

Here are a few scenarios of fire alarm installations that are showing their age and are in need of service. Consider what your thought processes might be with the goal of a quick resolution:

Scenario No. 1: A customer reports that their older “interconnected” FACP activated and promptly shut down the air handling unit, but that no signal was indicated at the modern (and new) main FACP/annunciator. You know that the duct detectors are apparently wired to the original FACP located in the other older building. You find that the main control panel status is “normal”. What would you check for?

The Solution: Make sure that all signals on the original FACP are relayed to the main FACP, not just ALARM (and TROUBLE) signals. Since duct detectors are required to cause a SUPERVISORY signal on the building’s fire alarm system, these supervisory signals must also be indicated on the main FACP and transmitted to the supervising station.

Scenario No. 2: What could cause a sprinkler water shut-off supervisory switch on a Class B, SLC to indicate a missing point ID input module several times during a 24-hour period — even though all the devices on the SLC wired before and after it report OK? Since all the other devices are still reporting normally, it does not seem like a loose SLC connection, because if that were the case, all the devices wired after the problem device on the SLC would also go “missing” at the same time. Consider that since the other devices are still reporting as usual, the problem could be a bad module or bad wiring connection. Should you replace the problematic input module?

The Solution: If you did, it was probably a good module and you probably fixed the actual reporting problem by accident when you securely tightened the terminal screws during replacement. However, the improper wiring method needed to be corrected as that is what caused the module to fail to report while still allowing all other addressable devices to report. The in and out wires must be allowed to separate when they come off the terminal connections. Looping the wires over the terminals, twisting the wires together before connecting them, or using one spade connector for both wires is prohibited.

Scenario No. 3: Future troubleshooting, according to NFPA 72, 2013, will require that all wiring circuits have their initial resistance measured so that may be compared to subsequent readings to determine the health of the wiring and wiring connections. Should a loop resistance test be performed with the end-of-line resistor in place?

The Solution: Section 12 of the Test Methods Table has a section called “Conductors - Metallic” and explains how to measure loop resistance. The EOL resistor and its variables should be left out of the loop resistance measurements: “With each initiating and indicating circuit installation conductor pair short-circuited at the far end, the resistance of each circuit shall be measured and recorded. It shall be verified that the loop resistance does not exceed the limits specified in the published manufacturer’s instructions for the installed equipment.”

Scenario No. 4: A duct detector on a SLC caused a “Duct Detector Trouble” message to appear on the annunciator’s display, yet no amber TROUBLE light activated. What caused the difference between what was reported and what was displayed?

The Solution: The annunciator was not programmed properly to indicate that this was a “Supervisory” initiating device causing a Supervisory signal. This misapplication and confusion has come from the Mechanical Code’s language that requires activation of any duct smoke detector to be indicated as “air duct detector trouble” on the remote test/reset annunciators. While this troubling wording is correct for remote test/reset stations installed under the mechanical code, it does not apply to fire alarm systems installed under the building and fire codes — where they are required to annunciate and report as a Supervisory signal. Reprogram the annunciator description to omit the “TROUBLE” designation. Check with the remote station’s zone/point description while you are clearing this up.

Scenario No. 5: When a supervisory device has not responded at the FACP/Annunciator after waiting almost a minute from the time the water was shut off using a wall PIV, is it safe to assume the water shut-off switch is bad?

The Solution: It is possible that the shut-off switch is malfunctioning, but that is easy to test with a VOM. If you find the switch closes within the first two revolutions of the hand wheel as required, then I would suspect the verbal complaint held a clue as to why a signal was not received. In this case, the technician may not have waited long enough for the panel to respond to the closing of the shut-off valve’s switch contacts. These contacts must remain closed, since a momentary short is usually not sufficiently long enough to activate the panel.

NFPA 72 allows Supervisory signals to take up to 90 seconds to be indicated at the FACP/annunciator. The test should be performed again and this time, verify the signal is received at the FACP for up to a full 90 seconds. If the FACP/annunciator indicates a supervisory signal this time, check to see if the PIV switch’s timing is adjustable or the delay time is programmable at the FACP. You might consider decreasing the delay to around 20 seconds since 90 seconds is just the maximum allowable delay.

Questions? Need clarification? Email SD&I fire and codes expert Greg Kessinger at [email protected].