In practice, low airflow is the most common problem. Sampling tube holes might be pointed in the wrong direction. A long sampling tube cut down might not have enough holes, or the duct detector might simply be installed in the wrong location.
You must measure the pressure differential across intake and exhaust tubes when a duct detector is first installed, and the only way to do this is with a manometer – making it an essential installation tool. You also have to measure the pressure differential at every annual inspection, making it an essential inspection tool as well.
Fire alarm inspections frequently proceed without this code-required step because techs don’t have a manometer; however, the requirement has been in the code and the manuals for years. Anyone responsible for final commissioning or annual inspections should treat a manometer as mandatory.
Tone Generator & Inductive Amplifier:
If you work on older systems or if you are picking up an install where another tech left off, you will eventually need to trace out a wire. A tone generator with an inductive amplifier remains one of the simplest and fastest ways to do it.
A tone generator injects a small AC signal onto a conductor pair. The inductive amplifier lets you locate that signal without having to trace it out by hand or meter every pair one at a time.
There are three practical rules for using a tone generator: Use tone mode, not continuity mode; never put a tone generator on a live circuit (injecting a few volts of AC into a powered fire alarm panel can cause unpredictable behavior); and don’t try to tone out a shorted circuit, because you won’t get any tone.
A good habit is to confirm the tone before heading out to trace the wire. Many techs have wasted time searching for a tone that wasn’t there – usually because the battery was dead or the conductors were shorted.
Butt Set:
Even though traditional POTS lines are disappearing, many panels still use a phone line-style dialer (DACT). For example, cellular communicators often rely on dialer capture, emulating phone-line behavior so they can interface with legacy DACTs.
When something goes wrong with communication, a butt set remains the definitive tool for isolating where the failure is occurring. With a butt set, you can listen for dial tone, verify line seizure, hear the DACT dial out, and confirm whether the central station or cellular communicator is negotiating the handshake and providing a kiss-off.
Without being able to listen to the actual communication, all you can do is read the log and guess.
Label Maker:
A label maker is ideal for marking wires, modules, breaker locations, circuits, and any junction box used solely for fire alarms. Code requires these boxes to be identified, and a printed FIRE ALARM label is much cleaner than writing F/A with a Sharpie.
The benefit comes in the future. When you return months or years later, descriptive labels help you understand the system quickly. Printed labels also make you look like a pro – compared to the competition, who is still subjecting us to their messy handwriting.
Electrical Tape Holder:
If you work in the field, you probably carry electrical tape, but is it handy or is it buried at the bottom of your tool bag? To ensure you always have electrical tape when you need it, use a tape holder.
I’m not a fan of the leather ones electricians carry. I find that rolls of tape are too hard to get off the holder. That style is better for keeping multiple colors together on a tool pouch when you don’t use the tape often. For frequent use during an install, I prefer the style with a metal chain and a loop with Velcro or a snap for attaching to your belt.
