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Employee Alarm Systems

Alarm System Purpose


The purpose of the employee alarm system is to reduce the severity of workplace accidents and injuries by ensuring that alarm systems operate properly and procedures are in place to alert employees to workplace emergencies.

OSHA Standard

OSHA's employee alarm systems standard 29 CFR 1910.165 applies to all employers who use an alarm system to satisfy any OSHA standard that requires employers to provide an early warning for emergency action, or reaction time for employees to safely escape the work place, the immediate work area, or both.

1. The purpose of the employee alarm system is to reduce the _____ of workplace accidents and injuries.

a. frequency
b. severity
c. duration
d. amount

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Alarm Device Requirements


The employee alarm system must provide warning for necessary emergency action as called for in the emergency action plan, or for reaction time for safe escape of employees from the workplace or the immediate work area, or both.

An employee alarm system can be any piece of equipment and/or device designed to inform employees an emergency exists or to signal the presence of a hazard requiring urgent attention.

National Fire Protection Association (NFPA) 72, National Fire Alarm Code, requires a fire alarm signal to be distinctive in sound from other signals and can not be used for any other purpose.

The employee alarm must be capable of being perceived above ambient noise or light levels by all employees in the affected portions of the workplace.

Tactile devices may be used to alert those employees who would not otherwise be able to recognize the audible or visual alarm.

The two most common types of alarms are audible and visual devices.

2. Which of the following devices must be used to alert employees who can not otherwise hear or see an alarm?

a. Tactile
b. Audible
c. Visual
d. Sensory

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Audible Alarms

Temporal and voice signals are the most effective means. In the United States, fire alarm evacuation signals are required to use a standardized interrupted four count temporal pattern to avoid confusion with other signals using similar sounding appliances. This pattern for smoke alarms is named the Code-3 temporal pattern (often referred to as T3) and produces an interrupted four count (three half second pulses, followed by a one and one half second pause). CO (carbon monoxide) detectors are specified to use a similar pattern using four pulses of tone (often referred to as T4)(Wikipedia).

Audible notification devices such as horns, bells, or sirens are no longer recognized for new systems by NFPA 72. The National Fire Alarm Code only recognizes temporal signals or voice signals. For visual signals, only strobe lights are now recognized by NFPA 72 and the Americans with Disabilities Act (ADA).

The following bells, horns and sirens, are only permitted in existing systems.

  • Bells: Vibrating bells are the most common signal device. Bells are commonly used in schools for fire alarms.
  • Horns; Horns produce a very loud distinctive sound that immediately attracts attention. Horns can be useful to call attention to critical situations. Signals other than those used for evacuation purposes do not have to produce the temporal coded signal.
  • Sirens: Sirens produce a loud piercing wail that makes them ideally suitable for initiating a site-wide evacuation.

Workplace Announcement System: Speakers can be used to play a live or recorded voice message. They are often ideally suited for large workplaces where phased or guided evacuations are needed.

3. Which of the following are allowed in both existing and new audible alarm systems?

a. Temporal coded signals or voice signals
b. Bells and audible warble tones
c. Horns or klaxons
d. Sirens and whistles

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Visual Alarms


Visual alarms use steady, flashing, or strobe lights to alert workers to an emergency situation in areas where noise levels are high, especially where ear protection must be worn and audible signals may not be heard or may be misunderstood. Visual signals also provide an effective way to alert workers with hearing loss about an emergency. Provide visible signals in restrooms, in other general and common use areas, and in hallways and lobbies.

Flashing/Steady Lights: These lights are well suited for areas where ambient noise makes audible signals difficult to hear. These types of lights come with different colored covers for increased attention and can be ordered with rotating or flashing lights.

Strobe Lights: Strobe lights use high intensity flash tubes that are ideally suited for areas where high ambient light levels make traditional rotating or flashing lights difficult to distinguish or where ambient noise makes audible signals difficult to hear. Strobe lights are recognized as the most effective means. Only strobe lights are now recognized by NFPA 72 and the Americans with Disabilities Act (ADA).

4. Which lights are recognized by NFPA 72 and the Americans with Disabilities Act (ADA)?

a. Steady
b. Variable
c. Strobe
d. Rotating

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Installation and Restoration


For alarm systems to provide adequate notification in the event of an emergency, all devices, components, combinations of devices or systems constructed and installed must meet OSHA requirements and be approved.

Steam whistles, air horns, strobe lights or similar lighting devices, or tactile devices meeting the requirements of the OSHA standard are considered to meet this requirement for approval.

Make sure your installed alarm systems are:

  • Capable of being heard, seen, or otherwise perceived by everyone in the workplace.
  • Distinctive and easily identified by all employees as a signal to evacuate the work area or perform actions identified in your emergency action plan, such as "shelter-in-place".
  • Supervised if they were installed after January 1, 1981 and contain circuitry that is capable of being supervised. These systems must also provide positive notification to assigned personnel whenever a deficiency exists in the system.

5. Installed alarms systems must be _____.

a. supervised if installed before January 1,1981
b. distinctive and easily identifiable by all employees
c. capable of being heard by nearby employees
d. inspected by the safety committee semi-annually

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Alarm Selection Guidelines

To get the most from an alarm system, follow these guidelines when selecting devices:

  • Make sure the alarm sound is as different from the background noise and light as possible. Audible alarms should exceed the ambient noise level by at least six decibels. The light intensity for visual alarms should be at least 75 candela.
  • Use alarms with integrated audible and visual signals to accommodate the hearing and visually impaired, and for areas where a person may be working alone. This includes areas such as restrooms, storage areas, offices, and similar areas. (These devices are available for about the same cost as an audible or visual signal alone).
  • Avoid using strobe devices that flash at rates above five flashes per second (fps). Rates above five fps can trigger seizures in people with certain forms of epilepsy. When multiple devices are used, either synchronize or reduce their flash rate so that the combined rate does not exceed five fps.

6. What action should a FPP plan administrator take when a worker is hearing or visually impaired, or working alone?

a. Use integrated audible and visual signal alarms
b. Ensure a co-worker is present
c. Prevent the worker from working alone
d. Use only tactile alarms

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Protection of Alarms

To make sure devices stay operable, follow these guidelines:

  • Alarm system components that may be exposed to corrosive environments should be either made or coated with a non-corrosive material.
  • Position alarm devices away from or out of contact with materials or equipment which may cause physical damage.
  • Alarms that are installed outdoors and need to be shielded from the weather to work properly must be protected with a canopy, hood, or other suitable device.
  • All devices should be securely mounted to a solid surface, such as screwed to a junction box with a mounting plate or other appropriate method that prevents them from putting pressure or stress on attached wires or tubing.

7. Each of the following are ways to protect alarm systems EXCEPT _____.

a. securely mount alarms to solid surface
b. coat alarms with non-corrosive material
c. posting warning signs near alarms
d. shield outside alarms from the weather

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Alarm Placement Guidelines

To ensure your alarm system provides adequate coverage, follow these guidelines when placing alarm devices:

  • Put at least one visual alarm in each room and any other general usage areas (guest restrooms, meeting rooms) which may be occupied by those with hearing impairments. You may need more than one alarm per room for those that exceed the manufacturer's spacing requirements. For example, if your alarm is rated for 50 feet, install alarms so they are evenly spaced with no more then 50 feet between devices.
  • Mount visual and audible devices 80 inches above the highest floor level within the space or six inches below the ceiling, whichever is lower.
  • Make sure manually activated devices for use in conjunction with alarms are unobstructed, conspicuous, and readily accessible.
  • Make available an emergency communications system such as a public address system, telephone, portable radio unit, or other means to notify employees of the emergency and to contact local law enforcement, the fire department, and others.

8. How many visual alarms should be located in general usage areas occupied by those with impaired hearing?

a. One
b. At least one
c. More than one
d. At least two

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Maintenance and Testing


Employee alarm systems are important life safety devices and must be maintained in an operating condition at all times except during repairs or maintenance.

Routine Test and Maintenance: Test the reliability and adequacy of non-supervised employee alarm systems every two months.

  • Use a different actuation device in each test of a multi-actuation device system.
  • Maintain or replace power supplies as often as necessary to ensure a fully operational condition.
  • Provide a back-up means of alarm when systems are out of service, such as employee runners or telephones.
  • Use properly trained persons to service, maintain, and test employee alarms.
  • Do a visual check to ensure employee alarm devices are not obstructed/installed in a manner which would prevent sound or light from reaching or entering the protected areas.
  • Restore all employee alarm systems to normal operating condition as soon as possible after each test or alarm.
  • Spare alarm devices and components must be readily available in sufficient quantities and locations for prompt restoration of the system.

9. What should be done during testing and maintenance of employee alarm systems?

a. Ensure at least one spare alarm device
b. Inform employees of maintenance
c. Disconnect power supplies
d. Provide a back-up means of alarm

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Employee Training and Education


Employees must know what types of emergencies may occur and what course of action they must take. Make sure all your employees understand the function and elements of your emergency action plan, including types of potential emergencies, reporting procedures, alarm systems, evacuation plans, and shutdown procedures. Discuss any special hazards your workplace may have such as flammable materials, toxic chemicals, radioactive sources, and/or water-reactive substances. Your training should address the following 7 subjects:

  1. Individual roles and responsibilities
  2. Threats, hazards, and protective actions
  3. Location and operation of manually activated pull stations and communication equipment
  4. Emergency response procedures
  5. Evacuation, shelter, and accountability procedures
  6. Location and use of common emergency equipment
  7. Emergency shutdown procedures

When your employees know how to sound an alarm and/or notify emergency personnel at the first sign of an emergency, it may make the difference between life and death.

10. Each of the following topics need to be discussed during emergency action plan training EXCEPT _____.

a. emergency response procedures
b. the location of emergency equipment
c. individual roles and responsibilities
d. employee personal information

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