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Door Alarms Helena MT

Local resource for door alarms in Helena. Includes detailed information on local businesses that provide access to portable door alarms, burglar alarms, door wedge alarms, door knob alarms, vibration sensors, and home security systems, as well as advice and content on security door stops.

Northerntier Fire & Safety
(406) 475-3208
124 E Lyndale Ave
Helena, MT
A & U Security
(406) 458-9668
813 Rinay Rd
Helena, MT
Bud's Extinguisher Svc
(406) 449-3032
789 Carter Dr
Helena, MT
Action Fire Extinguisher Svc
(406) 439-7010
PO Box 521
East Helena, MT
Smith & Wesson Security Services of MT
(406) 443-7233
1420 Cedar Street
Helena, MT
Alternate Phone Number
Security Systems for Home or Business
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Guaranteed lowest rates of any company in Montana

(406) 449-6616
614 N Last Chance Gulch
Helena, MT
Securitas Security Svc USA Inc
(406) 443-2368
1123 Euclid Ave
Helena, MT
Fire Guys Leasing Inc
(406) 442-4980
3203 Cooney Dr
Helena, MT
Armored Stagecoach Express
(406) 594-1240
8 Henry St
Clancy, MT
ADT® Home Security
(888) 542-4123
1940 C St
Butte, MT
Get a Security System for Just $99! Protect Your Home and Call ADT® Home Security Today.
Phone Hours
MON - FRI 9:00AM - 11:00PM; SAT 9:00AM - 6:00PM; SUN CLOSED

Door Alarms


Doors can utilize magnetic contact sensors to detect when a door is opened. The sensor mechanism is housed in the switch side of the sensor and a magnet is housed in the other half. Most door alarms utilize a contact switch, which has two metallic parts that must stay in contact when the sensor is armed. In order for a door to be slid or swung open, the mechanism's metallic contacts lose contact with one another. One half of the door sensor is attached to the fixed side of the doorway, and the other is attached to the movable door. When the door is opened the two parts of the mechanism are separated and the alarm signal is sent.

These mechanisms use a strong magnet that can maintain magnetic contact even when the door is opened slightly. This makes it possible to leave a door open to allow airflow between rooms, yet still have all the protection of armed door alarms.

Electromechanical door locks are powerful electrified lock mechanisms which keep them from being opened. They are an important form of security in commercial properties but can also be used in home security systems. These systems often integrate a magnetic contact sensor so if by chance the door should be opened, an alarm would be activated.

Learn more about home security systems .

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