Industry Tips
Residential Alarm Systems
Your home may still be your castle, but these days you cannot protect it from fire by building it entirely of stone, nor from thefts by surrounding it with a moat and lowering a drawbridge only for friendly visitors. Today, instead of relying on human sentries posted at strategic locations, people frequently must turn to electronic devices to secure property against fire and burglary.
Fire alarms
Fire breaks out in more than seven million American homes each year, resulting in thousands of deaths and hundreds of thousands of injuries. Even though you scrupulously take precautions including using matches carefully, storing combustible materials safely and keeping your heating system in good repair, many fires start in locations you least expect or have no control over, such as appliance motors and hidden electrical wiring. Your television's 26,000 volts of stored energy can cause a fire hours after the set has been turned off.
Significantly, most serious house fires occur at night, while sleeping occupants miss the first signs of trouble. And since one byproduct of a smoldering fire is the odorless poison carbon monoxide, you cannot rely on the hope that you will awaken before some harm has been done.
A good early warning system, properly selected, correctly installed, and regularly tested, can do much to prevent loss of life and property. Heat detectors have the lowest false alarm rate of all fire detection devices, but they are also the slowest and therefore may not be the primary source of warning. Most fire-related deaths are caused by inhalation of smoke and poisonous gases rather than by burn injury. The U.S. Fire Administration estimates that use of smoke detectors and other fire alarms can reduce the loss of life from home fires by over 40 percent.
The widespread availability of fire alarms for residential use is a recent development. From an annual production rate of a half-million of these alarms in 1973, sales and advertising have increased rapidly in the 1980's. Part of that dramatic rise in sales can be attributed to recent legislation in about half the states requiring at least one fire alarm in all newly constructed housing units. Some building codes go further, requiring installation of one alarm or more in existing homes and apartments as well. In addition, the Department of Housing and Urban Development now requires at least one in all new mobile homes. Also, a number of insurance companies offer discounts on homeowner’s policies covering residences where fire alarms are installed.
How They Work
The approximately 100 brands of fire alarms available in the United States today are of two main types. (A gas-sensing variety sold in Japan does not meet U.S. standards.)
Ionization fire alarms have a small shielded piece of radioactive material that senses changes in the flow of electrical currents in the air when tiny particles of smoke drift into the detection chamber. Since blazing fires produce many small particles of smoke that float upwards quickly in the rising hot air, ionization alarms usually warn of open, flaming fires quicker than do other heat or smoke detectors.
The U.S. Nuclear Regulatory Commission reported in 1978 that the amount of radiation in ionization alarms is so minor that even constant exposure to it is insignificant. Advances in solid-state electronics have allowed some manufacturers to reduce the amount of radioactive materials in their alarms to less than one microcurie of americium 241, an amount within the most restrictive limits presently under consideration by nuclear safety regulatory agencies in various countries.
Photoelectric alarms use a photoelectric beam of light similar to the "electric eye" that opens doors automatically. This type of alarm "sees" particles of smoke when they are carried into the detector by room air circulating through it, scattering the beam of light. Large particles of smoke -- produced mainly by smoldering fires -- scatter light faster than do small particles, so this type of alarm is especially suited to sensing a smoldering fire before it erupts into flame.
Sources of Power
Whether to use an alarm which operates on house current or battery power is a significant consideration.
Alkaline batteries have a constantly decreasing voltage curve as they wear out. Nine-volt alkaline batteries -- the kind also used in transistor radios -- are readily available and relatively inexpensive. But some alarms using these batteries require periodic adjustment to maintain their sensitivity to smoke. Failure to readjust such an alarm could result in delayed detection or complete failure of the unit.
Mercury batteries have a constant voltage throughout most of their life, but they undergo such a rapid drop in voltage when they wear out that the reduced power available may shorten the operating time of the alarm horn. And the voltage may suddenly become so weak that it even prevents the unit from sounding the prescribed warning to indicate the need for a new battery.
Household electrical current, while offering a more steady source of power than batteries yield, presents several problems. You may have to hire an electrician, if no convenient electrical outlet exists at the best location for the alarm. A plug-in unit should not be used at an outlet controlled by an on-off switch, nor should it ever get its power from a distant outlet by means of an extension cord. Obviously, an alarm operating on household current is useless if the supply of power is cut off. The chance also exists -- especially where aluminum wiring is involved -- that a fire could actually start in the circuit which supplies power to the detector, causing the unit to fail even before it could sound an alarm.
Household current with a backup battery is the source of power in some of the newest fire alarms. In the event electricity is cut off, the battery automatically takes over. While the alarm is operating on household current, the battery voltage is being monitored. When reserve power in the battery drops to a low level, the unit sounds a warning -- even though the alarm is still on the primary power supply -- to signal that the battery should be replaced.
Performance Standards
In July 1977, Underwriters Laboratories (UL) adopted a standard for both photoelectric and ionization fire alarms. Standard 217 requires that alarms carrying UL certification must function at prescribed speeds in flaming test fires, exhibit overall electronic reliability, and pass sensitivity tests at low air velocities. Underwriters Laboratories has developed a test for smoldering fire and manufacturers are redesigning the models which could not pass it. Whatever fire alarm you buy should bear the UL seal.
Under early applications of Standard 217, a fire alarm could be certified if it performed correctly for a minimum of 30 days, providing it gave a warning before failure. Alarms which fail first after installation generally are photoelectric models using incandescent light bulbs. Newer models substitute light-emitting diodes (LEDs), with a projected life of 50 years, for conventional bulbs whose average life in fire alarms is three years. Present requirements for battery-operated devices call for at least one-year lifetime and an audible trouble signal lasting seven days when voltage drops to a predetermined level.
Most household fires produce both large and small particles of smoke, giving you a high probability of receiving adequate warning from either ionization or photoelectric alarms. Tests in typical houses by the Center for Fire Research, a part of the National Bureau of Standards, showed that even the slowest ionization and photoelectric units responding to both flaming and smoldering fires gave more than five minutes of escape time. The fastest alarm responded to a smoldering fire 33 minutes before flames built up enough to cut off escape.
Proper Location
For maximum protection, follow these rules for installing fire alarms:
1.) Because smoke rises, the best place to put an alarm is on the ceiling or high on an inside wall just below the ceiling. But since the area on either surface within four inches of where the wall and ceiling meet is a dead-air space that gets little circulation, avoid putting units there.
2.) If the ceiling is below an uninsulated attic or in a mobile home, place an alarm on an inside wall four to twelve inches below the ceiling.
3.) In a multi-level house, install an alarm on each level, especially if the house is air-conditioned. For basements, locate the alarm on the ceiling, near the bottom of the steps to the rest of the house. Likewise, for other floors, locate an alarm above the base of the stairway to the next level.
4.) Do not put an alarm within three feet of an air supply register that might blow smoke away from the unit.
5.) Do not install an alarm between the bedrooms and the air return to the furnace, because recirculated and diluted smoke will result in a delayed alarm.
6.) Corridors more than 30 feet long should have alarms at each end.
7.) An alarm should be installed close enough to the bedrooms that it can be heard when the doors are closed. If you usually sleep with bedroom doors closed, consider installing additional alarms inside each bedroom. If a fire starts in a bedroom, the alarm in that room will respond faster than the one in the hallway.
8.) Be sure to put an alarm in any room whose occupant has the dangerous habit of smoking in bed. (And tell him or her to stop smoking in bed.)
9.) Do not install a fire alarm in the kitchen, where cooking can trigger false alarms. Not only are false alarms annoying but they also deplete the power in battery-operated models. For adequate protection, locate a photoelectric alarm near -- but not in -- the kitchen.
10.) To obtain optimal coverage with several alarms, don't use a single type exclusively. One consumer testing service suggests installing both battery-operated ionization models and photoelectric units using the household current. You will find on the market single units containing both types of sensors.
11.) If you are installing more than one alarm, consider interconnecting them so that when one unit detects smoke, all units will sound their alarms. Pulling wires through the walls is a permanent method of connecting the units and may require the services of an electrician. Recently a new method has been developed using a transmitter operating on a radio frequency. No wiring is needed. The receiver is placed in a bedroom. When transmitter-equipped alarms detect smoke anywhere in the house, the receiver sounds an alarm in the bedroom. You can relocate the receiver in a neighbor's house up to 200 feet away when you're not home. The cost of a receiver and a transmitter-equipped detector is approximately the cost of two ordinary alarms; the method of interconnection can be done with units powered by either batteries or household current.
12.) Consult an expert about placement of alarms when unusual architectural features, such as cathedral ceilings, exist.
Routine Maintenance and Testing
The one essential requirement for maintaining fire protection with fire alarms is to test each one at least every 30 days and every week if it is battery powered. To perform this test, hold a candle six inches under the unit. If you're checking an ionization alarm, let the flame burn; for a photoelectric model blow the flame out and let the smoke drift into the detector. Within 20 seconds the alarm horn should sound briefly until you remove the candle and fan away the smoke. Using real smoke is more dependable than pressing the "test" button found on many models. In some older units the bottom only activates the warning horn and does not tell you whether the detector itself is working. Should the alarm not sound, check the power source and replace the battery or light bulb if necessary.
Follow the instructions supplied with your alarm for routine maintenance. At least twice a year, use a vacuum cleaner to get rid of accumulated dust and grime. Avoid extreme changes in temperature -- some early detectors still in use have components that malfunction at high temperatures even though no fire or smoke is present. Another early fire alarm, inoperable when the humidity exceeds 70 percent, should never be used near a bathroom or in subtropical climates.
It is important to realize that fire alarms themselves will need replacement at periodic intervals, perhaps a few times during the use of a home or apartment. One way to accomplish this might be to replace alarm units each time a house or apartment changes ownership or occupancy. Fortunately, competition has lowered the once formidable cost of fire alarms to modest prices, while at the same time the reliability of the units has improved dramatically.
Burglar alarms
According to the FBI, a burglary takes place in the United States every 10 seconds. Unlike fires, which do their worst damage at night, burglaries occur five times more often during the day than after dark. It's been estimated that 10:30 to noon and 1:30 to 3 p.m. are the most likely times for residential break-ins, although nighttime burglaries have increased in recent years. Some studies show that less than 10 percent of all stolen property is ever returned to the victim, and FBI statistics indicate that only a small percentage of burglaries are eventually solved.
Know Your Options
No such thing as a completely burglar-proof alarm system exists, regardless of what an enthusiastic salesperson tells you. No national standards specify required levels of performance, and the best protective device cannot compensate for a lack of basic common sense. The appearance of your house can deter thieves or offer an invitation to burglary. Many police departments throughout the nation are cooperating in an Operation Identification campaign to prevent break-ins. Contact your local police department to arrange for a free inspection of your premises. If you feel the need to upgrade locks, trim shrubbery or engrave all household items with an identification number, you have two choices: hire a company to install an alarm system, or do it yourself.
Naturally, in a matter as crucial as the security of your family and your possessions, you need to be especially careful in deciding on the type of alarm system to use and who will install it. Check with local authorities to see whether ordinances control the types of alarm horns or bells you may use. Some companies are more interested in
how much they can sell you than in whether the equipment is both reliable and right for your circumstances. Do not fall for scare
tactics aimed at convincing you that most burglars are also child molesters or rapists. Your police department and the national Burglar and Fire Alarm Association can help you locate reputable alarm companies in your area. You may then want to check with Better Business Bureau. Another safeguard is to be sure that all equipment you purchase or lease has been tested by Underwriters Laboratories. Your best protection is to be fully informed about the types of alarm systems available, so that you can ask knowledgeable questions and make intelligent decisions.
Sensors
Like fire alarm systems, burglar alarms rely on well-placed sensors to detect trouble. Two main categories of sensors are available: those that encircle your house, monitoring the perimeter, principally windows and doors; and volume detectors that monitor interior spaces.
Magnetic contacts are the most commonly used perimeter devices. They consist of a magnet on one surface of the door or window and a switch opposite it on the door or window frame. Opening the door or window breaks the magnetic connection and triggers the alarm. These magnetic switches can be put on doors that can be reached from the ground and on upper windows and balcony doors that have access from nearby trees or roofs.
One drawback is that, given time and privacy, a burglar can bypass a switch entirely. Using the cover of shrubbery at a side entrance, for example, he could enter by sawing a hole in the door instead of opening it. If a wooden door is not visible to neighbors or passersby, you might want to consider replacing it with a metal one.
Wired screens, custom-made for each window, have an unobtrusive alarm wire woven through them. If a screen is cut or removed, the alarm sounds. While it should not be difficult to replace conventional screens with these designed for security, be sure to ask whether these are compatible with combination storm-and-screen windows if you have them or think you might want to add them later.
The advantages of perimeter sensors are their ability to detect a would-be intruder before he can get inside, the relatively low cost of the materials involved, the unlikelihood of a false alarm unless you forget the system is turned on and try to open a door or window, and the low voltage used to operate the system.
The chief disadvantage is the great amount of labor involved in custom-making the screens and in writing and connecting the switches and screens. This becomes even more complicated if you want the wiring hidden. A wireless system has recently been introduced, using switches connected to transmitters about the size of a pack of cigarettes. When a switch is opened, the transmitter signals a master receiver to sound the alarm. Since every switch must have its own transmitter and battery, you should consider the additional expense. And transmitters are not as easy to conceal as wires.
Pressure mats are spot protectors closely related to and frequently wired into the same circuit as perimeter switches. They have flat switches activated by pressure from a footstep and are generally installed under carpeting in doorways, under windows, in corridors and at the base of stairways. They are sometimes put in front of valuable objects, such as cabinets containing rare collections. Usually, switches in such mats are set to open when subjected to pressure above a given minimum -- 20 pounds, for example -- so that pets won't trigger the alarm.
Photoelectric beams, operating on the same principle as photoelectric smoke detectors, sound an alarm whenever someone walks through the path of the beam. Unobtrusive units are available, some even designed to look like a book on a shelf or
table. Locating them properly can pose a problem, however: if you have them aimed high enough so that pets and small children moving freely throughout the house do not cause false alarms, you run the risk that a clever burglar can go about his business
undisturbed, merely by crawling through the room on his hands and knees. Low-power laser diodes, a new component, have brought improved reliability to photoelectric systems.
Ultrasonic sensors, about the size of a table-model radio, or professional models which attach to the wall or ceiling, bounce inaudible sound waves off furniture and walls. With some models no wires or switches are needed -- you can just aim a unit toward the area you want protected and plug it into any electrical outlet not controlled by an on-off switch. This feature makes ultrasonic sensors convenient for apartment dwellers and people who change residences frequently.
Unlike photoelectric beams, an ultrasonic sensor is virtually impossible to outwit, because it detects all motion in the area, regardless of its source. This sensitivity is a mixed blessing, though. Ultrasonic detectors as a class have a very high false alarm rate, since they can be triggered by air currents from heating and air conditioning vents and even by the sound of a ringing telephone. New models with electronic "brains" are designed to tell the difference between random disturbances and actual intrusions. If you consider purchasing this type of alarm, insist on an in-home demonstration. Most people cannot hear ultrasonic sound waves, but the high-pitched sound bothers some people and most animals.
Microwave sensors, like ultrasonic ones, detect motion in a specific area. They are more expensive than ultrasonic detectors but are good in large open areas. Because they penetrate most building materials, you can protect more than one room at a time. That characteristic, however, can trigger false alarms from motion in an adjoining apartment and even from passersby such as your letter carrier or meter reader.
Control Units
The control unit is the heart of the system. Activated by an indoor switch or an outdoor key, it receives the information that a sensor has been disturbed and triggers the alarm. Devices called panic buttons can be connected to the control unit. They allow you to activate the alarm by pushing a button and are usually placed inside the front door or by your bed.
Be sure that any control unit you use allows sufficient time for authorized people to enter and leave the house without sounding the alarm. Some units have "good neighbor" automatic shutoffs after a certain time to keep an alarm powered by household current from ringing indefinitely. A tamper switch, which sounds the alarm if anyone tries to open the control box or rip it from the wall, is also a good idea. Medical alert can also be added to the control capability along with digital dialer reporting to an alarm company of your choice.
Alarms
A local alarm is the simplest to install and the least expensive, if your goal is to frighten the burglar and alert people in the immediate vicinity. For maximum range, the alarm device is usually located in the attic or under the eaves of the roof. Some people invest in an inexpensive burglar alarm and connect it to their stereo speaker and outdoor floodlights. Others wire the alarm system into an intercom
system already present in the house. For most homes, an eight-inch bell is sufficient, though if you are wiring together all your fire alarms, you might want to wire your burglar alarms to sound throughout the house as well. In that case, be sure to use two distinctly different signals, such as a bell for burglary and a siren for fire.
Whatever system you select should have standby power. Battery-powered alarms gradually run down, and crafty burglars have been known to wait until the alarm dies out and then go on about their business. Professional burglars are, of course, well known for cutting electric and telephone wires.
A remote alarm can work in several ways. It can send a prerecorded message -- such as "This is John Doe. A burglary is in progress at my house, located at 1234 Main Street. Please call the police" -- over telephone lines to an answering service, a neighbor or a relative. To be effective, this method depends on someone being present to answer the telephone and notify police (the answering service being most dependable). In some areas you may be able to transmit the alarm signal directly to the police department. But because of numerous false alarms, many jurisdictions no longer allow this. A third option is to pay a monthly service fee for the privilege of sending alarm signals to a private security company. In addition to notifying the police, some security companies also send someone immediately to your home to investigate.
Costs
Do-it-yourself systems are available in hardware, catalog, and electronics stores and from locksmiths. Because you supply the labor, you can usually install a burglar alarm system for less than you would pay to have it professionally installed. If you are handy and electrically inclined, you may want to consider this approach for a simple system. However, if you are thinking of a more complex fire and burglary system, you will also want at least to consider a professional alarm company. The object of your system is to have it working properly at all times. To guarantee this level of depend-ability, it usually takes 24-hour professional back-up. If you decide to hire professional installers, plan carefully in advance and wire the entire house on the basis of your most ambitious plan for both burglar and fire alarm systems, even if you do not add some components until later.
Costs for different alarm systems vary greatly, not only for the equipment but for other reasons such as the amount of wiring required, the construction material for your house, and telephone rates if you need a line for a remote alarm. Some professional alarm companies sell systems; others lease the equipment.
In dealing with an alarm company you will usually receive two cost figures: the installation charge for the burglar or fire alarm system or both, and the monthly service charge. Study the contract carefully. Never sign a contract which does not list the points of protection and does not itemize the equipment to be installed. Typically, alarm company service contracts are for two to five years. Be sure the contract spells out clearly the company's responsibilities for maintaining the system.
Alarm Checklist
When shopping for an alarm system, whether to protect against fire or theft, be sure to follow these tips:
- Find out about local building codes and regulations regarding such systems.
- Know your options. Consider the advantages and disadvantages of each system and decide which will be best for your particular situation.
- Deal only with reputable firms. Call Better Business Bureau for a Business Review.
- Do not be pressured into buying more than you really need.
- Look for systems which bear the UL seal.
- Get bids from several installers. Be sure they include all costs.
- Study the contract carefully. Be sure it includes in writing all promises, service obligations and a warranty.
