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The Most Common Fire Alarm Installation Mistake: And How We Catch It Before You Leave the Counter

By Ron Broussard

TL;DR — Across Security Data Supply’s 20-plus locations, counter staff catch one of these five mistakes two to three times a week per branch. That adds up fast. Here is what Brent Capulli sees most often at the Security Data Supply Fort Worth counter, and what to have ready before you walk in.

Every fire alarm contractor has been there. You get to the job, open the box, and something is off. Wrong wire type. Missing resistors. A hundred addressable smokes when the panel wants conventional two-wire. What felt like a clean order at the counter turns into next-day air freight and a conversation nobody wants to have.

At Security Data Supply Fort Worth, Brent Capulli sees these moments coming before they happen. Here are the five parts list mistakes he catches most often, and exactly what to do differently.

Mistake 1: Missing the Accessories Nobody Thinks to List

Batteries, power supplies, and doc boxes. Every job needs them. They almost never make the initial parts list.

These items feel obvious in the field but easy to skip when you’re building a quote fast. A power supply without a battery gets you a system that won’t pass standby inspection. A panel without a doc box is a problem the AHJ will flag before they look at anything else. These are not optional and they are not available at the hardware store.

What to do: Treat batteries, power supplies, and doc boxes as line items on every order, not afterthoughts. If you’re not sure which power supply pairs with the panel you’re running, ask at the counter. That is a thirty-second conversation that saves a half-day.

Mistake 2: Not Ordering Wire, or Ordering the Wrong Type

Wire gets left off the list more often than almost anything else. And when it is on the list, the wrong type frequently shows up.

For fire alarm installations, the two wire types you need to know are FPLP and FPLR. FPLP (Fire Power Limited Plenum) is required in plenum spaces, meaning the air-handling spaces above drop ceilings or below raised floors. FPLR (Fire Power Limited Riser) is rated for vertical runs between floors in non-plenum spaces. These are not interchangeable. Using FPLR in a plenum space is a code violation and a failed inspection.

What to do: Know the installation environment before you order. Plenum or non-plenum determines the wire. If you are not sure, bring the job details to the counter and we can confirm it with you.

Mistake 3: Not Stating Whether the System Is Conventional or Addressable

This is the one that costs the most when it goes wrong.

“We had a customer who needed to replace over 100 smokes. The sales associate asked the brand of the panel but did not ask whether it was conventional or addressable. The order came in for 100-plus addressable smokes. The job needed 100-plus conventional two-wire smokes. That meant next-day air freight charges, restock fees, and inventory overages, on top of the time the contractor lost on the job.”

— Brent Capulli, Fort Worth Branch Manager, Security Data Supply

Conventional and addressable systems are fundamentally different. A conventional panel groups devices into zones and knows a zone triggered, not which device. An addressable panel assigns a unique address to each device on the signaling line circuit and identifies exactly what activated. The devices, the wiring, and the components are different throughout. Swapping them is not a field fix.

In the Fort Worth market, Honeywell Fire Products is the dominant manufacturer across commercial fire jobs. Security Data Supply Fort Worth stocks three of their sub-brands: Fire Lite, Silent Knight, and Farenhyt. Each is designed for different system types and applications. Knowing which sub-brand is on your job, and whether the system is conventional or addressable, changes every line item on your order.

What to do: Before you come to the counter, confirm two things: the panel brand and sub-brand, and whether the system is conventional or addressable. Those two answers determine your entire parts list.

Mistake 4: Skipping End of Line Resistors and Sync Modules on Conventional Systems

Contractors running a conventional sounding smoke series frequently leave end of line resistors and sync modules off the list entirely. Both are required and neither is optional.

End of line resistors allow the panel to supervise the circuit wiring. Without them, the panel cannot detect an open circuit condition, which is a basic supervision requirement. Sync modules coordinate strobe timing across the notification appliance circuit. In a conventional system with multiple strobes, unsynced strobes can create a seizure risk for building occupants and will fail inspection in most jurisdictions.

What to do: If you are running conventional, put end of line resistors and sync modules on the list before you leave for the supply house. If you are not sure which resistor value or which sync module pairs with your strobe brand, the counter team can tell you in about two minutes.

Mistake 5: Not Asking About Surge Protection

Surge protection is the item contractors almost never ask about and almost always wish they had ordered after a failure shows up down the line.

On a fire alarm system, the two places where surge damage hits hardest are the 120V AC input and the SLC loops on addressable systems. A voltage spike on the AC input can take out the main board. A surge on an SLC loop can wipe addressable devices across the entire circuit. Both are expensive failures that happen after the job is done and the contractor is long gone, which makes them particularly frustrating.

Surge protection on these points is not a major line item cost. The cost of a service call, a board replacement, or readdressing a loop makes it look very reasonable in hindsight.

What to do: Ask about surge protection when you order. It takes one question at the counter. We stock the right devices for both 120V protection and SLC loop protection and can spec the correct one for your panel.

What This Looks Like Across 20-Plus Locations

Each of these five mistakes shows up two to three times per week at each Security Data Supply branch. Across more than 20 locations, that is a consistent pattern, not the exception. Most of these get caught at the counter before the order ships. The ones that don’t get caught become return trips, freight charges, and lost days on the job.

The counter at Security Data Supply Fort Worth is not just a place to pick up parts. It is where the list gets reviewed. Brent and the team know which panels are running on Fort Worth-area commercial jobs right now. They know which Fire Lite, Silent Knight, and Farenhyt components are compatible with which system types. And they will read your list before you leave.

Before you leave the counter, let us check the list.

Frequently Asked Questions

What is the difference between FPLP and FPLR fire alarm wire?

FPLP (Fire Power Limited Plenum) is rated for use in plenum spaces, meaning air-handling spaces above drop ceilings or in raised floors. FPLR (Fire Power Limited Riser) is rated for vertical runs between floors in non-plenum spaces. Using the wrong wire type is a code violation and a failed inspection. Confirm the installation environment before ordering.

What is the difference between a conventional and an addressable fire alarm system?

A conventional fire alarm system groups detectors into zones. When a device triggers, you know the zone but not the exact device. An addressable system assigns a unique address to each device on the SLC loop, so the panel identifies exactly which detector activated. The two systems use different devices, different wiring, and different components throughout. Ordering parts for the wrong system type is one of the most costly mistakes a contractor can make.

Do I need end of line resistors for a conventional fire alarm system?

Yes. End of line resistors are required on conventional fire alarm circuits to allow the panel to supervise the wiring. Without them, the panel cannot detect an open circuit condition. When running a conventional sounding smoke series, sync modules are also required to coordinate strobe timing across the notification appliance circuit.

Why do Fire Lite, Silent Knight, and Farenhyt all fall under Honeywell Fire Products?

Fire Lite, Silent Knight, and Farenhyt are all sub-brands under the Honeywell Fire Products umbrella. Each line is designed for different market segments and system types, but all are manufactured under Honeywell’s quality and certification standards. Security Data Supply Fort Worth stocks all three lines and can help you identify which sub-brand is specified for your job.

What accessories do contractors most often forget when ordering fire alarm parts?

The most commonly forgotten accessories are batteries, power supplies, and doc boxes. These are required on nearly every job but frequently left off the initial parts list. Wire is also a common omission, and when it is included, the wrong type is often specified. End of line resistors, sync modules, and surge protection devices round out the list of most-missed items.

About the Author

Ron Broussard is Chief Executive Officer of Security Data Supply and has spent more than 30 years helping security, fire, and low-voltage businesses grow through strong distribution partnerships. Throughout his career, he has held executive leadership roles across distribution and manufacturing, giving him a unique perspective on the challenges contractors, integrators, and distributors face every day. At Security Data Supply, he helps guide the company’s franchise network, vendor relationships, and long-term growth strategy.

Methodology

This post is based on direct counter experience at Security Data Supply Fort Worth and reflects the parts list errors Brent Capulli encounters regularly during interactions with licensed fire alarm contractors sourcing components for commercial installations in the Fort Worth area. Frequency estimates are based on Brent’s observations across Security Data Supply’s 20-plus branch locations. Product references reflect current Security Data Supply Fort Worth inventory across the Honeywell Fire Products family (Fire Lite, Silent Knight, Farenhyt).

Sources and Further Reading