SAFETY AT HOME
Aug 1, 1998 12:00 PM, Steve Filipini
So you've been installing residential sound systems for some time now, andyou're thinking about branching out to include home automation and securitysystems. The transition is not as difficult as you might think. In fact,the skillsyou've developed installing sound systems is an excellentfoundation to build on.
The hardest thing you need to do is run cable from a central location toeach point of protection without disturbing the decor of the home. This canbe a challenge when you are dealing with unique building structures andinterior decorators. The former can be overcome with a little imaginationand some cable running experience. The latter can be the toughest hurdle.
Let's start with the easier challenge. The main control panel for a basicsecurity system needs to be in a central location. This will cut down onthe length of cable runs and (under the right conditions) balance thecurrent draw among peripheral devices. Each point of protection needs a 2-4conductor, 22 gauge cable homerun back to the main control panel. Most ofthe sensing contacts on the market today use only two conductors; the othertwo are nice to have around for spares in case of a break from a misguidednail. With each cable homerun, you can identify each opening individuallyand group them according to area or room. The point of protection can be assimple as a single door or window, but getting the cable to it can be anissue.
If you have an open attic or basement that runs the length of the home, youare in a security installer's dream house. Thick shag carpet in every roomto cover any baseboard drilling is an added bonus. If you come across ahome with wood floors, no basement and a flat roof, you've entered a homethat will test both your imagination and patience.
Attics are nice but not always friendly. Freshly blown insulation is ablast to roll in on those 100 degrees F days. There is also the chance ofcritters living in the attic. I used to be the attic monkey when I wassmaller in stature . They would tie a cable to my ankle, tape a flashlightto my head and send me on my way. Elbows and toes were relied upon heavily.I never stepped through the floor of the attic into the room below, butmany times it was close. Once, when I was in my immortal years and mishapsfell upon other people, I was halfway into a tight fit crawl of 75 feet (23m) when the cable attached to my ankle snagged on a turn some 20 feet (6.1m) behind me. As I rested (elbows and toes on the two by four supportsbelow me, I was suddenly aware that I was resting above a 4'x 8' (1.2 m x2.4 m) sheet of mirror that was bolted to the ceiling of the room below me(master bedroom, of course). It took me an additional hour of backing up tothe snag and pulling enough cable up to get to the other attic hatch.
Carefully remove the baseboard and look for channels to route the cable.That's just one suggestion. Each home is different and presents variousopportunities for learning the fine art of hiding the cable from view. Butenough of that. You do that now with speaker cables. Let's assume you'vereached the wall with your cable, now what?
Some walls are filled with paper-backed insulation. If you can get betweenthe paper and the inner wall, snaking a cable is a breeze. Some walls arefilled with blown insulation. If you're not patient, it can bunch up andstop you from getting through. Some outside walls have the injected foam.Depending on the material, you may need to find another route for yourcable.
Your best friend will be the three to six foot (0.9 m to 1.8 m) flexibledrill bit. In the right hands, you can slide the length of the bit into apilot hole and maneuver around the inside of the wall until you reach todesired spot to drill through to the next floor level or up into an atticspace. Be certain of the direction the drill bit is headed when it isrotating and you are applying pressure to bore through the obstructivematerial. One nail in the wall can detour the bit either to exit a work ofart hanging on the wall or gather up (melting them together to the drillbit) strands of shag carpet while coming up in the middle of the livingroom carpet.
If you have long hair (like me), tie it back. I've seen parts of someone'sscalp flapping wildly around the shaft of the bit when they got too closeto the drill while it was in use.
Once you have run a cable from point "A" to point "B", you need to drill ahole for the contact and magnet that senses the opening and closing of thepoint of protection. The type of opening and the building materials usedwill determine the style of contacts. The style and range of the contactwill determine the drilling methods used. Refer to the documentation thatis usually packaged with the contacts. In today's market, the smaller andless obvious contacts are preferred. One widely used style of contact isthe barrel contact (so named because of its round barrel shape). These comein two sizes for the common installation, 1/4 inch (6.4 mm) or 3/16 inch(4.8 mm) diameter and are recessed into the door/window and its frame. Aslong as the contact and magnet line up when the door is closed, theprotection loop is in a closed circuit condition, and everyone is happy.When installed correctly, if you open the door/window with the systemarmed, the bells and whistles will sound off. Another type of contact isthe step contact, so named because of its small rectangle shape with a"step" protruding from the length of the contact to accommodate mountingscrews. These usually have double-back tape stuck to the backs for quickinstallations. One thing I have found when using both types of contacts isthe addition of clear silicone adhesive. With barrel contacts, fill theholes the contact and magnet will occupy to seal the wooden frame frommoisture and keep the contact/magnet from falling out of its location. Thestep contacts will stay in place longer when a dab of silicone is appliedat the ends of the contact/magnet to re-enforce the bond with the protectedframe. Areas of high humidity or extreme heat (window sills that face mostof the sunlight in summer) will loosen or dry out the adhesive material.This will result in minor vibrations causing the contact/magnet to fall offthe protected area. If the system is armed (which is usually the case whenthis happens), your customer will experience a false alarm.
A word to the wise, silicone, no matter how well you wipe your hands clean,will leave an oily film on your fingers that counteracts the sticky stuffon electrical tape when taping up splices. This has been a problem when youbelieve the splice is properly insulated only to have the tape fall off themoment you coil the splice into a splice can and secure the lid. Caution(or another set of clean hands) should be used when taping up aftersilicone has been opened and used.
Now's a good time to talk about how improper splices may have an adverseaffect on your wiring. I'm from the old school of solder and tape. Full,shiny solder splices reduce loop resistance and false alarm potentials. Beaware that some inventive installers have been known to use Bic lighters inplace of soldering irons. While using this unorthodox method, solder tendsto drip into the well of the lighter flint. This sometimes keeps the fueltrigger from fully closing when it is released, and you can end up slippinga lit lighter into your shirt pocket. It took me two shirts and the aromaof smoldering flesh to realize that maybe I needed to invest in a decentsoldering iron. You may want to look into a portable butane soldering pen.They are easy to refill, and they don't require an AC outlet for power.
I've followed up on many installations where the installer thought a tightwrap of two wires and tape would hold just fine. The problem is, wire is ametal-based object. Metal has the uncanny ability to expand and contractwith changes in air temperature. A series of warm and cold days will looseneven the best twisted splice and start raising the resistance of theprotected loop. This will cause false alarms and, in some cases, theinability to arm the security system. Some installers use a splice cap I'veheard referred to as "Chiclets". Just strip the wires, twist together andslide this cap over the exposed wires. Using a crimping tool, applypressure on the body of the cap. This collapsesthe metal wrap inside thejacket of the cap (complete with tiny teeth) and secures the cap.
Interior motion sensors (infrared or IR sensors to be exact) are a littleeasier to install, depending on the location of the motion sensor. Themotion sensor looks at the temperature of the protected area's walls andfurniture. Once stable, the sensor will trip when it detects a rapid,concentrated +/-10degrees F change of temperature. Motion sensors areusually placed in the corner of a room about five to six feet (1.5 m to 1.8m) from the ground and are aimed to cover as much of the protected room aspossible. This is dependent upon the style and range of motion sensor. Somepoints to remember:
* Do not aim motion sensors at heating/cooling ducts.
* Do not aim motion sensors at outside windows where sunlight and halogencar headlamps may shine directly into the motion sensors lens.
* Do not aim motion sensors at system keypads (unless the customer doesn'thave a problem remaining immobile during the arming sequence).
* Do not aim motion sensors at doors of entry leading from the outside. Themotion sensor may detect the outside temperature change before the doorcontact trips to begin the entry delay.
* Do not aim motion sensors at fireplaces. Log flare ups after the customerhas armed the system can cause the motion sensor to trip.
Unless the manufacturer of the motion sensing device guarantees thathousehold pets will not set off the unit, do not install or use motionsensors with the system. No matter how insistent the pet owners may be thatthe pets are well trained, dogs and especially cats will climb up on thefurniture and countertops. Some manufacturers supply "Pet Alley" lensesthat will cut off the sensing range of the sensor from the floor to about 3feet (0.6 m) off the ground. This is fine if your pet is old and can'tjump. Cats are notorious for walking along and suddenly jumping up in theair for no apparent reason. Don't cheat by taking a standard lens motionsensor and mounting it upside down. You may keep the sensing field off ofthe ground, but you are now sensing all temperature changes at the ceilingof the room. Refer to the packaged instructions.
Fire circuits are done a little differently. In order to supervise the firesensing devices on the loop fully, you need to leave the main control panelwith a two or four conductor (the main control panel and model of smokedetector will decide that one for you), 18 gauge approved fire wire cable.This cable is red with a fire retardant jacket. From the main controlpanel, go directly to the first fire-sensing device. >From there you go tothe next one and so on. At the last device, include an end-of-line resistoror module. This will monitor the circuit for breaks in the sensing loop orpower source. This is the only way you should wire the fire circuit; anydeviation can prove fatal to the customer.
Smoke detectors have no business being installed in kitchens (for obviousreasons), garages or dusty attics. Heat detectors are designed to protectthose areas, and they come in various styles and temperature ranges. Someare one-shot types that are destroyed when a flame or source of highlyconcentrated heat is detected; others will sense the heat, trip and resetwhen it cools down. Standard temperature ratings are divided into tworanges, 135degrees F and 199degrees F. The 135degrees F detectors can gointo kitchens and small, enclosed areas. The 199degrees F detectors can gointo garages, hot water closets and attics. The manufacturer's spec sheetsthat are packaged with the detectors will guide you further on making theproper selection.
Next comes the user interface keypads. These can be placed near entry andexit doors for easy arming and disarming of the system. Customers need tohave one in or near the master bedroom for quick reference and access inthe event of an alarm condition. Mount at eye level, and a four conductorwire is usually used in today's systems. Most interior walls are hollow andeasy to run wires through.
Want to alert the neighbor's of an alarm condition? Use a loud, penetratingsiren. Sirens need to be located in a secured area that prohibits outsidetampering. Many installations have the siren placed in the attic facing outa ventilation grill. The louder the siren, the quicker the response in theevent the alarm trips. If you need to locate it at street level, ahigh-quality metal enclosure (or something that won't easily rust) withbuilt in tampers is recommended. The enclosure should have a rear tamper todetect the box being removed from the wall and a front tamper to detect thebox being opened (well, from the front). The cable run for the siren shouldbe at least 18 gauge and the tamper circuits should be at least 22 gauge.
Now, you probably want this security system to be monitored by a local (ornational) monitoring center. To do this properly, you need to run a fourconductor, 22 gauge cable from the main security panel to the phone boxlocated on the side of the house. This is where the phone company ties inthe outside world.
The next step is required. All house phones (from one designated line) needto be wired through the security panel (see Figure 1). To do this, you needan RJ31X (or clone) line seizure interface phone block. This 8 pin,standard phone module interfaces the security panel and the incoming phoneline to allow instant separation of the house phones from outside callers.In the event of an alarm, you need the ability to take full control of theoutside phone line to provide a clear dialing path to the securitymonitoring center. This stops would-be burglars from breaking in andlifting a phone from the receiver, thereby interrupting any outgoing callsfrom the security panel. Wiring is easy. The red (ring) and green (tip)wires from the street tie into terminals four and five (respectively) atthe RJ block. From terminals one and 8 eight of the RJ block, you wouldconnect the house phones. There is an 8 pin RJ cord that plugs into theblock, and depending on the security panel, it either wires in or plugsinto the main security panel. The rest is laying the wires down to theappropriate terminals and programming the panel to provide the featuresdesired. Wiring the points of protection and peripheral devices is a snapif you know the difference between series and parallel circuits.
If you were smart, you labeled the cables leaving the main control panelwith their final destination. If you live in the real world, you didn't.There are a few methods to identifying cables. For keypads and otherobvious devices (meaning that they are not door/window contacts) I use atone generator and sound pick. The pick will "hear" and amplify the tonesfrom the generator. It requires some leg work, but quite effective.
To determine the end location of each door/window cable, I wire them intothe security panel and program each point with a generic number. Then Ifire up the system and place the system into a chime or walk test mode.Most of today's systems have this feature. From there, I walk around andopen points of protection, keeping track of the location with the genericname that appears at the keypad. Then I go back and properly label andsecure the points of protection. One easy way to lay out the system'sdoor/window zoning pattern is to face the front door from inside the homeand call it point number one. Go to the next perimeter point to your rightand call it point number two and so on. Then do the same with the interiordetection devices. This way, you will always know where you are in thelayout by knowing at least one point number.
Doors and windows are either individually wired into the main control panelor series together to group points of protection from a common area to onesensing zone. The rule of thumb is no more than three points should becombined. Keypads and power for the motion sensors are wired parallel. Allkeypads go to one set of terminals, and all power for the motions go toanother. Sometimes the security is so large you will need to use anexternal power supply to burden some of the load off of the control. That'sa judgment call, but always lean towards supplying more than the immediatedemand requires. You'll save on fuses and service calls.
An unswitched AC outlet that's within at least 20 feet (6 m) from the mainsecurity panel is best for the location of the system's power transformer.Use 18 gauge wire and secure the transformer to the outlets cover plate toensure it doesn't fall out or get bumped out of the outlet.
Well, after looking at the information in this body of text, it's apparentthat even though there are a lot more cables to be reckoned with, the basicconcept is the same. All security systems use the basic rules of detectionand wiring. The more sophisticated the panel, the more creative thefeatures, the most flashy display, the loudest siren and the scariestlooking keypad on the market still rely on the contact at the point ofprotection to open when the system is armed. I'll admit, there is a lotmore to becoming a full fledged security installer, but understanding thebasics is the first step to getting there.