Detailed Security System & Fire Alarm Definitions
Quick Reference Security Systems Definitions
Fire Alarms & Accessories Definitions
Door Access Control Definitions
Closed Circuit Television CCTV Definitions
Phone Systems Definitions

Control Panels and Features

The most important part of any security system is the control panel. It monitors the condition of all the devices and reacts to changes, based upon the status of the system. It also accepts commands from the users via command stations. Early controls consisted of a few relays, dry cell batteries, and a key to turn the system on or off. Today's controls are microprocessor based, allowing them to perform a multitude of functions and provide a powerful yet easy to use interface for the user.

If you are considering the installation of a security system this will help you decide on what you want your system to do and allow you to properly evaluate the estimates.

General Features - In addition to arming/disarming the control can support many other functions. Among the most common are System Test, User code changes, schedule control, time setting, reset smoke detectors, silence sounder, view event memory, bypass zones, and relay control. I will not describe the operation of these features in detail but they will be briefly covered under the appropriate sections that follow. The important thing to remember is that there are a number of functions that your security control can perform.

All controls should be equipped with a rechargeable standby battery to power the system in the event of a power outage. You should have sufficient battery standby to operate the system for the duration of outages you are likely to experience in your area. Most controls can be equipped with enough batteries to power the system for up to 80 hours if needed, although some may require additional charging modules. The amount of batteries needed depends upon the type and amount of devices used and how long you want the system to function without normal electrical power.

Wired or Wireless - Security systems can use wired, wireless, or a combination of wired and wireless devices. The type you use depends upon many factors such as ease of wiring, building construction, timing of the installation, and cost. Wireless systems have a much higher equipment cost and require battery changing every few years, but can be installed very quickly. If your major concern is disruption of your home routine, then wireless may be a good option. Wireless is also good when you want to have detectors installed in unattached garages or sheds. Some controls are either one or the other but many manufacturers have introduced controls that allow both to be used as needed. If you decide to use wireless make sure that the system supervises every transmitter for low battery, transmitter functioning, and whether the door is open or closed. Many low cost wireless system do not tell you when a battery gets low or if a transmitter has failed completely.

Number of Zones - A zone can be a single point of protection, such as the front door, or a group of points, such as bedroom windows. Point of protection zoning, that is every point is its own zone, can make the system easier to use, repair, and reduce false alarms since the exact location of any problem is immediately identified. Some control panels can monitor over 100 points of protection, more than enough for most installations. How many zones you require depends upon the number of devices you will have and room for future potential additions. Make sure that your control can be expanded to meet your future needs or you may be faced with replacing the control when you want to add devices. Zones can either be supervised or non-supervised. Supervised zones use an end of line resistor (EOL) to maintain a given voltage, if the zone is opened or shorted this voltage will change and activate the control. Unsupervised zones may be normally open or normally closed, normal being the non-alarm state. Zones that are normally open, non-supervised will not alert you to a broken wire in the system. A normally closed, non-supervised system would, but it would not notify you if the wires were accidentally shorted. For the best security, zones should be supervised with an EOL resistor electronically located at the end of the wire run.

Types of Zones - Zones fall into 5 major categories fire, hold-up, medical, burglary, and supervisory. Each type of device has a specific alarm and trouble procedure, for example a fire device will always cause the sounders to activate and notify the monitoring location, but many control panels allow you to program a custom response to any type of detector.

1. Fire zones can be smoke detectors, heat detectors, or manual stations(deices that you activate if you detect a fire). Fire zones are always active, ready to alert you in the event of a fire. A useful feature for smoke detectors is verification. This is a feature where if a smoke detector trips the control will not immediately sound the alarm, but will reset the smoke detector and wait a predetermined period of time for a second trip. Only if the smoke detector trips again during this period the alarm will sound. This feature helps reduce false alarms cause by insects or dust entering the detector.
2. Hold-up zones can be audible or silent(Note: Silent hold-up requires remote monitoring). You may choose either or both. Audible hold-up can be used to "scare' away prowlers but care must always be exercised when activating hold-up devices since there is no way of predicting the action a prowler may take when he hears the sounders or the police arrive. Even if your system is monitored, you can even have an audible hold-up that does not send a signal to the monitoring location.
3. Medical alert devices work basically the same as hold-up devices and have the same options. The only difference is the action that the monitoring company takes when it receives the signals.
4. Burglary devices fall into 3 categories, 24 hour(always active), perimeter(doors and windows), and interior(motion detectors).
5. Supervisory devices can be water or gas detectors, low temperature and the like. Normally these devices are active 24 hours a day and when tripped they do not cause the sounders to sound. They will enunciate at the command center and send a signal to the monitoring location. I have connected my outside speakers, storage shed, and pool alarm as supervisory zones.

Arming Levels - In the past, a security system was either on or off. Today's control panels allow many levels of arming. The basic ones are AWAY, HOME DELAY, and HOME INSTANT. AWAY arms all perimeter and interior devices and provides an exit/entry delay. It is used when everyone is leaving the home. HOME DELAY arms only perimeter devices and provides exit/entry delay. It is used if some are leaving and some are still home. HOME INSTANT arms only perimeter devices without any exit/entry delay. It is used when everyone is at home.

Arming Devices or Command Stations - These are the devices that you would use to arm/disarm and control your system. They may be Alphanumeric, that is they display information in text format, LED, which use light emitting diodes to indicate system status, key switch, requires a key to turn the system on or off, or wireless. Which type you use depends upon several factors such as control type, personal taste, and of course budget. The alphanumeric are generally the most expensive of the wired devices with key switches being the least expensive. Many controls can support only a limited number of command stations, so make sure that the control you choose has the ability to supervise the number of command stations you need.

The alphanumeric command stations may be capable of displaying true custom text, such as Jacks door, or may use a library of pre-programmed descriptions like North door. The display may be LCD, liquid crystal display, or fluorescent. The LCD's tend to be less expensive while the fluorescent are generally brighter and easier to read. While these devices are the most expensive arming device, I believe that they are worth the money, since they are the only part of the system that you will use every day and it makes sense to have a unit that makes operating the system very simple. They can prompt you for the required data, such as Enter Code when the system is activated and provide a clear visual indication of the system status. It is very uncommon for a security systems to be key operated, since a simple key can not perform all of the functions that the control can support. They do have applications, the most important of which is the interfacing with a home automation system. The automation controller can provide an output that can be used to arm/disarm the security system. While this is not a true key switch, it appears that way to the control.

Wireless arming devices may be 1 way, that is they are only capable of sending a signal, or 2 way. The 2 way devices are more expensive but they do confirm that your command was received and carried out. These devices are necessary when you want to arm/disarm the system from your car or when it would not be possible to run wire to a location that needs a command station. Most systems limit the functions of wireless command stations so it is important that you have at least 1 wired station as part of your system.

Outputs - All controls have some output to activate a sounder but many can also be equipped with relays that can be controlled from a command station, by some type of system activity, or by a pre-programmed time schedule. These relays can allow you to perform many functions such as sprinkler control or as a means of interfacing with a home automation system. The number of available relays depends upon the control used, but some manufacturers have the ability to connect over 100 outputs to the system.

User Codes and Authority Levels - Most controls provide multiple user codes. This allows the user to assign each operator of the system their own code, making it easy to remember. The authority levels allow you to control what features/functions each user can perform. You may want your code to control every feature but the codes you give to your children may only arm/disarm the system. Having the ability to add or delete codes can be very useful when you have weekend guests or employ a baby-sitter. You can assign them a simple code and then delete it after they no longer need it, keeping your code secure and your security intact. If your control has a viewable memory log you can review it and determine exactly who performed a function and at what time, an easy way to tell if the curfew was violated or if the system was armed when your spouse went shopping.

Multiple Areas - It may be desirable to divide your security system into a few areas, such as Main, Interior, Safe, and Gun Cabinet. A multiple area system allows one control to be segregated into a number of areas that can be armed/disarmed individually. This allows you to keep the system active for your safe while the rest of the security system is off. If your control has authority levels you can also assign the areas to the individual codes. This feature allows your children to arm/disarm the main system but will not allow them to turn off your gun cabinet or safe. This feature is also useful if you have married children or parents living in a separate part of the house. You could assign all of the protection in their part of the home to one area and allow them access to only that area.

Zone Bypassing and Forced Arming - Sometimes you may want to disconnect, bypass, some of your protection. If you are having a window replaced, you may have to bypass the protection on that zone until your security company can reinstall the device. Force arming is the arming of a system with one or more zones in trouble. It is similar to bypassing with one exception. If the troubled zone returns to normal after the system is force armed it can become active. This is helpful if the zone was a motion detector that was not reset when you were arming the system but does reset a minute later. A variation of bypassing is called swinger shunt. This is a control panel function that will automatically bypass a zone if it trips more than a preprogrammed number of times. For example if a severe storm should cause a motion detector to continually trip, the control will bypass it after 3 or 4 alarms to prevent additional signals. Once a zone is bypassed in this manner it may remain bypassed until the system is disarmed or some controls will reactivate it, if it remains stable for a period of time, typically 1 hour. This allows the system to maintain the maximum level of protection at all times.

Communication Techniques - If your system is monitored it must be connected to the monitoring office by some means of communication. The most common used today is called digital communication, using your existing telephone line. When the control needs to send a signal it "seizes" the line, disconnecting your telephones, and calls the monitoring office. These systems do not require any special telephone lines but have the disadvantage that if your telephone line is out the control cannot communicate. Your control can be programmed to send a simple test message to the monitoring office every 24 hours to check the integrity of the line. If this signal is not received then the monitoring office knows that something is wrong. It may not detect a burglar cutting the line but it is better than nothing. You can also connect a telephone line monitor to your telephone line to activate your system if the line fails, providing a local indication of the problem.

If additional security is desired you may be able to add cellular telephone, long range radio, derived channel, or one of the special lines that are available from the telephone company in your area. Cellular uses the wireless cellular network to provide a path for your control panel to call the monitoring office. Long range radio provides a wireless path between your home and the monitoring office. Derived channel is a service offered by some telephone companies that uses your existing telephone line and adds a special tone to the line to detect someone cutting the wires. Unlike cellular or radio this system will not send the alarm to the monitoring office, after the wires are cut, it only tells them that they were cut. In certain areas the telephone company will lease a dedicated line that connects your home to the monitoring office. This approach is the most expensive and has limited applications in home security.

Security Devices and Accessories:

Keypads - The name keypad is a hold over from the days when the only way to turn the system on or off was with a key. Today most controls use digital pads, which resemble a telephone number pad, to control the system. In fact some systems in use today can even use your existing telephones to control the system. The display can consist of LED's or an Alphanumeric display. I think that the Alpha displays are worth the additional cost since they make using the system much easier, and since the keypad is the one part of the system you use every day it makes sense to make it as simple as possible.

You should have 1 pad located by the entrance door, to allow for quick arming and dis-arming, and another pad in the master bedroom, for use if the system trips at night.

If your system has more than 1 partition you should have a pad for each additional partition. For example if your gun cabinet is a partition you should have a pad located by the cabinet so you can arm and dis-arm the cabinet as needed. Partitioning is also useful in "Mother and Daughter" layouts. This way each of the occupied areas of the house have independent control of their area, but share a common control. Some systems allow any pad to control any partition or area, which makes operating the entire system very easy.

Sounders - In the past, the word sounder for an alarm system meant a bell. Today bells are rarely used, they have been replaced by solid state electronic sirens. These sirens provide a higher level of sound output as well as a number of sound types. Some sirens "speak" English, French, Spanish, etc., while there is another that can be custom programmed to "say" anything you want. I find that the talking sirens are best for home use since they make it very easy to tell the difference between a Fire and Burglary alarm. Whichever you choose make sure that the control automatically shuts off the sounders within any local ordinance time limit or you may face a fine.

In addition to sounding devices you can also have your system trigger strobe lights or, by using an interface, your existing outside lights.

Contacts - Contacts are the most common devices used in burglary systems. Their purpose is to trigger an alarm whenever a door or window is opened. These devices can be surface mounted or depending on the type of door/window, recessed. Since recessing contacts requires more labor, the installation charge for recessed contacts is higher than for surface mount.

In addition to the standard door/window contacts there are a number of specialty contacts for use outside, on safes, or for high security applications. The standard contacts are available, depending on the manufacturer, in a small range of sizes and colors such as brown, white, ivory, or gray. Ask the companies you will be getting estimates from to show you a "cut sheet" or sample of the contacts they are planing to use. Most contacts consist of 2 parts, a switch which is mounted on the fixed structure (frame) and a magnet which is mounted on the movable door/window. When the magnet is in close proximity to the switch the magnetic field "closes" the switch. Opening the door/window causes the switch to "open".

Please note that while most burglary systems trigger an alarm when a zone "opens" (called normally closed), some systems trigger an alarm when a zone "closes or shorts" (called normally open). A normally closed system will trigger an alarm if a detection device trips or a wire breaks. The exception to this are Fire Alarms. In a Fire system a short is an alarm while an open is a trouble. This is to prevent a broken wire from causing a false fire alarm.

In cases where you want to be able to leave a window open a little for ventilation, it may be possible to use 2 magnets and 1 switch. In this configuration the first magnet is mounted in the window closed position and the second is mounted in a location where it will align with the switch when the window is open a few inches, typically 3 or 4 inches. This allows for ventilation but will sound the alarm if the window is fully opened. The alarm system must be dis-armed whenever the window is moved between the 2 positions or the alarm will sound. An alternative to this is to use a 2 part "pull-apart-plug" with a small length of wire, or a roller switch. These methods allow you to open and close the window to a pre-set limit without dis-arming the system.

In addition to magnetic contacts there are plunger switches which mount in the frame and the action of closing the door/window pushes the plunger in completing the zone.

Deciding which doors/windows should be contacted depends upon the accessibility of the windows and your budget. The best security is achieved by installing contacts on all doors and windows which are accessible. This provides the earliest notification of an intrusion.

Window or wall mounted air conditioners may also require protection if they can be easily removed from the opening. The standard method used to protect these units is to either install a contact on the unit or run a "trap" wire across the unit and secure it to the wall on both sides. If you remove the unit during the winter it may be possible to wire the window contact and the air conditioner trap in parallel, so that both must be triggered before the alarm will sound. In this manner you do not have to call the Security Company in every time you install or remove the unit.

Motion Detectors - PIRs are the most common motion detector used by security companies today for interior use. But what is a PIR, how does it work, and should they be part of your security system? Good questions, read on for the inside scoop on PIRs.

PIR detectors are electronic devices that detect an intruder by sensing his body heat when he enters or moves around the area of protection. The device consists of a mirror or lens that can focus the energy, a thermal sensor to detect the energy, and associated electronics to analyze the information. The area that a unit can protect is usually given in feet representing the length and width of it pattern, such as 35 X 35 feet. or 150 X 8 feet.

The mirror/lens divides the area of coverage into multiple zones of detection. This can be visualized by holding your hand out and spreading your fingers. Each finger represents one optic zone of the detector. An actual PIR detector actually uses much more than 5 zones of detection, and some models can detect motion up to 200 feet from the unit. The PIR can only detect motion within one of its zones and is most sensitive to motion across the zones since this is what causes the greatest change in energy.

Many manufacturers make a selection of lens or mirrors for the detector so that the area of coverage can be changed by simply replacing the optics. This is particularly helpful if you decide to get a pet after your security system has been installed. Another feature of the mirror/lens is that you can mask, block out, any segment that may cause a problem by covering it with the tape supplied by the manufacturer. For example, if there is a radiator within one of the protected zones, you can place the tape on that segment and by doing so prevent it from causing a false alarm.

The thermal sensor used in todays PIRs is actually two or four sensors in a single unit. The two-element device, which is commonly called a Dual PIR, divides each zone into two distinct, side-by-side detection areas. A person moving will first activate one of these sensors and then the other. This allows the PIR to reject alarms that originate from heated surfaces or even RF interference, since both of these are detected simultaneously by both elements.

A four-element device, which is commonly called a Quad PIR, further divides the zones into an upper and lower area. This allows the unit to compare the signals received, further reducing the possibility of false alarms.

PIRs incorporate additional features that help to minimize false alarms, such as white-light filters and pulse-count circuits. The white-light filters, for example, prevent the device from falsing (false alarming) when exposed to a source of direct light where the pulse-count circuit tells the unit not to activate unless it detects motion multiple times in rapid succession.

Some PIRs have a special Pet Alley lens that prevents them from detecting motion near the floor. This option can allow your pet to roam the area when the system is on, as long as it does not jump or climb on something inside the detection area.

Proper PIR placement is essential for good protection and false alarm reduction. The following guidelines should be considered when using PIR detectors:

• Match the PIR to the area. Using a unit that has a 100-foot range in a twenty foot room can cause false alarms.
• Do not mount the unit facing windows or any source of rapidly changing heat or cold air.
• Seal all openings into the unit to prevent insects and drafts from entering the unit and causing false alarms.
• Mount the unit so that an intruder will have to walk across the detection pattern, rather than towards the detector.
• If using a Pet Alley lens, carefully examine the room to ensure that the pet cannot climb high enough to activate the unit.
• Be careful with mylar balloons and other hanging objects. A PIR is capable of detecting them when they are within the detection area and if they can move when the air is turbulent.
• Mask any zones that may cause false alarms.
• Last but certainly not least carefully walk test each unit to accurately determine the area of coverage.

Glass Break Detectors - We are surrounded by glass and it offers very little deterrence to a would be burglar. It is no small wonder that good security can only be achieved by detecting breaking glass. One of the major advantages of this is that the burglar is detected before he enters your home not after, as is the case with motion detectors.

The original method used to protect glass required the application of a conductive metallic tape, called foil, directly to the glass. This foil was typically 3/8 wide and .0015 inches thick, which when stretched during proper installation became even thinner. The foil was adhered to the glass approximately 3 inches from the edge and applied around the entire perimeter of the glass. If the glass were broken the cracks would extend and cause the foil to break. While this was a very reliable method of detecting glass breakage, it was also very expensive due to the labor intensive nature of the installation.

Today electronics has almost totally eliminated the use of foil and glass is now protected by using vibration or acoustical devices. There are many advantages to using these detectors, they are visually more appealing, they are less expensive to install/maintain, and they are less prone to service problems. This article will briefly explain the operation of these devices to help you decide which is right for you. The information contained is of a general nature and you should obtain the specific operational parameters of any devices proposed for use in your system.

Types of Glass - It is important when selecting glass protection that the type of glass be considered. Some detectors are designed to only work with certain types of glass and in other cases the type of glass will affect the range and performance of the unit. The most common types of glass are plate the most common which contains few impurities, tempered which breaks into rounded grains instead of jagged shards, and laminated which resists shattering, generally a composite of two sheets of glass with an intermediate layer of transparent plastic.

Vibration Detectors - Vibration detectors fall into 2 categories; those that mount on the glass and those that are frame/wall mounted. The glass mount type may be specifically tuned to the vibration of breaking glass or a basic vibration detector. The units that are tuned to sense only breaking glass will not trip if someone simply knocks on the glass. The optimal mounting location for these detectors is in a corner approximately 1 inch from the frame. The reason for this is that the shock waves tend to concentrate in the corners of the window. Basic vibration detectors sense any vibration within their range. They are often connected to a control/analyzer which allows the installer to control the strength, duration, and time interval that will activate the alarm. These units can also be used to detect wood or other materials being attacked. The typical range of vibration detectors is a radius of 10 feet, although you should have 1 detector for each window unit being protected regardless of size.

Acoustical Detectors - Acoustical or sound discriminators work by "hearing" the noise of breaking glass. The unit may be tuned to react only to the specific frequency of glass breaking, typically 4 to 6 Khz, or may react to any loud noise. In an effort to reduce false alarms some manufacturers have designed their units to activate only when a specific pattern or wave form is sensed. Despite this, care must always be exercise when installing sound detecting devices. Loud music, high background noise levels, ceiling fans or other machinery(can generate harmonics), and very high humidity such as in bathrooms, can adversely affect the performance of sound detectors. A major advantage of these units is their ability to protect multiple windows, detection range can extend up to 35 feet. Window coverings must also be considered, drapes, curtains, and shutters can affect the sound transmission, so it is important that the installer test the units with them closed.

Dual Technology Units - Some manufacturers have combined vibration and sound detectors into one unit that will not activate unless both are detected. These units may be used where the normal conditions would cause a single technology detector to generate false alarms. If using these units remember that any window coverings will also affect their performance, so make sure that the final testing is performed with them closed.

Fire and Gas Detection Devices:

Smoke Detectors - Installing smoke detectors in your home is not only the law in most regions of the U.S., but it can also save your life. It is therefore important that you understand how smoke detectors work, how they are wired, and where they should be located. This article addresses these issues as well as the proper maintenance and testing of smoke detectors.

How Do Smoke Detectors Work - There are 2 basic types of smoke detectors, photoelectric and ionization. Photoelectric detectors use a light source, usually IR, and a photoelectric detector. These elements are arraigned inside a chamber so that under normal conditions the photoelectric detector does not "see" the light emitted by the light source. When large smoke particles enter the chamber they reflect the light on the photoelectric detector which in turn causes the alarm to activate.

Ionization detectors use a small amount of radioactive material located within a chamber that contain positive and negative electrodes. Under normal conditions the radioactive material allows electrons to flow inside the chamber, but when small smoke particulates enter the chamber they interfere with this flow, which in turn causes the alarm to activate.

Due to the basic design differences between the two detectors, photoelectric detectors are more sensitive to slow burning, low energy, high smoke fires - such as burning chair cushions - while ionization detectors are more sensitive to fast burning fires from gasoline and other similar fuels.

How To Wire Smoke Detectors - Smoke detectors can be wired in either a 2- or 4-wire configuration. In the 2-wire configuration, these detectors use the same 2 wires that power them to detect an alarm. The 4-wire version uses 2 of the four wires for power and the other 2 for alarm. Which wiring configuration that you or your alarm company uses will depend largely on the alarm control panel being used. If the panel supports the 2-wire configuration, then use 2-wire smoke detectors because they are easier to install and require smaller, less expensive cable.

When wiring smoke detectors it is important to fully supervise all wiring and connections, since the alarm contacts of the detector are normally open (short on alarm). In normally-open systems, a broken wire or loose connection is not detected unless you are using some form of loop supervision - like an end-of-line (EOL) resistor.

End-Of-Line Resistors - An EOL loop has a resistor located after the last detector, which causes a small amount of current to flow. The control panel monitors the loop and will alert you if the amount of current decreases (broken wire) or increases (smoke detector trip) beyond a preset level. The alarm control panel should also be programmed so a broken wire causes a trouble condition while an activated smoke detector causes an alarm. This is done to prevent false alarms caused by wiring problems.

When connecting the wires to the detector you should cut the wire and place only 1 wire under each screw terminal. If you simply strip back the insulation and "loop" the wire around the screw, the system may not be able to alert you if one of the wires come off of a terminal screw.

When using 4-wire smoke detectors, you should also install a power monitor after the last detector on each separate loop. This insures that the detectors are receiving power. This monitor is basically a relay which has its coil connected to the power wires (keeping it energized) and its contacts connected in series with the detection loop, so that if the power is removed the relay will drop out causing an open (trouble condition).

Smoke detector zones can be programmed to activate the alarm as soon as any smoke detector activates or only if more than 1 trip is detected (Alarm Verification). Verification is used to minimize false alarms and works as follows:

1. Smoke detector trips
2. The control panel automatically resets the detector
3. Only if a second smoke detector trip occurs within a short time, typically 60 seconds, or if the detector fails to reset, an alarm is activated

Where Should They Be Located - Smoke detectors should be located on the ceiling at least 4 inches from any walls, or when wall mounting they should be installed between 4 and 12 inches down from the ceiling line to the top of the detector. You should install detectors outside every separate sleeping area, on every level of the home (including basement), and inside each bedroom. You should avoid placing smoke detectors in kitchens, garages, and attics to prevent false alarms. Rate-of-rise and fixed-heat detectors should also be installed in these locations.

Powering Detectors - Smoke detectors can be powered by an internal replaceable battery, standard house 110 VAC, standard house 110 VAC with battery backup, or from a central security control panel.

If you use battery powered detectors make sure that you replace the batteries every year. Set a fixed date, Thanksgiving, New Years, etc. and replace every battery each year. If the units are powered by standard house 110 with a battery backup, those batteries must also be replaced, check the documentation that comes with the unit for the suggested replacement frequency.

Fire Alarm Sounders - Since the primary purpose of a fire alarm is to save lives, you must make sure that you will be able to hear the sounders no matter where you are or what you are doing. Pay particular attention to sleeping areas- must be loud enough to wake you and your family up, workshops- where noise from tools etc. could drown out the sounders, and bathrooms- with the door closed, taking a shower, playing radio/singing.

Make sure that you know the difference between the burglary sound and the fire sound, voice sirens that "speak" in plain language eliminate this concern. Many smoke detectors have a built in horn to alert you in case of a fire, some detectors that connect to standard house 110 VAC can also be wired so that if any of the detectors is activated the horns in every unit will sound. This feature is especially valuable in multistory or large homes.

Testing Smoke Detectors - You should test your smoke detectors every month. Some units have a test button, some allow you to shine a light on them, and others require that you blow smoke into them. Read the documentation that comes with your unit to determine which is the correct method for your detector. If the unit has a LED it may flash at a specific frequency to show that the unit is functioning and at a different rate or not at all if there is a problem.

Again read the documentation and periodically look at the LED. If your system is monitored make sure that you notify your security company before you begin testing.

Cleaning Smoke Detectors - Like testing procedures how you should clean your detector will vary, so check the documentation. It is a good idea to clean the outside of the detector with your vacuum cleaner when you are doing your floors. This will prevent dust from clogging up the chamber and also remove any debris that may accumulate on the unit.

For additional information you can contact your security company, insurance company, or local fire department.

Gas Detectors - This article will briefly explain the potential problems of carbon monoxide poisoning, gas leaks and the proper installation and maintenance of carbon monoxide (CO) and gas detectors. For additional information check your local library or you can contact your gas supplier, utility company, local fire department, or HVAC contractor.

Carbon Monoxide - CO is a colorless, odorless, and highly poisonous gas that is produced when fuels containing carbon are burned. It is about 3% lighter than air and as such tends to rise under normal conditions. It is dangerous because when it is inhaled it combines with hemoglobin, the oxygen carrying substance in blood cells, and prevents them from absorbing needed oxygen. This lack of oxygen causes headaches, nausea, followed by unconsciousness and ultimately death. As little as 1/5 of 1% may prove fatal in less than 30 minutes. CO is a particularly insidious gas since it is odorless and someone may be exposed to dangerous levels without knowing it.

Symptoms of Carbon Monoxide poisoning -

• Mild exposure - Slight headache, nausea, vomiting, and fatigue. These symptoms are sometimes described as "flu like".
• Medium exposure- Severe throbbing headache, drowsiness, confusion, fast heart rate.
• Extreme exposure- Unconsciousness, convulsions, cardio-respiratory failure, death.
• The disorientating effects of CO poisoning often prevent the victims from seeking help even though they are aware that they are not feeling well.

Each year many deaths are caused by CO gas escaping from furnaces, stoves, and fireplaces when the ventilation is not properly regulated. If you develop CO poisoning symptoms leave immediately and call your local fire department or ambulance if the symptoms are severe. You may also notify your local gas company or HVAC contractor.

If your CO detector activates you should leave the location immediately and check to make sure everyone got out. Call your local fire department, your local gas company or HVAC contractor. You can open the windows to ventilate the area and clean out the CO buildup. Do not take any chances, it is much better to call for assistance than to become another statistic.

It is also possible for CO poisoning to occur from faulty exhaust pipes on automobiles or trucks. If you begin to experience headaches or nausea while driving or riding in an automobile or truck, you should open the windows immediately and have the exhaust system checked.

Due to its lighter than air composition CO detectors should be located near the top of a wall or on a ceiling. Do not mount it directly in a corner since the normal movement of air causes a dead spot in that area. In addition do not locate it within 5 feet of a CO producing source, such as furnace, since false alarms may occur. Due to the unique composition of CO, detectors are specifically designed to react only to its presence and are not combined with other types of gas detection.

Natural Gas - Natural gas is actually a mixture of various hydrocarbons such as methane and ethane. Other gases are manufactured from petroleum or coal. Methane is also called marsh gas since it can be formed by the decomposition of vegetable matter under water.

Natural gas (methane), propane and butane are odorless in their natural state, although suppliers add sulfur compounds to produce the unpleasant odor we associate with gas. It is extremely toxic, combustible, and explosive in a mixture of only 5 to 14 %. The chemical composition of propane and butane make them heavier than air and therefore these detectors must be located low on a wall about 4 to 6 inches from the floor. Methane gas is lighter than air so the detectors should be mounted on the wall 6 to 12 inches below the ceiling line. If you are not sure of the type of gas used in your home you can contact your supplier or utility company. Since the molecules of these gases are very similar, a single unit can be used to detect their presence.

If your detector activates you should A) immediately extinguish all open flames, smoking materials, gas cooking appliances, etc. B) open windows and doors to ventilate the location C) do not turn on or off any electrical devices D) turn off the main gas supply valve E) leave the location F) call your gas supplier and have them check for and repair the source of the leaking gas G) only re-enter the location after the ventilation has removed all traces of gas. Remember to re-light any gas pilot lights that may have been extinguished when you turned the gas supply off.

Power and connection to security systems - The detectors currently available may be powered by batteries, 110 vac, 12 vdc, or 110 vac with battery backup.. Some 110 volt units have the ability to interconnect so that when 1 unit activates it will cause the horns in the other units to sound. Units may also be purchased that have a relay output for connection to any security system control or wireless transmitter. If you will connecting your detectors to your security system, they must be installed on dedicated 24 hour zones to insure proper reaction to an activation. As always, make sure that you completely read the detector instructions that are packed with each unit, and follow all of the manufacturers directions.

Monthly maintenance -

Cleaning- You should clean the outside of the detector with a vacuum or soft brush and make sure that no objects are blocking the unit or restricting air flow around it.

Testing CO detectors- These units are designed to detect only Carbon monoxide so they can not be checked for actual operation. If the unit is equipped with a test button you should use it to test the unit. If your detector is connected to a remote monitoring office please remember to notify your security company prior to testing.

Testing gas detectors- Unlike CO detectors it is possible to test natural gas detectors using a butane cigarette lighter. Once a month release a small quantity of gas from a cigarette lighter (make sure that there is no flame) directly into the unit. The unit should activate. If your detector is connected to a remote monitoring office please remember to notify your security company prior to testing.

Underwriters Laboratory Listing:

UL, a not for profit organization, has established standards for all components of security systems and their installation. If the product has the UL label it means that the device meets or exceeds their requirements. Does this mean that non-UL products are bad? Not at all, having it does mean that an outside agency, UL, has tested the product and found that it will perform its intended function safely. It is always a good idea to use products that are listed whenever possible. For additional information on UL, you can call their office nearest your home or business, or by calling the Northbrook Illinois office at 708-272-8800.