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What is a residential fire alarm system (single & multiple station)?
In this series, we are focusing on the different types of fire alarm systems. In our last video, we discussed municipal fire alarm systems. Today we are going to focus on residential fire alarm systems. In our series here, we’ll divide residential fire alarm systems into two parts: Part 1 Single- Station and Multi-Station, and Part 2 Household and combination fire alarm systems. We’ll cover Part 2 in the next segment. Let’s talk about single-station smoke alarms. Single station smoke alarms have been in the code for quite some time, let’s be crystal clear on the distinction here, a smoke alarm is not a smoke detector, and the noise from smoke alarms are local only to the room and/or house if the smoke alarms are interconnected. Smoke detectors are connected to a fire alarm control unit which sends a signal to a supervising station. Single station smoke alarms are by far the most common device in the household fire alarm industry. A quick google search yields multiple results of hard wired or battery-operated smoke alarms which on average cost $14 a unit for UL 217 Listed device. Smoke alarms now come with a 10-year worry-free lithium battery, so that annoying chirp will only happen every 10 years instead of every year. Back in the day when I would teach fire safety to University of California staff, I would say you change your battery when you change your clock in the spring and the fall, that still applies to most of us. New technology has emerged with voice technology for combination smoke and carbon monoxide alarms with smart features that link to your phone, these devices will run you around $80 per unit. All new residential construction at a minimum requires smoke alarms in every bedroom, in the hallway outside of each bedroom, and on each story or basement level. Smoke alarms are required to be hardwired to the household wiring system, interconnected, and provided with a battery backup. What about multiple-station smoke alarms? A single station alarm becomes a multiple station alarm through interconnection, when one smoke alarm is actuated, all of the smoke alarms throughout the household will go into alarm. It is quite the fun experience when you set off the multiple station alarms in your house through cooking and have to fan the detectors to clear the smoke before the neighbors come knocking… NFPA 72 Chapter 29 provides the installation requirements for single station smoke alarms. The key highlights are: Do not install within 3-feet of a shower room, unless you want to know when someone is taking too long of a shower… Do not install within 20-feet of permanently installed cooking equipment – My son set off our smoke alarms last night when he was heating up a pan of oil to sear fish, that’s what happens when you watch too many cooking shows… Do not install within 3-feet of fan blades or a supply registers for forced air units as they will possibly prevent smoke from entering the chamber. Single station smoke alarms come in either photo electric or ionization sensors with ionization being the most common. Getting into the science behind each technology is worthy of its own video for each type, so we will not go there for now, just know that ionization detectors have two electrically charged plates which creates an ion current, if the current is disrupted by smoke the device will go into alarm. A photo electric smoke alarm works based on a light source being aimed at an angle within the smoke chamber, when the light source is obscured by smoke, the device will go into alarm. Most people, including myself, do not pay attention to what type of device is being sold at the local home supply store, we just grab the package and go home. There is much debate about what type of alarm you should install. Ionization detectors react more quickly to flaming fires as opposed to photo electric which are more effective with smoldering fires, not the open flame. Since ionization is the most commonly sold, they are to blame for most of the nuisance alarms people complain about, statistics show that they are 8 times more likely to be intentionally disabled. Based on test results, Ionization smoke alarms will respond 30-90 seconds faster in a fast flame fire such as cooking oil, grease, or paper fires and 5 to 50 minutes slower than Photo electric smoke alarms for smoldering fires which include faulty electrical wiring within walls or cigarettes in couches or beds. So, you can either purchase individual ionization or photo electric smoke alarms and strategically place them throughout the house, or you can now purchase dual sensing smoke alarms which feature both technologies in one. Bottom line, you want to make sure your smoke alarms are installed and maintained per the manufacturer’s instructions and whatever you do, don’t be that person that pulls the smoke alarm down because it was annoying and failed to put it back. In summary, smoke alarms are photo electric, ionization or dual-sensing devices that emit a temporal code 3 alarm around 85 decibels. Single station applies to a single smoke alarm which is a standalone whereas multiple station means two or more alarms which are interconnected so that they will all go into alarm when any one of the group is activated. Next time you go to your big box home improvement store, go down the safety aisle and peruse all of the new technology in smoke alarms. Maybe you will come home with a device that says “Don’t Burn The Popcorn” hahaha… In our next video, we will discuss household and combination fire alarm systems. Until next time, I’m Al Yakel and this is Meyer Fire University.
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