Home Security

Home Security Terms

Surface-Mounted Deadbolt

  • Squarish in shape and mounted on the surface of the inside of the door.
  • The bolt may be turned with a key or a turn knob.
  • Instead of sliding into the door frame, the bolt slides into a surface-mounted strike.


  • Usually an entry set that combines a lockset with a deadbolt, the deadbolt is located just above the knob or handle. Can be a one- or two-piece unit.
  • Available with both single- and double-cylinder deadbolts. Styles of locksets also will vary widely.
  • Available in a variety of styles and finishes.

Mortise Lock

  • Consists of a flat, rectangular box that fits into a recess in the door from its edge. Also includes two faceplates that include the knobs and keyholes.
  • Available in right- or left-handed styles.
  • Has a pin tumbler locking mechanism in a cylinder.
  • Latch operates from either side except when the outside knob is locked.
  • Deadbolt operates by a turn of the inside knob.
  • A key from the outside operates both the deadbolt and latchbolt.
  • Used on many types of doors, from heavy entrance doors to apartment buildings and residential doors.

Night Latch

  • Installed on the inside surface of the door.
  • Has an automatic locking feature. The large, spring loaded latch automatically locks whenever the door is closed.
  • For light security and usually used in combination with another lock.

Keyless Entry System

  • For advanced home security and convenience.
  • Audio and visual indicators confirm the lockset is activated.
  • Uses a keypad on the door or a remote control to open the door.
  • Some models will sound an alarm after the incorrect code has been entered more than three consecutive times.
  • Anti-theft rolling code feature ensures the same code is never used twice.
  • Some systems are compatible with some garage door openers so the homeowner only needs one remote.


  • Consists of a metal hinge and an anchoring bolt so locks can be secured to gates, sheds and garages.
  • Conceals the mounting screws when the lock is in place.
  • Insert a padlock through the ring and lock to secure the hasp.
  • Another type is the hasplock, which has a padlock attached to it, which makes it impossible to lose the padlock when the hasp is open.

Barrel Bolt

  • A sliding lock mechanism used to provide security for average weight doors and windows.
  • Is surface mounted where the bolt slides into a catch on the other side of the door.
  • Available in decorative finishes and with surface or universal strikes.
  • Some have spring action to hold the bolt in place, and some are lockable.


  • The metal plate the latch slides into on the doorjamb or frame.
  • All new locksets come with strikes, but some homeowners may want to replace them with high-security strikes or replace damaged ones.
  • Adjustable strikes are available that provide 1/4” adjustment to allow for door and frame warpage.

Latch Guard

  • Used on in-opening doors.
  • Reinforces the door and prevents spreading of the frame.
  • The standard 7” latch guard fits all backsets, deadbolts and key-in-knob locks.
  • The 12” latch guard also fits all double locks, mortise locks and access control locks.
  • Latch guards for out-opening doors protect the latch or bolt. Several sizes and types are available, ranging from 6” to 12”.

Combination Lock

  • User must dial a combination to open the lock.
  • Hardened solid steel alloys make better locks and shackles.

Pin-Tumbler Padlock

  • Provides maximum security for valuables.
  • Pin-tumbler locking mechanisms make padlocks harder for thieves to pick.
  • Tumblers with five or more pins provide the best security, while four pin is the next best.
  • Hardened solid steel and steel alloys make better locks and shackles.
  • Solid extruded brass padlocks are more resistant to rust than steel, but can be damaged more easily.

Tubular Cylinder Padlock

  • Offers many key changes by replacing the cylinder.
  • Usually used in electronic security systems, but some owners of motorcycles and expensive bikes use them as well.
  • Pins are arranged in a circle and are exposed.
  • The key is cylindrical.

Cable Lock

  • Uses the combination of a lock and cable to lock and secure objects in a variety of applications.
  • Some models have a chain or cable permanently attached to a combination or keyed lock.
  • Chain or cable often has a protective plastic coating to prevent scratching.

U-Bar Lock

  • Provides maximum protection for bicycles, gates, etc.
  • Hardened steel shanks resist cutting.
  • Available in combination lock or keyed lock versions.

Gun Lock

  • Fits over the trigger housing of guns to prevent firing of the weapon.
  • Some models have a sound alarm to warn that the gun is being tampered with.
  • Some have tamper-evident devices to alert owners that the gun has been disturbed.
  • Some models can lock multiple guns at once.

Trailer Lock

  • Used to secure standing trailers by rendering the towing device inoperable.
  • Locks cover or fill the coupler socket so it cannot be mounted on a ball.

Home Intrusion Alarm

  • Wide variety of types available. Selection will depend on what you want to accomplish. Some feel a loud alarm at the point of entry will scare away the intruder. Others prefer a remote alarm located in a bedroom that will alert only the homeowner. Others prefer an outside alarm that will alert neighbors. Other kinds will sound an alarm and are connected directly to monitoring systems that will alert the police.
  • Simple alarms may consist of a door-locking device with a buzzer attached. When the device is tampered with or the door opened, the alarm sounds.
  • Many intrusion alarms are more elaborate and have twocomponents. A perimeter alarm detects intrusion at points of entry, such as door and windows. An area alarm detects motion inside a room.

Home Perimeter Alarm

  • Some types use low-voltage wire, similar to stereo speaker wire, to connect magnetic window and door sensors to a control panel.
  • Other types use radio transmitters at each door and window sensors to trigger an alarm at the control panel.
  • Alarm sounds when the window or door opens.
  • Alarm systems designed for d-i-y installation are frequently battery powered, so ease in testing the batteries can be an important feature. Some systems sound a warning when the batteries are low.
  • Hard-wired systems may have a button on the control panel that checks the entire system.

Home Area Alarm

  • Uses either ultrasonic waves or microwaves to detect motion. When it detects motion, it triggers an alarm.
  • Generally plugs into a standard electrical outlet, so they’re easy to install.
  • Ultrasonic detector waves only go as far as the wall of the room, while microwaves penetrate walls and windows.
  • Some ultrasonic alarms use a narrow sonic beam that must be bounced off a hard surface. Here, the intruder must break the beam to be detected.
  • Other ultrasonic alarms use a wide beam that fills the room and detects motion anywhere in the trap zone.
  • The most important consideration with this type of alarm is avoiding false alarms. These can be caused by air conditioners or drapery moving above a hot air register. Better systems have built in circuitry that does not respond to these types of signals.
  • Some systems have extra repeater alarms or satellites. These can be plugged in anywhere in the home to add extra noise and relay the warning to remote rooms.

Ionization Fire Detector

  • Measures the changes in electric current caused by invisible particles ionized in the heat of combustion.
  • Transforms air inside the detector into a conductor of electric current. When smoke enters the detector and impedes the flow of current, the alarm sounds.
  • Responds particularly well to the smoke caused by a flaming fire.
  • Requires little power and is effectively powered by household batteries.
  • Slower to respond to a smoldering fire.
  • Detectors are required to emit a low warning when batteries are weak.

Photoelectric Fire Detector

  • Uses a small lamp adjusted to direct a narrow light beam across the detection chamber. Smoke entering the chamber scatters this light beam, causing it to hit a sensor and set off the alarm.
  • Usually more sensitive to smoke from a slow, smoldering fire than an ionization detector, but reacts less quickly to flaming fires.
  • Available in both battery-operated and plug-in versions.

Thermal Fire Detector

  • Used primarily by large commercial firms.
  • The alarm sounds when the temperature rises to a certain level.
  • Most are also triggered by a quick rise in temperature even if an extreme temperature is not reached.
  • Not as safe as other types of fire detectors as fire usually must be intense before the thermal unit will sound.

Carbon Monoxide Detector

  • Detects carbon monoxide, a colorless, odorless, deadly gas that poses a potentially deadly health risk to people.
  • Measures the amount of carbon monoxide over time and sounds an alarm before people would experience symptoms.
  • Operates on batteries or can be plugged in.
  • Some models provide a running digital readout of CO levels.
  • Hard-wired or plug-in models typically use some type of solid-state sensor, which purges itself and resamples the air periodically. That cycle increases the power demand.
  • Battery-powered detectors typically use a passive sensor. They will operate even in case of a power failure.
  • Available in combination units that have CO and smoke detectors in the same unit.

Alpha-Track Radon Detector

  • Detects radon, a colorless, odorless, radioactive gas formed wherever there is uranium, an element present throughout the crust of the earth. It poses little risk if it makes its way to open air, but if it seeps into a house, it can collect in hazardous concentrations.
  • This detector consists of a small sheet of plastic. Alpha particles that strike the plastic cause microscopic pockmarks.
  • After an exposure period, users mail the detector to a lab. The lab’s count of the pockmarks gives a direct measure of the mean radon concentration.
  • Another type uses activated-charcoal granules, which trap radon gas. After an exposure time, the container is resealed and shipped back to a lab for analysis.

Continuous Monitor Radon Detector

  • Plugs into a standard outlet.
  • Samples air continuously for radon and provides updated reading on the display.
  • Alarm sounds when the long-term average of radon level passes an acceptable level.
  • Alarm will be repeated until the radon level drops back to the accepted level.

Carbon Dioxide Extinguisher

  • Extinguishes Class B and C fires.
  • Class B fires involve flammable liquids, gases and greases.
  • Class C fires involve electrical equipment or wiring where the electric non-conductivity of the extinguishing agent is important.
  • Has a limited range and is affected by draft and wind.

Dry-Chemical Extinguisher

  • Some types extinguish only Class B and C fires.
  • Includes sodium and potassium bicarbonate base agents.
  • Some types are marked general-purpose or multi-purpose. These types can be used on Class A, B and C fires.

Foam Extinguisher

  • Extinguishes Class A and B fires.
  • Class A fires are the most common type. They involve ordinary combustibles such as wood, paper, cloth, rubber and many plastics.
  • Not effective on flammable liquids or gases escaping under pressure.

Fire Safe

  • Protects valuables and documents exposed to fire.
  • According to UL, a fire safe should maintain an inside temperature below 350º for an hour or more.
  • The safe should also be resistant to rupture and explosion at these temperatures.
  • Some safes can be mounted in walls, floors and other areas.

Fire Safety Ladder

  • Used to escape from an upper story window.
  • Comes in varying lengths, but most are sold for second-story rooms.
  • Features include tangle-free designs, compactness and strength ratings of the lines and footsteps.

Passage Lockset

  • An interior lockset used inside the home in hallways or closets between rooms where privacy is not important.
  • Has two, non-locking knobs, one on each side of the door. Some models use levers instead of knobs.
  • Available in a wide variety of styles and finishes.

Privacy Lockset

  • An interior lockset.
  • Designed for privacy rather than for security.
  • Has a locking button on the inside knob but no key device on the outside knob.
  • Can be either a knob or a lever.
  • In an emergency, the lock can be opened from the outside by inserting a narrow object through the small hole in the outside knob and either depressing or turning the locking mechanism inside, depending on the type of lock.
  • Available in a wide variety of styles and finishes.

Dummy Knob

  • Used only for decoration or applications that do not need a latch.
  • Has no latching mechanism and does not turn.
  • Available in a wide variety of styles and finishes.

Entry Lockset

  • Two doorknobs that can be locked from both the inside and the outside.
  • One type locks from the inside by turning or depressing a small button, while a key must unlock the outside knob.
  • Some models must be locked with a key on both the inside and outside.
  • In other models, only the inside knob can lock or unlock both sides of the set.
  • A medium security entrance-door lock.
  • A quality feature on entry locksets is a deadlatch.

Deadbolt Lock

  • Provides maximum security on a door.
  • Called “dead” because there are no springs to operate the bolt. It is only operated manually with a key or a thumb turn from the inside.
  • The bolt locks the door to the frame and helps prevent someone from prying the door open.
  • The throw is the length the bolt is extended from the lock housing.The industry standard is a 1” throw.
  • Locks are designed to fit specific size holes and backsets. Backset refers to the distance between the edge of the door and the center of the handle.
  • A single-cylinder deadbolt is operated with a key from the outside and with a turn button on the inside. It is used mostly with solid metal or wood doors.
  • A double-cylinder deadbolt is operated with a key on both the inside and outside. It is best used on a door with glass in or around them as the style prevents someone from breaking the glass, reaching in and unlocking the door.
  • Double-cylinder deadbolts can pose a danger during an emergency. If the key is missing or not readily available, people could be trapped inside a locked house. In some areas, codes may not permit this style of deadbolt.